1	// Components for manipulating sequences of characters -*- C++ -*-
2
3	// Copyright (C) 1997-2021 Free Software Foundation, Inc.
4	//
5	// This file is part of the GNU ISO C++ Library. This library is free
6	// software; you can redistribute it and/or modify it under the
7	// terms of the GNU General Public License as published by the
8	// Free Software Foundation; either version 3, or (at your option)
9	// any later version.
10
11	// This library is distributed in the hope that it will be useful,
12	// but WITHOUT ANY WARRANTY; without even the implied warranty of
13	// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	// GNU General Public License for more details.
15
16	// Under Section 7 of GPL version 3, you are granted additional
17	// permissions described in the GCC Runtime Library Exception, version
18	// 3.1, as published by the Free Software Foundation.
19
20	// You should have received a copy of the GNU General Public License and
21	// a copy of the GCC Runtime Library Exception along with this program;
22	// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23	// <http://www.gnu.org/licenses/>.
24
25	/** @file bits/basic_string.h
26	* This is an internal header file, included by other library headers.
27	* Do not attempt to use it directly. @headername{string}
28	*/
29
30	//
31	// ISO C++ 14882: 21 Strings library
32	//
33
34	#ifndef _BASIC_STRING_H
35	#define _BASIC_STRING_H 1
36
37	#pragma GCC system_header
38
39	#include <ext/atomicity.h>
40	#include <ext/alloc_traits.h>
41	#include <debug/debug.h>
42
43	#if __cplusplus >= 201103L
44	#include <initializer_list>
45	#endif
46
47	#if __cplusplus >= 201703L
48	# include <string_view>
49	#endif
50
51	namespace std _GLIBCXX_VISIBILITY(default)
52	{
53	_GLIBCXX_BEGIN_NAMESPACE_VERSION
54
55	#ifdef __cpp_lib_is_constant_evaluated
56	// Support P1032R1 in C++20 (but not P0980R1 yet).
57	# define __cpp_lib_constexpr_string 201811L
58	#elif __cplusplus >= 201703L
59	// Support P0426R1 changes to char_traits in C++17.
60	# define __cpp_lib_constexpr_string 201611L
61	#elif __cplusplus > 201703L
62	#endif
63
64	#if _GLIBCXX_USE_CXX11_ABI
65	_GLIBCXX_BEGIN_NAMESPACE_CXX11
66	/**
67	* @class basic_string basic_string.h <string>
68	* @brief Managing sequences of characters and character-like objects.
69	*
70	* @ingroup strings
71	* @ingroup sequences
72	*
73	* @tparam _CharT Type of character
74	* @tparam _Traits Traits for character type, defaults to
75	* char_traits<_CharT>.
76	* @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
77	*
78	* Meets the requirements of a <a href="tables.html#65">container</a>, a
79	* <a href="tables.html#66">reversible container</a>, and a
80	* <a href="tables.html#67">sequence</a>. Of the
81	* <a href="tables.html#68">optional sequence requirements</a>, only
82	* @c push_back, @c at, and @c %array access are supported.
83	*/
84	template<typename _CharT, typename _Traits, typename _Alloc>
85	class basic_string
86	{
87	typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
88	rebind<_CharT>::other _Char_alloc_type;
89	typedef __gnu_cxx::__alloc_traits<_Char_alloc_type> _Alloc_traits;
90
91	// Types:
92	public:
93	typedef _Traits traits_type;
94	typedef typename _Traits::char_type value_type;
95	typedef _Char_alloc_type allocator_type;
96	typedef typename _Alloc_traits::size_type size_type;
97	typedef typename _Alloc_traits::difference_type difference_type;
98	typedef typename _Alloc_traits::reference reference;
99	typedef typename _Alloc_traits::const_reference const_reference;
100	typedef typename _Alloc_traits::pointer pointer;
101	typedef typename _Alloc_traits::const_pointer const_pointer;
102	typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
103	typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
104	const_iterator;
105	typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
106	typedef std::reverse_iterator<iterator> reverse_iterator;
107
108	/// Value returned by various member functions when they fail.
109	static const size_type npos = static_cast<size_type>(-1);
110
111	protected:
112	// type used for positions in insert, erase etc.
113	#if __cplusplus < 201103L
114	typedef iterator __const_iterator;
115	#else
116	typedef const_iterator __const_iterator;
117	#endif
118
119	private:
120	#if __cplusplus >= 201703L
121	// A helper type for avoiding boiler-plate.
122	typedef basic_string_view<_CharT, _Traits> __sv_type;
123
124	template<typename _Tp, typename _Res>
125	using _If_sv = enable_if_t<
126	__and_<is_convertible<const _Tp&, __sv_type>,
127	__not_<is_convertible<const _Tp*, const basic_string*>>,
128	__not_<is_convertible<const _Tp&, const _CharT*>>>::value,
129	_Res>;
130
131	// Allows an implicit conversion to __sv_type.
132	static __sv_type
133	_S_to_string_view(__sv_type __svt) noexcept
134	{ return __svt; }
135
136	// Wraps a string_view by explicit conversion and thus
137	// allows to add an internal constructor that does not
138	// participate in overload resolution when a string_view
139	// is provided.
140	struct __sv_wrapper
141	{
142	explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
143	__sv_type _M_sv;
144	};
145
146	/**
147	* @brief Only internally used: Construct string from a string view
148	* wrapper.
149	* @param __svw string view wrapper.
150	* @param __a Allocator to use.
151	*/
152	explicit
153	basic_string(__sv_wrapper __svw, const _Alloc& __a)
154	: basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
155	#endif
156
157	// Use empty-base optimization: http://www.cantrip.org/emptyopt.html
158	struct _Alloc_hider : allocator_type // TODO check __is_final
159	{
160	#if __cplusplus < 201103L
161	_Alloc_hider(pointer __dat, const _Alloc& __a = _Alloc())
162	: allocator_type(__a), _M_p(__dat) { }
163	#else
164	_Alloc_hider(pointer __dat, const _Alloc& __a)
165	: allocator_type(__a), _M_p(__dat) { }
166
167	_Alloc_hider(pointer __dat, _Alloc&& __a = _Alloc())
168	: allocator_type(std::move(__a)), _M_p(__dat) { }
169	#endif
170
171	pointer _M_p; // The actual data.
172	};
173
174	_Alloc_hider _M_dataplus;
175	size_type _M_string_length;
176
177	enum { _S_local_capacity = 15 / sizeof(_CharT) };
178
179	union
180	{
181	_CharT _M_local_buf[_S_local_capacity + 1];
182	size_type _M_allocated_capacity;
183	};
184
185	void
186	_M_data(pointer __p)
187	{ _M_dataplus._M_p = __p; }
188
189	void
190	_M_length(size_type __length)
191	{ _M_string_length = __length; }
192
193	pointer
194	_M_data() const
195	{ return _M_dataplus._M_p; }
196
197	pointer
198	_M_local_data()
199	{
200	#if __cplusplus >= 201103L
201	return std::pointer_traits<pointer>::pointer_to(*_M_local_buf);
202	#else
203	return pointer(_M_local_buf);
204	#endif
205	}
206
207	const_pointer
208	_M_local_data() const
209	{
210	#if __cplusplus >= 201103L
211	return std::pointer_traits<const_pointer>::pointer_to(*_M_local_buf);
212	#else
213	return const_pointer(_M_local_buf);
214	#endif
215	}
216
217	void
218	_M_capacity(size_type __capacity)
219	{ _M_allocated_capacity = __capacity; }
220
221	void
222	_M_set_length(size_type __n)
223	{
224	_M_length(length: __n);
225	traits_type::assign(_M_data()[__n], _CharT());
226	}
227
228	bool
229	_M_is_local() const
230	{ return _M_data() == _M_local_data(); }
231
232	// Create & Destroy
233	pointer
234	_M_create(size_type&, size_type);
235
236	void
237	_M_dispose()
238	{
239	if (!_M_is_local())
240	_M_destroy(size: _M_allocated_capacity);
241	}
242
243	void
244	_M_destroy(size_type __size) throw()
245	{ _Alloc_traits::deallocate(_M_get_allocator(), _M_data(), __size + 1); }
246
247	// _M_construct_aux is used to implement the 21.3.1 para 15 which
248	// requires special behaviour if _InIterator is an integral type
249	template<typename _InIterator>
250	void
251	_M_construct_aux(_InIterator __beg, _InIterator __end,
252	std::__false_type)
253	{
254	typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
255	_M_construct(__beg, __end, _Tag());
256	}
257
258	// _GLIBCXX_RESOLVE_LIB_DEFECTS
259	// 438. Ambiguity in the "do the right thing" clause
260	template<typename _Integer>
261	void
262	_M_construct_aux(_Integer __beg, _Integer __end, std::__true_type)
263	{ _M_construct_aux_2(req: static_cast<size_type>(__beg), c: __end); }
264
265	void
266	_M_construct_aux_2(size_type __req, _CharT __c)
267	{ _M_construct(__req, __c); }
268
269	template<typename _InIterator>
270	void
271	_M_construct(_InIterator __beg, _InIterator __end)
272	{
273	typedef typename std::__is_integer<_InIterator>::__type _Integral;
274	_M_construct_aux(__beg, __end, _Integral());
275	}
276
277	// For Input Iterators, used in istreambuf_iterators, etc.
278	template<typename _InIterator>
279	void
280	_M_construct(_InIterator __beg, _InIterator __end,
281	std::input_iterator_tag);
282
283	// For forward_iterators up to random_access_iterators, used for
284	// string::iterator, _CharT*, etc.
285	template<typename _FwdIterator>
286	void
287	_M_construct(_FwdIterator __beg, _FwdIterator __end,
288	std::forward_iterator_tag);
289
290	void
291	_M_construct(size_type __req, _CharT __c);
292
293	allocator_type&
294	_M_get_allocator()
295	{ return _M_dataplus; }
296
297	const allocator_type&
298	_M_get_allocator() const
299	{ return _M_dataplus; }
300
301	private:
302
303	#ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
304	// The explicit instantiations in misc-inst.cc require this due to
305	// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64063
306	template<typename _Tp, bool _Requires =
307	!__are_same<_Tp, _CharT*>::__value
308	&& !__are_same<_Tp, const _CharT*>::__value
309	&& !__are_same<_Tp, iterator>::__value
310	&& !__are_same<_Tp, const_iterator>::__value>
311	struct __enable_if_not_native_iterator
312	{ typedef basic_string& __type; };
313	template<typename _Tp>
314	struct __enable_if_not_native_iterator<_Tp, false> { };
315	#endif
316
317	size_type
318	_M_check(size_type __pos, const char* __s) const
319	{
320	if (__pos > this->size())
321	__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
322	"this->size() (which is %zu)"),
323	__s, __pos, this->size());
324	return __pos;
325	}
326
327	void
328	_M_check_length(size_type __n1, size_type __n2, const char* __s) const
329	{
330	if (this->max_size() - (this->size() - __n1) < __n2)
331	__throw_length_error(__N(__s));
332	}
333
334
335	// NB: _M_limit doesn't check for a bad __pos value.
336	size_type
337	_M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
338	{
339	const bool __testoff = __off < this->size() - __pos;
340	return __testoff ? __off : this->size() - __pos;
341	}
342
343	// True if _Rep and source do not overlap.
344	bool
345	_M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
346	{
347	return (less<const _CharT*>()(__s, _M_data())
348	|| less<const _CharT*>()(_M_data() + this->size(), __s));
349	}
350
351	// When __n = 1 way faster than the general multichar
352	// traits_type::copy/move/assign.
353	static void
354	_S_copy(_CharT* __d, const _CharT* __s, size_type __n)
355	{
356	if (__n == 1)
357	traits_type::assign(*__d, *__s);
358	else
359	traits_type::copy(__d, __s, __n);
360	}
361
362	static void
363	_S_move(_CharT* __d, const _CharT* __s, size_type __n)
364	{
365	if (__n == 1)
366	traits_type::assign(*__d, *__s);
367	else
368	traits_type::move(__d, __s, __n);
369	}
370
371	static void
372	_S_assign(_CharT* __d, size_type __n, _CharT __c)
373	{
374	if (__n == 1)
375	traits_type::assign(*__d, __c);
376	else
377	traits_type::assign(__d, __n, __c);
378	}
379
380	// _S_copy_chars is a separate template to permit specialization
381	// to optimize for the common case of pointers as iterators.
382	template<class _Iterator>
383	static void
384	_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
385	{
386	for (; __k1 != __k2; ++__k1, (void)++__p)
387	traits_type::assign(*__p, *__k1); // These types are off.
388	}
389
390	static void
391	_S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
392	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
393
394	static void
395	_S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
396	_GLIBCXX_NOEXCEPT
397	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
398
399	static void
400	_S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
401	{ _S_copy(d: __p, s: __k1, n: __k2 - __k1); }
402
403	static void
404	_S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
405	_GLIBCXX_NOEXCEPT
406	{ _S_copy(d: __p, s: __k1, n: __k2 - __k1); }
407
408	static int
409	_S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
410	{
411	const difference_type __d = difference_type(__n1 - __n2);
412
413	if (__d > __gnu_cxx::__numeric_traits<int>::__max)
414	return __gnu_cxx::__numeric_traits<int>::__max;
415	else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
416	return __gnu_cxx::__numeric_traits<int>::__min;
417	else
418	return int(__d);
419	}
420
421	void
422	_M_assign(const basic_string&);
423
424	void
425	_M_mutate(size_type __pos, size_type __len1, const _CharT* __s,
426	size_type __len2);
427
428	void
429	_M_erase(size_type __pos, size_type __n);
430
431	public:
432	// Construct/copy/destroy:
433	// NB: We overload ctors in some cases instead of using default
434	// arguments, per 17.4.4.4 para. 2 item 2.
435
436	/**
437	* @brief Default constructor creates an empty string.
438	*/
439	basic_string()
440	_GLIBCXX_NOEXCEPT_IF(is_nothrow_default_constructible<_Alloc>::value)
441	: _M_dataplus(_M_local_data())
442	{ _M_set_length(n: 0); }
443
444	/**
445	* @brief Construct an empty string using allocator @a a.
446	*/
447	explicit
448	basic_string(const _Alloc& __a) _GLIBCXX_NOEXCEPT
449	: _M_dataplus(_M_local_data(), __a)
450	{ _M_set_length(n: 0); }
451
452	/**
453	* @brief Construct string with copy of value of @a __str.
454	* @param __str Source string.
455	*/
456	basic_string(const basic_string& __str)
457	: _M_dataplus(_M_local_data(),
458	_Alloc_traits::_S_select_on_copy(__str._M_get_allocator()))
459	{ _M_construct(__str._M_data(), __str._M_data() + __str.length()); }
460
461	// _GLIBCXX_RESOLVE_LIB_DEFECTS
462	// 2583. no way to supply an allocator for basic_string(str, pos)
463	/**
464	* @brief Construct string as copy of a substring.
465	* @param __str Source string.
466	* @param __pos Index of first character to copy from.
467	* @param __a Allocator to use.
468	*/
469	basic_string(const basic_string& __str, size_type __pos,
470	const _Alloc& __a = _Alloc())
471	: _M_dataplus(_M_local_data(), __a)
472	{
473	const _CharT* __start = __str._M_data()
474	+ __str._M_check(__pos, "basic_string::basic_string");
475	_M_construct(__start, __start + __str._M_limit(__pos, npos));
476	}
477
478	/**
479	* @brief Construct string as copy of a substring.
480	* @param __str Source string.
481	* @param __pos Index of first character to copy from.
482	* @param __n Number of characters to copy.
483	*/
484	basic_string(const basic_string& __str, size_type __pos,
485	size_type __n)
486	: _M_dataplus(_M_local_data())
487	{
488	const _CharT* __start = __str._M_data()
489	+ __str._M_check(__pos, "basic_string::basic_string");
490	_M_construct(__start, __start + __str._M_limit(__pos, __n));
491	}
492
493	/**
494	* @brief Construct string as copy of a substring.
495	* @param __str Source string.
496	* @param __pos Index of first character to copy from.
497	* @param __n Number of characters to copy.
498	* @param __a Allocator to use.
499	*/
500	basic_string(const basic_string& __str, size_type __pos,
501	size_type __n, const _Alloc& __a)
502	: _M_dataplus(_M_local_data(), __a)
503	{
504	const _CharT* __start
505	= __str._M_data() + __str._M_check(__pos, "string::string");
506	_M_construct(__start, __start + __str._M_limit(__pos, __n));
507	}
508
509	/**
510	* @brief Construct string initialized by a character %array.
511	* @param __s Source character %array.
512	* @param __n Number of characters to copy.
513	* @param __a Allocator to use (default is default allocator).
514	*
515	* NB: @a __s must have at least @a __n characters, &apos;\\0&apos;
516	* has no special meaning.
517	*/
518	basic_string(const _CharT* __s, size_type __n,
519	const _Alloc& __a = _Alloc())
520	: _M_dataplus(_M_local_data(), __a)
521	{ _M_construct(__s, __s + __n); }
522
523	/**
524	* @brief Construct string as copy of a C string.
525	* @param __s Source C string.
526	* @param __a Allocator to use (default is default allocator).
527	*/
528	#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
529	// _GLIBCXX_RESOLVE_LIB_DEFECTS
530	// 3076. basic_string CTAD ambiguity
531	template<typename = _RequireAllocator<_Alloc>>
532	#endif
533	basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
534	: _M_dataplus(_M_local_data(), __a)
535	{
536	const _CharT* __end = __s ? __s + traits_type::length(__s)
537	// We just need a non-null pointer here to get an exception:
538	: reinterpret_cast<const _CharT*>(__alignof__(_CharT));
539	_M_construct(__s, __end, random_access_iterator_tag());
540	}
541
542	/**
543	* @brief Construct string as multiple characters.
544	* @param __n Number of characters.
545	* @param __c Character to use.
546	* @param __a Allocator to use (default is default allocator).
547	*/
548	#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
549	// _GLIBCXX_RESOLVE_LIB_DEFECTS
550	// 3076. basic_string CTAD ambiguity
551	template<typename = _RequireAllocator<_Alloc>>
552	#endif
553	basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc())
554	: _M_dataplus(_M_local_data(), __a)
555	{ _M_construct(__n, __c); }
556
557	#if __cplusplus >= 201103L
558	/**
559	* @brief Move construct string.
560	* @param __str Source string.
561	*
562	* The newly-created string contains the exact contents of @a __str.
563	* @a __str is a valid, but unspecified string.
564	*/
565	basic_string(basic_string&& __str) noexcept
566	: _M_dataplus(_M_local_data(), std::move(__str._M_get_allocator()))
567	{
568	if (__str._M_is_local())
569	{
570	traits_type::copy(_M_local_buf, __str._M_local_buf,
571	_S_local_capacity + 1);
572	}
573	else
574	{
575	_M_data(__str._M_data());
576	_M_capacity(capacity: __str._M_allocated_capacity);
577	}
578
579	// Must use _M_length() here not _M_set_length() because
580	// basic_stringbuf relies on writing into unallocated capacity so
581	// we mess up the contents if we put a '\0' in the string.
582	_M_length(length: __str.length());
583	__str._M_data(__str._M_local_data());
584	__str._M_set_length(0);
585	}
586
587	/**
588	* @brief Construct string from an initializer %list.
589	* @param __l std::initializer_list of characters.
590	* @param __a Allocator to use (default is default allocator).
591	*/
592	basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
593	: _M_dataplus(_M_local_data(), __a)
594	{ _M_construct(__l.begin(), __l.end()); }
595
596	basic_string(const basic_string& __str, const _Alloc& __a)
597	: _M_dataplus(_M_local_data(), __a)
598	{ _M_construct(__str.begin(), __str.end()); }
599
600	basic_string(basic_string&& __str, const _Alloc& __a)
601	noexcept(_Alloc_traits::_S_always_equal())
602	: _M_dataplus(_M_local_data(), __a)
603	{
604	if (__str._M_is_local())
605	{
606	traits_type::copy(_M_local_buf, __str._M_local_buf,
607	_S_local_capacity + 1);
608	_M_length(length: __str.length());
609	__str._M_set_length(0);
610	}
611	else if (_Alloc_traits::_S_always_equal()
612	|| __str.get_allocator() == __a)
613	{
614	_M_data(__str._M_data());
615	_M_length(length: __str.length());
616	_M_capacity(capacity: __str._M_allocated_capacity);
617	__str._M_data(__str._M_local_buf);
618	__str._M_set_length(0);
619	}
620	else
621	_M_construct(__str.begin(), __str.end());
622	}
623
624	#endif // C++11
625
626	/**
627	* @brief Construct string as copy of a range.
628	* @param __beg Start of range.
629	* @param __end End of range.
630	* @param __a Allocator to use (default is default allocator).
631	*/
632	#if __cplusplus >= 201103L
633	template<typename _InputIterator,
634	typename = std::_RequireInputIter<_InputIterator>>
635	#else
636	template<typename _InputIterator>
637	#endif
638	basic_string(_InputIterator __beg, _InputIterator __end,
639	const _Alloc& __a = _Alloc())
640	: _M_dataplus(_M_local_data(), __a)
641	{ _M_construct(__beg, __end); }
642
643	#if __cplusplus >= 201703L
644	/**
645	* @brief Construct string from a substring of a string_view.
646	* @param __t Source object convertible to string view.
647	* @param __pos The index of the first character to copy from __t.
648	* @param __n The number of characters to copy from __t.
649	* @param __a Allocator to use.
650	*/
651	template<typename _Tp,
652	typename = enable_if_t<is_convertible_v<const _Tp&, __sv_type>>>
653	basic_string(const _Tp& __t, size_type __pos, size_type __n,
654	const _Alloc& __a = _Alloc())
655	: basic_string(_S_to_string_view(svt: __t).substr(__pos, __n), __a) { }
656
657	/**
658	* @brief Construct string from a string_view.
659	* @param __t Source object convertible to string view.
660	* @param __a Allocator to use (default is default allocator).
661	*/
662	template<typename _Tp, typename = _If_sv<_Tp, void>>
663	explicit
664	basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
665	: basic_string(__sv_wrapper(_S_to_string_view(svt: __t)), __a) { }
666	#endif // C++17
667
668	/**
669	* @brief Destroy the string instance.
670	*/
671	~basic_string()
672	{ _M_dispose(); }
673
674	/**
675	* @brief Assign the value of @a str to this string.
676	* @param __str Source string.
677	*/
678	basic_string&
679	operator=(const basic_string& __str)
680	{
681	return this->assign(__str);
682	}
683
684	/**
685	* @brief Copy contents of @a s into this string.
686	* @param __s Source null-terminated string.
687	*/
688	basic_string&
689	operator=(const _CharT* __s)
690	{ return this->assign(__s); }
691
692	/**
693	* @brief Set value to string of length 1.
694	* @param __c Source character.
695	*
696	* Assigning to a character makes this string length 1 and
697	* (*this)[0] == @a c.
698	*/
699	basic_string&
700	operator=(_CharT __c)
701	{
702	this->assign(1, __c);
703	return *this;
704	}
705
706	#if __cplusplus >= 201103L
707	/**
708	* @brief Move assign the value of @a str to this string.
709	* @param __str Source string.
710	*
711	* The contents of @a str are moved into this string (without copying).
712	* @a str is a valid, but unspecified string.
713	*/
714	// _GLIBCXX_RESOLVE_LIB_DEFECTS
715	// 2063. Contradictory requirements for string move assignment
716	basic_string&
717	operator=(basic_string&& __str)
718	noexcept(_Alloc_traits::_S_nothrow_move())
719	{
720	if (!_M_is_local() && _Alloc_traits::_S_propagate_on_move_assign()
721	&& !_Alloc_traits::_S_always_equal()
722	&& _M_get_allocator() != __str._M_get_allocator())
723	{
724	// Destroy existing storage before replacing allocator.
725	_M_destroy(size: _M_allocated_capacity);
726	_M_data(_M_local_data());
727	_M_set_length(n: 0);
728	}
729	// Replace allocator if POCMA is true.
730	std::__alloc_on_move(_M_get_allocator(), __str._M_get_allocator());
731
732	if (__str._M_is_local())
733	{
734	// We've always got room for a short string, just copy it
735	// (unless this is a self-move, because that would violate the
736	// char_traits::copy precondition that the ranges don't overlap).
737	if (__builtin_expect(std::__addressof(__str) != this, true))
738	{
739	if (__str.size())
740	this->_S_copy(_M_data(), __str._M_data(), __str.size());
741	_M_set_length(n: __str.size());
742	}
743	}
744	else if (_Alloc_traits::_S_propagate_on_move_assign()
745	|| _Alloc_traits::_S_always_equal()
746	|| _M_get_allocator() == __str._M_get_allocator())
747	{
748	// Just move the allocated pointer, our allocator can free it.
749	pointer __data = nullptr;
750	size_type __capacity;
751	if (!_M_is_local())
752	{
753	if (_Alloc_traits::_S_always_equal())
754	{
755	// __str can reuse our existing storage.
756	__data = _M_data();
757	__capacity = _M_allocated_capacity;
758	}
759	else // __str can't use it, so free it.
760	_M_destroy(size: _M_allocated_capacity);
761	}
762
763	_M_data(__str._M_data());
764	_M_length(length: __str.length());
765	_M_capacity(capacity: __str._M_allocated_capacity);
766	if (__data)
767	{
768	__str._M_data(__data);
769	__str._M_capacity(__capacity);
770	}
771	else
772	__str._M_data(__str._M_local_buf);
773	}
774	else // Need to do a deep copy
775	assign(__str);
776	__str.clear();
777	return *this;
778	}
779
780	/**
781	* @brief Set value to string constructed from initializer %list.
782	* @param __l std::initializer_list.
783	*/
784	basic_string&
785	operator=(initializer_list<_CharT> __l)
786	{
787	this->assign(__l.begin(), __l.size());
788	return *this;
789	}
790	#endif // C++11
791
792	#if __cplusplus >= 201703L
793	/**
794	* @brief Set value to string constructed from a string_view.
795	* @param __svt An object convertible to string_view.
796	*/
797	template<typename _Tp>
798	_If_sv<_Tp, basic_string&>
799	operator=(const _Tp& __svt)
800	{ return this->assign(__svt); }
801
802	/**
803	* @brief Convert to a string_view.
804	* @return A string_view.
805	*/
806	operator __sv_type() const noexcept
807	{ return __sv_type(data(), size()); }
808	#endif // C++17
809
810	// Iterators:
811	/**
812	* Returns a read/write iterator that points to the first character in
813	* the %string.
814	*/
815	iterator
816	begin() _GLIBCXX_NOEXCEPT
817	{ return iterator(_M_data()); }
818
819	/**
820	* Returns a read-only (constant) iterator that points to the first
821	* character in the %string.
822	*/
823	const_iterator
824	begin() const _GLIBCXX_NOEXCEPT
825	{ return const_iterator(_M_data()); }
826
827	/**
828	* Returns a read/write iterator that points one past the last
829	* character in the %string.
830	*/
831	iterator
832	end() _GLIBCXX_NOEXCEPT
833	{ return iterator(_M_data() + this->size()); }
834
835	/**
836	* Returns a read-only (constant) iterator that points one past the
837	* last character in the %string.
838	*/
839	const_iterator
840	end() const _GLIBCXX_NOEXCEPT
841	{ return const_iterator(_M_data() + this->size()); }
842
843	/**
844	* Returns a read/write reverse iterator that points to the last
845	* character in the %string. Iteration is done in reverse element
846	* order.
847	*/
848	reverse_iterator
849	rbegin() _GLIBCXX_NOEXCEPT
850	{ return reverse_iterator(this->end()); }
851
852	/**
853	* Returns a read-only (constant) reverse iterator that points
854	* to the last character in the %string. Iteration is done in
855	* reverse element order.
856	*/
857	const_reverse_iterator
858	rbegin() const _GLIBCXX_NOEXCEPT
859	{ return const_reverse_iterator(this->end()); }
860
861	/**
862	* Returns a read/write reverse iterator that points to one before the
863	* first character in the %string. Iteration is done in reverse
864	* element order.
865	*/
866	reverse_iterator
867	rend() _GLIBCXX_NOEXCEPT
868	{ return reverse_iterator(this->begin()); }
869
870	/**
871	* Returns a read-only (constant) reverse iterator that points
872	* to one before the first character in the %string. Iteration
873	* is done in reverse element order.
874	*/
875	const_reverse_iterator
876	rend() const _GLIBCXX_NOEXCEPT
877	{ return const_reverse_iterator(this->begin()); }
878
879	#if __cplusplus >= 201103L
880	/**
881	* Returns a read-only (constant) iterator that points to the first
882	* character in the %string.
883	*/
884	const_iterator
885	cbegin() const noexcept
886	{ return const_iterator(this->_M_data()); }
887
888	/**
889	* Returns a read-only (constant) iterator that points one past the
890	* last character in the %string.
891	*/
892	const_iterator
893	cend() const noexcept
894	{ return const_iterator(this->_M_data() + this->size()); }
895
896	/**
897	* Returns a read-only (constant) reverse iterator that points
898	* to the last character in the %string. Iteration is done in
899	* reverse element order.
900	*/
901	const_reverse_iterator
902	crbegin() const noexcept
903	{ return const_reverse_iterator(this->end()); }
904
905	/**
906	* Returns a read-only (constant) reverse iterator that points
907	* to one before the first character in the %string. Iteration
908	* is done in reverse element order.
909	*/
910	const_reverse_iterator
911	crend() const noexcept
912	{ return const_reverse_iterator(this->begin()); }
913	#endif
914
915	public:
916	// Capacity:
917	/// Returns the number of characters in the string, not including any
918	/// null-termination.
919	size_type
920	size() const _GLIBCXX_NOEXCEPT
921	{ return _M_string_length; }
922
923	/// Returns the number of characters in the string, not including any
924	/// null-termination.
925	size_type
926	length() const _GLIBCXX_NOEXCEPT
927	{ return _M_string_length; }
928
929	/// Returns the size() of the largest possible %string.
930	size_type
931	max_size() const _GLIBCXX_NOEXCEPT
932	{ return (_Alloc_traits::max_size(_M_get_allocator()) - 1) / 2; }
933
934	/**
935	* @brief Resizes the %string to the specified number of characters.
936	* @param __n Number of characters the %string should contain.
937	* @param __c Character to fill any new elements.
938	*
939	* This function will %resize the %string to the specified
940	* number of characters. If the number is smaller than the
941	* %string's current size the %string is truncated, otherwise
942	* the %string is extended and new elements are %set to @a __c.
943	*/
944	void
945	resize(size_type __n, _CharT __c);
946
947	/**
948	* @brief Resizes the %string to the specified number of characters.
949	* @param __n Number of characters the %string should contain.
950	*
951	* This function will resize the %string to the specified length. If
952	* the new size is smaller than the %string's current size the %string
953	* is truncated, otherwise the %string is extended and new characters
954	* are default-constructed. For basic types such as char, this means
955	* setting them to 0.
956	*/
957	void
958	resize(size_type __n)
959	{ this->resize(__n, _CharT()); }
960
961	#if __cplusplus >= 201103L
962	#pragma GCC diagnostic push
963	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
964	/// A non-binding request to reduce capacity() to size().
965	void
966	shrink_to_fit() noexcept
967	{ reserve(); }
968	#pragma GCC diagnostic pop
969	#endif
970
971	/**
972	* Returns the total number of characters that the %string can hold
973	* before needing to allocate more memory.
974	*/
975	size_type
976	capacity() const _GLIBCXX_NOEXCEPT
977	{
978	return _M_is_local() ? size_type(_S_local_capacity)
979	: _M_allocated_capacity;
980	}
981
982	/**
983	* @brief Attempt to preallocate enough memory for specified number of
984	* characters.
985	* @param __res_arg Number of characters required.
986	* @throw std::length_error If @a __res_arg exceeds @c max_size().
987	*
988	* This function attempts to reserve enough memory for the
989	* %string to hold the specified number of characters. If the
990	* number requested is more than max_size(), length_error is
991	* thrown.
992	*
993	* The advantage of this function is that if optimal code is a
994	* necessity and the user can determine the string length that will be
995	* required, the user can reserve the memory in %advance, and thus
996	* prevent a possible reallocation of memory and copying of %string
997	* data.
998	*/
999	void
1000	reserve(size_type __res_arg);
1001
1002	/**
1003	* Equivalent to shrink_to_fit().
1004	*/
1005	#if __cplusplus > 201703L
1006	[[deprecated("use shrink_to_fit() instead")]]
1007	#endif
1008	void
1009	reserve();
1010
1011	/**
1012	* Erases the string, making it empty.
1013	*/
1014	void
1015	clear() _GLIBCXX_NOEXCEPT
1016	{ _M_set_length(n: 0); }
1017
1018	/**
1019	* Returns true if the %string is empty. Equivalent to
1020	* <code>*this == ""</code>.
1021	*/
1022	_GLIBCXX_NODISCARD bool
1023	empty() const _GLIBCXX_NOEXCEPT
1024	{ return this->size() == 0; }
1025
1026	// Element access:
1027	/**
1028	* @brief Subscript access to the data contained in the %string.
1029	* @param __pos The index of the character to access.
1030	* @return Read-only (constant) reference to the character.
1031	*
1032	* This operator allows for easy, array-style, data access.
1033	* Note that data access with this operator is unchecked and
1034	* out_of_range lookups are not defined. (For checked lookups
1035	* see at().)
1036	*/
1037	const_reference
1038	operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
1039	{
1040	__glibcxx_assert(__pos <= size());
1041	return _M_data()[__pos];
1042	}
1043
1044	/**
1045	* @brief Subscript access to the data contained in the %string.
1046	* @param __pos The index of the character to access.
1047	* @return Read/write reference to the character.
1048	*
1049	* This operator allows for easy, array-style, data access.
1050	* Note that data access with this operator is unchecked and
1051	* out_of_range lookups are not defined. (For checked lookups
1052	* see at().)
1053	*/
1054	reference
1055	operator[](size_type __pos)
1056	{
1057	// Allow pos == size() both in C++98 mode, as v3 extension,
1058	// and in C++11 mode.
1059	__glibcxx_assert(__pos <= size());
1060	// In pedantic mode be strict in C++98 mode.
1061	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L || __pos < size());
1062	return _M_data()[__pos];
1063	}
1064
1065	/**
1066	* @brief Provides access to the data contained in the %string.
1067	* @param __n The index of the character to access.
1068	* @return Read-only (const) reference to the character.
1069	* @throw std::out_of_range If @a n is an invalid index.
1070	*
1071	* This function provides for safer data access. The parameter is
1072	* first checked that it is in the range of the string. The function
1073	* throws out_of_range if the check fails.
1074	*/
1075	const_reference
1076	at(size_type __n) const
1077	{
1078	if (__n >= this->size())
1079	__throw_out_of_range_fmt(__N("basic_string::at: __n "
1080	"(which is %zu) >= this->size() "
1081	"(which is %zu)"),
1082	__n, this->size());
1083	return _M_data()[__n];
1084	}
1085
1086	/**
1087	* @brief Provides access to the data contained in the %string.
1088	* @param __n The index of the character to access.
1089	* @return Read/write reference to the character.
1090	* @throw std::out_of_range If @a n is an invalid index.
1091	*
1092	* This function provides for safer data access. The parameter is
1093	* first checked that it is in the range of the string. The function
1094	* throws out_of_range if the check fails.
1095	*/
1096	reference
1097	at(size_type __n)
1098	{
1099	if (__n >= size())
1100	__throw_out_of_range_fmt(__N("basic_string::at: __n "
1101	"(which is %zu) >= this->size() "
1102	"(which is %zu)"),
1103	__n, this->size());
1104	return _M_data()[__n];
1105	}
1106
1107	#if __cplusplus >= 201103L
1108	/**
1109	* Returns a read/write reference to the data at the first
1110	* element of the %string.
1111	*/
1112	reference
1113	front() noexcept
1114	{
1115	__glibcxx_assert(!empty());
1116	return operator[](0);
1117	}
1118
1119	/**
1120	* Returns a read-only (constant) reference to the data at the first
1121	* element of the %string.
1122	*/
1123	const_reference
1124	front() const noexcept
1125	{
1126	__glibcxx_assert(!empty());
1127	return operator[](0);
1128	}
1129
1130	/**
1131	* Returns a read/write reference to the data at the last
1132	* element of the %string.
1133	*/
1134	reference
1135	back() noexcept
1136	{
1137	__glibcxx_assert(!empty());
1138	return operator[](this->size() - 1);
1139	}
1140
1141	/**
1142	* Returns a read-only (constant) reference to the data at the
1143	* last element of the %string.
1144	*/
1145	const_reference
1146	back() const noexcept
1147	{
1148	__glibcxx_assert(!empty());
1149	return operator[](this->size() - 1);
1150	}
1151	#endif
1152
1153	// Modifiers:
1154	/**
1155	* @brief Append a string to this string.
1156	* @param __str The string to append.
1157	* @return Reference to this string.
1158	*/
1159	basic_string&
1160	operator+=(const basic_string& __str)
1161	{ return this->append(__str); }
1162
1163	/**
1164	* @brief Append a C string.
1165	* @param __s The C string to append.
1166	* @return Reference to this string.
1167	*/
1168	basic_string&
1169	operator+=(const _CharT* __s)
1170	{ return this->append(__s); }
1171
1172	/**
1173	* @brief Append a character.
1174	* @param __c The character to append.
1175	* @return Reference to this string.
1176	*/
1177	basic_string&
1178	operator+=(_CharT __c)
1179	{
1180	this->push_back(__c);
1181	return *this;
1182	}
1183
1184	#if __cplusplus >= 201103L
1185	/**
1186	* @brief Append an initializer_list of characters.
1187	* @param __l The initializer_list of characters to be appended.
1188	* @return Reference to this string.
1189	*/
1190	basic_string&
1191	operator+=(initializer_list<_CharT> __l)
1192	{ return this->append(__l.begin(), __l.size()); }
1193	#endif // C++11
1194
1195	#if __cplusplus >= 201703L
1196	/**
1197	* @brief Append a string_view.
1198	* @param __svt An object convertible to string_view to be appended.
1199	* @return Reference to this string.
1200	*/
1201	template<typename _Tp>
1202	_If_sv<_Tp, basic_string&>
1203	operator+=(const _Tp& __svt)
1204	{ return this->append(__svt); }
1205	#endif // C++17
1206
1207	/**
1208	* @brief Append a string to this string.
1209	* @param __str The string to append.
1210	* @return Reference to this string.
1211	*/
1212	basic_string&
1213	append(const basic_string& __str)
1214	{ return _M_append(s: __str._M_data(), n: __str.size()); }
1215
1216	/**
1217	* @brief Append a substring.
1218	* @param __str The string to append.
1219	* @param __pos Index of the first character of str to append.
1220	* @param __n The number of characters to append.
1221	* @return Reference to this string.
1222	* @throw std::out_of_range if @a __pos is not a valid index.
1223	*
1224	* This function appends @a __n characters from @a __str
1225	* starting at @a __pos to this string. If @a __n is is larger
1226	* than the number of available characters in @a __str, the
1227	* remainder of @a __str is appended.
1228	*/
1229	basic_string&
1230	append(const basic_string& __str, size_type __pos, size_type __n = npos)
1231	{ return _M_append(s: __str._M_data()
1232	+ __str._M_check(__pos, "basic_string::append"),
1233	n: __str._M_limit(__pos, __n)); }
1234
1235	/**
1236	* @brief Append a C substring.
1237	* @param __s The C string to append.
1238	* @param __n The number of characters to append.
1239	* @return Reference to this string.
1240	*/
1241	basic_string&
1242	append(const _CharT* __s, size_type __n)
1243	{
1244	__glibcxx_requires_string_len(__s, __n);
1245	_M_check_length(n1: size_type(0), n2: __n, s: "basic_string::append");
1246	return _M_append(__s, __n);
1247	}
1248
1249	/**
1250	* @brief Append a C string.
1251	* @param __s The C string to append.
1252	* @return Reference to this string.
1253	*/
1254	basic_string&
1255	append(const _CharT* __s)
1256	{
1257	__glibcxx_requires_string(__s);
1258	const size_type __n = traits_type::length(__s);
1259	_M_check_length(n1: size_type(0), n2: __n, s: "basic_string::append");
1260	return _M_append(__s, __n);
1261	}
1262
1263	/**
1264	* @brief Append multiple characters.
1265	* @param __n The number of characters to append.
1266	* @param __c The character to use.
1267	* @return Reference to this string.
1268	*
1269	* Appends __n copies of __c to this string.
1270	*/
1271	basic_string&
1272	append(size_type __n, _CharT __c)
1273	{ return _M_replace_aux(pos1: this->size(), n1: size_type(0), n2: __n, __c); }
1274
1275	#if __cplusplus >= 201103L
1276	/**
1277	* @brief Append an initializer_list of characters.
1278	* @param __l The initializer_list of characters to append.
1279	* @return Reference to this string.
1280	*/
1281	basic_string&
1282	append(initializer_list<_CharT> __l)
1283	{ return this->append(__l.begin(), __l.size()); }
1284	#endif // C++11
1285
1286	/**
1287	* @brief Append a range of characters.
1288	* @param __first Iterator referencing the first character to append.
1289	* @param __last Iterator marking the end of the range.
1290	* @return Reference to this string.
1291	*
1292	* Appends characters in the range [__first,__last) to this string.
1293	*/
1294	#if __cplusplus >= 201103L
1295	template<class _InputIterator,
1296	typename = std::_RequireInputIter<_InputIterator>>
1297	#else
1298	template<class _InputIterator>
1299	#endif
1300	basic_string&
1301	append(_InputIterator __first, _InputIterator __last)
1302	{ return this->replace(end(), end(), __first, __last); }
1303
1304	#if __cplusplus >= 201703L
1305	/**
1306	* @brief Append a string_view.
1307	* @param __svt An object convertible to string_view to be appended.
1308	* @return Reference to this string.
1309	*/
1310	template<typename _Tp>
1311	_If_sv<_Tp, basic_string&>
1312	append(const _Tp& __svt)
1313	{
1314	__sv_type __sv = __svt;
1315	return this->append(__sv.data(), __sv.size());
1316	}
1317
1318	/**
1319	* @brief Append a range of characters from a string_view.
1320	* @param __svt An object convertible to string_view to be appended from.
1321	* @param __pos The position in the string_view to append from.
1322	* @param __n The number of characters to append from the string_view.
1323	* @return Reference to this string.
1324	*/
1325	template<typename _Tp>
1326	_If_sv<_Tp, basic_string&>
1327	append(const _Tp& __svt, size_type __pos, size_type __n = npos)
1328	{
1329	__sv_type __sv = __svt;
1330	return _M_append(s: __sv.data()
1331	+ std::__sv_check(size: __sv.size(), __pos, s: "basic_string::append"),
1332	n: std::__sv_limit(size: __sv.size(), __pos, off: __n));
1333	}
1334	#endif // C++17
1335
1336	/**
1337	* @brief Append a single character.
1338	* @param __c Character to append.
1339	*/
1340	void
1341	push_back(_CharT __c)
1342	{
1343	const size_type __size = this->size();
1344	if (__size + 1 > this->capacity())
1345	this->_M_mutate(__size, size_type(0), 0, size_type(1));
1346	traits_type::assign(this->_M_data()[__size], __c);
1347	this->_M_set_length(__size + 1);
1348	}
1349
1350	/**
1351	* @brief Set value to contents of another string.
1352	* @param __str Source string to use.
1353	* @return Reference to this string.
1354	*/
1355	basic_string&
1356	assign(const basic_string& __str)
1357	{
1358	#if __cplusplus >= 201103L
1359	if (_Alloc_traits::_S_propagate_on_copy_assign())
1360	{
1361	if (!_Alloc_traits::_S_always_equal() && !_M_is_local()
1362	&& _M_get_allocator() != __str._M_get_allocator())
1363	{
1364	// Propagating allocator cannot free existing storage so must
1365	// deallocate it before replacing current allocator.
1366	if (__str.size() <= _S_local_capacity)
1367	{
1368	_M_destroy(size: _M_allocated_capacity);
1369	_M_data(_M_local_data());
1370	_M_set_length(n: 0);
1371	}
1372	else
1373	{
1374	const auto __len = __str.size();
1375	auto __alloc = __str._M_get_allocator();
1376	// If this allocation throws there are no effects:
1377	auto __ptr = _Alloc_traits::allocate(__alloc, __len + 1);
1378	_M_destroy(size: _M_allocated_capacity);
1379	_M_data(__ptr);
1380	_M_capacity(capacity: __len);
1381	_M_set_length(n: __len);
1382	}
1383	}
1384	std::__alloc_on_copy(_M_get_allocator(), __str._M_get_allocator());
1385	}
1386	#endif
1387	this->_M_assign(__str);
1388	return *this;
1389	}
1390
1391	#if __cplusplus >= 201103L
1392	/**
1393	* @brief Set value to contents of another string.
1394	* @param __str Source string to use.
1395	* @return Reference to this string.
1396	*
1397	* This function sets this string to the exact contents of @a __str.
1398	* @a __str is a valid, but unspecified string.
1399	*/
1400	basic_string&
1401	assign(basic_string&& __str)
1402	noexcept(_Alloc_traits::_S_nothrow_move())
1403	{
1404	// _GLIBCXX_RESOLVE_LIB_DEFECTS
1405	// 2063. Contradictory requirements for string move assignment
1406	return *this = std::move(__str);
1407	}
1408	#endif // C++11
1409
1410	/**
1411	* @brief Set value to a substring of a string.
1412	* @param __str The string to use.
1413	* @param __pos Index of the first character of str.
1414	* @param __n Number of characters to use.
1415	* @return Reference to this string.
1416	* @throw std::out_of_range if @a pos is not a valid index.
1417	*
1418	* This function sets this string to the substring of @a __str
1419	* consisting of @a __n characters at @a __pos. If @a __n is
1420	* is larger than the number of available characters in @a
1421	* __str, the remainder of @a __str is used.
1422	*/
1423	basic_string&
1424	assign(const basic_string& __str, size_type __pos, size_type __n = npos)
1425	{ return _M_replace(pos: size_type(0), len1: this->size(), s: __str._M_data()
1426	+ __str._M_check(__pos, "basic_string::assign"),
1427	len2: __str._M_limit(__pos, __n)); }
1428
1429	/**
1430	* @brief Set value to a C substring.
1431	* @param __s The C string to use.
1432	* @param __n Number of characters to use.
1433	* @return Reference to this string.
1434	*
1435	* This function sets the value of this string to the first @a __n
1436	* characters of @a __s. If @a __n is is larger than the number of
1437	* available characters in @a __s, the remainder of @a __s is used.
1438	*/
1439	basic_string&
1440	assign(const _CharT* __s, size_type __n)
1441	{
1442	__glibcxx_requires_string_len(__s, __n);
1443	return _M_replace(pos: size_type(0), len1: this->size(), __s, len2: __n);
1444	}
1445
1446	/**
1447	* @brief Set value to contents of a C string.
1448	* @param __s The C string to use.
1449	* @return Reference to this string.
1450	*
1451	* This function sets the value of this string to the value of @a __s.
1452	* The data is copied, so there is no dependence on @a __s once the
1453	* function returns.
1454	*/
1455	basic_string&
1456	assign(const _CharT* __s)
1457	{
1458	__glibcxx_requires_string(__s);
1459	return _M_replace(pos: size_type(0), len1: this->size(), __s,
1460	len2: traits_type::length(__s));
1461	}
1462
1463	/**
1464	* @brief Set value to multiple characters.
1465	* @param __n Length of the resulting string.
1466	* @param __c The character to use.
1467	* @return Reference to this string.
1468	*
1469	* This function sets the value of this string to @a __n copies of
1470	* character @a __c.
1471	*/
1472	basic_string&
1473	assign(size_type __n, _CharT __c)
1474	{ return _M_replace_aux(pos1: size_type(0), n1: this->size(), n2: __n, __c); }
1475
1476	/**
1477	* @brief Set value to a range of characters.
1478	* @param __first Iterator referencing the first character to append.
1479	* @param __last Iterator marking the end of the range.
1480	* @return Reference to this string.
1481	*
1482	* Sets value of string to characters in the range [__first,__last).
1483	*/
1484	#if __cplusplus >= 201103L
1485	template<class _InputIterator,
1486	typename = std::_RequireInputIter<_InputIterator>>
1487	#else
1488	template<class _InputIterator>
1489	#endif
1490	basic_string&
1491	assign(_InputIterator __first, _InputIterator __last)
1492	{ return this->replace(begin(), end(), __first, __last); }
1493
1494	#if __cplusplus >= 201103L
1495	/**
1496	* @brief Set value to an initializer_list of characters.
1497	* @param __l The initializer_list of characters to assign.
1498	* @return Reference to this string.
1499	*/
1500	basic_string&
1501	assign(initializer_list<_CharT> __l)
1502	{ return this->assign(__l.begin(), __l.size()); }
1503	#endif // C++11
1504
1505	#if __cplusplus >= 201703L
1506	/**
1507	* @brief Set value from a string_view.
1508	* @param __svt The source object convertible to string_view.
1509	* @return Reference to this string.
1510	*/
1511	template<typename _Tp>
1512	_If_sv<_Tp, basic_string&>
1513	assign(const _Tp& __svt)
1514	{
1515	__sv_type __sv = __svt;
1516	return this->assign(__sv.data(), __sv.size());
1517	}
1518
1519	/**
1520	* @brief Set value from a range of characters in a string_view.
1521	* @param __svt The source object convertible to string_view.
1522	* @param __pos The position in the string_view to assign from.
1523	* @param __n The number of characters to assign.
1524	* @return Reference to this string.
1525	*/
1526	template<typename _Tp>
1527	_If_sv<_Tp, basic_string&>
1528	assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
1529	{
1530	__sv_type __sv = __svt;
1531	return _M_replace(pos: size_type(0), len1: this->size(),
1532	s: __sv.data()
1533	+ std::__sv_check(size: __sv.size(), __pos, s: "basic_string::assign"),
1534	len2: std::__sv_limit(size: __sv.size(), __pos, off: __n));
1535	}
1536	#endif // C++17
1537
1538	#if __cplusplus >= 201103L
1539	/**
1540	* @brief Insert multiple characters.
1541	* @param __p Const_iterator referencing location in string to
1542	* insert at.
1543	* @param __n Number of characters to insert
1544	* @param __c The character to insert.
1545	* @return Iterator referencing the first inserted char.
1546	* @throw std::length_error If new length exceeds @c max_size().
1547	*
1548	* Inserts @a __n copies of character @a __c starting at the
1549	* position referenced by iterator @a __p. If adding
1550	* characters causes the length to exceed max_size(),
1551	* length_error is thrown. The value of the string doesn't
1552	* change if an error is thrown.
1553	*/
1554	iterator
1555	insert(const_iterator __p, size_type __n, _CharT __c)
1556	{
1557	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1558	const size_type __pos = __p - begin();
1559	this->replace(__p, __p, __n, __c);
1560	return iterator(this->_M_data() + __pos);
1561	}
1562	#else
1563	/**
1564	* @brief Insert multiple characters.
1565	* @param __p Iterator referencing location in string to insert at.
1566	* @param __n Number of characters to insert
1567	* @param __c The character to insert.
1568	* @throw std::length_error If new length exceeds @c max_size().
1569	*
1570	* Inserts @a __n copies of character @a __c starting at the
1571	* position referenced by iterator @a __p. If adding
1572	* characters causes the length to exceed max_size(),
1573	* length_error is thrown. The value of the string doesn't
1574	* change if an error is thrown.
1575	*/
1576	void
1577	insert(iterator __p, size_type __n, _CharT __c)
1578	{ this->replace(__p, __p, __n, __c); }
1579	#endif
1580
1581	#if __cplusplus >= 201103L
1582	/**
1583	* @brief Insert a range of characters.
1584	* @param __p Const_iterator referencing location in string to
1585	* insert at.
1586	* @param __beg Start of range.
1587	* @param __end End of range.
1588	* @return Iterator referencing the first inserted char.
1589	* @throw std::length_error If new length exceeds @c max_size().
1590	*
1591	* Inserts characters in range [beg,end). If adding characters
1592	* causes the length to exceed max_size(), length_error is
1593	* thrown. The value of the string doesn't change if an error
1594	* is thrown.
1595	*/
1596	template<class _InputIterator,
1597	typename = std::_RequireInputIter<_InputIterator>>
1598	iterator
1599	insert(const_iterator __p, _InputIterator __beg, _InputIterator __end)
1600	{
1601	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1602	const size_type __pos = __p - begin();
1603	this->replace(__p, __p, __beg, __end);
1604	return iterator(this->_M_data() + __pos);
1605	}
1606	#else
1607	/**
1608	* @brief Insert a range of characters.
1609	* @param __p Iterator referencing location in string to insert at.
1610	* @param __beg Start of range.
1611	* @param __end End of range.
1612	* @throw std::length_error If new length exceeds @c max_size().
1613	*
1614	* Inserts characters in range [__beg,__end). If adding
1615	* characters causes the length to exceed max_size(),
1616	* length_error is thrown. The value of the string doesn't
1617	* change if an error is thrown.
1618	*/
1619	template<class _InputIterator>
1620	void
1621	insert(iterator __p, _InputIterator __beg, _InputIterator __end)
1622	{ this->replace(__p, __p, __beg, __end); }
1623	#endif
1624
1625	#if __cplusplus >= 201103L
1626	/**
1627	* @brief Insert an initializer_list of characters.
1628	* @param __p Iterator referencing location in string to insert at.
1629	* @param __l The initializer_list of characters to insert.
1630	* @throw std::length_error If new length exceeds @c max_size().
1631	*/
1632	iterator
1633	insert(const_iterator __p, initializer_list<_CharT> __l)
1634	{ return this->insert(__p, __l.begin(), __l.end()); }
1635
1636	#ifdef _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
1637	// See PR libstdc++/83328
1638	void
1639	insert(iterator __p, initializer_list<_CharT> __l)
1640	{
1641	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1642	this->insert(__p - begin(), __l.begin(), __l.size());
1643	}
1644	#endif
1645	#endif // C++11
1646
1647	/**
1648	* @brief Insert value of a string.
1649	* @param __pos1 Position in string to insert at.
1650	* @param __str The string to insert.
1651	* @return Reference to this string.
1652	* @throw std::length_error If new length exceeds @c max_size().
1653	*
1654	* Inserts value of @a __str starting at @a __pos1. If adding
1655	* characters causes the length to exceed max_size(),
1656	* length_error is thrown. The value of the string doesn't
1657	* change if an error is thrown.
1658	*/
1659	basic_string&
1660	insert(size_type __pos1, const basic_string& __str)
1661	{ return this->replace(__pos1, size_type(0),
1662	__str._M_data(), __str.size()); }
1663
1664	/**
1665	* @brief Insert a substring.
1666	* @param __pos1 Position in string to insert at.
1667	* @param __str The string to insert.
1668	* @param __pos2 Start of characters in str to insert.
1669	* @param __n Number of characters to insert.
1670	* @return Reference to this string.
1671	* @throw std::length_error If new length exceeds @c max_size().
1672	* @throw std::out_of_range If @a pos1 > size() or
1673	* @a __pos2 > @a str.size().
1674	*
1675	* Starting at @a pos1, insert @a __n character of @a __str
1676	* beginning with @a __pos2. If adding characters causes the
1677	* length to exceed max_size(), length_error is thrown. If @a
1678	* __pos1 is beyond the end of this string or @a __pos2 is
1679	* beyond the end of @a __str, out_of_range is thrown. The
1680	* value of the string doesn't change if an error is thrown.
1681	*/
1682	basic_string&
1683	insert(size_type __pos1, const basic_string& __str,
1684	size_type __pos2, size_type __n = npos)
1685	{ return this->replace(__pos1, size_type(0), __str._M_data()
1686	+ __str._M_check(__pos2, "basic_string::insert"),
1687	__str._M_limit(__pos2, __n)); }
1688
1689	/**
1690	* @brief Insert a C substring.
1691	* @param __pos Position in string to insert at.
1692	* @param __s The C string to insert.
1693	* @param __n The number of characters to insert.
1694	* @return Reference to this string.
1695	* @throw std::length_error If new length exceeds @c max_size().
1696	* @throw std::out_of_range If @a __pos is beyond the end of this
1697	* string.
1698	*
1699	* Inserts the first @a __n characters of @a __s starting at @a
1700	* __pos. If adding characters causes the length to exceed
1701	* max_size(), length_error is thrown. If @a __pos is beyond
1702	* end(), out_of_range is thrown. The value of the string
1703	* doesn't change if an error is thrown.
1704	*/
1705	basic_string&
1706	insert(size_type __pos, const _CharT* __s, size_type __n)
1707	{ return this->replace(__pos, size_type(0), __s, __n); }
1708
1709	/**
1710	* @brief Insert a C string.
1711	* @param __pos Position in string to insert at.
1712	* @param __s The C string to insert.
1713	* @return Reference to this string.
1714	* @throw std::length_error If new length exceeds @c max_size().
1715	* @throw std::out_of_range If @a pos is beyond the end of this
1716	* string.
1717	*
1718	* Inserts the first @a n characters of @a __s starting at @a __pos. If
1719	* adding characters causes the length to exceed max_size(),
1720	* length_error is thrown. If @a __pos is beyond end(), out_of_range is
1721	* thrown. The value of the string doesn't change if an error is
1722	* thrown.
1723	*/
1724	basic_string&
1725	insert(size_type __pos, const _CharT* __s)
1726	{
1727	__glibcxx_requires_string(__s);
1728	return this->replace(__pos, size_type(0), __s,
1729	traits_type::length(__s));
1730	}
1731
1732	/**
1733	* @brief Insert multiple characters.
1734	* @param __pos Index in string to insert at.
1735	* @param __n Number of characters to insert
1736	* @param __c The character to insert.
1737	* @return Reference to this string.
1738	* @throw std::length_error If new length exceeds @c max_size().
1739	* @throw std::out_of_range If @a __pos is beyond the end of this
1740	* string.
1741	*
1742	* Inserts @a __n copies of character @a __c starting at index
1743	* @a __pos. If adding characters causes the length to exceed
1744	* max_size(), length_error is thrown. If @a __pos > length(),
1745	* out_of_range is thrown. The value of the string doesn't
1746	* change if an error is thrown.
1747	*/
1748	basic_string&
1749	insert(size_type __pos, size_type __n, _CharT __c)
1750	{ return _M_replace_aux(pos1: _M_check(__pos, s: "basic_string::insert"),
1751	n1: size_type(0), n2: __n, __c); }
1752
1753	/**
1754	* @brief Insert one character.
1755	* @param __p Iterator referencing position in string to insert at.
1756	* @param __c The character to insert.
1757	* @return Iterator referencing newly inserted char.
1758	* @throw std::length_error If new length exceeds @c max_size().
1759	*
1760	* Inserts character @a __c at position referenced by @a __p.
1761	* If adding character causes the length to exceed max_size(),
1762	* length_error is thrown. If @a __p is beyond end of string,
1763	* out_of_range is thrown. The value of the string doesn't
1764	* change if an error is thrown.
1765	*/
1766	iterator
1767	insert(__const_iterator __p, _CharT __c)
1768	{
1769	_GLIBCXX_DEBUG_PEDASSERT(__p >= begin() && __p <= end());
1770	const size_type __pos = __p - begin();
1771	_M_replace_aux(pos1: __pos, n1: size_type(0), n2: size_type(1), __c);
1772	return iterator(_M_data() + __pos);
1773	}
1774
1775	#if __cplusplus >= 201703L
1776	/**
1777	* @brief Insert a string_view.
1778	* @param __pos Position in string to insert at.
1779	* @param __svt The object convertible to string_view to insert.
1780	* @return Reference to this string.
1781	*/
1782	template<typename _Tp>
1783	_If_sv<_Tp, basic_string&>
1784	insert(size_type __pos, const _Tp& __svt)
1785	{
1786	__sv_type __sv = __svt;
1787	return this->insert(__pos, __sv.data(), __sv.size());
1788	}
1789
1790	/**
1791	* @brief Insert a string_view.
1792	* @param __pos1 Position in string to insert at.
1793	* @param __svt The object convertible to string_view to insert from.
1794	* @param __pos2 Start of characters in str to insert.
1795	* @param __n The number of characters to insert.
1796	* @return Reference to this string.
1797	*/
1798	template<typename _Tp>
1799	_If_sv<_Tp, basic_string&>
1800	insert(size_type __pos1, const _Tp& __svt,
1801	size_type __pos2, size_type __n = npos)
1802	{
1803	__sv_type __sv = __svt;
1804	return this->replace(__pos1, size_type(0),
1805	__sv.data()
1806	+ std::__sv_check(size: __sv.size(), pos: __pos2, s: "basic_string::insert"),
1807	std::__sv_limit(size: __sv.size(), pos: __pos2, off: __n));
1808	}
1809	#endif // C++17
1810
1811	/**
1812	* @brief Remove characters.
1813	* @param __pos Index of first character to remove (default 0).
1814	* @param __n Number of characters to remove (default remainder).
1815	* @return Reference to this string.
1816	* @throw std::out_of_range If @a pos is beyond the end of this
1817	* string.
1818	*
1819	* Removes @a __n characters from this string starting at @a
1820	* __pos. The length of the string is reduced by @a __n. If
1821	* there are < @a __n characters to remove, the remainder of
1822	* the string is truncated. If @a __p is beyond end of string,
1823	* out_of_range is thrown. The value of the string doesn't
1824	* change if an error is thrown.
1825	*/
1826	basic_string&
1827	erase(size_type __pos = 0, size_type __n = npos)
1828	{
1829	_M_check(__pos, s: "basic_string::erase");
1830	if (__n == npos)
1831	this->_M_set_length(__pos);
1832	else if (__n != 0)
1833	this->_M_erase(__pos, _M_limit(__pos, off: __n));
1834	return *this;
1835	}
1836
1837	/**
1838	* @brief Remove one character.
1839	* @param __position Iterator referencing the character to remove.
1840	* @return iterator referencing same location after removal.
1841	*
1842	* Removes the character at @a __position from this string. The value
1843	* of the string doesn't change if an error is thrown.
1844	*/
1845	iterator
1846	erase(__const_iterator __position)
1847	{
1848	_GLIBCXX_DEBUG_PEDASSERT(__position >= begin()
1849	&& __position < end());
1850	const size_type __pos = __position - begin();
1851	this->_M_erase(__pos, size_type(1));
1852	return iterator(_M_data() + __pos);
1853	}
1854
1855	/**
1856	* @brief Remove a range of characters.
1857	* @param __first Iterator referencing the first character to remove.
1858	* @param __last Iterator referencing the end of the range.
1859	* @return Iterator referencing location of first after removal.
1860	*
1861	* Removes the characters in the range [first,last) from this string.
1862	* The value of the string doesn't change if an error is thrown.
1863	*/
1864	iterator
1865	erase(__const_iterator __first, __const_iterator __last)
1866	{
1867	_GLIBCXX_DEBUG_PEDASSERT(__first >= begin() && __first <= __last
1868	&& __last <= end());
1869	const size_type __pos = __first - begin();
1870	if (__last == end())
1871	this->_M_set_length(__pos);
1872	else
1873	this->_M_erase(__pos, __last - __first);
1874	return iterator(this->_M_data() + __pos);
1875	}
1876
1877	#if __cplusplus >= 201103L
1878	/**
1879	* @brief Remove the last character.
1880	*
1881	* The string must be non-empty.
1882	*/
1883	void
1884	pop_back() noexcept
1885	{
1886	__glibcxx_assert(!empty());
1887	_M_erase(pos: size() - 1, n: 1);
1888	}
1889	#endif // C++11
1890
1891	/**
1892	* @brief Replace characters with value from another string.
1893	* @param __pos Index of first character to replace.
1894	* @param __n Number of characters to be replaced.
1895	* @param __str String to insert.
1896	* @return Reference to this string.
1897	* @throw std::out_of_range If @a pos is beyond the end of this
1898	* string.
1899	* @throw std::length_error If new length exceeds @c max_size().
1900	*
1901	* Removes the characters in the range [__pos,__pos+__n) from
1902	* this string. In place, the value of @a __str is inserted.
1903	* If @a __pos is beyond end of string, out_of_range is thrown.
1904	* If the length of the result exceeds max_size(), length_error
1905	* is thrown. The value of the string doesn't change if an
1906	* error is thrown.
1907	*/
1908	basic_string&
1909	replace(size_type __pos, size_type __n, const basic_string& __str)
1910	{ return this->replace(__pos, __n, __str._M_data(), __str.size()); }
1911
1912	/**
1913	* @brief Replace characters with value from another string.
1914	* @param __pos1 Index of first character to replace.
1915	* @param __n1 Number of characters to be replaced.
1916	* @param __str String to insert.
1917	* @param __pos2 Index of first character of str to use.
1918	* @param __n2 Number of characters from str to use.
1919	* @return Reference to this string.
1920	* @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
1921	* __str.size().
1922	* @throw std::length_error If new length exceeds @c max_size().
1923	*
1924	* Removes the characters in the range [__pos1,__pos1 + n) from this
1925	* string. In place, the value of @a __str is inserted. If @a __pos is
1926	* beyond end of string, out_of_range is thrown. If the length of the
1927	* result exceeds max_size(), length_error is thrown. The value of the
1928	* string doesn't change if an error is thrown.
1929	*/
1930	basic_string&
1931	replace(size_type __pos1, size_type __n1, const basic_string& __str,
1932	size_type __pos2, size_type __n2 = npos)
1933	{ return this->replace(__pos1, __n1, __str._M_data()
1934	+ __str._M_check(__pos2, "basic_string::replace"),
1935	__str._M_limit(__pos2, __n2)); }
1936
1937	/**
1938	* @brief Replace characters with value of a C substring.
1939	* @param __pos Index of first character to replace.
1940	* @param __n1 Number of characters to be replaced.
1941	* @param __s C string to insert.
1942	* @param __n2 Number of characters from @a s to use.
1943	* @return Reference to this string.
1944	* @throw std::out_of_range If @a pos1 > size().
1945	* @throw std::length_error If new length exceeds @c max_size().
1946	*
1947	* Removes the characters in the range [__pos,__pos + __n1)
1948	* from this string. In place, the first @a __n2 characters of
1949	* @a __s are inserted, or all of @a __s if @a __n2 is too large. If
1950	* @a __pos is beyond end of string, out_of_range is thrown. If
1951	* the length of result exceeds max_size(), length_error is
1952	* thrown. The value of the string doesn't change if an error
1953	* is thrown.
1954	*/
1955	basic_string&
1956	replace(size_type __pos, size_type __n1, const _CharT* __s,
1957	size_type __n2)
1958	{
1959	__glibcxx_requires_string_len(__s, __n2);
1960	return _M_replace(pos: _M_check(__pos, s: "basic_string::replace"),
1961	len1: _M_limit(__pos, off: __n1), __s, len2: __n2);
1962	}
1963
1964	/**
1965	* @brief Replace characters with value of a C string.
1966	* @param __pos Index of first character to replace.
1967	* @param __n1 Number of characters to be replaced.
1968	* @param __s C string to insert.
1969	* @return Reference to this string.
1970	* @throw std::out_of_range If @a pos > size().
1971	* @throw std::length_error If new length exceeds @c max_size().
1972	*
1973	* Removes the characters in the range [__pos,__pos + __n1)
1974	* from this string. In place, the characters of @a __s are
1975	* inserted. If @a __pos is beyond end of string, out_of_range
1976	* is thrown. If the length of result exceeds max_size(),
1977	* length_error is thrown. The value of the string doesn't
1978	* change if an error is thrown.
1979	*/
1980	basic_string&
1981	replace(size_type __pos, size_type __n1, const _CharT* __s)
1982	{
1983	__glibcxx_requires_string(__s);
1984	return this->replace(__pos, __n1, __s, traits_type::length(__s));
1985	}
1986
1987	/**
1988	* @brief Replace characters with multiple characters.
1989	* @param __pos Index of first character to replace.
1990	* @param __n1 Number of characters to be replaced.
1991	* @param __n2 Number of characters to insert.
1992	* @param __c Character to insert.
1993	* @return Reference to this string.
1994	* @throw std::out_of_range If @a __pos > size().
1995	* @throw std::length_error If new length exceeds @c max_size().
1996	*
1997	* Removes the characters in the range [pos,pos + n1) from this
1998	* string. In place, @a __n2 copies of @a __c are inserted.
1999	* If @a __pos is beyond end of string, out_of_range is thrown.
2000	* If the length of result exceeds max_size(), length_error is
2001	* thrown. The value of the string doesn't change if an error
2002	* is thrown.
2003	*/
2004	basic_string&
2005	replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
2006	{ return _M_replace_aux(pos1: _M_check(__pos, s: "basic_string::replace"),
2007	n1: _M_limit(__pos, off: __n1), __n2, __c); }
2008
2009	/**
2010	* @brief Replace range of characters with string.
2011	* @param __i1 Iterator referencing start of range to replace.
2012	* @param __i2 Iterator referencing end of range to replace.
2013	* @param __str String value to insert.
2014	* @return Reference to this string.
2015	* @throw std::length_error If new length exceeds @c max_size().
2016	*
2017	* Removes the characters in the range [__i1,__i2). In place,
2018	* the value of @a __str is inserted. If the length of result
2019	* exceeds max_size(), length_error is thrown. The value of
2020	* the string doesn't change if an error is thrown.
2021	*/
2022	basic_string&
2023	replace(__const_iterator __i1, __const_iterator __i2,
2024	const basic_string& __str)
2025	{ return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
2026
2027	/**
2028	* @brief Replace range of characters with C substring.
2029	* @param __i1 Iterator referencing start of range to replace.
2030	* @param __i2 Iterator referencing end of range to replace.
2031	* @param __s C string value to insert.
2032	* @param __n Number of characters from s to insert.
2033	* @return Reference to this string.
2034	* @throw std::length_error If new length exceeds @c max_size().
2035	*
2036	* Removes the characters in the range [__i1,__i2). In place,
2037	* the first @a __n characters of @a __s are inserted. If the
2038	* length of result exceeds max_size(), length_error is thrown.
2039	* The value of the string doesn't change if an error is
2040	* thrown.
2041	*/
2042	basic_string&
2043	replace(__const_iterator __i1, __const_iterator __i2,
2044	const _CharT* __s, size_type __n)
2045	{
2046	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2047	&& __i2 <= end());
2048	return this->replace(__i1 - begin(), __i2 - __i1, __s, __n);
2049	}
2050
2051	/**
2052	* @brief Replace range of characters with C string.
2053	* @param __i1 Iterator referencing start of range to replace.
2054	* @param __i2 Iterator referencing end of range to replace.
2055	* @param __s C string value to insert.
2056	* @return Reference to this string.
2057	* @throw std::length_error If new length exceeds @c max_size().
2058	*
2059	* Removes the characters in the range [__i1,__i2). In place,
2060	* the characters of @a __s are inserted. If the length of
2061	* result exceeds max_size(), length_error is thrown. The
2062	* value of the string doesn't change if an error is thrown.
2063	*/
2064	basic_string&
2065	replace(__const_iterator __i1, __const_iterator __i2, const _CharT* __s)
2066	{
2067	__glibcxx_requires_string(__s);
2068	return this->replace(__i1, __i2, __s, traits_type::length(__s));
2069	}
2070
2071	/**
2072	* @brief Replace range of characters with multiple characters
2073	* @param __i1 Iterator referencing start of range to replace.
2074	* @param __i2 Iterator referencing end of range to replace.
2075	* @param __n Number of characters to insert.
2076	* @param __c Character to insert.
2077	* @return Reference to this string.
2078	* @throw std::length_error If new length exceeds @c max_size().
2079	*
2080	* Removes the characters in the range [__i1,__i2). In place,
2081	* @a __n copies of @a __c are inserted. If the length of
2082	* result exceeds max_size(), length_error is thrown. The
2083	* value of the string doesn't change if an error is thrown.
2084	*/
2085	basic_string&
2086	replace(__const_iterator __i1, __const_iterator __i2, size_type __n,
2087	_CharT __c)
2088	{
2089	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2090	&& __i2 <= end());
2091	return _M_replace_aux(pos1: __i1 - begin(), n1: __i2 - __i1, n2: __n, __c);
2092	}
2093
2094	/**
2095	* @brief Replace range of characters with range.
2096	* @param __i1 Iterator referencing start of range to replace.
2097	* @param __i2 Iterator referencing end of range to replace.
2098	* @param __k1 Iterator referencing start of range to insert.
2099	* @param __k2 Iterator referencing end of range to insert.
2100	* @return Reference to this string.
2101	* @throw std::length_error If new length exceeds @c max_size().
2102	*
2103	* Removes the characters in the range [__i1,__i2). In place,
2104	* characters in the range [__k1,__k2) are inserted. If the
2105	* length of result exceeds max_size(), length_error is thrown.
2106	* The value of the string doesn't change if an error is
2107	* thrown.
2108	*/
2109	#if __cplusplus >= 201103L
2110	template<class _InputIterator,
2111	typename = std::_RequireInputIter<_InputIterator>>
2112	basic_string&
2113	replace(const_iterator __i1, const_iterator __i2,
2114	_InputIterator __k1, _InputIterator __k2)
2115	{
2116	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2117	&& __i2 <= end());
2118	__glibcxx_requires_valid_range(__k1, __k2);
2119	return this->_M_replace_dispatch(__i1, __i2, __k1, __k2,
2120	std::__false_type());
2121	}
2122	#else
2123	template<class _InputIterator>
2124	#ifdef _GLIBCXX_DISAMBIGUATE_REPLACE_INST
2125	typename __enable_if_not_native_iterator<_InputIterator>::__type
2126	#else
2127	basic_string&
2128	#endif
2129	replace(iterator __i1, iterator __i2,
2130	_InputIterator __k1, _InputIterator __k2)
2131	{
2132	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2133	&& __i2 <= end());
2134	__glibcxx_requires_valid_range(__k1, __k2);
2135	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
2136	return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
2137	}
2138	#endif
2139
2140	// Specializations for the common case of pointer and iterator:
2141	// useful to avoid the overhead of temporary buffering in _M_replace.
2142	basic_string&
2143	replace(__const_iterator __i1, __const_iterator __i2,
2144	_CharT* __k1, _CharT* __k2)
2145	{
2146	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2147	&& __i2 <= end());
2148	__glibcxx_requires_valid_range(__k1, __k2);
2149	return this->replace(__i1 - begin(), __i2 - __i1,
2150	__k1, __k2 - __k1);
2151	}
2152
2153	basic_string&
2154	replace(__const_iterator __i1, __const_iterator __i2,
2155	const _CharT* __k1, const _CharT* __k2)
2156	{
2157	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2158	&& __i2 <= end());
2159	__glibcxx_requires_valid_range(__k1, __k2);
2160	return this->replace(__i1 - begin(), __i2 - __i1,
2161	__k1, __k2 - __k1);
2162	}
2163
2164	basic_string&
2165	replace(__const_iterator __i1, __const_iterator __i2,
2166	iterator __k1, iterator __k2)
2167	{
2168	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2169	&& __i2 <= end());
2170	__glibcxx_requires_valid_range(__k1, __k2);
2171	return this->replace(__i1 - begin(), __i2 - __i1,
2172	__k1.base(), __k2 - __k1);
2173	}
2174
2175	basic_string&
2176	replace(__const_iterator __i1, __const_iterator __i2,
2177	const_iterator __k1, const_iterator __k2)
2178	{
2179	_GLIBCXX_DEBUG_PEDASSERT(begin() <= __i1 && __i1 <= __i2
2180	&& __i2 <= end());
2181	__glibcxx_requires_valid_range(__k1, __k2);
2182	return this->replace(__i1 - begin(), __i2 - __i1,
2183	__k1.base(), __k2 - __k1);
2184	}
2185
2186	#if __cplusplus >= 201103L
2187	/**
2188	* @brief Replace range of characters with initializer_list.
2189	* @param __i1 Iterator referencing start of range to replace.
2190	* @param __i2 Iterator referencing end of range to replace.
2191	* @param __l The initializer_list of characters to insert.
2192	* @return Reference to this string.
2193	* @throw std::length_error If new length exceeds @c max_size().
2194	*
2195	* Removes the characters in the range [__i1,__i2). In place,
2196	* characters in the range [__k1,__k2) are inserted. If the
2197	* length of result exceeds max_size(), length_error is thrown.
2198	* The value of the string doesn't change if an error is
2199	* thrown.
2200	*/
2201	basic_string& replace(const_iterator __i1, const_iterator __i2,
2202	initializer_list<_CharT> __l)
2203	{ return this->replace(__i1, __i2, __l.begin(), __l.size()); }
2204	#endif // C++11
2205
2206	#if __cplusplus >= 201703L
2207	/**
2208	* @brief Replace range of characters with string_view.
2209	* @param __pos The position to replace at.
2210	* @param __n The number of characters to replace.
2211	* @param __svt The object convertible to string_view to insert.
2212	* @return Reference to this string.
2213	*/
2214	template<typename _Tp>
2215	_If_sv<_Tp, basic_string&>
2216	replace(size_type __pos, size_type __n, const _Tp& __svt)
2217	{
2218	__sv_type __sv = __svt;
2219	return this->replace(__pos, __n, __sv.data(), __sv.size());
2220	}
2221
2222	/**
2223	* @brief Replace range of characters with string_view.
2224	* @param __pos1 The position to replace at.
2225	* @param __n1 The number of characters to replace.
2226	* @param __svt The object convertible to string_view to insert from.
2227	* @param __pos2 The position in the string_view to insert from.
2228	* @param __n2 The number of characters to insert.
2229	* @return Reference to this string.
2230	*/
2231	template<typename _Tp>
2232	_If_sv<_Tp, basic_string&>
2233	replace(size_type __pos1, size_type __n1, const _Tp& __svt,
2234	size_type __pos2, size_type __n2 = npos)
2235	{
2236	__sv_type __sv = __svt;
2237	return this->replace(__pos1, __n1,
2238	__sv.data()
2239	+ std::__sv_check(size: __sv.size(), pos: __pos2, s: "basic_string::replace"),
2240	std::__sv_limit(size: __sv.size(), pos: __pos2, off: __n2));
2241	}
2242
2243	/**
2244	* @brief Replace range of characters with string_view.
2245	* @param __i1 An iterator referencing the start position
2246	to replace at.
2247	* @param __i2 An iterator referencing the end position
2248	for the replace.
2249	* @param __svt The object convertible to string_view to insert from.
2250	* @return Reference to this string.
2251	*/
2252	template<typename _Tp>
2253	_If_sv<_Tp, basic_string&>
2254	replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
2255	{
2256	__sv_type __sv = __svt;
2257	return this->replace(__i1 - begin(), __i2 - __i1, __sv);
2258	}
2259	#endif // C++17
2260
2261	private:
2262	template<class _Integer>
2263	basic_string&
2264	_M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2265	_Integer __n, _Integer __val, __true_type)
2266	{ return _M_replace_aux(pos1: __i1 - begin(), n1: __i2 - __i1, n2: __n, c: __val); }
2267
2268	template<class _InputIterator>
2269	basic_string&
2270	_M_replace_dispatch(const_iterator __i1, const_iterator __i2,
2271	_InputIterator __k1, _InputIterator __k2,
2272	__false_type);
2273
2274	basic_string&
2275	_M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
2276	_CharT __c);
2277
2278	basic_string&
2279	_M_replace(size_type __pos, size_type __len1, const _CharT* __s,
2280	const size_type __len2);
2281
2282	basic_string&
2283	_M_append(const _CharT* __s, size_type __n);
2284
2285	public:
2286
2287	/**
2288	* @brief Copy substring into C string.
2289	* @param __s C string to copy value into.
2290	* @param __n Number of characters to copy.
2291	* @param __pos Index of first character to copy.
2292	* @return Number of characters actually copied
2293	* @throw std::out_of_range If __pos > size().
2294	*
2295	* Copies up to @a __n characters starting at @a __pos into the
2296	* C string @a __s. If @a __pos is %greater than size(),
2297	* out_of_range is thrown.
2298	*/
2299	size_type
2300	copy(_CharT* __s, size_type __n, size_type __pos = 0) const;
2301
2302	/**
2303	* @brief Swap contents with another string.
2304	* @param __s String to swap with.
2305	*
2306	* Exchanges the contents of this string with that of @a __s in constant
2307	* time.
2308	*/
2309	void
2310	swap(basic_string& __s) _GLIBCXX_NOEXCEPT;
2311
2312	// String operations:
2313	/**
2314	* @brief Return const pointer to null-terminated contents.
2315	*
2316	* This is a handle to internal data. Do not modify or dire things may
2317	* happen.
2318	*/
2319	const _CharT*
2320	c_str() const _GLIBCXX_NOEXCEPT
2321	{ return _M_data(); }
2322
2323	/**
2324	* @brief Return const pointer to contents.
2325	*
2326	* This is a pointer to internal data. It is undefined to modify
2327	* the contents through the returned pointer. To get a pointer that
2328	* allows modifying the contents use @c &str[0] instead,
2329	* (or in C++17 the non-const @c str.data() overload).
2330	*/
2331	const _CharT*
2332	data() const _GLIBCXX_NOEXCEPT
2333	{ return _M_data(); }
2334
2335	#if __cplusplus >= 201703L
2336	/**
2337	* @brief Return non-const pointer to contents.
2338	*
2339	* This is a pointer to the character sequence held by the string.
2340	* Modifying the characters in the sequence is allowed.
2341	*/
2342	_CharT*
2343	data() noexcept
2344	{ return _M_data(); }
2345	#endif
2346
2347	/**
2348	* @brief Return copy of allocator used to construct this string.
2349	*/
2350	allocator_type
2351	get_allocator() const _GLIBCXX_NOEXCEPT
2352	{ return _M_get_allocator(); }
2353
2354	/**
2355	* @brief Find position of a C substring.
2356	* @param __s C string to locate.
2357	* @param __pos Index of character to search from.
2358	* @param __n Number of characters from @a s to search for.
2359	* @return Index of start of first occurrence.
2360	*
2361	* Starting from @a __pos, searches forward for the first @a
2362	* __n characters in @a __s within this string. If found,
2363	* returns the index where it begins. If not found, returns
2364	* npos.
2365	*/
2366	size_type
2367	find(const _CharT* __s, size_type __pos, size_type __n) const
2368	_GLIBCXX_NOEXCEPT;
2369
2370	/**
2371	* @brief Find position of a string.
2372	* @param __str String to locate.
2373	* @param __pos Index of character to search from (default 0).
2374	* @return Index of start of first occurrence.
2375	*
2376	* Starting from @a __pos, searches forward for value of @a __str within
2377	* this string. If found, returns the index where it begins. If not
2378	* found, returns npos.
2379	*/
2380	size_type
2381	find(const basic_string& __str, size_type __pos = 0) const
2382	_GLIBCXX_NOEXCEPT
2383	{ return this->find(__str.data(), __pos, __str.size()); }
2384
2385	#if __cplusplus >= 201703L
2386	/**
2387	* @brief Find position of a string_view.
2388	* @param __svt The object convertible to string_view to locate.
2389	* @param __pos Index of character to search from (default 0).
2390	* @return Index of start of first occurrence.
2391	*/
2392	template<typename _Tp>
2393	_If_sv<_Tp, size_type>
2394	find(const _Tp& __svt, size_type __pos = 0) const
2395	noexcept(is_same<_Tp, __sv_type>::value)
2396	{
2397	__sv_type __sv = __svt;
2398	return this->find(__sv.data(), __pos, __sv.size());
2399	}
2400	#endif // C++17
2401
2402	/**
2403	* @brief Find position of a C string.
2404	* @param __s C string to locate.
2405	* @param __pos Index of character to search from (default 0).
2406	* @return Index of start of first occurrence.
2407	*
2408	* Starting from @a __pos, searches forward for the value of @a
2409	* __s within this string. If found, returns the index where
2410	* it begins. If not found, returns npos.
2411	*/
2412	size_type
2413	find(const _CharT* __s, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
2414	{
2415	__glibcxx_requires_string(__s);
2416	return this->find(__s, __pos, traits_type::length(__s));
2417	}
2418
2419	/**
2420	* @brief Find position of a character.
2421	* @param __c Character to locate.
2422	* @param __pos Index of character to search from (default 0).
2423	* @return Index of first occurrence.
2424	*
2425	* Starting from @a __pos, searches forward for @a __c within
2426	* this string. If found, returns the index where it was
2427	* found. If not found, returns npos.
2428	*/
2429	size_type
2430	find(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT;
2431
2432	/**
2433	* @brief Find last position of a string.
2434	* @param __str String to locate.
2435	* @param __pos Index of character to search back from (default end).
2436	* @return Index of start of last occurrence.
2437	*
2438	* Starting from @a __pos, searches backward for value of @a
2439	* __str within this string. If found, returns the index where
2440	* it begins. If not found, returns npos.
2441	*/
2442	size_type
2443	rfind(const basic_string& __str, size_type __pos = npos) const
2444	_GLIBCXX_NOEXCEPT
2445	{ return this->rfind(__str.data(), __pos, __str.size()); }
2446
2447	#if __cplusplus >= 201703L
2448	/**
2449	* @brief Find last position of a string_view.
2450	* @param __svt The object convertible to string_view to locate.
2451	* @param __pos Index of character to search back from (default end).
2452	* @return Index of start of last occurrence.
2453	*/
2454	template<typename _Tp>
2455	_If_sv<_Tp, size_type>
2456	rfind(const _Tp& __svt, size_type __pos = npos) const
2457	noexcept(is_same<_Tp, __sv_type>::value)
2458	{
2459	__sv_type __sv = __svt;
2460	return this->rfind(__sv.data(), __pos, __sv.size());
2461	}
2462	#endif // C++17
2463
2464	/**
2465	* @brief Find last position of a C substring.
2466	* @param __s C string to locate.
2467	* @param __pos Index of character to search back from.
2468	* @param __n Number of characters from s to search for.
2469	* @return Index of start of last occurrence.
2470	*
2471	* Starting from @a __pos, searches backward for the first @a
2472	* __n characters in @a __s within this string. If found,
2473	* returns the index where it begins. If not found, returns
2474	* npos.
2475	*/
2476	size_type
2477	rfind(const _CharT* __s, size_type __pos, size_type __n) const
2478	_GLIBCXX_NOEXCEPT;
2479
2480	/**
2481	* @brief Find last position of a C string.
2482	* @param __s C string to locate.
2483	* @param __pos Index of character to start search at (default end).
2484	* @return Index of start of last occurrence.
2485	*
2486	* Starting from @a __pos, searches backward for the value of
2487	* @a __s within this string. If found, returns the index
2488	* where it begins. If not found, returns npos.
2489	*/
2490	size_type
2491	rfind(const _CharT* __s, size_type __pos = npos) const
2492	{
2493	__glibcxx_requires_string(__s);
2494	return this->rfind(__s, __pos, traits_type::length(__s));
2495	}
2496
2497	/**
2498	* @brief Find last position of a character.
2499	* @param __c Character to locate.
2500	* @param __pos Index of character to search back from (default end).
2501	* @return Index of last occurrence.
2502	*
2503	* Starting from @a __pos, searches backward for @a __c within
2504	* this string. If found, returns the index where it was
2505	* found. If not found, returns npos.
2506	*/
2507	size_type
2508	rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
2509
2510	/**
2511	* @brief Find position of a character of string.
2512	* @param __str String containing characters to locate.
2513	* @param __pos Index of character to search from (default 0).
2514	* @return Index of first occurrence.
2515	*
2516	* Starting from @a __pos, searches forward for one of the
2517	* characters of @a __str within this string. If found,
2518	* returns the index where it was found. If not found, returns
2519	* npos.
2520	*/
2521	size_type
2522	find_first_of(const basic_string& __str, size_type __pos = 0) const
2523	_GLIBCXX_NOEXCEPT
2524	{ return this->find_first_of(__str.data(), __pos, __str.size()); }
2525
2526	#if __cplusplus >= 201703L
2527	/**
2528	* @brief Find position of a character of a string_view.
2529	* @param __svt An object convertible to string_view containing
2530	* characters to locate.
2531	* @param __pos Index of character to search from (default 0).
2532	* @return Index of first occurrence.
2533	*/
2534	template<typename _Tp>
2535	_If_sv<_Tp, size_type>
2536	find_first_of(const _Tp& __svt, size_type __pos = 0) const
2537	noexcept(is_same<_Tp, __sv_type>::value)
2538	{
2539	__sv_type __sv = __svt;
2540	return this->find_first_of(__sv.data(), __pos, __sv.size());
2541	}
2542	#endif // C++17
2543
2544	/**
2545	* @brief Find position of a character of C substring.
2546	* @param __s String containing characters to locate.
2547	* @param __pos Index of character to search from.
2548	* @param __n Number of characters from s to search for.
2549	* @return Index of first occurrence.
2550	*
2551	* Starting from @a __pos, searches forward for one of the
2552	* first @a __n characters of @a __s within this string. If
2553	* found, returns the index where it was found. If not found,
2554	* returns npos.
2555	*/
2556	size_type
2557	find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
2558	_GLIBCXX_NOEXCEPT;
2559
2560	/**
2561	* @brief Find position of a character of C string.
2562	* @param __s String containing characters to locate.
2563	* @param __pos Index of character to search from (default 0).
2564	* @return Index of first occurrence.
2565	*
2566	* Starting from @a __pos, searches forward for one of the
2567	* characters of @a __s within this string. If found, returns
2568	* the index where it was found. If not found, returns npos.
2569	*/
2570	size_type
2571	find_first_of(const _CharT* __s, size_type __pos = 0) const
2572	_GLIBCXX_NOEXCEPT
2573	{
2574	__glibcxx_requires_string(__s);
2575	return this->find_first_of(__s, __pos, traits_type::length(__s));
2576	}
2577
2578	/**
2579	* @brief Find position of a character.
2580	* @param __c Character to locate.
2581	* @param __pos Index of character to search from (default 0).
2582	* @return Index of first occurrence.
2583	*
2584	* Starting from @a __pos, searches forward for the character
2585	* @a __c within this string. If found, returns the index
2586	* where it was found. If not found, returns npos.
2587	*
2588	* Note: equivalent to find(__c, __pos).
2589	*/
2590	size_type
2591	find_first_of(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
2592	{ return this->find(__c, __pos); }
2593
2594	/**
2595	* @brief Find last position of a character of string.
2596	* @param __str String containing characters to locate.
2597	* @param __pos Index of character to search back from (default end).
2598	* @return Index of last occurrence.
2599	*
2600	* Starting from @a __pos, searches backward for one of the
2601	* characters of @a __str within this string. If found,
2602	* returns the index where it was found. If not found, returns
2603	* npos.
2604	*/
2605	size_type
2606	find_last_of(const basic_string& __str, size_type __pos = npos) const
2607	_GLIBCXX_NOEXCEPT
2608	{ return this->find_last_of(__str.data(), __pos, __str.size()); }
2609
2610	#if __cplusplus >= 201703L
2611	/**
2612	* @brief Find last position of a character of string.
2613	* @param __svt An object convertible to string_view containing
2614	* characters to locate.
2615	* @param __pos Index of character to search back from (default end).
2616	* @return Index of last occurrence.
2617	*/
2618	template<typename _Tp>
2619	_If_sv<_Tp, size_type>
2620	find_last_of(const _Tp& __svt, size_type __pos = npos) const
2621	noexcept(is_same<_Tp, __sv_type>::value)
2622	{
2623	__sv_type __sv = __svt;
2624	return this->find_last_of(__sv.data(), __pos, __sv.size());
2625	}
2626	#endif // C++17
2627
2628	/**
2629	* @brief Find last position of a character of C substring.
2630	* @param __s C string containing characters to locate.
2631	* @param __pos Index of character to search back from.
2632	* @param __n Number of characters from s to search for.
2633	* @return Index of last occurrence.
2634	*
2635	* Starting from @a __pos, searches backward for one of the
2636	* first @a __n characters of @a __s within this string. If
2637	* found, returns the index where it was found. If not found,
2638	* returns npos.
2639	*/
2640	size_type
2641	find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
2642	_GLIBCXX_NOEXCEPT;
2643
2644	/**
2645	* @brief Find last position of a character of C string.
2646	* @param __s C string containing characters to locate.
2647	* @param __pos Index of character to search back from (default end).
2648	* @return Index of last occurrence.
2649	*
2650	* Starting from @a __pos, searches backward for one of the
2651	* characters of @a __s within this string. If found, returns
2652	* the index where it was found. If not found, returns npos.
2653	*/
2654	size_type
2655	find_last_of(const _CharT* __s, size_type __pos = npos) const
2656	_GLIBCXX_NOEXCEPT
2657	{
2658	__glibcxx_requires_string(__s);
2659	return this->find_last_of(__s, __pos, traits_type::length(__s));
2660	}
2661
2662	/**
2663	* @brief Find last position of a character.
2664	* @param __c Character to locate.
2665	* @param __pos Index of character to search back from (default end).
2666	* @return Index of last occurrence.
2667	*
2668	* Starting from @a __pos, searches backward for @a __c within
2669	* this string. If found, returns the index where it was
2670	* found. If not found, returns npos.
2671	*
2672	* Note: equivalent to rfind(__c, __pos).
2673	*/
2674	size_type
2675	find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
2676	{ return this->rfind(__c, __pos); }
2677
2678	/**
2679	* @brief Find position of a character not in string.
2680	* @param __str String containing characters to avoid.
2681	* @param __pos Index of character to search from (default 0).
2682	* @return Index of first occurrence.
2683	*
2684	* Starting from @a __pos, searches forward for a character not contained
2685	* in @a __str within this string. If found, returns the index where it
2686	* was found. If not found, returns npos.
2687	*/
2688	size_type
2689	find_first_not_of(const basic_string& __str, size_type __pos = 0) const
2690	_GLIBCXX_NOEXCEPT
2691	{ return this->find_first_not_of(__str.data(), __pos, __str.size()); }
2692
2693	#if __cplusplus >= 201703L
2694	/**
2695	* @brief Find position of a character not in a string_view.
2696	* @param __svt A object convertible to string_view containing
2697	* characters to avoid.
2698	* @param __pos Index of character to search from (default 0).
2699	* @return Index of first occurrence.
2700	*/
2701	template<typename _Tp>
2702	_If_sv<_Tp, size_type>
2703	find_first_not_of(const _Tp& __svt, size_type __pos = 0) const
2704	noexcept(is_same<_Tp, __sv_type>::value)
2705	{
2706	__sv_type __sv = __svt;
2707	return this->find_first_not_of(__sv.data(), __pos, __sv.size());
2708	}
2709	#endif // C++17
2710
2711	/**
2712	* @brief Find position of a character not in C substring.
2713	* @param __s C string containing characters to avoid.
2714	* @param __pos Index of character to search from.
2715	* @param __n Number of characters from __s to consider.
2716	* @return Index of first occurrence.
2717	*
2718	* Starting from @a __pos, searches forward for a character not
2719	* contained in the first @a __n characters of @a __s within
2720	* this string. If found, returns the index where it was
2721	* found. If not found, returns npos.
2722	*/
2723	size_type
2724	find_first_not_of(const _CharT* __s, size_type __pos,
2725	size_type __n) const _GLIBCXX_NOEXCEPT;
2726
2727	/**
2728	* @brief Find position of a character not in C string.
2729	* @param __s C string containing characters to avoid.
2730	* @param __pos Index of character to search from (default 0).
2731	* @return Index of first occurrence.
2732	*
2733	* Starting from @a __pos, searches forward for a character not
2734	* contained in @a __s within this string. If found, returns
2735	* the index where it was found. If not found, returns npos.
2736	*/
2737	size_type
2738	find_first_not_of(const _CharT* __s, size_type __pos = 0) const
2739	_GLIBCXX_NOEXCEPT
2740	{
2741	__glibcxx_requires_string(__s);
2742	return this->find_first_not_of(__s, __pos, traits_type::length(__s));
2743	}
2744
2745	/**
2746	* @brief Find position of a different character.
2747	* @param __c Character to avoid.
2748	* @param __pos Index of character to search from (default 0).
2749	* @return Index of first occurrence.
2750	*
2751	* Starting from @a __pos, searches forward for a character
2752	* other than @a __c within this string. If found, returns the
2753	* index where it was found. If not found, returns npos.
2754	*/
2755	size_type
2756	find_first_not_of(_CharT __c, size_type __pos = 0) const
2757	_GLIBCXX_NOEXCEPT;
2758
2759	/**
2760	* @brief Find last position of a character not in string.
2761	* @param __str String containing characters to avoid.
2762	* @param __pos Index of character to search back from (default end).
2763	* @return Index of last occurrence.
2764	*
2765	* Starting from @a __pos, searches backward for a character
2766	* not contained in @a __str within this string. If found,
2767	* returns the index where it was found. If not found, returns
2768	* npos.
2769	*/
2770	size_type
2771	find_last_not_of(const basic_string& __str, size_type __pos = npos) const
2772	_GLIBCXX_NOEXCEPT
2773	{ return this->find_last_not_of(__str.data(), __pos, __str.size()); }
2774
2775	#if __cplusplus >= 201703L
2776	/**
2777	* @brief Find last position of a character not in a string_view.
2778	* @param __svt An object convertible to string_view containing
2779	* characters to avoid.
2780	* @param __pos Index of character to search back from (default end).
2781	* @return Index of last occurrence.
2782	*/
2783	template<typename _Tp>
2784	_If_sv<_Tp, size_type>
2785	find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
2786	noexcept(is_same<_Tp, __sv_type>::value)
2787	{
2788	__sv_type __sv = __svt;
2789	return this->find_last_not_of(__sv.data(), __pos, __sv.size());
2790	}
2791	#endif // C++17
2792
2793	/**
2794	* @brief Find last position of a character not in C substring.
2795	* @param __s C string containing characters to avoid.
2796	* @param __pos Index of character to search back from.
2797	* @param __n Number of characters from s to consider.
2798	* @return Index of last occurrence.
2799	*
2800	* Starting from @a __pos, searches backward for a character not
2801	* contained in the first @a __n characters of @a __s within this string.
2802	* If found, returns the index where it was found. If not found,
2803	* returns npos.
2804	*/
2805	size_type
2806	find_last_not_of(const _CharT* __s, size_type __pos,
2807	size_type __n) const _GLIBCXX_NOEXCEPT;
2808	/**
2809	* @brief Find last position of a character not in C string.
2810	* @param __s C string containing characters to avoid.
2811	* @param __pos Index of character to search back from (default end).
2812	* @return Index of last occurrence.
2813	*
2814	* Starting from @a __pos, searches backward for a character
2815	* not contained in @a __s within this string. If found,
2816	* returns the index where it was found. If not found, returns
2817	* npos.
2818	*/
2819	size_type
2820	find_last_not_of(const _CharT* __s, size_type __pos = npos) const
2821	_GLIBCXX_NOEXCEPT
2822	{
2823	__glibcxx_requires_string(__s);
2824	return this->find_last_not_of(__s, __pos, traits_type::length(__s));
2825	}
2826
2827	/**
2828	* @brief Find last position of a different character.
2829	* @param __c Character to avoid.
2830	* @param __pos Index of character to search back from (default end).
2831	* @return Index of last occurrence.
2832	*
2833	* Starting from @a __pos, searches backward for a character other than
2834	* @a __c within this string. If found, returns the index where it was
2835	* found. If not found, returns npos.
2836	*/
2837	size_type
2838	find_last_not_of(_CharT __c, size_type __pos = npos) const
2839	_GLIBCXX_NOEXCEPT;
2840
2841	/**
2842	* @brief Get a substring.
2843	* @param __pos Index of first character (default 0).
2844	* @param __n Number of characters in substring (default remainder).
2845	* @return The new string.
2846	* @throw std::out_of_range If __pos > size().
2847	*
2848	* Construct and return a new string using the @a __n
2849	* characters starting at @a __pos. If the string is too
2850	* short, use the remainder of the characters. If @a __pos is
2851	* beyond the end of the string, out_of_range is thrown.
2852	*/
2853	basic_string
2854	substr(size_type __pos = 0, size_type __n = npos) const
2855	{ return basic_string(*this,
2856	_M_check(__pos, s: "basic_string::substr"), __n); }
2857
2858	/**
2859	* @brief Compare to a string.
2860	* @param __str String to compare against.
2861	* @return Integer < 0, 0, or > 0.
2862	*
2863	* Returns an integer < 0 if this string is ordered before @a
2864	* __str, 0 if their values are equivalent, or > 0 if this
2865	* string is ordered after @a __str. Determines the effective
2866	* length rlen of the strings to compare as the smallest of
2867	* size() and str.size(). The function then compares the two
2868	* strings by calling traits::compare(data(), str.data(),rlen).
2869	* If the result of the comparison is nonzero returns it,
2870	* otherwise the shorter one is ordered first.
2871	*/
2872	int
2873	compare(const basic_string& __str) const
2874	{
2875	const size_type __size = this->size();
2876	const size_type __osize = __str.size();
2877	const size_type __len = std::min(__size, __osize);
2878
2879	int __r = traits_type::compare(_M_data(), __str.data(), __len);
2880	if (!__r)
2881	__r = _S_compare(n1: __size, n2: __osize);
2882	return __r;
2883	}
2884
2885	#if __cplusplus >= 201703L
2886	/**
2887	* @brief Compare to a string_view.
2888	* @param __svt An object convertible to string_view to compare against.
2889	* @return Integer < 0, 0, or > 0.
2890	*/
2891	template<typename _Tp>
2892	_If_sv<_Tp, int>
2893	compare(const _Tp& __svt) const
2894	noexcept(is_same<_Tp, __sv_type>::value)
2895	{
2896	__sv_type __sv = __svt;
2897	const size_type __size = this->size();
2898	const size_type __osize = __sv.size();
2899	const size_type __len = std::min(__size, __osize);
2900
2901	int __r = traits_type::compare(_M_data(), __sv.data(), __len);
2902	if (!__r)
2903	__r = _S_compare(n1: __size, n2: __osize);
2904	return __r;
2905	}
2906
2907	/**
2908	* @brief Compare to a string_view.
2909	* @param __pos A position in the string to start comparing from.
2910	* @param __n The number of characters to compare.
2911	* @param __svt An object convertible to string_view to compare
2912	* against.
2913	* @return Integer < 0, 0, or > 0.
2914	*/
2915	template<typename _Tp>
2916	_If_sv<_Tp, int>
2917	compare(size_type __pos, size_type __n, const _Tp& __svt) const
2918	noexcept(is_same<_Tp, __sv_type>::value)
2919	{
2920	__sv_type __sv = __svt;
2921	return __sv_type(*this).substr(__pos, __n).compare(__sv);
2922	}
2923
2924	/**
2925	* @brief Compare to a string_view.
2926	* @param __pos1 A position in the string to start comparing from.
2927	* @param __n1 The number of characters to compare.
2928	* @param __svt An object convertible to string_view to compare
2929	* against.
2930	* @param __pos2 A position in the string_view to start comparing from.
2931	* @param __n2 The number of characters to compare.
2932	* @return Integer < 0, 0, or > 0.
2933	*/
2934	template<typename _Tp>
2935	_If_sv<_Tp, int>
2936	compare(size_type __pos1, size_type __n1, const _Tp& __svt,
2937	size_type __pos2, size_type __n2 = npos) const
2938	noexcept(is_same<_Tp, __sv_type>::value)
2939	{
2940	__sv_type __sv = __svt;
2941	return __sv_type(*this)
2942	.substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
2943	}
2944	#endif // C++17
2945
2946	/**
2947	* @brief Compare substring to a string.
2948	* @param __pos Index of first character of substring.
2949	* @param __n Number of characters in substring.
2950	* @param __str String to compare against.
2951	* @return Integer < 0, 0, or > 0.
2952	*
2953	* Form the substring of this string from the @a __n characters
2954	* starting at @a __pos. Returns an integer < 0 if the
2955	* substring is ordered before @a __str, 0 if their values are
2956	* equivalent, or > 0 if the substring is ordered after @a
2957	* __str. Determines the effective length rlen of the strings
2958	* to compare as the smallest of the length of the substring
2959	* and @a __str.size(). The function then compares the two
2960	* strings by calling
2961	* traits::compare(substring.data(),str.data(),rlen). If the
2962	* result of the comparison is nonzero returns it, otherwise
2963	* the shorter one is ordered first.
2964	*/
2965	int
2966	compare(size_type __pos, size_type __n, const basic_string& __str) const;
2967
2968	/**
2969	* @brief Compare substring to a substring.
2970	* @param __pos1 Index of first character of substring.
2971	* @param __n1 Number of characters in substring.
2972	* @param __str String to compare against.
2973	* @param __pos2 Index of first character of substring of str.
2974	* @param __n2 Number of characters in substring of str.
2975	* @return Integer < 0, 0, or > 0.
2976	*
2977	* Form the substring of this string from the @a __n1
2978	* characters starting at @a __pos1. Form the substring of @a
2979	* __str from the @a __n2 characters starting at @a __pos2.
2980	* Returns an integer < 0 if this substring is ordered before
2981	* the substring of @a __str, 0 if their values are equivalent,
2982	* or > 0 if this substring is ordered after the substring of
2983	* @a __str. Determines the effective length rlen of the
2984	* strings to compare as the smallest of the lengths of the
2985	* substrings. The function then compares the two strings by
2986	* calling
2987	* traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
2988	* If the result of the comparison is nonzero returns it,
2989	* otherwise the shorter one is ordered first.
2990	*/
2991	int
2992	compare(size_type __pos1, size_type __n1, const basic_string& __str,
2993	size_type __pos2, size_type __n2 = npos) const;
2994
2995	/**
2996	* @brief Compare to a C string.
2997	* @param __s C string to compare against.
2998	* @return Integer < 0, 0, or > 0.
2999	*
3000	* Returns an integer < 0 if this string is ordered before @a __s, 0 if
3001	* their values are equivalent, or > 0 if this string is ordered after
3002	* @a __s. Determines the effective length rlen of the strings to
3003	* compare as the smallest of size() and the length of a string
3004	* constructed from @a __s. The function then compares the two strings
3005	* by calling traits::compare(data(),s,rlen). If the result of the
3006	* comparison is nonzero returns it, otherwise the shorter one is
3007	* ordered first.
3008	*/
3009	int
3010	compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
3011
3012	// _GLIBCXX_RESOLVE_LIB_DEFECTS
3013	// 5 String::compare specification questionable
3014	/**
3015	* @brief Compare substring to a C string.
3016	* @param __pos Index of first character of substring.
3017	* @param __n1 Number of characters in substring.
3018	* @param __s C string to compare against.
3019	* @return Integer < 0, 0, or > 0.
3020	*
3021	* Form the substring of this string from the @a __n1
3022	* characters starting at @a pos. Returns an integer < 0 if
3023	* the substring is ordered before @a __s, 0 if their values
3024	* are equivalent, or > 0 if the substring is ordered after @a
3025	* __s. Determines the effective length rlen of the strings to
3026	* compare as the smallest of the length of the substring and
3027	* the length of a string constructed from @a __s. The
3028	* function then compares the two string by calling
3029	* traits::compare(substring.data(),__s,rlen). If the result of
3030	* the comparison is nonzero returns it, otherwise the shorter
3031	* one is ordered first.
3032	*/
3033	int
3034	compare(size_type __pos, size_type __n1, const _CharT* __s) const;
3035
3036	/**
3037	* @brief Compare substring against a character %array.
3038	* @param __pos Index of first character of substring.
3039	* @param __n1 Number of characters in substring.
3040	* @param __s character %array to compare against.
3041	* @param __n2 Number of characters of s.
3042	* @return Integer < 0, 0, or > 0.
3043	*
3044	* Form the substring of this string from the @a __n1
3045	* characters starting at @a __pos. Form a string from the
3046	* first @a __n2 characters of @a __s. Returns an integer < 0
3047	* if this substring is ordered before the string from @a __s,
3048	* 0 if their values are equivalent, or > 0 if this substring
3049	* is ordered after the string from @a __s. Determines the
3050	* effective length rlen of the strings to compare as the
3051	* smallest of the length of the substring and @a __n2. The
3052	* function then compares the two strings by calling
3053	* traits::compare(substring.data(),s,rlen). If the result of
3054	* the comparison is nonzero returns it, otherwise the shorter
3055	* one is ordered first.
3056	*
3057	* NB: s must have at least n2 characters, &apos;\\0&apos; has
3058	* no special meaning.
3059	*/
3060	int
3061	compare(size_type __pos, size_type __n1, const _CharT* __s,
3062	size_type __n2) const;
3063
3064	#if __cplusplus > 201703L
3065	bool
3066	starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3067	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3068
3069	bool
3070	starts_with(_CharT __x) const noexcept
3071	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3072
3073	bool
3074	starts_with(const _CharT* __x) const noexcept
3075	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
3076
3077	bool
3078	ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
3079	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3080
3081	bool
3082	ends_with(_CharT __x) const noexcept
3083	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3084
3085	bool
3086	ends_with(const _CharT* __x) const noexcept
3087	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
3088	#endif // C++20
3089
3090	#if __cplusplus > 202002L
3091	bool
3092	contains(basic_string_view<_CharT, _Traits> __x) const noexcept
3093	{ return __sv_type(this->data(), this->size()).contains(__x); }
3094
3095	bool
3096	contains(_CharT __x) const noexcept
3097	{ return __sv_type(this->data(), this->size()).contains(__x); }
3098
3099	bool
3100	contains(const _CharT* __x) const noexcept
3101	{ return __sv_type(this->data(), this->size()).contains(__x); }
3102	#endif // C++23
3103
3104	// Allow basic_stringbuf::__xfer_bufptrs to call _M_length:
3105	template<typename, typename, typename> friend class basic_stringbuf;
3106	};
3107	_GLIBCXX_END_NAMESPACE_CXX11
3108	#else // !_GLIBCXX_USE_CXX11_ABI
3109	// Reference-counted COW string implentation
3110
3111	/**
3112	* @class basic_string basic_string.h <string>
3113	* @brief Managing sequences of characters and character-like objects.
3114	*
3115	* @ingroup strings
3116	* @ingroup sequences
3117	*
3118	* @tparam _CharT Type of character
3119	* @tparam _Traits Traits for character type, defaults to
3120	* char_traits<_CharT>.
3121	* @tparam _Alloc Allocator type, defaults to allocator<_CharT>.
3122	*
3123	* Meets the requirements of a <a href="tables.html#65">container</a>, a
3124	* <a href="tables.html#66">reversible container</a>, and a
3125	* <a href="tables.html#67">sequence</a>. Of the
3126	* <a href="tables.html#68">optional sequence requirements</a>, only
3127	* @c push_back, @c at, and @c %array access are supported.
3128	*
3129	* @doctodo
3130	*
3131	*
3132	* Documentation? What's that?
3133	* Nathan Myers <ncm@cantrip.org>.
3134	*
3135	* A string looks like this:
3136	*
3137	* @code
3138	* [_Rep]
3139	* _M_length
3140	* [basic_string<char_type>] _M_capacity
3141	* _M_dataplus _M_refcount
3142	* _M_p ----------------> unnamed array of char_type
3143	* @endcode
3144	*
3145	* Where the _M_p points to the first character in the string, and
3146	* you cast it to a pointer-to-_Rep and subtract 1 to get a
3147	* pointer to the header.
3148	*
3149	* This approach has the enormous advantage that a string object
3150	* requires only one allocation. All the ugliness is confined
3151	* within a single %pair of inline functions, which each compile to
3152	* a single @a add instruction: _Rep::_M_data(), and
3153	* string::_M_rep(); and the allocation function which gets a
3154	* block of raw bytes and with room enough and constructs a _Rep
3155	* object at the front.
3156	*
3157	* The reason you want _M_data pointing to the character %array and
3158	* not the _Rep is so that the debugger can see the string
3159	* contents. (Probably we should add a non-inline member to get
3160	* the _Rep for the debugger to use, so users can check the actual
3161	* string length.)
3162	*
3163	* Note that the _Rep object is a POD so that you can have a
3164	* static <em>empty string</em> _Rep object already @a constructed before
3165	* static constructors have run. The reference-count encoding is
3166	* chosen so that a 0 indicates one reference, so you never try to
3167	* destroy the empty-string _Rep object.
3168	*
3169	* All but the last paragraph is considered pretty conventional
3170	* for a C++ string implementation.
3171	*/
3172	// 21.3 Template class basic_string
3173	template<typename _CharT, typename _Traits, typename _Alloc>
3174	class basic_string
3175	{
3176	typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
3177	rebind<_CharT>::other _CharT_alloc_type;
3178	typedef __gnu_cxx::__alloc_traits<_CharT_alloc_type> _CharT_alloc_traits;
3179
3180	// Types:
3181	public:
3182	typedef _Traits traits_type;
3183	typedef typename _Traits::char_type value_type;
3184	typedef _Alloc allocator_type;
3185	typedef typename _CharT_alloc_traits::size_type size_type;
3186	typedef typename _CharT_alloc_traits::difference_type difference_type;
3187	#if __cplusplus < 201103L
3188	typedef typename _CharT_alloc_type::reference reference;
3189	typedef typename _CharT_alloc_type::const_reference const_reference;
3190	#else
3191	typedef value_type& reference;
3192	typedef const value_type& const_reference;
3193	#endif
3194	typedef typename _CharT_alloc_traits::pointer pointer;
3195	typedef typename _CharT_alloc_traits::const_pointer const_pointer;
3196	typedef __gnu_cxx::__normal_iterator<pointer, basic_string> iterator;
3197	typedef __gnu_cxx::__normal_iterator<const_pointer, basic_string>
3198	const_iterator;
3199	typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
3200	typedef std::reverse_iterator<iterator> reverse_iterator;
3201
3202	protected:
3203	// type used for positions in insert, erase etc.
3204	typedef iterator __const_iterator;
3205
3206	private:
3207	// _Rep: string representation
3208	// Invariants:
3209	// 1. String really contains _M_length + 1 characters: due to 21.3.4
3210	// must be kept null-terminated.
3211	// 2. _M_capacity >= _M_length
3212	// Allocated memory is always (_M_capacity + 1) * sizeof(_CharT).
3213	// 3. _M_refcount has three states:
3214	// -1: leaked, one reference, no ref-copies allowed, non-const.
3215	// 0: one reference, non-const.
3216	// n>0: n + 1 references, operations require a lock, const.
3217	// 4. All fields==0 is an empty string, given the extra storage
3218	// beyond-the-end for a null terminator; thus, the shared
3219	// empty string representation needs no constructor.
3220
3221	struct _Rep_base
3222	{
3223	size_type _M_length;
3224	size_type _M_capacity;
3225	_Atomic_word _M_refcount;
3226	};
3227
3228	struct _Rep : _Rep_base
3229	{
3230	// Types:
3231	typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
3232	rebind<char>::other _Raw_bytes_alloc;
3233
3234	// (Public) Data members:
3235
3236	// The maximum number of individual char_type elements of an
3237	// individual string is determined by _S_max_size. This is the
3238	// value that will be returned by max_size(). (Whereas npos
3239	// is the maximum number of bytes the allocator can allocate.)
3240	// If one was to divvy up the theoretical largest size string,
3241	// with a terminating character and m _CharT elements, it'd
3242	// look like this:
3243	// npos = sizeof(_Rep) + (m * sizeof(_CharT)) + sizeof(_CharT)
3244	// Solving for m:
3245	// m = ((npos - sizeof(_Rep))/sizeof(CharT)) - 1
3246	// In addition, this implementation quarters this amount.
3247	static const size_type _S_max_size;
3248	static const _CharT _S_terminal;
3249
3250	// The following storage is init'd to 0 by the linker, resulting
3251	// (carefully) in an empty string with one reference.
3252	static size_type _S_empty_rep_storage[];
3253
3254	static _Rep&
3255	_S_empty_rep() _GLIBCXX_NOEXCEPT
3256	{
3257	// NB: Mild hack to avoid strict-aliasing warnings. Note that
3258	// _S_empty_rep_storage is never modified and the punning should
3259	// be reasonably safe in this case.
3260	void* __p = reinterpret_cast<void*>(&_S_empty_rep_storage);
3261	return *reinterpret_cast<_Rep*>(__p);
3262	}
3263
3264	bool
3265	_M_is_leaked() const _GLIBCXX_NOEXCEPT
3266	{
3267	#if defined(__GTHREADS)
3268	// _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3269	// so we need to use an atomic load. However, _M_is_leaked
3270	// predicate does not change concurrently (i.e. the string is either
3271	// leaked or not), so a relaxed load is enough.
3272	return __atomic_load_n(&this->_M_refcount, __ATOMIC_RELAXED) < 0;
3273	#else
3274	return this->_M_refcount < 0;
3275	#endif
3276	}
3277
3278	bool
3279	_M_is_shared() const _GLIBCXX_NOEXCEPT
3280	{
3281	#if defined(__GTHREADS)
3282	// _M_refcount is mutated concurrently by _M_refcopy/_M_dispose,
3283	// so we need to use an atomic load. Another thread can drop last
3284	// but one reference concurrently with this check, so we need this
3285	// load to be acquire to synchronize with release fetch_and_add in
3286	// _M_dispose.
3287	return __atomic_load_n(&this->_M_refcount, __ATOMIC_ACQUIRE) > 0;
3288	#else
3289	return this->_M_refcount > 0;
3290	#endif
3291	}
3292
3293	void
3294	_M_set_leaked() _GLIBCXX_NOEXCEPT
3295	{ this->_M_refcount = -1; }
3296
3297	void
3298	_M_set_sharable() _GLIBCXX_NOEXCEPT
3299	{ this->_M_refcount = 0; }
3300
3301	void
3302	_M_set_length_and_sharable(size_type __n) _GLIBCXX_NOEXCEPT
3303	{
3304	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3305	if (__builtin_expect(this != &_S_empty_rep(), false))
3306	#endif
3307	{
3308	this->_M_set_sharable(); // One reference.
3309	this->_M_length = __n;
3310	traits_type::assign(this->_M_refdata()[__n], _S_terminal);
3311	// grrr. (per 21.3.4)
3312	// You cannot leave those LWG people alone for a second.
3313	}
3314	}
3315
3316	_CharT*
3317	_M_refdata() throw()
3318	{ return reinterpret_cast<_CharT*>(this + 1); }
3319
3320	_CharT*
3321	_M_grab(const _Alloc& __alloc1, const _Alloc& __alloc2)
3322	{
3323	return (!_M_is_leaked() && __alloc1 == __alloc2)
3324	? _M_refcopy() : _M_clone(__alloc1);
3325	}
3326
3327	// Create & Destroy
3328	static _Rep*
3329	_S_create(size_type, size_type, const _Alloc&);
3330
3331	void
3332	_M_dispose(const _Alloc& __a) _GLIBCXX_NOEXCEPT
3333	{
3334	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3335	if (__builtin_expect(this != &_S_empty_rep(), false))
3336	#endif
3337	{
3338	// Be race-detector-friendly. For more info see bits/c++config.
3339	_GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&this->_M_refcount);
3340	// Decrement of _M_refcount is acq_rel, because:
3341	// - all but last decrements need to release to synchronize with
3342	// the last decrement that will delete the object.
3343	// - the last decrement needs to acquire to synchronize with
3344	// all the previous decrements.
3345	// - last but one decrement needs to release to synchronize with
3346	// the acquire load in _M_is_shared that will conclude that
3347	// the object is not shared anymore.
3348	if (__gnu_cxx::__exchange_and_add_dispatch(&this->_M_refcount,
3349	-1) <= 0)
3350	{
3351	_GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&this->_M_refcount);
3352	_M_destroy(__a);
3353	}
3354	}
3355	} // XXX MT
3356
3357	void
3358	_M_destroy(const _Alloc&) throw();
3359
3360	_CharT*
3361	_M_refcopy() throw()
3362	{
3363	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3364	if (__builtin_expect(this != &_S_empty_rep(), false))
3365	#endif
3366	__gnu_cxx::__atomic_add_dispatch(&this->_M_refcount, 1);
3367	return _M_refdata();
3368	} // XXX MT
3369
3370	_CharT*
3371	_M_clone(const _Alloc&, size_type __res = 0);
3372	};
3373
3374	// Use empty-base optimization: http://www.cantrip.org/emptyopt.html
3375	struct _Alloc_hider : _Alloc
3376	{
3377	_Alloc_hider(_CharT* __dat, const _Alloc& __a) _GLIBCXX_NOEXCEPT
3378	: _Alloc(__a), _M_p(__dat) { }
3379
3380	_CharT* _M_p; // The actual data.
3381	};
3382
3383	public:
3384	// Data Members (public):
3385	// NB: This is an unsigned type, and thus represents the maximum
3386	// size that the allocator can hold.
3387	/// Value returned by various member functions when they fail.
3388	static const size_type npos = static_cast<size_type>(-1);
3389
3390	private:
3391	// Data Members (private):
3392	mutable _Alloc_hider _M_dataplus;
3393
3394	_CharT*
3395	_M_data() const _GLIBCXX_NOEXCEPT
3396	{ return _M_dataplus._M_p; }
3397
3398	_CharT*
3399	_M_data(_CharT* __p) _GLIBCXX_NOEXCEPT
3400	{ return (_M_dataplus._M_p = __p); }
3401
3402	_Rep*
3403	_M_rep() const _GLIBCXX_NOEXCEPT
3404	{ return &((reinterpret_cast<_Rep*> (_M_data()))[-1]); }
3405
3406	// For the internal use we have functions similar to `begin'/`end'
3407	// but they do not call _M_leak.
3408	iterator
3409	_M_ibegin() const _GLIBCXX_NOEXCEPT
3410	{ return iterator(_M_data()); }
3411
3412	iterator
3413	_M_iend() const _GLIBCXX_NOEXCEPT
3414	{ return iterator(_M_data() + this->size()); }
3415
3416	void
3417	_M_leak() // for use in begin() & non-const op[]
3418	{
3419	if (!_M_rep()->_M_is_leaked())
3420	_M_leak_hard();
3421	}
3422
3423	size_type
3424	_M_check(size_type __pos, const char* __s) const
3425	{
3426	if (__pos > this->size())
3427	__throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > "
3428	"this->size() (which is %zu)"),
3429	__s, __pos, this->size());
3430	return __pos;
3431	}
3432
3433	void
3434	_M_check_length(size_type __n1, size_type __n2, const char* __s) const
3435	{
3436	if (this->max_size() - (this->size() - __n1) < __n2)
3437	__throw_length_error(__N(__s));
3438	}
3439
3440	// NB: _M_limit doesn't check for a bad __pos value.
3441	size_type
3442	_M_limit(size_type __pos, size_type __off) const _GLIBCXX_NOEXCEPT
3443	{
3444	const bool __testoff = __off < this->size() - __pos;
3445	return __testoff ? __off : this->size() - __pos;
3446	}
3447
3448	// True if _Rep and source do not overlap.
3449	bool
3450	_M_disjunct(const _CharT* __s) const _GLIBCXX_NOEXCEPT
3451	{
3452	return (less<const _CharT*>()(__s, _M_data())
3453	|| less<const _CharT*>()(_M_data() + this->size(), __s));
3454	}
3455
3456	// When __n = 1 way faster than the general multichar
3457	// traits_type::copy/move/assign.
3458	static void
3459	_M_copy(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3460	{
3461	if (__n == 1)
3462	traits_type::assign(*__d, *__s);
3463	else
3464	traits_type::copy(__d, __s, __n);
3465	}
3466
3467	static void
3468	_M_move(_CharT* __d, const _CharT* __s, size_type __n) _GLIBCXX_NOEXCEPT
3469	{
3470	if (__n == 1)
3471	traits_type::assign(*__d, *__s);
3472	else
3473	traits_type::move(__d, __s, __n);
3474	}
3475
3476	static void
3477	_M_assign(_CharT* __d, size_type __n, _CharT __c) _GLIBCXX_NOEXCEPT
3478	{
3479	if (__n == 1)
3480	traits_type::assign(*__d, __c);
3481	else
3482	traits_type::assign(__d, __n, __c);
3483	}
3484
3485	// _S_copy_chars is a separate template to permit specialization
3486	// to optimize for the common case of pointers as iterators.
3487	template<class _Iterator>
3488	static void
3489	_S_copy_chars(_CharT* __p, _Iterator __k1, _Iterator __k2)
3490	{
3491	for (; __k1 != __k2; ++__k1, (void)++__p)
3492	traits_type::assign(*__p, *__k1); // These types are off.
3493	}
3494
3495	static void
3496	_S_copy_chars(_CharT* __p, iterator __k1, iterator __k2) _GLIBCXX_NOEXCEPT
3497	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
3498
3499	static void
3500	_S_copy_chars(_CharT* __p, const_iterator __k1, const_iterator __k2)
3501	_GLIBCXX_NOEXCEPT
3502	{ _S_copy_chars(__p, __k1.base(), __k2.base()); }
3503
3504	static void
3505	_S_copy_chars(_CharT* __p, _CharT* __k1, _CharT* __k2) _GLIBCXX_NOEXCEPT
3506	{ _M_copy(__p, __k1, __k2 - __k1); }
3507
3508	static void
3509	_S_copy_chars(_CharT* __p, const _CharT* __k1, const _CharT* __k2)
3510	_GLIBCXX_NOEXCEPT
3511	{ _M_copy(__p, __k1, __k2 - __k1); }
3512
3513	static int
3514	_S_compare(size_type __n1, size_type __n2) _GLIBCXX_NOEXCEPT
3515	{
3516	const difference_type __d = difference_type(__n1 - __n2);
3517
3518	if (__d > __gnu_cxx::__numeric_traits<int>::__max)
3519	return __gnu_cxx::__numeric_traits<int>::__max;
3520	else if (__d < __gnu_cxx::__numeric_traits<int>::__min)
3521	return __gnu_cxx::__numeric_traits<int>::__min;
3522	else
3523	return int(__d);
3524	}
3525
3526	void
3527	_M_mutate(size_type __pos, size_type __len1, size_type __len2);
3528
3529	void
3530	_M_leak_hard();
3531
3532	static _Rep&
3533	_S_empty_rep() _GLIBCXX_NOEXCEPT
3534	{ return _Rep::_S_empty_rep(); }
3535
3536	#if __cplusplus >= 201703L
3537	// A helper type for avoiding boiler-plate.
3538	typedef basic_string_view<_CharT, _Traits> __sv_type;
3539
3540	template<typename _Tp, typename _Res>
3541	using _If_sv = enable_if_t<
3542	__and_<is_convertible<const _Tp&, __sv_type>,
3543	__not_<is_convertible<const _Tp*, const basic_string*>>,
3544	__not_<is_convertible<const _Tp&, const _CharT*>>>::value,
3545	_Res>;
3546
3547	// Allows an implicit conversion to __sv_type.
3548	static __sv_type
3549	_S_to_string_view(__sv_type __svt) noexcept
3550	{ return __svt; }
3551
3552	// Wraps a string_view by explicit conversion and thus
3553	// allows to add an internal constructor that does not
3554	// participate in overload resolution when a string_view
3555	// is provided.
3556	struct __sv_wrapper
3557	{
3558	explicit __sv_wrapper(__sv_type __sv) noexcept : _M_sv(__sv) { }
3559	__sv_type _M_sv;
3560	};
3561
3562	/**
3563	* @brief Only internally used: Construct string from a string view
3564	* wrapper.
3565	* @param __svw string view wrapper.
3566	* @param __a Allocator to use.
3567	*/
3568	explicit
3569	basic_string(__sv_wrapper __svw, const _Alloc& __a)
3570	: basic_string(__svw._M_sv.data(), __svw._M_sv.size(), __a) { }
3571	#endif
3572
3573	public:
3574	// Construct/copy/destroy:
3575	// NB: We overload ctors in some cases instead of using default
3576	// arguments, per 17.4.4.4 para. 2 item 2.
3577
3578	/**
3579	* @brief Default constructor creates an empty string.
3580	*/
3581	basic_string()
3582	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3583	_GLIBCXX_NOEXCEPT
3584	: _M_dataplus(_S_empty_rep()._M_refdata(), _Alloc())
3585	#else
3586	: _M_dataplus(_S_construct(size_type(), _CharT(), _Alloc()), _Alloc())
3587	#endif
3588	{ }
3589
3590	/**
3591	* @brief Construct an empty string using allocator @a a.
3592	*/
3593	explicit
3594	basic_string(const _Alloc& __a)
3595	: _M_dataplus(_S_construct(size_type(), _CharT(), __a), __a)
3596	{ }
3597
3598	// NB: per LWG issue 42, semantics different from IS:
3599	/**
3600	* @brief Construct string with copy of value of @a str.
3601	* @param __str Source string.
3602	*/
3603	basic_string(const basic_string& __str)
3604	: _M_dataplus(__str._M_rep()->_M_grab(_Alloc(__str.get_allocator()),
3605	__str.get_allocator()),
3606	__str.get_allocator())
3607	{ }
3608
3609	// _GLIBCXX_RESOLVE_LIB_DEFECTS
3610	// 2583. no way to supply an allocator for basic_string(str, pos)
3611	/**
3612	* @brief Construct string as copy of a substring.
3613	* @param __str Source string.
3614	* @param __pos Index of first character to copy from.
3615	* @param __a Allocator to use.
3616	*/
3617	basic_string(const basic_string& __str, size_type __pos,
3618	const _Alloc& __a = _Alloc());
3619
3620	/**
3621	* @brief Construct string as copy of a substring.
3622	* @param __str Source string.
3623	* @param __pos Index of first character to copy from.
3624	* @param __n Number of characters to copy.
3625	*/
3626	basic_string(const basic_string& __str, size_type __pos,
3627	size_type __n);
3628	/**
3629	* @brief Construct string as copy of a substring.
3630	* @param __str Source string.
3631	* @param __pos Index of first character to copy from.
3632	* @param __n Number of characters to copy.
3633	* @param __a Allocator to use.
3634	*/
3635	basic_string(const basic_string& __str, size_type __pos,
3636	size_type __n, const _Alloc& __a);
3637
3638	/**
3639	* @brief Construct string initialized by a character %array.
3640	* @param __s Source character %array.
3641	* @param __n Number of characters to copy.
3642	* @param __a Allocator to use (default is default allocator).
3643	*
3644	* NB: @a __s must have at least @a __n characters, &apos;\\0&apos;
3645	* has no special meaning.
3646	*/
3647	basic_string(const _CharT* __s, size_type __n,
3648	const _Alloc& __a = _Alloc())
3649	: _M_dataplus(_S_construct(__s, __s + __n, __a), __a)
3650	{ }
3651
3652	/**
3653	* @brief Construct string as copy of a C string.
3654	* @param __s Source C string.
3655	* @param __a Allocator to use (default is default allocator).
3656	*/
3657	#if __cpp_deduction_guides && ! defined _GLIBCXX_DEFINING_STRING_INSTANTIATIONS
3658	// _GLIBCXX_RESOLVE_LIB_DEFECTS
3659	// 3076. basic_string CTAD ambiguity
3660	template<typename = _RequireAllocator<_Alloc>>
3661	#endif
3662	basic_string(const _CharT* __s, const _Alloc& __a = _Alloc())
3663	: _M_dataplus(_S_construct(__s, __s ? __s + traits_type::length(__s) :
3664	__s + npos, __a), __a)
3665	{ }
3666
3667	/**
3668	* @brief Construct string as multiple characters.
3669	* @param __n Number of characters.
3670	* @param __c Character to use.
3671	* @param __a Allocator to use (default is default allocator).
3672	*/
3673	basic_string(size_type __n, _CharT __c, const _Alloc& __a = _Alloc())
3674	: _M_dataplus(_S_construct(__n, __c, __a), __a)
3675	{ }
3676
3677	#if __cplusplus >= 201103L
3678	/**
3679	* @brief Move construct string.
3680	* @param __str Source string.
3681	*
3682	* The newly-created string contains the exact contents of @a __str.
3683	* @a __str is a valid, but unspecified string.
3684	*/
3685	basic_string(basic_string&& __str)
3686	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3687	noexcept // FIXME C++11: should always be noexcept.
3688	#endif
3689	: _M_dataplus(std::move(__str._M_dataplus))
3690	{
3691	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3692	__str._M_data(_S_empty_rep()._M_refdata());
3693	#else
3694	__str._M_data(_S_construct(size_type(), _CharT(), get_allocator()));
3695	#endif
3696	}
3697
3698	/**
3699	* @brief Construct string from an initializer %list.
3700	* @param __l std::initializer_list of characters.
3701	* @param __a Allocator to use (default is default allocator).
3702	*/
3703	basic_string(initializer_list<_CharT> __l, const _Alloc& __a = _Alloc())
3704	: _M_dataplus(_S_construct(__l.begin(), __l.end(), __a), __a)
3705	{ }
3706
3707	basic_string(const basic_string& __str, const _Alloc& __a)
3708	: _M_dataplus(__str._M_rep()->_M_grab(__a, __str.get_allocator()), __a)
3709	{ }
3710
3711	basic_string(basic_string&& __str, const _Alloc& __a)
3712	: _M_dataplus(__str._M_data(), __a)
3713	{
3714	if (__a == __str.get_allocator())
3715	{
3716	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
3717	__str._M_data(_S_empty_rep()._M_refdata());
3718	#else
3719	__str._M_data(_S_construct(size_type(), _CharT(), __a));
3720	#endif
3721	}
3722	else
3723	_M_dataplus._M_p = _S_construct(__str.begin(), __str.end(), __a);
3724	}
3725	#endif // C++11
3726
3727	/**
3728	* @brief Construct string as copy of a range.
3729	* @param __beg Start of range.
3730	* @param __end End of range.
3731	* @param __a Allocator to use (default is default allocator).
3732	*/
3733	template<class _InputIterator>
3734	basic_string(_InputIterator __beg, _InputIterator __end,
3735	const _Alloc& __a = _Alloc())
3736	: _M_dataplus(_S_construct(__beg, __end, __a), __a)
3737	{ }
3738
3739	#if __cplusplus >= 201703L
3740	/**
3741	* @brief Construct string from a substring of a string_view.
3742	* @param __t Source object convertible to string view.
3743	* @param __pos The index of the first character to copy from __t.
3744	* @param __n The number of characters to copy from __t.
3745	* @param __a Allocator to use.
3746	*/
3747	template<typename _Tp,
3748	typename = enable_if_t<is_convertible_v<const _Tp&, __sv_type>>>
3749	basic_string(const _Tp& __t, size_type __pos, size_type __n,
3750	const _Alloc& __a = _Alloc())
3751	: basic_string(_S_to_string_view(__t).substr(__pos, __n), __a) { }
3752
3753	/**
3754	* @brief Construct string from a string_view.
3755	* @param __t Source object convertible to string view.
3756	* @param __a Allocator to use (default is default allocator).
3757	*/
3758	template<typename _Tp, typename = _If_sv<_Tp, void>>
3759	explicit
3760	basic_string(const _Tp& __t, const _Alloc& __a = _Alloc())
3761	: basic_string(__sv_wrapper(_S_to_string_view(__t)), __a) { }
3762	#endif // C++17
3763
3764	/**
3765	* @brief Destroy the string instance.
3766	*/
3767	~basic_string() _GLIBCXX_NOEXCEPT
3768	{ _M_rep()->_M_dispose(this->get_allocator()); }
3769
3770	/**
3771	* @brief Assign the value of @a str to this string.
3772	* @param __str Source string.
3773	*/
3774	basic_string&
3775	operator=(const basic_string& __str)
3776	{ return this->assign(__str); }
3777
3778	/**
3779	* @brief Copy contents of @a s into this string.
3780	* @param __s Source null-terminated string.
3781	*/
3782	basic_string&
3783	operator=(const _CharT* __s)
3784	{ return this->assign(__s); }
3785
3786	/**
3787	* @brief Set value to string of length 1.
3788	* @param __c Source character.
3789	*
3790	* Assigning to a character makes this string length 1 and
3791	* (*this)[0] == @a c.
3792	*/
3793	basic_string&
3794	operator=(_CharT __c)
3795	{
3796	this->assign(1, __c);
3797	return *this;
3798	}
3799
3800	#if __cplusplus >= 201103L
3801	/**
3802	* @brief Move assign the value of @a str to this string.
3803	* @param __str Source string.
3804	*
3805	* The contents of @a str are moved into this string (without copying).
3806	* @a str is a valid, but unspecified string.
3807	*/
3808	basic_string&
3809	operator=(basic_string&& __str)
3810	_GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value)
3811	{
3812	// NB: DR 1204.
3813	this->swap(__str);
3814	return *this;
3815	}
3816
3817	/**
3818	* @brief Set value to string constructed from initializer %list.
3819	* @param __l std::initializer_list.
3820	*/
3821	basic_string&
3822	operator=(initializer_list<_CharT> __l)
3823	{
3824	this->assign(__l.begin(), __l.size());
3825	return *this;
3826	}
3827	#endif // C++11
3828
3829	#if __cplusplus >= 201703L
3830	/**
3831	* @brief Set value to string constructed from a string_view.
3832	* @param __svt An object convertible to string_view.
3833	*/
3834	template<typename _Tp>
3835	_If_sv<_Tp, basic_string&>
3836	operator=(const _Tp& __svt)
3837	{ return this->assign(__svt); }
3838
3839	/**
3840	* @brief Convert to a string_view.
3841	* @return A string_view.
3842	*/
3843	operator __sv_type() const noexcept
3844	{ return __sv_type(data(), size()); }
3845	#endif // C++17
3846
3847	// Iterators:
3848	/**
3849	* Returns a read/write iterator that points to the first character in
3850	* the %string. Unshares the string.
3851	*/
3852	iterator
3853	begin() // FIXME C++11: should be noexcept.
3854	{
3855	_M_leak();
3856	return iterator(_M_data());
3857	}
3858
3859	/**
3860	* Returns a read-only (constant) iterator that points to the first
3861	* character in the %string.
3862	*/
3863	const_iterator
3864	begin() const _GLIBCXX_NOEXCEPT
3865	{ return const_iterator(_M_data()); }
3866
3867	/**
3868	* Returns a read/write iterator that points one past the last
3869	* character in the %string. Unshares the string.
3870	*/
3871	iterator
3872	end() // FIXME C++11: should be noexcept.
3873	{
3874	_M_leak();
3875	return iterator(_M_data() + this->size());
3876	}
3877
3878	/**
3879	* Returns a read-only (constant) iterator that points one past the
3880	* last character in the %string.
3881	*/
3882	const_iterator
3883	end() const _GLIBCXX_NOEXCEPT
3884	{ return const_iterator(_M_data() + this->size()); }
3885
3886	/**
3887	* Returns a read/write reverse iterator that points to the last
3888	* character in the %string. Iteration is done in reverse element
3889	* order. Unshares the string.
3890	*/
3891	reverse_iterator
3892	rbegin() // FIXME C++11: should be noexcept.
3893	{ return reverse_iterator(this->end()); }
3894
3895	/**
3896	* Returns a read-only (constant) reverse iterator that points
3897	* to the last character in the %string. Iteration is done in
3898	* reverse element order.
3899	*/
3900	const_reverse_iterator
3901	rbegin() const _GLIBCXX_NOEXCEPT
3902	{ return const_reverse_iterator(this->end()); }
3903
3904	/**
3905	* Returns a read/write reverse iterator that points to one before the
3906	* first character in the %string. Iteration is done in reverse
3907	* element order. Unshares the string.
3908	*/
3909	reverse_iterator
3910	rend() // FIXME C++11: should be noexcept.
3911	{ return reverse_iterator(this->begin()); }
3912
3913	/**
3914	* Returns a read-only (constant) reverse iterator that points
3915	* to one before the first character in the %string. Iteration
3916	* is done in reverse element order.
3917	*/
3918	const_reverse_iterator
3919	rend() const _GLIBCXX_NOEXCEPT
3920	{ return const_reverse_iterator(this->begin()); }
3921
3922	#if __cplusplus >= 201103L
3923	/**
3924	* Returns a read-only (constant) iterator that points to the first
3925	* character in the %string.
3926	*/
3927	const_iterator
3928	cbegin() const noexcept
3929	{ return const_iterator(this->_M_data()); }
3930
3931	/**
3932	* Returns a read-only (constant) iterator that points one past the
3933	* last character in the %string.
3934	*/
3935	const_iterator
3936	cend() const noexcept
3937	{ return const_iterator(this->_M_data() + this->size()); }
3938
3939	/**
3940	* Returns a read-only (constant) reverse iterator that points
3941	* to the last character in the %string. Iteration is done in
3942	* reverse element order.
3943	*/
3944	const_reverse_iterator
3945	crbegin() const noexcept
3946	{ return const_reverse_iterator(this->end()); }
3947
3948	/**
3949	* Returns a read-only (constant) reverse iterator that points
3950	* to one before the first character in the %string. Iteration
3951	* is done in reverse element order.
3952	*/
3953	const_reverse_iterator
3954	crend() const noexcept
3955	{ return const_reverse_iterator(this->begin()); }
3956	#endif
3957
3958	public:
3959	// Capacity:
3960	/// Returns the number of characters in the string, not including any
3961	/// null-termination.
3962	size_type
3963	size() const _GLIBCXX_NOEXCEPT
3964	{ return _M_rep()->_M_length; }
3965
3966	/// Returns the number of characters in the string, not including any
3967	/// null-termination.
3968	size_type
3969	length() const _GLIBCXX_NOEXCEPT
3970	{ return _M_rep()->_M_length; }
3971
3972	/// Returns the size() of the largest possible %string.
3973	size_type
3974	max_size() const _GLIBCXX_NOEXCEPT
3975	{ return _Rep::_S_max_size; }
3976
3977	/**
3978	* @brief Resizes the %string to the specified number of characters.
3979	* @param __n Number of characters the %string should contain.
3980	* @param __c Character to fill any new elements.
3981	*
3982	* This function will %resize the %string to the specified
3983	* number of characters. If the number is smaller than the
3984	* %string's current size the %string is truncated, otherwise
3985	* the %string is extended and new elements are %set to @a __c.
3986	*/
3987	void
3988	resize(size_type __n, _CharT __c);
3989
3990	/**
3991	* @brief Resizes the %string to the specified number of characters.
3992	* @param __n Number of characters the %string should contain.
3993	*
3994	* This function will resize the %string to the specified length. If
3995	* the new size is smaller than the %string's current size the %string
3996	* is truncated, otherwise the %string is extended and new characters
3997	* are default-constructed. For basic types such as char, this means
3998	* setting them to 0.
3999	*/
4000	void
4001	resize(size_type __n)
4002	{ this->resize(__n, _CharT()); }
4003
4004	#if __cplusplus >= 201103L
4005	#pragma GCC diagnostic push
4006	#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
4007	/// A non-binding request to reduce capacity() to size().
4008	void
4009	shrink_to_fit() noexcept
4010	{ reserve(); }
4011	#pragma GCC diagnostic pop
4012	#endif
4013
4014	/**
4015	* Returns the total number of characters that the %string can hold
4016	* before needing to allocate more memory.
4017	*/
4018	size_type
4019	capacity() const _GLIBCXX_NOEXCEPT
4020	{ return _M_rep()->_M_capacity; }
4021
4022	/**
4023	* @brief Attempt to preallocate enough memory for specified number of
4024	* characters.
4025	* @param __res_arg Number of characters required.
4026	* @throw std::length_error If @a __res_arg exceeds @c max_size().
4027	*
4028	* This function attempts to reserve enough memory for the
4029	* %string to hold the specified number of characters. If the
4030	* number requested is more than max_size(), length_error is
4031	* thrown.
4032	*
4033	* The advantage of this function is that if optimal code is a
4034	* necessity and the user can determine the string length that will be
4035	* required, the user can reserve the memory in %advance, and thus
4036	* prevent a possible reallocation of memory and copying of %string
4037	* data.
4038	*/
4039	void
4040	reserve(size_type __res_arg);
4041
4042	/// Equivalent to shrink_to_fit().
4043	#if __cplusplus > 201703L
4044	[[deprecated("use shrink_to_fit() instead")]]
4045	#endif
4046	void
4047	reserve();
4048
4049	/**
4050	* Erases the string, making it empty.
4051	*/
4052	#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
4053	void
4054	clear() _GLIBCXX_NOEXCEPT
4055	{
4056	if (_M_rep()->_M_is_shared())
4057	{
4058	_M_rep()->_M_dispose(this->get_allocator());
4059	_M_data(_S_empty_rep()._M_refdata());
4060	}
4061	else
4062	_M_rep()->_M_set_length_and_sharable(0);
4063	}
4064	#else
4065	// PR 56166: this should not throw.
4066	void
4067	clear()
4068	{ _M_mutate(0, this->size(), 0); }
4069	#endif
4070
4071	/**
4072	* Returns true if the %string is empty. Equivalent to
4073	* <code>*this == ""</code>.
4074	*/
4075	_GLIBCXX_NODISCARD bool
4076	empty() const _GLIBCXX_NOEXCEPT
4077	{ return this->size() == 0; }
4078
4079	// Element access:
4080	/**
4081	* @brief Subscript access to the data contained in the %string.
4082	* @param __pos The index of the character to access.
4083	* @return Read-only (constant) reference to the character.
4084	*
4085	* This operator allows for easy, array-style, data access.
4086	* Note that data access with this operator is unchecked and
4087	* out_of_range lookups are not defined. (For checked lookups
4088	* see at().)
4089	*/
4090	const_reference
4091	operator[] (size_type __pos) const _GLIBCXX_NOEXCEPT
4092	{
4093	__glibcxx_assert(__pos <= size());
4094	return _M_data()[__pos];
4095	}
4096
4097	/**
4098	* @brief Subscript access to the data contained in the %string.
4099	* @param __pos The index of the character to access.
4100	* @return Read/write reference to the character.
4101	*
4102	* This operator allows for easy, array-style, data access.
4103	* Note that data access with this operator is unchecked and
4104	* out_of_range lookups are not defined. (For checked lookups
4105	* see at().) Unshares the string.
4106	*/
4107	reference
4108	operator[](size_type __pos)
4109	{
4110	// Allow pos == size() both in C++98 mode, as v3 extension,
4111	// and in C++11 mode.
4112	__glibcxx_assert(__pos <= size());
4113	// In pedantic mode be strict in C++98 mode.
4114	_GLIBCXX_DEBUG_PEDASSERT(__cplusplus >= 201103L || __pos < size());
4115	_M_leak();
4116	return _M_data()[__pos];
4117	}
4118
4119	/**
4120	* @brief Provides access to the data contained in the %string.
4121	* @param __n The index of the character to access.
4122	* @return Read-only (const) reference to the character.
4123	* @throw std::out_of_range If @a n is an invalid index.
4124	*
4125	* This function provides for safer data access. The parameter is
4126	* first checked that it is in the range of the string. The function
4127	* throws out_of_range if the check fails.
4128	*/
4129	const_reference
4130	at(size_type __n) const
4131	{
4132	if (__n >= this->size())
4133	__throw_out_of_range_fmt(__N("basic_string::at: __n "
4134	"(which is %zu) >= this->size() "
4135	"(which is %zu)"),
4136	__n, this->size());
4137	return _M_data()[__n];
4138	}
4139
4140	/**
4141	* @brief Provides access to the data contained in the %string.
4142	* @param __n The index of the character to access.
4143	* @return Read/write reference to the character.
4144	* @throw std::out_of_range If @a n is an invalid index.
4145	*
4146	* This function provides for safer data access. The parameter is
4147	* first checked that it is in the range of the string. The function
4148	* throws out_of_range if the check fails. Success results in
4149	* unsharing the string.
4150	*/
4151	reference
4152	at(size_type __n)
4153	{
4154	if (__n >= size())
4155	__throw_out_of_range_fmt(__N("basic_string::at: __n "
4156	"(which is %zu) >= this->size() "
4157	"(which is %zu)"),
4158	__n, this->size());
4159	_M_leak();
4160	return _M_data()[__n];
4161	}
4162
4163	#if __cplusplus >= 201103L
4164	/**
4165	* Returns a read/write reference to the data at the first
4166	* element of the %string.
4167	*/
4168	reference
4169	front()
4170	{
4171	__glibcxx_assert(!empty());
4172	return operator[](0);
4173	}
4174
4175	/**
4176	* Returns a read-only (constant) reference to the data at the first
4177	* element of the %string.
4178	*/
4179	const_reference
4180	front() const noexcept
4181	{
4182	__glibcxx_assert(!empty());
4183	return operator[](0);
4184	}
4185
4186	/**
4187	* Returns a read/write reference to the data at the last
4188	* element of the %string.
4189	*/
4190	reference
4191	back()
4192	{
4193	__glibcxx_assert(!empty());
4194	return operator[](this->size() - 1);
4195	}
4196
4197	/**
4198	* Returns a read-only (constant) reference to the data at the
4199	* last element of the %string.
4200	*/
4201	const_reference
4202	back() const noexcept
4203	{
4204	__glibcxx_assert(!empty());
4205	return operator[](this->size() - 1);
4206	}
4207	#endif
4208
4209	// Modifiers:
4210	/**
4211	* @brief Append a string to this string.
4212	* @param __str The string to append.
4213	* @return Reference to this string.
4214	*/
4215	basic_string&
4216	operator+=(const basic_string& __str)
4217	{ return this->append(__str); }
4218
4219	/**
4220	* @brief Append a C string.
4221	* @param __s The C string to append.
4222	* @return Reference to this string.
4223	*/
4224	basic_string&
4225	operator+=(const _CharT* __s)
4226	{ return this->append(__s); }
4227
4228	/**
4229	* @brief Append a character.
4230	* @param __c The character to append.
4231	* @return Reference to this string.
4232	*/
4233	basic_string&
4234	operator+=(_CharT __c)
4235	{
4236	this->push_back(__c);
4237	return *this;
4238	}
4239
4240	#if __cplusplus >= 201103L
4241	/**
4242	* @brief Append an initializer_list of characters.
4243	* @param __l The initializer_list of characters to be appended.
4244	* @return Reference to this string.
4245	*/
4246	basic_string&
4247	operator+=(initializer_list<_CharT> __l)
4248	{ return this->append(__l.begin(), __l.size()); }
4249	#endif // C++11
4250
4251	#if __cplusplus >= 201703L
4252	/**
4253	* @brief Append a string_view.
4254	* @param __svt The object convertible to string_view to be appended.
4255	* @return Reference to this string.
4256	*/
4257	template<typename _Tp>
4258	_If_sv<_Tp, basic_string&>
4259	operator+=(const _Tp& __svt)
4260	{ return this->append(__svt); }
4261	#endif // C++17
4262
4263	/**
4264	* @brief Append a string to this string.
4265	* @param __str The string to append.
4266	* @return Reference to this string.
4267	*/
4268	basic_string&
4269	append(const basic_string& __str);
4270
4271	/**
4272	* @brief Append a substring.
4273	* @param __str The string to append.
4274	* @param __pos Index of the first character of str to append.
4275	* @param __n The number of characters to append.
4276	* @return Reference to this string.
4277	* @throw std::out_of_range if @a __pos is not a valid index.
4278	*
4279	* This function appends @a __n characters from @a __str
4280	* starting at @a __pos to this string. If @a __n is is larger
4281	* than the number of available characters in @a __str, the
4282	* remainder of @a __str is appended.
4283	*/
4284	basic_string&
4285	append(const basic_string& __str, size_type __pos, size_type __n = npos);
4286
4287	/**
4288	* @brief Append a C substring.
4289	* @param __s The C string to append.
4290	* @param __n The number of characters to append.
4291	* @return Reference to this string.
4292	*/
4293	basic_string&
4294	append(const _CharT* __s, size_type __n);
4295
4296	/**
4297	* @brief Append a C string.
4298	* @param __s The C string to append.
4299	* @return Reference to this string.
4300	*/
4301	basic_string&
4302	append(const _CharT* __s)
4303	{
4304	__glibcxx_requires_string(__s);
4305	return this->append(__s, traits_type::length(__s));
4306	}
4307
4308	/**
4309	* @brief Append multiple characters.
4310	* @param __n The number of characters to append.
4311	* @param __c The character to use.
4312	* @return Reference to this string.
4313	*
4314	* Appends __n copies of __c to this string.
4315	*/
4316	basic_string&
4317	append(size_type __n, _CharT __c);
4318
4319	#if __cplusplus >= 201103L
4320	/**
4321	* @brief Append an initializer_list of characters.
4322	* @param __l The initializer_list of characters to append.
4323	* @return Reference to this string.
4324	*/
4325	basic_string&
4326	append(initializer_list<_CharT> __l)
4327	{ return this->append(__l.begin(), __l.size()); }
4328	#endif // C++11
4329
4330	/**
4331	* @brief Append a range of characters.
4332	* @param __first Iterator referencing the first character to append.
4333	* @param __last Iterator marking the end of the range.
4334	* @return Reference to this string.
4335	*
4336	* Appends characters in the range [__first,__last) to this string.
4337	*/
4338	template<class _InputIterator>
4339	basic_string&
4340	append(_InputIterator __first, _InputIterator __last)
4341	{ return this->replace(_M_iend(), _M_iend(), __first, __last); }
4342
4343	#if __cplusplus >= 201703L
4344	/**
4345	* @brief Append a string_view.
4346	* @param __svt The object convertible to string_view to be appended.
4347	* @return Reference to this string.
4348	*/
4349	template<typename _Tp>
4350	_If_sv<_Tp, basic_string&>
4351	append(const _Tp& __svt)
4352	{
4353	__sv_type __sv = __svt;
4354	return this->append(__sv.data(), __sv.size());
4355	}
4356
4357	/**
4358	* @brief Append a range of characters from a string_view.
4359	* @param __svt The object convertible to string_view to be appended
4360	* from.
4361	* @param __pos The position in the string_view to append from.
4362	* @param __n The number of characters to append from the string_view.
4363	* @return Reference to this string.
4364	*/
4365	template<typename _Tp>
4366	_If_sv<_Tp, basic_string&>
4367	append(const _Tp& __svt, size_type __pos, size_type __n = npos)
4368	{
4369	__sv_type __sv = __svt;
4370	return append(__sv.data()
4371	+ std::__sv_check(__sv.size(), __pos, "basic_string::append"),
4372	std::__sv_limit(__sv.size(), __pos, __n));
4373	}
4374	#endif // C++17
4375
4376	/**
4377	* @brief Append a single character.
4378	* @param __c Character to append.
4379	*/
4380	void
4381	push_back(_CharT __c)
4382	{
4383	const size_type __len = 1 + this->size();
4384	if (__len > this->capacity() || _M_rep()->_M_is_shared())
4385	this->reserve(__len);
4386	traits_type::assign(_M_data()[this->size()], __c);
4387	_M_rep()->_M_set_length_and_sharable(__len);
4388	}
4389
4390	/**
4391	* @brief Set value to contents of another string.
4392	* @param __str Source string to use.
4393	* @return Reference to this string.
4394	*/
4395	basic_string&
4396	assign(const basic_string& __str);
4397
4398	#if __cplusplus >= 201103L
4399	/**
4400	* @brief Set value to contents of another string.
4401	* @param __str Source string to use.
4402	* @return Reference to this string.
4403	*
4404	* This function sets this string to the exact contents of @a __str.
4405	* @a __str is a valid, but unspecified string.
4406	*/
4407	basic_string&
4408	assign(basic_string&& __str)
4409	noexcept(allocator_traits<_Alloc>::is_always_equal::value)
4410	{
4411	this->swap(__str);
4412	return *this;
4413	}
4414	#endif // C++11
4415
4416	/**
4417	* @brief Set value to a substring of a string.
4418	* @param __str The string to use.
4419	* @param __pos Index of the first character of str.
4420	* @param __n Number of characters to use.
4421	* @return Reference to this string.
4422	* @throw std::out_of_range if @a pos is not a valid index.
4423	*
4424	* This function sets this string to the substring of @a __str
4425	* consisting of @a __n characters at @a __pos. If @a __n is
4426	* is larger than the number of available characters in @a
4427	* __str, the remainder of @a __str is used.
4428	*/
4429	basic_string&
4430	assign(const basic_string& __str, size_type __pos, size_type __n = npos)
4431	{ return this->assign(__str._M_data()
4432	+ __str._M_check(__pos, "basic_string::assign"),
4433	__str._M_limit(__pos, __n)); }
4434
4435	/**
4436	* @brief Set value to a C substring.
4437	* @param __s The C string to use.
4438	* @param __n Number of characters to use.
4439	* @return Reference to this string.
4440	*
4441	* This function sets the value of this string to the first @a __n
4442	* characters of @a __s. If @a __n is is larger than the number of
4443	* available characters in @a __s, the remainder of @a __s is used.
4444	*/
4445	basic_string&
4446	assign(const _CharT* __s, size_type __n);
4447
4448	/**
4449	* @brief Set value to contents of a C string.
4450	* @param __s The C string to use.
4451	* @return Reference to this string.
4452	*
4453	* This function sets the value of this string to the value of @a __s.
4454	* The data is copied, so there is no dependence on @a __s once the
4455	* function returns.
4456	*/
4457	basic_string&
4458	assign(const _CharT* __s)
4459	{
4460	__glibcxx_requires_string(__s);
4461	return this->assign(__s, traits_type::length(__s));
4462	}
4463
4464	/**
4465	* @brief Set value to multiple characters.
4466	* @param __n Length of the resulting string.
4467	* @param __c The character to use.
4468	* @return Reference to this string.
4469	*
4470	* This function sets the value of this string to @a __n copies of
4471	* character @a __c.
4472	*/
4473	basic_string&
4474	assign(size_type __n, _CharT __c)
4475	{ return _M_replace_aux(size_type(0), this->size(), __n, __c); }
4476
4477	/**
4478	* @brief Set value to a range of characters.
4479	* @param __first Iterator referencing the first character to append.
4480	* @param __last Iterator marking the end of the range.
4481	* @return Reference to this string.
4482	*
4483	* Sets value of string to characters in the range [__first,__last).
4484	*/
4485	template<class _InputIterator>
4486	basic_string&
4487	assign(_InputIterator __first, _InputIterator __last)
4488	{ return this->replace(_M_ibegin(), _M_iend(), __first, __last); }
4489
4490	#if __cplusplus >= 201103L
4491	/**
4492	* @brief Set value to an initializer_list of characters.
4493	* @param __l The initializer_list of characters to assign.
4494	* @return Reference to this string.
4495	*/
4496	basic_string&
4497	assign(initializer_list<_CharT> __l)
4498	{ return this->assign(__l.begin(), __l.size()); }
4499	#endif // C++11
4500
4501	#if __cplusplus >= 201703L
4502	/**
4503	* @brief Set value from a string_view.
4504	* @param __svt The source object convertible to string_view.
4505	* @return Reference to this string.
4506	*/
4507	template<typename _Tp>
4508	_If_sv<_Tp, basic_string&>
4509	assign(const _Tp& __svt)
4510	{
4511	__sv_type __sv = __svt;
4512	return this->assign(__sv.data(), __sv.size());
4513	}
4514
4515	/**
4516	* @brief Set value from a range of characters in a string_view.
4517	* @param __svt The source object convertible to string_view.
4518	* @param __pos The position in the string_view to assign from.
4519	* @param __n The number of characters to assign.
4520	* @return Reference to this string.
4521	*/
4522	template<typename _Tp>
4523	_If_sv<_Tp, basic_string&>
4524	assign(const _Tp& __svt, size_type __pos, size_type __n = npos)
4525	{
4526	__sv_type __sv = __svt;
4527	return assign(__sv.data()
4528	+ std::__sv_check(__sv.size(), __pos, "basic_string::assign"),
4529	std::__sv_limit(__sv.size(), __pos, __n));
4530	}
4531	#endif // C++17
4532
4533	/**
4534	* @brief Insert multiple characters.
4535	* @param __p Iterator referencing location in string to insert at.
4536	* @param __n Number of characters to insert
4537	* @param __c The character to insert.
4538	* @throw std::length_error If new length exceeds @c max_size().
4539	*
4540	* Inserts @a __n copies of character @a __c starting at the
4541	* position referenced by iterator @a __p. If adding
4542	* characters causes the length to exceed max_size(),
4543	* length_error is thrown. The value of the string doesn't
4544	* change if an error is thrown.
4545	*/
4546	void
4547	insert(iterator __p, size_type __n, _CharT __c)
4548	{ this->replace(__p, __p, __n, __c); }
4549
4550	/**
4551	* @brief Insert a range of characters.
4552	* @param __p Iterator referencing location in string to insert at.
4553	* @param __beg Start of range.
4554	* @param __end End of range.
4555	* @throw std::length_error If new length exceeds @c max_size().
4556	*
4557	* Inserts characters in range [__beg,__end). If adding
4558	* characters causes the length to exceed max_size(),
4559	* length_error is thrown. The value of the string doesn't
4560	* change if an error is thrown.
4561	*/
4562	template<class _InputIterator>
4563	void
4564	insert(iterator __p, _InputIterator __beg, _InputIterator __end)
4565	{ this->replace(__p, __p, __beg, __end); }
4566
4567	#if __cplusplus >= 201103L
4568	/**
4569	* @brief Insert an initializer_list of characters.
4570	* @param __p Iterator referencing location in string to insert at.
4571	* @param __l The initializer_list of characters to insert.
4572	* @throw std::length_error If new length exceeds @c max_size().
4573	*/
4574	void
4575	insert(iterator __p, initializer_list<_CharT> __l)
4576	{
4577	_GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4578	this->insert(__p - _M_ibegin(), __l.begin(), __l.size());
4579	}
4580	#endif // C++11
4581
4582	/**
4583	* @brief Insert value of a string.
4584	* @param __pos1 Position in string to insert at.
4585	* @param __str The string to insert.
4586	* @return Reference to this string.
4587	* @throw std::length_error If new length exceeds @c max_size().
4588	*
4589	* Inserts value of @a __str starting at @a __pos1. If adding
4590	* characters causes the length to exceed max_size(),
4591	* length_error is thrown. The value of the string doesn't
4592	* change if an error is thrown.
4593	*/
4594	basic_string&
4595	insert(size_type __pos1, const basic_string& __str)
4596	{ return this->insert(__pos1, __str, size_type(0), __str.size()); }
4597
4598	/**
4599	* @brief Insert a substring.
4600	* @param __pos1 Position in string to insert at.
4601	* @param __str The string to insert.
4602	* @param __pos2 Start of characters in str to insert.
4603	* @param __n Number of characters to insert.
4604	* @return Reference to this string.
4605	* @throw std::length_error If new length exceeds @c max_size().
4606	* @throw std::out_of_range If @a pos1 > size() or
4607	* @a __pos2 > @a str.size().
4608	*
4609	* Starting at @a pos1, insert @a __n character of @a __str
4610	* beginning with @a __pos2. If adding characters causes the
4611	* length to exceed max_size(), length_error is thrown. If @a
4612	* __pos1 is beyond the end of this string or @a __pos2 is
4613	* beyond the end of @a __str, out_of_range is thrown. The
4614	* value of the string doesn't change if an error is thrown.
4615	*/
4616	basic_string&
4617	insert(size_type __pos1, const basic_string& __str,
4618	size_type __pos2, size_type __n = npos)
4619	{ return this->insert(__pos1, __str._M_data()
4620	+ __str._M_check(__pos2, "basic_string::insert"),
4621	__str._M_limit(__pos2, __n)); }
4622
4623	/**
4624	* @brief Insert a C substring.
4625	* @param __pos Position in string to insert at.
4626	* @param __s The C string to insert.
4627	* @param __n The number of characters to insert.
4628	* @return Reference to this string.
4629	* @throw std::length_error If new length exceeds @c max_size().
4630	* @throw std::out_of_range If @a __pos is beyond the end of this
4631	* string.
4632	*
4633	* Inserts the first @a __n characters of @a __s starting at @a
4634	* __pos. If adding characters causes the length to exceed
4635	* max_size(), length_error is thrown. If @a __pos is beyond
4636	* end(), out_of_range is thrown. The value of the string
4637	* doesn't change if an error is thrown.
4638	*/
4639	basic_string&
4640	insert(size_type __pos, const _CharT* __s, size_type __n);
4641
4642	/**
4643	* @brief Insert a C string.
4644	* @param __pos Position in string to insert at.
4645	* @param __s The C string to insert.
4646	* @return Reference to this string.
4647	* @throw std::length_error If new length exceeds @c max_size().
4648	* @throw std::out_of_range If @a pos is beyond the end of this
4649	* string.
4650	*
4651	* Inserts the first @a n characters of @a __s starting at @a __pos. If
4652	* adding characters causes the length to exceed max_size(),
4653	* length_error is thrown. If @a __pos is beyond end(), out_of_range is
4654	* thrown. The value of the string doesn't change if an error is
4655	* thrown.
4656	*/
4657	basic_string&
4658	insert(size_type __pos, const _CharT* __s)
4659	{
4660	__glibcxx_requires_string(__s);
4661	return this->insert(__pos, __s, traits_type::length(__s));
4662	}
4663
4664	/**
4665	* @brief Insert multiple characters.
4666	* @param __pos Index in string to insert at.
4667	* @param __n Number of characters to insert
4668	* @param __c The character to insert.
4669	* @return Reference to this string.
4670	* @throw std::length_error If new length exceeds @c max_size().
4671	* @throw std::out_of_range If @a __pos is beyond the end of this
4672	* string.
4673	*
4674	* Inserts @a __n copies of character @a __c starting at index
4675	* @a __pos. If adding characters causes the length to exceed
4676	* max_size(), length_error is thrown. If @a __pos > length(),
4677	* out_of_range is thrown. The value of the string doesn't
4678	* change if an error is thrown.
4679	*/
4680	basic_string&
4681	insert(size_type __pos, size_type __n, _CharT __c)
4682	{ return _M_replace_aux(_M_check(__pos, "basic_string::insert"),
4683	size_type(0), __n, __c); }
4684
4685	/**
4686	* @brief Insert one character.
4687	* @param __p Iterator referencing position in string to insert at.
4688	* @param __c The character to insert.
4689	* @return Iterator referencing newly inserted char.
4690	* @throw std::length_error If new length exceeds @c max_size().
4691	*
4692	* Inserts character @a __c at position referenced by @a __p.
4693	* If adding character causes the length to exceed max_size(),
4694	* length_error is thrown. If @a __p is beyond end of string,
4695	* out_of_range is thrown. The value of the string doesn't
4696	* change if an error is thrown.
4697	*/
4698	iterator
4699	insert(iterator __p, _CharT __c)
4700	{
4701	_GLIBCXX_DEBUG_PEDASSERT(__p >= _M_ibegin() && __p <= _M_iend());
4702	const size_type __pos = __p - _M_ibegin();
4703	_M_replace_aux(__pos, size_type(0), size_type(1), __c);
4704	_M_rep()->_M_set_leaked();
4705	return iterator(_M_data() + __pos);
4706	}
4707
4708	#if __cplusplus >= 201703L
4709	/**
4710	* @brief Insert a string_view.
4711	* @param __pos Position in string to insert at.
4712	* @param __svt The object convertible to string_view to insert.
4713	* @return Reference to this string.
4714	*/
4715	template<typename _Tp>
4716	_If_sv<_Tp, basic_string&>
4717	insert(size_type __pos, const _Tp& __svt)
4718	{
4719	__sv_type __sv = __svt;
4720	return this->insert(__pos, __sv.data(), __sv.size());
4721	}
4722
4723	/**
4724	* @brief Insert a string_view.
4725	* @param __pos1 Position in string to insert at.
4726	* @param __svt The object convertible to string_view to insert from.
4727	* @param __pos2 Position in string_view to insert from.
4728	* @param __n The number of characters to insert.
4729	* @return Reference to this string.
4730	*/
4731	template<typename _Tp>
4732	_If_sv<_Tp, basic_string&>
4733	insert(size_type __pos1, const _Tp& __svt,
4734	size_type __pos2, size_type __n = npos)
4735	{
4736	__sv_type __sv = __svt;
4737	return this->replace(__pos1, size_type(0), __sv.data()
4738	+ std::__sv_check(__sv.size(), __pos2, "basic_string::insert"),
4739	std::__sv_limit(__sv.size(), __pos2, __n));
4740	}
4741	#endif // C++17
4742
4743	/**
4744	* @brief Remove characters.
4745	* @param __pos Index of first character to remove (default 0).
4746	* @param __n Number of characters to remove (default remainder).
4747	* @return Reference to this string.
4748	* @throw std::out_of_range If @a pos is beyond the end of this
4749	* string.
4750	*
4751	* Removes @a __n characters from this string starting at @a
4752	* __pos. The length of the string is reduced by @a __n. If
4753	* there are < @a __n characters to remove, the remainder of
4754	* the string is truncated. If @a __p is beyond end of string,
4755	* out_of_range is thrown. The value of the string doesn't
4756	* change if an error is thrown.
4757	*/
4758	basic_string&
4759	erase(size_type __pos = 0, size_type __n = npos)
4760	{
4761	_M_mutate(_M_check(__pos, "basic_string::erase"),
4762	_M_limit(__pos, __n), size_type(0));
4763	return *this;
4764	}
4765
4766	/**
4767	* @brief Remove one character.
4768	* @param __position Iterator referencing the character to remove.
4769	* @return iterator referencing same location after removal.
4770	*
4771	* Removes the character at @a __position from this string. The value
4772	* of the string doesn't change if an error is thrown.
4773	*/
4774	iterator
4775	erase(iterator __position)
4776	{
4777	_GLIBCXX_DEBUG_PEDASSERT(__position >= _M_ibegin()
4778	&& __position < _M_iend());
4779	const size_type __pos = __position - _M_ibegin();
4780	_M_mutate(__pos, size_type(1), size_type(0));
4781	_M_rep()->_M_set_leaked();
4782	return iterator(_M_data() + __pos);
4783	}
4784
4785	/**
4786	* @brief Remove a range of characters.
4787	* @param __first Iterator referencing the first character to remove.
4788	* @param __last Iterator referencing the end of the range.
4789	* @return Iterator referencing location of first after removal.
4790	*
4791	* Removes the characters in the range [first,last) from this string.
4792	* The value of the string doesn't change if an error is thrown.
4793	*/
4794	iterator
4795	erase(iterator __first, iterator __last);
4796
4797	#if __cplusplus >= 201103L
4798	/**
4799	* @brief Remove the last character.
4800	*
4801	* The string must be non-empty.
4802	*/
4803	void
4804	pop_back() // FIXME C++11: should be noexcept.
4805	{
4806	__glibcxx_assert(!empty());
4807	erase(size() - 1, 1);
4808	}
4809	#endif // C++11
4810
4811	/**
4812	* @brief Replace characters with value from another string.
4813	* @param __pos Index of first character to replace.
4814	* @param __n Number of characters to be replaced.
4815	* @param __str String to insert.
4816	* @return Reference to this string.
4817	* @throw std::out_of_range If @a pos is beyond the end of this
4818	* string.
4819	* @throw std::length_error If new length exceeds @c max_size().
4820	*
4821	* Removes the characters in the range [__pos,__pos+__n) from
4822	* this string. In place, the value of @a __str is inserted.
4823	* If @a __pos is beyond end of string, out_of_range is thrown.
4824	* If the length of the result exceeds max_size(), length_error
4825	* is thrown. The value of the string doesn't change if an
4826	* error is thrown.
4827	*/
4828	basic_string&
4829	replace(size_type __pos, size_type __n, const basic_string& __str)
4830	{ return this->replace(__pos, __n, __str._M_data(), __str.size()); }
4831
4832	/**
4833	* @brief Replace characters with value from another string.
4834	* @param __pos1 Index of first character to replace.
4835	* @param __n1 Number of characters to be replaced.
4836	* @param __str String to insert.
4837	* @param __pos2 Index of first character of str to use.
4838	* @param __n2 Number of characters from str to use.
4839	* @return Reference to this string.
4840	* @throw std::out_of_range If @a __pos1 > size() or @a __pos2 >
4841	* __str.size().
4842	* @throw std::length_error If new length exceeds @c max_size().
4843	*
4844	* Removes the characters in the range [__pos1,__pos1 + n) from this
4845	* string. In place, the value of @a __str is inserted. If @a __pos is
4846	* beyond end of string, out_of_range is thrown. If the length of the
4847	* result exceeds max_size(), length_error is thrown. The value of the
4848	* string doesn't change if an error is thrown.
4849	*/
4850	basic_string&
4851	replace(size_type __pos1, size_type __n1, const basic_string& __str,
4852	size_type __pos2, size_type __n2 = npos)
4853	{ return this->replace(__pos1, __n1, __str._M_data()
4854	+ __str._M_check(__pos2, "basic_string::replace"),
4855	__str._M_limit(__pos2, __n2)); }
4856
4857	/**
4858	* @brief Replace characters with value of a C substring.
4859	* @param __pos Index of first character to replace.
4860	* @param __n1 Number of characters to be replaced.
4861	* @param __s C string to insert.
4862	* @param __n2 Number of characters from @a s to use.
4863	* @return Reference to this string.
4864	* @throw std::out_of_range If @a pos1 > size().
4865	* @throw std::length_error If new length exceeds @c max_size().
4866	*
4867	* Removes the characters in the range [__pos,__pos + __n1)
4868	* from this string. In place, the first @a __n2 characters of
4869	* @a __s are inserted, or all of @a __s if @a __n2 is too large. If
4870	* @a __pos is beyond end of string, out_of_range is thrown. If
4871	* the length of result exceeds max_size(), length_error is
4872	* thrown. The value of the string doesn't change if an error
4873	* is thrown.
4874	*/
4875	basic_string&
4876	replace(size_type __pos, size_type __n1, const _CharT* __s,
4877	size_type __n2);
4878
4879	/**
4880	* @brief Replace characters with value of a C string.
4881	* @param __pos Index of first character to replace.
4882	* @param __n1 Number of characters to be replaced.
4883	* @param __s C string to insert.
4884	* @return Reference to this string.
4885	* @throw std::out_of_range If @a pos > size().
4886	* @throw std::length_error If new length exceeds @c max_size().
4887	*
4888	* Removes the characters in the range [__pos,__pos + __n1)
4889	* from this string. In place, the characters of @a __s are
4890	* inserted. If @a __pos is beyond end of string, out_of_range
4891	* is thrown. If the length of result exceeds max_size(),
4892	* length_error is thrown. The value of the string doesn't
4893	* change if an error is thrown.
4894	*/
4895	basic_string&
4896	replace(size_type __pos, size_type __n1, const _CharT* __s)
4897	{
4898	__glibcxx_requires_string(__s);
4899	return this->replace(__pos, __n1, __s, traits_type::length(__s));
4900	}
4901
4902	/**
4903	* @brief Replace characters with multiple characters.
4904	* @param __pos Index of first character to replace.
4905	* @param __n1 Number of characters to be replaced.
4906	* @param __n2 Number of characters to insert.
4907	* @param __c Character to insert.
4908	* @return Reference to this string.
4909	* @throw std::out_of_range If @a __pos > size().
4910	* @throw std::length_error If new length exceeds @c max_size().
4911	*
4912	* Removes the characters in the range [pos,pos + n1) from this
4913	* string. In place, @a __n2 copies of @a __c are inserted.
4914	* If @a __pos is beyond end of string, out_of_range is thrown.
4915	* If the length of result exceeds max_size(), length_error is
4916	* thrown. The value of the string doesn't change if an error
4917	* is thrown.
4918	*/
4919	basic_string&
4920	replace(size_type __pos, size_type __n1, size_type __n2, _CharT __c)
4921	{ return _M_replace_aux(_M_check(__pos, "basic_string::replace"),
4922	_M_limit(__pos, __n1), __n2, __c); }
4923
4924	/**
4925	* @brief Replace range of characters with string.
4926	* @param __i1 Iterator referencing start of range to replace.
4927	* @param __i2 Iterator referencing end of range to replace.
4928	* @param __str String value to insert.
4929	* @return Reference to this string.
4930	* @throw std::length_error If new length exceeds @c max_size().
4931	*
4932	* Removes the characters in the range [__i1,__i2). In place,
4933	* the value of @a __str is inserted. If the length of result
4934	* exceeds max_size(), length_error is thrown. The value of
4935	* the string doesn't change if an error is thrown.
4936	*/
4937	basic_string&
4938	replace(iterator __i1, iterator __i2, const basic_string& __str)
4939	{ return this->replace(__i1, __i2, __str._M_data(), __str.size()); }
4940
4941	/**
4942	* @brief Replace range of characters with C substring.
4943	* @param __i1 Iterator referencing start of range to replace.
4944	* @param __i2 Iterator referencing end of range to replace.
4945	* @param __s C string value to insert.
4946	* @param __n Number of characters from s to insert.
4947	* @return Reference to this string.
4948	* @throw std::length_error If new length exceeds @c max_size().
4949	*
4950	* Removes the characters in the range [__i1,__i2). In place,
4951	* the first @a __n characters of @a __s are inserted. If the
4952	* length of result exceeds max_size(), length_error is thrown.
4953	* The value of the string doesn't change if an error is
4954	* thrown.
4955	*/
4956	basic_string&
4957	replace(iterator __i1, iterator __i2, const _CharT* __s, size_type __n)
4958	{
4959	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
4960	&& __i2 <= _M_iend());
4961	return this->replace(__i1 - _M_ibegin(), __i2 - __i1, __s, __n);
4962	}
4963
4964	/**
4965	* @brief Replace range of characters with C string.
4966	* @param __i1 Iterator referencing start of range to replace.
4967	* @param __i2 Iterator referencing end of range to replace.
4968	* @param __s C string value to insert.
4969	* @return Reference to this string.
4970	* @throw std::length_error If new length exceeds @c max_size().
4971	*
4972	* Removes the characters in the range [__i1,__i2). In place,
4973	* the characters of @a __s are inserted. If the length of
4974	* result exceeds max_size(), length_error is thrown. The
4975	* value of the string doesn't change if an error is thrown.
4976	*/
4977	basic_string&
4978	replace(iterator __i1, iterator __i2, const _CharT* __s)
4979	{
4980	__glibcxx_requires_string(__s);
4981	return this->replace(__i1, __i2, __s, traits_type::length(__s));
4982	}
4983
4984	/**
4985	* @brief Replace range of characters with multiple characters
4986	* @param __i1 Iterator referencing start of range to replace.
4987	* @param __i2 Iterator referencing end of range to replace.
4988	* @param __n Number of characters to insert.
4989	* @param __c Character to insert.
4990	* @return Reference to this string.
4991	* @throw std::length_error If new length exceeds @c max_size().
4992	*
4993	* Removes the characters in the range [__i1,__i2). In place,
4994	* @a __n copies of @a __c are inserted. If the length of
4995	* result exceeds max_size(), length_error is thrown. The
4996	* value of the string doesn't change if an error is thrown.
4997	*/
4998	basic_string&
4999	replace(iterator __i1, iterator __i2, size_type __n, _CharT __c)
5000	{
5001	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5002	&& __i2 <= _M_iend());
5003	return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __c);
5004	}
5005
5006	/**
5007	* @brief Replace range of characters with range.
5008	* @param __i1 Iterator referencing start of range to replace.
5009	* @param __i2 Iterator referencing end of range to replace.
5010	* @param __k1 Iterator referencing start of range to insert.
5011	* @param __k2 Iterator referencing end of range to insert.
5012	* @return Reference to this string.
5013	* @throw std::length_error If new length exceeds @c max_size().
5014	*
5015	* Removes the characters in the range [__i1,__i2). In place,
5016	* characters in the range [__k1,__k2) are inserted. If the
5017	* length of result exceeds max_size(), length_error is thrown.
5018	* The value of the string doesn't change if an error is
5019	* thrown.
5020	*/
5021	template<class _InputIterator>
5022	basic_string&
5023	replace(iterator __i1, iterator __i2,
5024	_InputIterator __k1, _InputIterator __k2)
5025	{
5026	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5027	&& __i2 <= _M_iend());
5028	__glibcxx_requires_valid_range(__k1, __k2);
5029	typedef typename std::__is_integer<_InputIterator>::__type _Integral;
5030	return _M_replace_dispatch(__i1, __i2, __k1, __k2, _Integral());
5031	}
5032
5033	// Specializations for the common case of pointer and iterator:
5034	// useful to avoid the overhead of temporary buffering in _M_replace.
5035	basic_string&
5036	replace(iterator __i1, iterator __i2, _CharT* __k1, _CharT* __k2)
5037	{
5038	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5039	&& __i2 <= _M_iend());
5040	__glibcxx_requires_valid_range(__k1, __k2);
5041	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5042	__k1, __k2 - __k1);
5043	}
5044
5045	basic_string&
5046	replace(iterator __i1, iterator __i2,
5047	const _CharT* __k1, const _CharT* __k2)
5048	{
5049	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5050	&& __i2 <= _M_iend());
5051	__glibcxx_requires_valid_range(__k1, __k2);
5052	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5053	__k1, __k2 - __k1);
5054	}
5055
5056	basic_string&
5057	replace(iterator __i1, iterator __i2, iterator __k1, iterator __k2)
5058	{
5059	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5060	&& __i2 <= _M_iend());
5061	__glibcxx_requires_valid_range(__k1, __k2);
5062	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5063	__k1.base(), __k2 - __k1);
5064	}
5065
5066	basic_string&
5067	replace(iterator __i1, iterator __i2,
5068	const_iterator __k1, const_iterator __k2)
5069	{
5070	_GLIBCXX_DEBUG_PEDASSERT(_M_ibegin() <= __i1 && __i1 <= __i2
5071	&& __i2 <= _M_iend());
5072	__glibcxx_requires_valid_range(__k1, __k2);
5073	return this->replace(__i1 - _M_ibegin(), __i2 - __i1,
5074	__k1.base(), __k2 - __k1);
5075	}
5076
5077	#if __cplusplus >= 201103L
5078	/**
5079	* @brief Replace range of characters with initializer_list.
5080	* @param __i1 Iterator referencing start of range to replace.
5081	* @param __i2 Iterator referencing end of range to replace.
5082	* @param __l The initializer_list of characters to insert.
5083	* @return Reference to this string.
5084	* @throw std::length_error If new length exceeds @c max_size().
5085	*
5086	* Removes the characters in the range [__i1,__i2). In place,
5087	* characters in the range [__k1,__k2) are inserted. If the
5088	* length of result exceeds max_size(), length_error is thrown.
5089	* The value of the string doesn't change if an error is
5090	* thrown.
5091	*/
5092	basic_string& replace(iterator __i1, iterator __i2,
5093	initializer_list<_CharT> __l)
5094	{ return this->replace(__i1, __i2, __l.begin(), __l.end()); }
5095	#endif // C++11
5096
5097	#if __cplusplus >= 201703L
5098	/**
5099	* @brief Replace range of characters with string_view.
5100	* @param __pos The position to replace at.
5101	* @param __n The number of characters to replace.
5102	* @param __svt The object convertible to string_view to insert.
5103	* @return Reference to this string.
5104	*/
5105	template<typename _Tp>
5106	_If_sv<_Tp, basic_string&>
5107	replace(size_type __pos, size_type __n, const _Tp& __svt)
5108	{
5109	__sv_type __sv = __svt;
5110	return this->replace(__pos, __n, __sv.data(), __sv.size());
5111	}
5112
5113	/**
5114	* @brief Replace range of characters with string_view.
5115	* @param __pos1 The position to replace at.
5116	* @param __n1 The number of characters to replace.
5117	* @param __svt The object convertible to string_view to insert from.
5118	* @param __pos2 The position in the string_view to insert from.
5119	* @param __n2 The number of characters to insert.
5120	* @return Reference to this string.
5121	*/
5122	template<typename _Tp>
5123	_If_sv<_Tp, basic_string&>
5124	replace(size_type __pos1, size_type __n1, const _Tp& __svt,
5125	size_type __pos2, size_type __n2 = npos)
5126	{
5127	__sv_type __sv = __svt;
5128	return this->replace(__pos1, __n1,
5129	__sv.data()
5130	+ std::__sv_check(__sv.size(), __pos2, "basic_string::replace"),
5131	std::__sv_limit(__sv.size(), __pos2, __n2));
5132	}
5133
5134	/**
5135	* @brief Replace range of characters with string_view.
5136	* @param __i1 An iterator referencing the start position
5137	to replace at.
5138	* @param __i2 An iterator referencing the end position
5139	for the replace.
5140	* @param __svt The object convertible to string_view to insert from.
5141	* @return Reference to this string.
5142	*/
5143	template<typename _Tp>
5144	_If_sv<_Tp, basic_string&>
5145	replace(const_iterator __i1, const_iterator __i2, const _Tp& __svt)
5146	{
5147	__sv_type __sv = __svt;
5148	return this->replace(__i1 - begin(), __i2 - __i1, __sv);
5149	}
5150	#endif // C++17
5151
5152	private:
5153	template<class _Integer>
5154	basic_string&
5155	_M_replace_dispatch(iterator __i1, iterator __i2, _Integer __n,
5156	_Integer __val, __true_type)
5157	{ return _M_replace_aux(__i1 - _M_ibegin(), __i2 - __i1, __n, __val); }
5158
5159	template<class _InputIterator>
5160	basic_string&
5161	_M_replace_dispatch(iterator __i1, iterator __i2, _InputIterator __k1,
5162	_InputIterator __k2, __false_type);
5163
5164	basic_string&
5165	_M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,
5166	_CharT __c);
5167
5168	basic_string&
5169	_M_replace_safe(size_type __pos1, size_type __n1, const _CharT* __s,
5170	size_type __n2);
5171
5172	// _S_construct_aux is used to implement the 21.3.1 para 15 which
5173	// requires special behaviour if _InIter is an integral type
5174	template<class _InIterator>
5175	static _CharT*
5176	_S_construct_aux(_InIterator __beg, _InIterator __end,
5177	const _Alloc& __a, __false_type)
5178	{
5179	typedef typename iterator_traits<_InIterator>::iterator_category _Tag;
5180	return _S_construct(__beg, __end, __a, _Tag());
5181	}
5182
5183	// _GLIBCXX_RESOLVE_LIB_DEFECTS
5184	// 438. Ambiguity in the "do the right thing" clause
5185	template<class _Integer>
5186	static _CharT*
5187	_S_construct_aux(_Integer __beg, _Integer __end,
5188	const _Alloc& __a, __true_type)
5189	{ return _S_construct_aux_2(static_cast<size_type>(__beg),
5190	__end, __a); }
5191
5192	static _CharT*
5193	_S_construct_aux_2(size_type __req, _CharT __c, const _Alloc& __a)
5194	{ return _S_construct(__req, __c, __a); }
5195
5196	template<class _InIterator>
5197	static _CharT*
5198	_S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a)
5199	{
5200	typedef typename std::__is_integer<_InIterator>::__type _Integral;
5201	return _S_construct_aux(__beg, __end, __a, _Integral());
5202	}
5203
5204	// For Input Iterators, used in istreambuf_iterators, etc.
5205	template<class _InIterator>
5206	static _CharT*
5207	_S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,
5208	input_iterator_tag);
5209
5210	// For forward_iterators up to random_access_iterators, used for
5211	// string::iterator, _CharT*, etc.
5212	template<class _FwdIterator>
5213	static _CharT*
5214	_S_construct(_FwdIterator __beg, _FwdIterator __end, const _Alloc& __a,
5215	forward_iterator_tag);
5216
5217	static _CharT*
5218	_S_construct(size_type __req, _CharT __c, const _Alloc& __a);
5219
5220	public:
5221
5222	/**
5223	* @brief Copy substring into C string.
5224	* @param __s C string to copy value into.
5225	* @param __n Number of characters to copy.
5226	* @param __pos Index of first character to copy.
5227	* @return Number of characters actually copied
5228	* @throw std::out_of_range If __pos > size().
5229	*
5230	* Copies up to @a __n characters starting at @a __pos into the
5231	* C string @a __s. If @a __pos is %greater than size(),
5232	* out_of_range is thrown.
5233	*/
5234	size_type
5235	copy(_CharT* __s, size_type __n, size_type __pos = 0) const;
5236
5237	/**
5238	* @brief Swap contents with another string.
5239	* @param __s String to swap with.
5240	*
5241	* Exchanges the contents of this string with that of @a __s in constant
5242	* time.
5243	*/
5244	void
5245	swap(basic_string& __s)
5246	_GLIBCXX_NOEXCEPT_IF(allocator_traits<_Alloc>::is_always_equal::value);
5247
5248	// String operations:
5249	/**
5250	* @brief Return const pointer to null-terminated contents.
5251	*
5252	* This is a handle to internal data. Do not modify or dire things may
5253	* happen.
5254	*/
5255	const _CharT*
5256	c_str() const _GLIBCXX_NOEXCEPT
5257	{ return _M_data(); }
5258
5259	/**
5260	* @brief Return const pointer to contents.
5261	*
5262	* This is a pointer to internal data. It is undefined to modify
5263	* the contents through the returned pointer. To get a pointer that
5264	* allows modifying the contents use @c &str[0] instead,
5265	* (or in C++17 the non-const @c str.data() overload).
5266	*/
5267	const _CharT*
5268	data() const _GLIBCXX_NOEXCEPT
5269	{ return _M_data(); }
5270
5271	#if __cplusplus >= 201703L
5272	/**
5273	* @brief Return non-const pointer to contents.
5274	*
5275	* This is a pointer to the character sequence held by the string.
5276	* Modifying the characters in the sequence is allowed.
5277	*/
5278	_CharT*
5279	data() noexcept
5280	{
5281	_M_leak();
5282	return _M_data();
5283	}
5284	#endif
5285
5286	/**
5287	* @brief Return copy of allocator used to construct this string.
5288	*/
5289	allocator_type
5290	get_allocator() const _GLIBCXX_NOEXCEPT
5291	{ return _M_dataplus; }
5292
5293	/**
5294	* @brief Find position of a C substring.
5295	* @param __s C string to locate.
5296	* @param __pos Index of character to search from.
5297	* @param __n Number of characters from @a s to search for.
5298	* @return Index of start of first occurrence.
5299	*
5300	* Starting from @a __pos, searches forward for the first @a
5301	* __n characters in @a __s within this string. If found,
5302	* returns the index where it begins. If not found, returns
5303	* npos.
5304	*/
5305	size_type
5306	find(const _CharT* __s, size_type __pos, size_type __n) const
5307	_GLIBCXX_NOEXCEPT;
5308
5309	/**
5310	* @brief Find position of a string.
5311	* @param __str String to locate.
5312	* @param __pos Index of character to search from (default 0).
5313	* @return Index of start of first occurrence.
5314	*
5315	* Starting from @a __pos, searches forward for value of @a __str within
5316	* this string. If found, returns the index where it begins. If not
5317	* found, returns npos.
5318	*/
5319	size_type
5320	find(const basic_string& __str, size_type __pos = 0) const
5321	_GLIBCXX_NOEXCEPT
5322	{ return this->find(__str.data(), __pos, __str.size()); }
5323
5324	/**
5325	* @brief Find position of a C string.
5326	* @param __s C string to locate.
5327	* @param __pos Index of character to search from (default 0).
5328	* @return Index of start of first occurrence.
5329	*
5330	* Starting from @a __pos, searches forward for the value of @a
5331	* __s within this string. If found, returns the index where
5332	* it begins. If not found, returns npos.
5333	*/
5334	size_type
5335	find(const _CharT* __s, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
5336	{
5337	__glibcxx_requires_string(__s);
5338	return this->find(__s, __pos, traits_type::length(__s));
5339	}
5340
5341	/**
5342	* @brief Find position of a character.
5343	* @param __c Character to locate.
5344	* @param __pos Index of character to search from (default 0).
5345	* @return Index of first occurrence.
5346	*
5347	* Starting from @a __pos, searches forward for @a __c within
5348	* this string. If found, returns the index where it was
5349	* found. If not found, returns npos.
5350	*/
5351	size_type
5352	find(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT;
5353
5354	#if __cplusplus >= 201703L
5355	/**
5356	* @brief Find position of a string_view.
5357	* @param __svt The object convertible to string_view to locate.
5358	* @param __pos Index of character to search from (default 0).
5359	* @return Index of start of first occurrence.
5360	*/
5361	template<typename _Tp>
5362	_If_sv<_Tp, size_type>
5363	find(const _Tp& __svt, size_type __pos = 0) const
5364	noexcept(is_same<_Tp, __sv_type>::value)
5365	{
5366	__sv_type __sv = __svt;
5367	return this->find(__sv.data(), __pos, __sv.size());
5368	}
5369	#endif // C++17
5370
5371	/**
5372	* @brief Find last position of a string.
5373	* @param __str String to locate.
5374	* @param __pos Index of character to search back from (default end).
5375	* @return Index of start of last occurrence.
5376	*
5377	* Starting from @a __pos, searches backward for value of @a
5378	* __str within this string. If found, returns the index where
5379	* it begins. If not found, returns npos.
5380	*/
5381	size_type
5382	rfind(const basic_string& __str, size_type __pos = npos) const
5383	_GLIBCXX_NOEXCEPT
5384	{ return this->rfind(__str.data(), __pos, __str.size()); }
5385
5386	/**
5387	* @brief Find last position of a C substring.
5388	* @param __s C string to locate.
5389	* @param __pos Index of character to search back from.
5390	* @param __n Number of characters from s to search for.
5391	* @return Index of start of last occurrence.
5392	*
5393	* Starting from @a __pos, searches backward for the first @a
5394	* __n characters in @a __s within this string. If found,
5395	* returns the index where it begins. If not found, returns
5396	* npos.
5397	*/
5398	size_type
5399	rfind(const _CharT* __s, size_type __pos, size_type __n) const
5400	_GLIBCXX_NOEXCEPT;
5401
5402	/**
5403	* @brief Find last position of a C string.
5404	* @param __s C string to locate.
5405	* @param __pos Index of character to start search at (default end).
5406	* @return Index of start of last occurrence.
5407	*
5408	* Starting from @a __pos, searches backward for the value of
5409	* @a __s within this string. If found, returns the index
5410	* where it begins. If not found, returns npos.
5411	*/
5412	size_type
5413	rfind(const _CharT* __s, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5414	{
5415	__glibcxx_requires_string(__s);
5416	return this->rfind(__s, __pos, traits_type::length(__s));
5417	}
5418
5419	/**
5420	* @brief Find last position of a character.
5421	* @param __c Character to locate.
5422	* @param __pos Index of character to search back from (default end).
5423	* @return Index of last occurrence.
5424	*
5425	* Starting from @a __pos, searches backward for @a __c within
5426	* this string. If found, returns the index where it was
5427	* found. If not found, returns npos.
5428	*/
5429	size_type
5430	rfind(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT;
5431
5432	#if __cplusplus >= 201703L
5433	/**
5434	* @brief Find last position of a string_view.
5435	* @param __svt The object convertible to string_view to locate.
5436	* @param __pos Index of character to search back from (default end).
5437	* @return Index of start of last occurrence.
5438	*/
5439	template<typename _Tp>
5440	_If_sv<_Tp, size_type>
5441	rfind(const _Tp& __svt, size_type __pos = npos) const
5442	noexcept(is_same<_Tp, __sv_type>::value)
5443	{
5444	__sv_type __sv = __svt;
5445	return this->rfind(__sv.data(), __pos, __sv.size());
5446	}
5447	#endif // C++17
5448
5449	/**
5450	* @brief Find position of a character of string.
5451	* @param __str String containing characters to locate.
5452	* @param __pos Index of character to search from (default 0).
5453	* @return Index of first occurrence.
5454	*
5455	* Starting from @a __pos, searches forward for one of the
5456	* characters of @a __str within this string. If found,
5457	* returns the index where it was found. If not found, returns
5458	* npos.
5459	*/
5460	size_type
5461	find_first_of(const basic_string& __str, size_type __pos = 0) const
5462	_GLIBCXX_NOEXCEPT
5463	{ return this->find_first_of(__str.data(), __pos, __str.size()); }
5464
5465	/**
5466	* @brief Find position of a character of C substring.
5467	* @param __s String containing characters to locate.
5468	* @param __pos Index of character to search from.
5469	* @param __n Number of characters from s to search for.
5470	* @return Index of first occurrence.
5471	*
5472	* Starting from @a __pos, searches forward for one of the
5473	* first @a __n characters of @a __s within this string. If
5474	* found, returns the index where it was found. If not found,
5475	* returns npos.
5476	*/
5477	size_type
5478	find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
5479	_GLIBCXX_NOEXCEPT;
5480
5481	/**
5482	* @brief Find position of a character of C string.
5483	* @param __s String containing characters to locate.
5484	* @param __pos Index of character to search from (default 0).
5485	* @return Index of first occurrence.
5486	*
5487	* Starting from @a __pos, searches forward for one of the
5488	* characters of @a __s within this string. If found, returns
5489	* the index where it was found. If not found, returns npos.
5490	*/
5491	size_type
5492	find_first_of(const _CharT* __s, size_type __pos = 0) const
5493	_GLIBCXX_NOEXCEPT
5494	{
5495	__glibcxx_requires_string(__s);
5496	return this->find_first_of(__s, __pos, traits_type::length(__s));
5497	}
5498
5499	/**
5500	* @brief Find position of a character.
5501	* @param __c Character to locate.
5502	* @param __pos Index of character to search from (default 0).
5503	* @return Index of first occurrence.
5504	*
5505	* Starting from @a __pos, searches forward for the character
5506	* @a __c within this string. If found, returns the index
5507	* where it was found. If not found, returns npos.
5508	*
5509	* Note: equivalent to find(__c, __pos).
5510	*/
5511	size_type
5512	find_first_of(_CharT __c, size_type __pos = 0) const _GLIBCXX_NOEXCEPT
5513	{ return this->find(__c, __pos); }
5514
5515	#if __cplusplus >= 201703L
5516	/**
5517	* @brief Find position of a character of a string_view.
5518	* @param __svt An object convertible to string_view containing
5519	* characters to locate.
5520	* @param __pos Index of character to search from (default 0).
5521	* @return Index of first occurrence.
5522	*/
5523	template<typename _Tp>
5524	_If_sv<_Tp, size_type>
5525	find_first_of(const _Tp& __svt, size_type __pos = 0) const
5526	noexcept(is_same<_Tp, __sv_type>::value)
5527	{
5528	__sv_type __sv = __svt;
5529	return this->find_first_of(__sv.data(), __pos, __sv.size());
5530	}
5531	#endif // C++17
5532
5533	/**
5534	* @brief Find last position of a character of string.
5535	* @param __str String containing characters to locate.
5536	* @param __pos Index of character to search back from (default end).
5537	* @return Index of last occurrence.
5538	*
5539	* Starting from @a __pos, searches backward for one of the
5540	* characters of @a __str within this string. If found,
5541	* returns the index where it was found. If not found, returns
5542	* npos.
5543	*/
5544	size_type
5545	find_last_of(const basic_string& __str, size_type __pos = npos) const
5546	_GLIBCXX_NOEXCEPT
5547	{ return this->find_last_of(__str.data(), __pos, __str.size()); }
5548
5549	/**
5550	* @brief Find last position of a character of C substring.
5551	* @param __s C string containing characters to locate.
5552	* @param __pos Index of character to search back from.
5553	* @param __n Number of characters from s to search for.
5554	* @return Index of last occurrence.
5555	*
5556	* Starting from @a __pos, searches backward for one of the
5557	* first @a __n characters of @a __s within this string. If
5558	* found, returns the index where it was found. If not found,
5559	* returns npos.
5560	*/
5561	size_type
5562	find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
5563	_GLIBCXX_NOEXCEPT;
5564
5565	/**
5566	* @brief Find last position of a character of C string.
5567	* @param __s C string containing characters to locate.
5568	* @param __pos Index of character to search back from (default end).
5569	* @return Index of last occurrence.
5570	*
5571	* Starting from @a __pos, searches backward for one of the
5572	* characters of @a __s within this string. If found, returns
5573	* the index where it was found. If not found, returns npos.
5574	*/
5575	size_type
5576	find_last_of(const _CharT* __s, size_type __pos = npos) const
5577	_GLIBCXX_NOEXCEPT
5578	{
5579	__glibcxx_requires_string(__s);
5580	return this->find_last_of(__s, __pos, traits_type::length(__s));
5581	}
5582
5583	/**
5584	* @brief Find last position of a character.
5585	* @param __c Character to locate.
5586	* @param __pos Index of character to search back from (default end).
5587	* @return Index of last occurrence.
5588	*
5589	* Starting from @a __pos, searches backward for @a __c within
5590	* this string. If found, returns the index where it was
5591	* found. If not found, returns npos.
5592	*
5593	* Note: equivalent to rfind(__c, __pos).
5594	*/
5595	size_type
5596	find_last_of(_CharT __c, size_type __pos = npos) const _GLIBCXX_NOEXCEPT
5597	{ return this->rfind(__c, __pos); }
5598
5599	#if __cplusplus >= 201703L
5600	/**
5601	* @brief Find last position of a character of string.
5602	* @param __svt An object convertible to string_view containing
5603	* characters to locate.
5604	* @param __pos Index of character to search back from (default end).
5605	* @return Index of last occurrence.
5606	*/
5607	template<typename _Tp>
5608	_If_sv<_Tp, size_type>
5609	find_last_of(const _Tp& __svt, size_type __pos = npos) const
5610	noexcept(is_same<_Tp, __sv_type>::value)
5611	{
5612	__sv_type __sv = __svt;
5613	return this->find_last_of(__sv.data(), __pos, __sv.size());
5614	}
5615	#endif // C++17
5616
5617	/**
5618	* @brief Find position of a character not in string.
5619	* @param __str String containing characters to avoid.
5620	* @param __pos Index of character to search from (default 0).
5621	* @return Index of first occurrence.
5622	*
5623	* Starting from @a __pos, searches forward for a character not contained
5624	* in @a __str within this string. If found, returns the index where it
5625	* was found. If not found, returns npos.
5626	*/
5627	size_type
5628	find_first_not_of(const basic_string& __str, size_type __pos = 0) const
5629	_GLIBCXX_NOEXCEPT
5630	{ return this->find_first_not_of(__str.data(), __pos, __str.size()); }
5631
5632	/**
5633	* @brief Find position of a character not in C substring.
5634	* @param __s C string containing characters to avoid.
5635	* @param __pos Index of character to search from.
5636	* @param __n Number of characters from __s to consider.
5637	* @return Index of first occurrence.
5638	*
5639	* Starting from @a __pos, searches forward for a character not
5640	* contained in the first @a __n characters of @a __s within
5641	* this string. If found, returns the index where it was
5642	* found. If not found, returns npos.
5643	*/
5644	size_type
5645	find_first_not_of(const _CharT* __s, size_type __pos,
5646	size_type __n) const _GLIBCXX_NOEXCEPT;
5647
5648	/**
5649	* @brief Find position of a character not in C string.
5650	* @param __s C string containing characters to avoid.
5651	* @param __pos Index of character to search from (default 0).
5652	* @return Index of first occurrence.
5653	*
5654	* Starting from @a __pos, searches forward for a character not
5655	* contained in @a __s within this string. If found, returns
5656	* the index where it was found. If not found, returns npos.
5657	*/
5658	size_type
5659	find_first_not_of(const _CharT* __s, size_type __pos = 0) const
5660	_GLIBCXX_NOEXCEPT
5661	{
5662	__glibcxx_requires_string(__s);
5663	return this->find_first_not_of(__s, __pos, traits_type::length(__s));
5664	}
5665
5666	/**
5667	* @brief Find position of a different character.
5668	* @param __c Character to avoid.
5669	* @param __pos Index of character to search from (default 0).
5670	* @return Index of first occurrence.
5671	*
5672	* Starting from @a __pos, searches forward for a character
5673	* other than @a __c within this string. If found, returns the
5674	* index where it was found. If not found, returns npos.
5675	*/
5676	size_type
5677	find_first_not_of(_CharT __c, size_type __pos = 0) const
5678	_GLIBCXX_NOEXCEPT;
5679
5680	#if __cplusplus >= 201703L
5681	/**
5682	* @brief Find position of a character not in a string_view.
5683	* @param __svt An object convertible to string_view containing
5684	* characters to avoid.
5685	* @param __pos Index of character to search from (default 0).
5686	* @return Index of first occurrence.
5687	*/
5688	template<typename _Tp>
5689	_If_sv<_Tp, size_type>
5690	find_first_not_of(const _Tp& __svt, size_type __pos = 0) const
5691	noexcept(is_same<_Tp, __sv_type>::value)
5692	{
5693	__sv_type __sv = __svt;
5694	return this->find_first_not_of(__sv.data(), __pos, __sv.size());
5695	}
5696	#endif // C++17
5697
5698	/**
5699	* @brief Find last position of a character not in string.
5700	* @param __str String containing characters to avoid.
5701	* @param __pos Index of character to search back from (default end).
5702	* @return Index of last occurrence.
5703	*
5704	* Starting from @a __pos, searches backward for a character
5705	* not contained in @a __str within this string. If found,
5706	* returns the index where it was found. If not found, returns
5707	* npos.
5708	*/
5709	size_type
5710	find_last_not_of(const basic_string& __str, size_type __pos = npos) const
5711	_GLIBCXX_NOEXCEPT
5712	{ return this->find_last_not_of(__str.data(), __pos, __str.size()); }
5713
5714	/**
5715	* @brief Find last position of a character not in C substring.
5716	* @param __s C string containing characters to avoid.
5717	* @param __pos Index of character to search back from.
5718	* @param __n Number of characters from s to consider.
5719	* @return Index of last occurrence.
5720	*
5721	* Starting from @a __pos, searches backward for a character not
5722	* contained in the first @a __n characters of @a __s within this string.
5723	* If found, returns the index where it was found. If not found,
5724	* returns npos.
5725	*/
5726	size_type
5727	find_last_not_of(const _CharT* __s, size_type __pos,
5728	size_type __n) const _GLIBCXX_NOEXCEPT;
5729	/**
5730	* @brief Find last position of a character not in C string.
5731	* @param __s C string containing characters to avoid.
5732	* @param __pos Index of character to search back from (default end).
5733	* @return Index of last occurrence.
5734	*
5735	* Starting from @a __pos, searches backward for a character
5736	* not contained in @a __s within this string. If found,
5737	* returns the index where it was found. If not found, returns
5738	* npos.
5739	*/
5740	size_type
5741	find_last_not_of(const _CharT* __s, size_type __pos = npos) const
5742	_GLIBCXX_NOEXCEPT
5743	{
5744	__glibcxx_requires_string(__s);
5745	return this->find_last_not_of(__s, __pos, traits_type::length(__s));
5746	}
5747
5748	/**
5749	* @brief Find last position of a different character.
5750	* @param __c Character to avoid.
5751	* @param __pos Index of character to search back from (default end).
5752	* @return Index of last occurrence.
5753	*
5754	* Starting from @a __pos, searches backward for a character other than
5755	* @a __c within this string. If found, returns the index where it was
5756	* found. If not found, returns npos.
5757	*/
5758	size_type
5759	find_last_not_of(_CharT __c, size_type __pos = npos) const
5760	_GLIBCXX_NOEXCEPT;
5761
5762	#if __cplusplus >= 201703L
5763	/**
5764	* @brief Find last position of a character not in a string_view.
5765	* @param __svt An object convertible to string_view containing
5766	* characters to avoid.
5767	* @param __pos Index of character to search back from (default end).
5768	* @return Index of last occurrence.
5769	*/
5770	template<typename _Tp>
5771	_If_sv<_Tp, size_type>
5772	find_last_not_of(const _Tp& __svt, size_type __pos = npos) const
5773	noexcept(is_same<_Tp, __sv_type>::value)
5774	{
5775	__sv_type __sv = __svt;
5776	return this->find_last_not_of(__sv.data(), __pos, __sv.size());
5777	}
5778	#endif // C++17
5779
5780	/**
5781	* @brief Get a substring.
5782	* @param __pos Index of first character (default 0).
5783	* @param __n Number of characters in substring (default remainder).
5784	* @return The new string.
5785	* @throw std::out_of_range If __pos > size().
5786	*
5787	* Construct and return a new string using the @a __n
5788	* characters starting at @a __pos. If the string is too
5789	* short, use the remainder of the characters. If @a __pos is
5790	* beyond the end of the string, out_of_range is thrown.
5791	*/
5792	basic_string
5793	substr(size_type __pos = 0, size_type __n = npos) const
5794	{ return basic_string(*this,
5795	_M_check(__pos, "basic_string::substr"), __n); }
5796
5797	/**
5798	* @brief Compare to a string.
5799	* @param __str String to compare against.
5800	* @return Integer < 0, 0, or > 0.
5801	*
5802	* Returns an integer < 0 if this string is ordered before @a
5803	* __str, 0 if their values are equivalent, or > 0 if this
5804	* string is ordered after @a __str. Determines the effective
5805	* length rlen of the strings to compare as the smallest of
5806	* size() and str.size(). The function then compares the two
5807	* strings by calling traits::compare(data(), str.data(),rlen).
5808	* If the result of the comparison is nonzero returns it,
5809	* otherwise the shorter one is ordered first.
5810	*/
5811	int
5812	compare(const basic_string& __str) const
5813	{
5814	const size_type __size = this->size();
5815	const size_type __osize = __str.size();
5816	const size_type __len = std::min(__size, __osize);
5817
5818	int __r = traits_type::compare(_M_data(), __str.data(), __len);
5819	if (!__r)
5820	__r = _S_compare(__size, __osize);
5821	return __r;
5822	}
5823
5824	#if __cplusplus >= 201703L
5825	/**
5826	* @brief Compare to a string_view.
5827	* @param __svt An object convertible to string_view to compare against.
5828	* @return Integer < 0, 0, or > 0.
5829	*/
5830	template<typename _Tp>
5831	_If_sv<_Tp, int>
5832	compare(const _Tp& __svt) const
5833	noexcept(is_same<_Tp, __sv_type>::value)
5834	{
5835	__sv_type __sv = __svt;
5836	const size_type __size = this->size();
5837	const size_type __osize = __sv.size();
5838	const size_type __len = std::min(__size, __osize);
5839
5840	int __r = traits_type::compare(_M_data(), __sv.data(), __len);
5841	if (!__r)
5842	__r = _S_compare(__size, __osize);
5843	return __r;
5844	}
5845
5846	/**
5847	* @brief Compare to a string_view.
5848	* @param __pos A position in the string to start comparing from.
5849	* @param __n The number of characters to compare.
5850	* @param __svt An object convertible to string_view to compare
5851	* against.
5852	* @return Integer < 0, 0, or > 0.
5853	*/
5854	template<typename _Tp>
5855	_If_sv<_Tp, int>
5856	compare(size_type __pos, size_type __n, const _Tp& __svt) const
5857	noexcept(is_same<_Tp, __sv_type>::value)
5858	{
5859	__sv_type __sv = __svt;
5860	return __sv_type(*this).substr(__pos, __n).compare(__sv);
5861	}
5862
5863	/**
5864	* @brief Compare to a string_view.
5865	* @param __pos1 A position in the string to start comparing from.
5866	* @param __n1 The number of characters to compare.
5867	* @param __svt An object convertible to string_view to compare
5868	* against.
5869	* @param __pos2 A position in the string_view to start comparing from.
5870	* @param __n2 The number of characters to compare.
5871	* @return Integer < 0, 0, or > 0.
5872	*/
5873	template<typename _Tp>
5874	_If_sv<_Tp, int>
5875	compare(size_type __pos1, size_type __n1, const _Tp& __svt,
5876	size_type __pos2, size_type __n2 = npos) const
5877	noexcept(is_same<_Tp, __sv_type>::value)
5878	{
5879	__sv_type __sv = __svt;
5880	return __sv_type(*this)
5881	.substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
5882	}
5883	#endif // C++17
5884
5885	/**
5886	* @brief Compare substring to a string.
5887	* @param __pos Index of first character of substring.
5888	* @param __n Number of characters in substring.
5889	* @param __str String to compare against.
5890	* @return Integer < 0, 0, or > 0.
5891	*
5892	* Form the substring of this string from the @a __n characters
5893	* starting at @a __pos. Returns an integer < 0 if the
5894	* substring is ordered before @a __str, 0 if their values are
5895	* equivalent, or > 0 if the substring is ordered after @a
5896	* __str. Determines the effective length rlen of the strings
5897	* to compare as the smallest of the length of the substring
5898	* and @a __str.size(). The function then compares the two
5899	* strings by calling
5900	* traits::compare(substring.data(),str.data(),rlen). If the
5901	* result of the comparison is nonzero returns it, otherwise
5902	* the shorter one is ordered first.
5903	*/
5904	int
5905	compare(size_type __pos, size_type __n, const basic_string& __str) const;
5906
5907	/**
5908	* @brief Compare substring to a substring.
5909	* @param __pos1 Index of first character of substring.
5910	* @param __n1 Number of characters in substring.
5911	* @param __str String to compare against.
5912	* @param __pos2 Index of first character of substring of str.
5913	* @param __n2 Number of characters in substring of str.
5914	* @return Integer < 0, 0, or > 0.
5915	*
5916	* Form the substring of this string from the @a __n1
5917	* characters starting at @a __pos1. Form the substring of @a
5918	* __str from the @a __n2 characters starting at @a __pos2.
5919	* Returns an integer < 0 if this substring is ordered before
5920	* the substring of @a __str, 0 if their values are equivalent,
5921	* or > 0 if this substring is ordered after the substring of
5922	* @a __str. Determines the effective length rlen of the
5923	* strings to compare as the smallest of the lengths of the
5924	* substrings. The function then compares the two strings by
5925	* calling
5926	* traits::compare(substring.data(),str.substr(pos2,n2).data(),rlen).
5927	* If the result of the comparison is nonzero returns it,
5928	* otherwise the shorter one is ordered first.
5929	*/
5930	int
5931	compare(size_type __pos1, size_type __n1, const basic_string& __str,
5932	size_type __pos2, size_type __n2 = npos) const;
5933
5934	/**
5935	* @brief Compare to a C string.
5936	* @param __s C string to compare against.
5937	* @return Integer < 0, 0, or > 0.
5938	*
5939	* Returns an integer < 0 if this string is ordered before @a __s, 0 if
5940	* their values are equivalent, or > 0 if this string is ordered after
5941	* @a __s. Determines the effective length rlen of the strings to
5942	* compare as the smallest of size() and the length of a string
5943	* constructed from @a __s. The function then compares the two strings
5944	* by calling traits::compare(data(),s,rlen). If the result of the
5945	* comparison is nonzero returns it, otherwise the shorter one is
5946	* ordered first.
5947	*/
5948	int
5949	compare(const _CharT* __s) const _GLIBCXX_NOEXCEPT;
5950
5951	// _GLIBCXX_RESOLVE_LIB_DEFECTS
5952	// 5 String::compare specification questionable
5953	/**
5954	* @brief Compare substring to a C string.
5955	* @param __pos Index of first character of substring.
5956	* @param __n1 Number of characters in substring.
5957	* @param __s C string to compare against.
5958	* @return Integer < 0, 0, or > 0.
5959	*
5960	* Form the substring of this string from the @a __n1
5961	* characters starting at @a pos. Returns an integer < 0 if
5962	* the substring is ordered before @a __s, 0 if their values
5963	* are equivalent, or > 0 if the substring is ordered after @a
5964	* __s. Determines the effective length rlen of the strings to
5965	* compare as the smallest of the length of the substring and
5966	* the length of a string constructed from @a __s. The
5967	* function then compares the two string by calling
5968	* traits::compare(substring.data(),__s,rlen). If the result of
5969	* the comparison is nonzero returns it, otherwise the shorter
5970	* one is ordered first.
5971	*/
5972	int
5973	compare(size_type __pos, size_type __n1, const _CharT* __s) const;
5974
5975	/**
5976	* @brief Compare substring against a character %array.
5977	* @param __pos Index of first character of substring.
5978	* @param __n1 Number of characters in substring.
5979	* @param __s character %array to compare against.
5980	* @param __n2 Number of characters of s.
5981	* @return Integer < 0, 0, or > 0.
5982	*
5983	* Form the substring of this string from the @a __n1
5984	* characters starting at @a __pos. Form a string from the
5985	* first @a __n2 characters of @a __s. Returns an integer < 0
5986	* if this substring is ordered before the string from @a __s,
5987	* 0 if their values are equivalent, or > 0 if this substring
5988	* is ordered after the string from @a __s. Determines the
5989	* effective length rlen of the strings to compare as the
5990	* smallest of the length of the substring and @a __n2. The
5991	* function then compares the two strings by calling
5992	* traits::compare(substring.data(),s,rlen). If the result of
5993	* the comparison is nonzero returns it, otherwise the shorter
5994	* one is ordered first.
5995	*
5996	* NB: s must have at least n2 characters, &apos;\\0&apos; has
5997	* no special meaning.
5998	*/
5999	int
6000	compare(size_type __pos, size_type __n1, const _CharT* __s,
6001	size_type __n2) const;
6002
6003	#if __cplusplus > 201703L
6004	bool
6005	starts_with(basic_string_view<_CharT, _Traits> __x) const noexcept
6006	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
6007
6008	bool
6009	starts_with(_CharT __x) const noexcept
6010	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
6011
6012	bool
6013	starts_with(const _CharT* __x) const noexcept
6014	{ return __sv_type(this->data(), this->size()).starts_with(__x); }
6015
6016	bool
6017	ends_with(basic_string_view<_CharT, _Traits> __x) const noexcept
6018	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
6019
6020	bool
6021	ends_with(_CharT __x) const noexcept
6022	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
6023
6024	bool
6025	ends_with(const _CharT* __x) const noexcept
6026	{ return __sv_type(this->data(), this->size()).ends_with(__x); }
6027	#endif // C++20
6028
6029	#if __cplusplus > 202011L
6030	bool
6031	contains(basic_string_view<_CharT, _Traits> __x) const noexcept
6032	{ return __sv_type(this->data(), this->size()).contains(__x); }
6033
6034	bool
6035	contains(_CharT __x) const noexcept
6036	{ return __sv_type(this->data(), this->size()).contains(__x); }
6037
6038	bool
6039	contains(const _CharT* __x) const noexcept
6040	{ return __sv_type(this->data(), this->size()).contains(__x); }
6041	#endif // C++23
6042
6043	# ifdef _GLIBCXX_TM_TS_INTERNAL
6044	friend void
6045	::_txnal_cow_string_C1_for_exceptions(void* that, const char* s,
6046	void* exc);
6047	friend const char*
6048	::_txnal_cow_string_c_str(const void *that);
6049	friend void
6050	::_txnal_cow_string_D1(void *that);
6051	friend void
6052	::_txnal_cow_string_D1_commit(void *that);
6053	# endif
6054	};
6055	#endif // !_GLIBCXX_USE_CXX11_ABI
6056
6057	#if __cpp_deduction_guides >= 201606
6058	_GLIBCXX_BEGIN_NAMESPACE_CXX11
6059	template<typename _InputIterator, typename _CharT
6060	= typename iterator_traits<_InputIterator>::value_type,
6061	typename _Allocator = allocator<_CharT>,
6062	typename = _RequireInputIter<_InputIterator>,
6063	typename = _RequireAllocator<_Allocator>>
6064	basic_string(_InputIterator, _InputIterator, _Allocator = _Allocator())
6065	-> basic_string<_CharT, char_traits<_CharT>, _Allocator>;
6066
6067	// _GLIBCXX_RESOLVE_LIB_DEFECTS
6068	// 3075. basic_string needs deduction guides from basic_string_view
6069	template<typename _CharT, typename _Traits,
6070	typename _Allocator = allocator<_CharT>,
6071	typename = _RequireAllocator<_Allocator>>
6072	basic_string(basic_string_view<_CharT, _Traits>, const _Allocator& = _Allocator())
6073	-> basic_string<_CharT, _Traits, _Allocator>;
6074
6075	template<typename _CharT, typename _Traits,
6076	typename _Allocator = allocator<_CharT>,
6077	typename = _RequireAllocator<_Allocator>>
6078	basic_string(basic_string_view<_CharT, _Traits>,
6079	typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6080	typename basic_string<_CharT, _Traits, _Allocator>::size_type,
6081	const _Allocator& = _Allocator())
6082	-> basic_string<_CharT, _Traits, _Allocator>;
6083	_GLIBCXX_END_NAMESPACE_CXX11
6084	#endif
6085
6086	// operator+
6087	/**
6088	* @brief Concatenate two strings.
6089	* @param __lhs First string.
6090	* @param __rhs Last string.
6091	* @return New string with value of @a __lhs followed by @a __rhs.
6092	*/
6093	template<typename _CharT, typename _Traits, typename _Alloc>
6094	basic_string<_CharT, _Traits, _Alloc>
6095	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6096	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6097	{
6098	basic_string<_CharT, _Traits, _Alloc> __str(__lhs);
6099	__str.append(__rhs);
6100	return __str;
6101	}
6102
6103	/**
6104	* @brief Concatenate C string and string.
6105	* @param __lhs First string.
6106	* @param __rhs Last string.
6107	* @return New string with value of @a __lhs followed by @a __rhs.
6108	*/
6109	template<typename _CharT, typename _Traits, typename _Alloc>
6110	basic_string<_CharT,_Traits,_Alloc>
6111	operator+(const _CharT* __lhs,
6112	const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6113
6114	/**
6115	* @brief Concatenate character and string.
6116	* @param __lhs First string.
6117	* @param __rhs Last string.
6118	* @return New string with @a __lhs followed by @a __rhs.
6119	*/
6120	template<typename _CharT, typename _Traits, typename _Alloc>
6121	basic_string<_CharT,_Traits,_Alloc>
6122	operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs);
6123
6124	/**
6125	* @brief Concatenate string and C string.
6126	* @param __lhs First string.
6127	* @param __rhs Last string.
6128	* @return New string with @a __lhs followed by @a __rhs.
6129	*/
6130	template<typename _CharT, typename _Traits, typename _Alloc>
6131	inline basic_string<_CharT, _Traits, _Alloc>
6132	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6133	const _CharT* __rhs)
6134	{
6135	basic_string<_CharT, _Traits, _Alloc> __str(__lhs);
6136	__str.append(__rhs);
6137	return __str;
6138	}
6139
6140	/**
6141	* @brief Concatenate string and character.
6142	* @param __lhs First string.
6143	* @param __rhs Last string.
6144	* @return New string with @a __lhs followed by @a __rhs.
6145	*/
6146	template<typename _CharT, typename _Traits, typename _Alloc>
6147	inline basic_string<_CharT, _Traits, _Alloc>
6148	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
6149	{
6150	typedef basic_string<_CharT, _Traits, _Alloc> __string_type;
6151	typedef typename __string_type::size_type __size_type;
6152	__string_type __str(__lhs);
6153	__str.append(__size_type(1), __rhs);
6154	return __str;
6155	}
6156
6157	#if __cplusplus >= 201103L
6158	template<typename _CharT, typename _Traits, typename _Alloc>
6159	inline basic_string<_CharT, _Traits, _Alloc>
6160	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6161	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6162	{ return std::move(__lhs.append(__rhs)); }
6163
6164	template<typename _CharT, typename _Traits, typename _Alloc>
6165	inline basic_string<_CharT, _Traits, _Alloc>
6166	operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6167	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6168	{ return std::move(__rhs.insert(0, __lhs)); }
6169
6170	template<typename _CharT, typename _Traits, typename _Alloc>
6171	inline basic_string<_CharT, _Traits, _Alloc>
6172	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6173	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6174	{
6175	#if _GLIBCXX_USE_CXX11_ABI
6176	using _Alloc_traits = allocator_traits<_Alloc>;
6177	bool __use_rhs = false;
6178	if _GLIBCXX17_CONSTEXPR (typename _Alloc_traits::is_always_equal{})
6179	__use_rhs = true;
6180	else if (__lhs.get_allocator() == __rhs.get_allocator())
6181	__use_rhs = true;
6182	if (__use_rhs)
6183	#endif
6184	{
6185	const auto __size = __lhs.size() + __rhs.size();
6186	if (__size > __lhs.capacity() && __size <= __rhs.capacity())
6187	return std::move(__rhs.insert(0, __lhs));
6188	}
6189	return std::move(__lhs.append(__rhs));
6190	}
6191
6192	template<typename _CharT, typename _Traits, typename _Alloc>
6193	inline basic_string<_CharT, _Traits, _Alloc>
6194	operator+(const _CharT* __lhs,
6195	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6196	{ return std::move(__rhs.insert(0, __lhs)); }
6197
6198	template<typename _CharT, typename _Traits, typename _Alloc>
6199	inline basic_string<_CharT, _Traits, _Alloc>
6200	operator+(_CharT __lhs,
6201	basic_string<_CharT, _Traits, _Alloc>&& __rhs)
6202	{ return std::move(__rhs.insert(0, 1, __lhs)); }
6203
6204	template<typename _CharT, typename _Traits, typename _Alloc>
6205	inline basic_string<_CharT, _Traits, _Alloc>
6206	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6207	const _CharT* __rhs)
6208	{ return std::move(__lhs.append(__rhs)); }
6209
6210	template<typename _CharT, typename _Traits, typename _Alloc>
6211	inline basic_string<_CharT, _Traits, _Alloc>
6212	operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
6213	_CharT __rhs)
6214	{ return std::move(__lhs.append(1, __rhs)); }
6215	#endif
6216
6217	// operator ==
6218	/**
6219	* @brief Test equivalence of two strings.
6220	* @param __lhs First string.
6221	* @param __rhs Second string.
6222	* @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6223	*/
6224	template<typename _CharT, typename _Traits, typename _Alloc>
6225	inline bool
6226	operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6227	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6228	_GLIBCXX_NOEXCEPT
6229	{ return __lhs.compare(__rhs) == 0; }
6230
6231	template<typename _CharT>
6232	inline
6233	typename __gnu_cxx::__enable_if<__is_char<_CharT>::__value, bool>::__type
6234	operator==(const basic_string<_CharT>& __lhs,
6235	const basic_string<_CharT>& __rhs) _GLIBCXX_NOEXCEPT
6236	{ return (__lhs.size() == __rhs.size()
6237	&& !std::char_traits<_CharT>::compare(__lhs.data(), __rhs.data(),
6238	__lhs.size())); }
6239
6240	/**
6241	* @brief Test equivalence of string and C string.
6242	* @param __lhs String.
6243	* @param __rhs C string.
6244	* @return True if @a __lhs.compare(@a __rhs) == 0. False otherwise.
6245	*/
6246	template<typename _CharT, typename _Traits, typename _Alloc>
6247	inline bool
6248	operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6249	const _CharT* __rhs)
6250	{ return __lhs.compare(__rhs) == 0; }
6251
6252	#if __cpp_lib_three_way_comparison
6253	/**
6254	* @brief Three-way comparison of a string and a C string.
6255	* @param __lhs A string.
6256	* @param __rhs A null-terminated string.
6257	* @return A value indicating whether `__lhs` is less than, equal to,
6258	* greater than, or incomparable with `__rhs`.
6259	*/
6260	template<typename _CharT, typename _Traits, typename _Alloc>
6261	inline auto
6262	operator<=>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6263	const basic_string<_CharT, _Traits, _Alloc>& __rhs) noexcept
6264	-> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
6265	{ return __detail::__char_traits_cmp_cat<_Traits>(__lhs.compare(__rhs)); }
6266
6267	/**
6268	* @brief Three-way comparison of a string and a C string.
6269	* @param __lhs A string.
6270	* @param __rhs A null-terminated string.
6271	* @return A value indicating whether `__lhs` is less than, equal to,
6272	* greater than, or incomparable with `__rhs`.
6273	*/
6274	template<typename _CharT, typename _Traits, typename _Alloc>
6275	inline auto
6276	operator<=>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6277	const _CharT* __rhs) noexcept
6278	-> decltype(__detail::__char_traits_cmp_cat<_Traits>(0))
6279	{ return __detail::__char_traits_cmp_cat<_Traits>(__lhs.compare(__rhs)); }
6280	#else
6281	/**
6282	* @brief Test equivalence of C string and string.
6283	* @param __lhs C string.
6284	* @param __rhs String.
6285	* @return True if @a __rhs.compare(@a __lhs) == 0. False otherwise.
6286	*/
6287	template<typename _CharT, typename _Traits, typename _Alloc>
6288	inline bool
6289	operator==(const _CharT* __lhs,
6290	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6291	{ return __rhs.compare(__lhs) == 0; }
6292
6293	// operator !=
6294	/**
6295	* @brief Test difference of two strings.
6296	* @param __lhs First string.
6297	* @param __rhs Second string.
6298	* @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6299	*/
6300	template<typename _CharT, typename _Traits, typename _Alloc>
6301	inline bool
6302	operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6303	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6304	_GLIBCXX_NOEXCEPT
6305	{ return !(__lhs == __rhs); }
6306
6307	/**
6308	* @brief Test difference of C string and string.
6309	* @param __lhs C string.
6310	* @param __rhs String.
6311	* @return True if @a __rhs.compare(@a __lhs) != 0. False otherwise.
6312	*/
6313	template<typename _CharT, typename _Traits, typename _Alloc>
6314	inline bool
6315	operator!=(const _CharT* __lhs,
6316	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6317	{ return !(__lhs == __rhs); }
6318
6319	/**
6320	* @brief Test difference of string and C string.
6321	* @param __lhs String.
6322	* @param __rhs C string.
6323	* @return True if @a __lhs.compare(@a __rhs) != 0. False otherwise.
6324	*/
6325	template<typename _CharT, typename _Traits, typename _Alloc>
6326	inline bool
6327	operator!=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6328	const _CharT* __rhs)
6329	{ return !(__lhs == __rhs); }
6330
6331	// operator <
6332	/**
6333	* @brief Test if string precedes string.
6334	* @param __lhs First string.
6335	* @param __rhs Second string.
6336	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6337	*/
6338	template<typename _CharT, typename _Traits, typename _Alloc>
6339	inline bool
6340	operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6341	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6342	_GLIBCXX_NOEXCEPT
6343	{ return __lhs.compare(__rhs) < 0; }
6344
6345	/**
6346	* @brief Test if string precedes C string.
6347	* @param __lhs String.
6348	* @param __rhs C string.
6349	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6350	*/
6351	template<typename _CharT, typename _Traits, typename _Alloc>
6352	inline bool
6353	operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6354	const _CharT* __rhs)
6355	{ return __lhs.compare(__rhs) < 0; }
6356
6357	/**
6358	* @brief Test if C string precedes string.
6359	* @param __lhs C string.
6360	* @param __rhs String.
6361	* @return True if @a __lhs precedes @a __rhs. False otherwise.
6362	*/
6363	template<typename _CharT, typename _Traits, typename _Alloc>
6364	inline bool
6365	operator<(const _CharT* __lhs,
6366	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6367	{ return __rhs.compare(__lhs) > 0; }
6368
6369	// operator >
6370	/**
6371	* @brief Test if string follows string.
6372	* @param __lhs First string.
6373	* @param __rhs Second string.
6374	* @return True if @a __lhs follows @a __rhs. False otherwise.
6375	*/
6376	template<typename _CharT, typename _Traits, typename _Alloc>
6377	inline bool
6378	operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6379	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6380	_GLIBCXX_NOEXCEPT
6381	{ return __lhs.compare(__rhs) > 0; }
6382
6383	/**
6384	* @brief Test if string follows C string.
6385	* @param __lhs String.
6386	* @param __rhs C string.
6387	* @return True if @a __lhs follows @a __rhs. False otherwise.
6388	*/
6389	template<typename _CharT, typename _Traits, typename _Alloc>
6390	inline bool
6391	operator>(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6392	const _CharT* __rhs)
6393	{ return __lhs.compare(__rhs) > 0; }
6394
6395	/**
6396	* @brief Test if C string follows string.
6397	* @param __lhs C string.
6398	* @param __rhs String.
6399	* @return True if @a __lhs follows @a __rhs. False otherwise.
6400	*/
6401	template<typename _CharT, typename _Traits, typename _Alloc>
6402	inline bool
6403	operator>(const _CharT* __lhs,
6404	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6405	{ return __rhs.compare(__lhs) < 0; }
6406
6407	// operator <=
6408	/**
6409	* @brief Test if string doesn't follow string.
6410	* @param __lhs First string.
6411	* @param __rhs Second string.
6412	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6413	*/
6414	template<typename _CharT, typename _Traits, typename _Alloc>
6415	inline bool
6416	operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6417	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6418	_GLIBCXX_NOEXCEPT
6419	{ return __lhs.compare(__rhs) <= 0; }
6420
6421	/**
6422	* @brief Test if string doesn't follow C string.
6423	* @param __lhs String.
6424	* @param __rhs C string.
6425	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6426	*/
6427	template<typename _CharT, typename _Traits, typename _Alloc>
6428	inline bool
6429	operator<=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6430	const _CharT* __rhs)
6431	{ return __lhs.compare(__rhs) <= 0; }
6432
6433	/**
6434	* @brief Test if C string doesn't follow string.
6435	* @param __lhs C string.
6436	* @param __rhs String.
6437	* @return True if @a __lhs doesn't follow @a __rhs. False otherwise.
6438	*/
6439	template<typename _CharT, typename _Traits, typename _Alloc>
6440	inline bool
6441	operator<=(const _CharT* __lhs,
6442	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6443	{ return __rhs.compare(__lhs) >= 0; }
6444
6445	// operator >=
6446	/**
6447	* @brief Test if string doesn't precede string.
6448	* @param __lhs First string.
6449	* @param __rhs Second string.
6450	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6451	*/
6452	template<typename _CharT, typename _Traits, typename _Alloc>
6453	inline bool
6454	operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6455	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6456	_GLIBCXX_NOEXCEPT
6457	{ return __lhs.compare(__rhs) >= 0; }
6458
6459	/**
6460	* @brief Test if string doesn't precede C string.
6461	* @param __lhs String.
6462	* @param __rhs C string.
6463	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6464	*/
6465	template<typename _CharT, typename _Traits, typename _Alloc>
6466	inline bool
6467	operator>=(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
6468	const _CharT* __rhs)
6469	{ return __lhs.compare(__rhs) >= 0; }
6470
6471	/**
6472	* @brief Test if C string doesn't precede string.
6473	* @param __lhs C string.
6474	* @param __rhs String.
6475	* @return True if @a __lhs doesn't precede @a __rhs. False otherwise.
6476	*/
6477	template<typename _CharT, typename _Traits, typename _Alloc>
6478	inline bool
6479	operator>=(const _CharT* __lhs,
6480	const basic_string<_CharT, _Traits, _Alloc>& __rhs)
6481	{ return __rhs.compare(__lhs) <= 0; }
6482	#endif // three-way comparison
6483
6484	/**
6485	* @brief Swap contents of two strings.
6486	* @param __lhs First string.
6487	* @param __rhs Second string.
6488	*
6489	* Exchanges the contents of @a __lhs and @a __rhs in constant time.
6490	*/
6491	template<typename _CharT, typename _Traits, typename _Alloc>
6492	inline void
6493	swap(basic_string<_CharT, _Traits, _Alloc>& __lhs,
6494	basic_string<_CharT, _Traits, _Alloc>& __rhs)
6495	_GLIBCXX_NOEXCEPT_IF(noexcept(__lhs.swap(__rhs)))
6496	{ __lhs.swap(__rhs); }
6497
6498
6499	/**
6500	* @brief Read stream into a string.
6501	* @param __is Input stream.
6502	* @param __str Buffer to store into.
6503	* @return Reference to the input stream.
6504	*
6505	* Stores characters from @a __is into @a __str until whitespace is
6506	* found, the end of the stream is encountered, or str.max_size()
6507	* is reached. If is.width() is non-zero, that is the limit on the
6508	* number of characters stored into @a __str. Any previous
6509	* contents of @a __str are erased.
6510	*/
6511	template<typename _CharT, typename _Traits, typename _Alloc>
6512	basic_istream<_CharT, _Traits>&
6513	operator>>(basic_istream<_CharT, _Traits>& __is,
6514	basic_string<_CharT, _Traits, _Alloc>& __str);
6515
6516	template<>
6517	basic_istream<char>&
6518	operator>>(basic_istream<char>& __is, basic_string<char>& __str);
6519
6520	/**
6521	* @brief Write string to a stream.
6522	* @param __os Output stream.
6523	* @param __str String to write out.
6524	* @return Reference to the output stream.
6525	*
6526	* Output characters of @a __str into os following the same rules as for
6527	* writing a C string.
6528	*/
6529	template<typename _CharT, typename _Traits, typename _Alloc>
6530	inline basic_ostream<_CharT, _Traits>&
6531	operator<<(basic_ostream<_CharT, _Traits>& __os,
6532	const basic_string<_CharT, _Traits, _Alloc>& __str)
6533	{
6534	// _GLIBCXX_RESOLVE_LIB_DEFECTS
6535	// 586. string inserter not a formatted function
6536	return __ostream_insert(__os, __str.data(), __str.size());
6537	}
6538
6539	/**
6540	* @brief Read a line from stream into a string.
6541	* @param __is Input stream.
6542	* @param __str Buffer to store into.
6543	* @param __delim Character marking end of line.
6544	* @return Reference to the input stream.
6545	*
6546	* Stores characters from @a __is into @a __str until @a __delim is
6547	* found, the end of the stream is encountered, or str.max_size()
6548	* is reached. Any previous contents of @a __str are erased. If
6549	* @a __delim is encountered, it is extracted but not stored into
6550	* @a __str.
6551	*/
6552	template<typename _CharT, typename _Traits, typename _Alloc>
6553	basic_istream<_CharT, _Traits>&
6554	getline(basic_istream<_CharT, _Traits>& __is,
6555	basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim);
6556
6557	/**
6558	* @brief Read a line from stream into a string.
6559	* @param __is Input stream.
6560	* @param __str Buffer to store into.
6561	* @return Reference to the input stream.
6562	*
6563	* Stores characters from is into @a __str until &apos;\n&apos; is
6564	* found, the end of the stream is encountered, or str.max_size()
6565	* is reached. Any previous contents of @a __str are erased. If
6566	* end of line is encountered, it is extracted but not stored into
6567	* @a __str.
6568	*/
6569	template<typename _CharT, typename _Traits, typename _Alloc>
6570	inline basic_istream<_CharT, _Traits>&
6571	getline(basic_istream<_CharT, _Traits>& __is,
6572	basic_string<_CharT, _Traits, _Alloc>& __str)
6573	{ return std::getline(__is, __str, __is.widen('\n')); }
6574
6575	#if __cplusplus >= 201103L
6576	/// Read a line from an rvalue stream into a string.
6577	template<typename _CharT, typename _Traits, typename _Alloc>
6578	inline basic_istream<_CharT, _Traits>&
6579	getline(basic_istream<_CharT, _Traits>&& __is,
6580	basic_string<_CharT, _Traits, _Alloc>& __str, _CharT __delim)
6581	{ return std::getline(__is, __str, __delim); }
6582
6583	/// Read a line from an rvalue stream into a string.
6584	template<typename _CharT, typename _Traits, typename _Alloc>
6585	inline basic_istream<_CharT, _Traits>&
6586	getline(basic_istream<_CharT, _Traits>&& __is,
6587	basic_string<_CharT, _Traits, _Alloc>& __str)
6588	{ return std::getline(__is, __str); }
6589	#endif
6590
6591	template<>
6592	basic_istream<char>&
6593	getline(basic_istream<char>& __in, basic_string<char>& __str,
6594	char __delim);
6595
6596	#ifdef _GLIBCXX_USE_WCHAR_T
6597	template<>
6598	basic_istream<wchar_t>&
6599	getline(basic_istream<wchar_t>& __in, basic_string<wchar_t>& __str,
6600	wchar_t __delim);
6601	#endif
6602
6603	_GLIBCXX_END_NAMESPACE_VERSION
6604	} // namespace
6605
6606	#if __cplusplus >= 201103L
6607
6608	#include <ext/string_conversions.h>
6609	#include <bits/charconv.h>
6610
6611	namespace std _GLIBCXX_VISIBILITY(default)
6612	{
6613	_GLIBCXX_BEGIN_NAMESPACE_VERSION
6614	_GLIBCXX_BEGIN_NAMESPACE_CXX11
6615
6616	#if _GLIBCXX_USE_C99_STDLIB
6617	// 21.4 Numeric Conversions [string.conversions].
6618	inline int
6619	stoi(const string& __str, size_t* __idx = 0, int __base = 10)
6620	{ return __gnu_cxx::__stoa<long, int>(convf: &std::strtol, name: "stoi", str: __str.c_str(),
6621	__idx, __base); }
6622
6623	inline long
6624	stol(const string& __str, size_t* __idx = 0, int __base = 10)
6625	{ return __gnu_cxx::__stoa(convf: &std::strtol, name: "stol", str: __str.c_str(),
6626	__idx, __base); }
6627
6628	inline unsigned long
6629	stoul(const string& __str, size_t* __idx = 0, int __base = 10)
6630	{ return __gnu_cxx::__stoa(convf: &std::strtoul, name: "stoul", str: __str.c_str(),
6631	__idx, __base); }
6632
6633	inline long long
6634	stoll(const string& __str, size_t* __idx = 0, int __base = 10)
6635	{ return __gnu_cxx::__stoa(convf: &std::strtoll, name: "stoll", str: __str.c_str(),
6636	__idx, __base); }
6637
6638	inline unsigned long long
6639	stoull(const string& __str, size_t* __idx = 0, int __base = 10)
6640	{ return __gnu_cxx::__stoa(convf: &std::strtoull, name: "stoull", str: __str.c_str(),
6641	__idx, __base); }
6642
6643	// NB: strtof vs strtod.
6644	inline float
6645	stof(const string& __str, size_t* __idx = 0)
6646	{ return __gnu_cxx::__stoa(convf: &std::strtof, name: "stof", str: __str.c_str(), __idx); }
6647
6648	inline double
6649	stod(const string& __str, size_t* __idx = 0)
6650	{ return __gnu_cxx::__stoa(convf: &std::strtod, name: "stod", str: __str.c_str(), __idx); }
6651
6652	inline long double
6653	stold(const string& __str, size_t* __idx = 0)
6654	{ return __gnu_cxx::__stoa(convf: &std::strtold, name: "stold", str: __str.c_str(), __idx); }
6655	#endif // _GLIBCXX_USE_C99_STDLIB
6656
6657	// DR 1261. Insufficent overloads for to_string / to_wstring
6658
6659	inline string
6660	to_string(int __val)
6661	{
6662	const bool __neg = __val < 0;
6663	const unsigned __uval = __neg ? (unsigned)~__val + 1u : __val;
6664	const auto __len = __detail::__to_chars_len(value: __uval);
6665	string __str(__neg + __len, '-');
6666	__detail::__to_chars_10_impl(first: &__str[__neg], __len, val: __uval);
6667	return __str;
6668	}
6669
6670	inline string
6671	to_string(unsigned __val)
6672	{
6673	string __str(__detail::__to_chars_len(value: __val), '\0');
6674	__detail::__to_chars_10_impl(first: &__str[0], len: __str.size(), __val);
6675	return __str;
6676	}
6677
6678	inline string
6679	to_string(long __val)
6680	{
6681	const bool __neg = __val < 0;
6682	const unsigned long __uval = __neg ? (unsigned long)~__val + 1ul : __val;
6683	const auto __len = __detail::__to_chars_len(value: __uval);
6684	string __str(__neg + __len, '-');
6685	__detail::__to_chars_10_impl(first: &__str[__neg], __len, val: __uval);
6686	return __str;
6687	}
6688
6689	inline string
6690	to_string(unsigned long __val)
6691	{
6692	string __str(__detail::__to_chars_len(value: __val), '\0');
6693	__detail::__to_chars_10_impl(first: &__str[0], len: __str.size(), __val);
6694	return __str;
6695	}
6696
6697	inline string
6698	to_string(long long __val)
6699	{
6700	const bool __neg = __val < 0;
6701	const unsigned long long __uval
6702	= __neg ? (unsigned long long)~__val + 1ull : __val;
6703	const auto __len = __detail::__to_chars_len(value: __uval);
6704	string __str(__neg + __len, '-');
6705	__detail::__to_chars_10_impl(first: &__str[__neg], __len, val: __uval);
6706	return __str;
6707	}
6708
6709	inline string
6710	to_string(unsigned long long __val)
6711	{
6712	string __str(__detail::__to_chars_len(value: __val), '\0');
6713	__detail::__to_chars_10_impl(first: &__str[0], len: __str.size(), __val);
6714	return __str;
6715	}
6716
6717	#if _GLIBCXX_USE_C99_STDIO
6718	// NB: (v)snprintf vs sprintf.
6719
6720	inline string
6721	to_string(float __val)
6722	{
6723	const int __n =
6724	__gnu_cxx::__numeric_traits<float>::__max_exponent10 + 20;
6725	return __gnu_cxx::__to_xstring<string>(convf: &std::vsnprintf, __n,
6726	fmt: "%f", __val);
6727	}
6728
6729	inline string
6730	to_string(double __val)
6731	{
6732	const int __n =
6733	__gnu_cxx::__numeric_traits<double>::__max_exponent10 + 20;
6734	return __gnu_cxx::__to_xstring<string>(convf: &std::vsnprintf, __n,
6735	fmt: "%f", __val);
6736	}
6737
6738	inline string
6739	to_string(long double __val)
6740	{
6741	const int __n =
6742	__gnu_cxx::__numeric_traits<long double>::__max_exponent10 + 20;
6743	return __gnu_cxx::__to_xstring<string>(convf: &std::vsnprintf, __n,
6744	fmt: "%Lf", __val);
6745	}
6746	#endif // _GLIBCXX_USE_C99_STDIO
6747
6748	#if defined(_GLIBCXX_USE_WCHAR_T) && _GLIBCXX_USE_C99_WCHAR
6749	inline int
6750	stoi(const wstring& __str, size_t* __idx = 0, int __base = 10)
6751	{ return __gnu_cxx::__stoa<long, int>(convf: &std::wcstol, name: "stoi", str: __str.c_str(),
6752	__idx, __base); }
6753
6754	inline long
6755	stol(const wstring& __str, size_t* __idx = 0, int __base = 10)
6756	{ return __gnu_cxx::__stoa(convf: &std::wcstol, name: "stol", str: __str.c_str(),
6757	__idx, __base); }
6758
6759	inline unsigned long
6760	stoul(const wstring& __str, size_t* __idx = 0, int __base = 10)
6761	{ return __gnu_cxx::__stoa(convf: &std::wcstoul, name: "stoul", str: __str.c_str(),
6762	__idx, __base); }
6763
6764	inline long long
6765	stoll(const wstring& __str, size_t* __idx = 0, int __base = 10)
6766	{ return __gnu_cxx::__stoa(convf: &std::wcstoll, name: "stoll", str: __str.c_str(),
6767	__idx, __base); }
6768
6769	inline unsigned long long
6770	stoull(const wstring& __str, size_t* __idx = 0, int __base = 10)
6771	{ return __gnu_cxx::__stoa(convf: &std::wcstoull, name: "stoull", str: __str.c_str(),
6772	__idx, __base); }
6773
6774	// NB: wcstof vs wcstod.
6775	inline float
6776	stof(const wstring& __str, size_t* __idx = 0)
6777	{ return __gnu_cxx::__stoa(convf: &std::wcstof, name: "stof", str: __str.c_str(), __idx); }
6778
6779	inline double
6780	stod(const wstring& __str, size_t* __idx = 0)
6781	{ return __gnu_cxx::__stoa(convf: &std::wcstod, name: "stod", str: __str.c_str(), __idx); }
6782
6783	inline long double
6784	stold(const wstring& __str, size_t* __idx = 0)
6785	{ return __gnu_cxx::__stoa(convf: &std::wcstold, name: "stold", str: __str.c_str(), __idx); }
6786
6787	#ifndef _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6788	// DR 1261.
6789	inline wstring
6790	to_wstring(int __val)
6791	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf, n: 4 * sizeof(int),
6792	fmt: L"%d", __val); }
6793
6794	inline wstring
6795	to_wstring(unsigned __val)
6796	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf,
6797	n: 4 * sizeof(unsigned),
6798	fmt: L"%u", __val); }
6799
6800	inline wstring
6801	to_wstring(long __val)
6802	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf, n: 4 * sizeof(long),
6803	fmt: L"%ld", __val); }
6804
6805	inline wstring
6806	to_wstring(unsigned long __val)
6807	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf,
6808	n: 4 * sizeof(unsigned long),
6809	fmt: L"%lu", __val); }
6810
6811	inline wstring
6812	to_wstring(long long __val)
6813	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf,
6814	n: 4 * sizeof(long long),
6815	fmt: L"%lld", __val); }
6816
6817	inline wstring
6818	to_wstring(unsigned long long __val)
6819	{ return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf,
6820	n: 4 * sizeof(unsigned long long),
6821	fmt: L"%llu", __val); }
6822
6823	inline wstring
6824	to_wstring(float __val)
6825	{
6826	const int __n =
6827	__gnu_cxx::__numeric_traits<float>::__max_exponent10 + 20;
6828	return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf, __n,
6829	fmt: L"%f", __val);
6830	}
6831
6832	inline wstring
6833	to_wstring(double __val)
6834	{
6835	const int __n =
6836	__gnu_cxx::__numeric_traits<double>::__max_exponent10 + 20;
6837	return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf, __n,
6838	fmt: L"%f", __val);
6839	}
6840
6841	inline wstring
6842	to_wstring(long double __val)
6843	{
6844	const int __n =
6845	__gnu_cxx::__numeric_traits<long double>::__max_exponent10 + 20;
6846	return __gnu_cxx::__to_xstring<wstring>(convf: &std::vswprintf, __n,
6847	fmt: L"%Lf", __val);
6848	}
6849	#endif // _GLIBCXX_HAVE_BROKEN_VSWPRINTF
6850	#endif // _GLIBCXX_USE_WCHAR_T && _GLIBCXX_USE_C99_WCHAR
6851
6852	_GLIBCXX_END_NAMESPACE_CXX11
6853	_GLIBCXX_END_NAMESPACE_VERSION
6854	} // namespace
6855
6856	#endif /* C++11 */
6857
6858	#if __cplusplus >= 201103L
6859
6860	#include <bits/functional_hash.h>
6861
6862	namespace std _GLIBCXX_VISIBILITY(default)
6863	{
6864	_GLIBCXX_BEGIN_NAMESPACE_VERSION
6865
6866	// DR 1182.
6867
6868	#ifndef _GLIBCXX_COMPATIBILITY_CXX0X
6869	/// std::hash specialization for string.
6870	template<>
6871	struct hash<string>
6872	: public __hash_base<size_t, string>
6873	{
6874	size_t
6875	operator()(const string& __s) const noexcept
6876	{ return std::_Hash_impl::hash(ptr: __s.data(), clength: __s.length()); }
6877	};
6878
6879	template<>
6880	struct __is_fast_hash<hash<string>> : std::false_type
6881	{ };
6882
6883	#ifdef _GLIBCXX_USE_WCHAR_T
6884	/// std::hash specialization for wstring.
6885	template<>
6886	struct hash<wstring>
6887	: public __hash_base<size_t, wstring>
6888	{
6889	size_t
6890	operator()(const wstring& __s) const noexcept
6891	{ return std::_Hash_impl::hash(ptr: __s.data(),
6892	clength: __s.length() * sizeof(wchar_t)); }
6893	};
6894
6895	template<>
6896	struct __is_fast_hash<hash<wstring>> : std::false_type
6897	{ };
6898	#endif
6899	#endif /* _GLIBCXX_COMPATIBILITY_CXX0X */
6900
6901	#ifdef _GLIBCXX_USE_CHAR8_T
6902	/// std::hash specialization for u8string.
6903	template<>
6904	struct hash<u8string>
6905	: public __hash_base<size_t, u8string>
6906	{
6907	size_t
6908	operator()(const u8string& __s) const noexcept
6909	{ return std::_Hash_impl::hash(__s.data(),
6910	__s.length() * sizeof(char8_t)); }
6911	};
6912
6913	template<>
6914	struct __is_fast_hash<hash<u8string>> : std::false_type
6915	{ };
6916	#endif
6917
6918	/// std::hash specialization for u16string.
6919	template<>
6920	struct hash<u16string>
6921	: public __hash_base<size_t, u16string>
6922	{
6923	size_t
6924	operator()(const u16string& __s) const noexcept
6925	{ return std::_Hash_impl::hash(ptr: __s.data(),
6926	clength: __s.length() * sizeof(char16_t)); }
6927	};
6928
6929	template<>
6930	struct __is_fast_hash<hash<u16string>> : std::false_type
6931	{ };
6932
6933	/// std::hash specialization for u32string.
6934	template<>
6935	struct hash<u32string>
6936	: public __hash_base<size_t, u32string>
6937	{
6938	size_t
6939	operator()(const u32string& __s) const noexcept
6940	{ return std::_Hash_impl::hash(ptr: __s.data(),
6941	clength: __s.length() * sizeof(char32_t)); }
6942	};
6943
6944	template<>
6945	struct __is_fast_hash<hash<u32string>> : std::false_type
6946	{ };
6947
6948	#if __cplusplus >= 201402L
6949
6950	#define __cpp_lib_string_udls 201304
6951
6952	inline namespace literals
6953	{
6954	inline namespace string_literals
6955	{
6956	#pragma GCC diagnostic push
6957	#pragma GCC diagnostic ignored "-Wliteral-suffix"
6958	_GLIBCXX_DEFAULT_ABI_TAG
6959	inline basic_string<char>
6960	operator""s(const char* __str, size_t __len)
6961	{ return basic_string<char>{__str, __len}; }
6962
6963	#ifdef _GLIBCXX_USE_WCHAR_T
6964	_GLIBCXX_DEFAULT_ABI_TAG
6965	inline basic_string<wchar_t>
6966	operator""s(const wchar_t* __str, size_t __len)
6967	{ return basic_string<wchar_t>{__str, __len}; }
6968	#endif
6969
6970	#ifdef _GLIBCXX_USE_CHAR8_T
6971	_GLIBCXX_DEFAULT_ABI_TAG
6972	inline basic_string<char8_t>
6973	operator""s(const char8_t* __str, size_t __len)
6974	{ return basic_string<char8_t>{__str, __len}; }
6975	#endif
6976
6977	_GLIBCXX_DEFAULT_ABI_TAG
6978	inline basic_string<char16_t>
6979	operator""s(const char16_t* __str, size_t __len)
6980	{ return basic_string<char16_t>{__str, __len}; }
6981
6982	_GLIBCXX_DEFAULT_ABI_TAG
6983	inline basic_string<char32_t>
6984	operator""s(const char32_t* __str, size_t __len)
6985	{ return basic_string<char32_t>{__str, __len}; }
6986
6987	#pragma GCC diagnostic pop
6988	} // inline namespace string_literals
6989	} // inline namespace literals
6990
6991	#if __cplusplus >= 201703L
6992	namespace __detail::__variant
6993	{
6994	template<typename> struct _Never_valueless_alt; // see <variant>
6995
6996	// Provide the strong exception-safety guarantee when emplacing a
6997	// basic_string into a variant, but only if moving the string cannot throw.
6998	template<typename _Tp, typename _Traits, typename _Alloc>
6999	struct _Never_valueless_alt<std::basic_string<_Tp, _Traits, _Alloc>>
7000	: __and_<
7001	is_nothrow_move_constructible<std::basic_string<_Tp, _Traits, _Alloc>>,
7002	is_nothrow_move_assignable<std::basic_string<_Tp, _Traits, _Alloc>>
7003	>::type
7004	{ };
7005	} // namespace __detail::__variant
7006	#endif // C++17
7007	#endif // C++14
7008
7009	_GLIBCXX_END_NAMESPACE_VERSION
7010	} // namespace std
7011
7012	#endif // C++11
7013
7014	#endif /* _BASIC_STRING_H */
7015