1// ----------------------------------------------------------------------------
2// parsing.hpp : implementation of the parsing member functions
3// ( parse, parse_printf_directive)
4// ----------------------------------------------------------------------------
5
6// Copyright Samuel Krempp 2003. Use, modification, and distribution are
7// subject to the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9
10// see http://www.boost.org/libs/format for library home page
11
12// ----------------------------------------------------------------------------
13
14#ifndef BOOST_FORMAT_PARSING_HPP
15#define BOOST_FORMAT_PARSING_HPP
16
17
18#include <boost/format/format_class.hpp>
19#include <boost/format/exceptions.hpp>
20#include <boost/throw_exception.hpp>
21#include <boost/assert.hpp>
22#include <boost/config.hpp>
23#include <boost/core/ignore_unused.hpp>
24
25namespace boost {
26namespace io {
27namespace detail {
28
29#if defined(BOOST_NO_STD_LOCALE)
30 // streams will be used for narrow / widen. but these methods are not const
31 template<class T>
32 T& const_or_not(const T& x) {
33 return const_cast<T&> (x);
34 }
35#else
36 template<class T>
37 const T& const_or_not(const T& x) {
38 return x;
39 }
40#endif
41
42 template<class Ch, class Facet> inline
43 char wrap_narrow(const Facet& fac, Ch c, char deflt) {
44 return const_or_not(fac).narrow(c, deflt);
45 }
46
47 template<class Ch, class Facet> inline
48 bool wrap_isdigit(const Facet& fac, Ch c) {
49#if ! defined( BOOST_NO_LOCALE_ISDIGIT )
50 return fac.is(std::ctype<Ch>::digit, c);
51# else
52 ignore_unused(fac);
53 using namespace std;
54 return isdigit(c) != 0;
55#endif
56 }
57
58 template<class Iter, class Facet>
59 Iter wrap_scan_notdigit(const Facet & fac, Iter beg, Iter end) {
60 using namespace std;
61 for( ; beg!=end && wrap_isdigit(fac, *beg); ++beg) ;
62 return beg;
63 }
64
65
66 // Input : [start, last) iterators range and a
67 // a Facet to use its widen/narrow member function
68 // Effects : read sequence and convert digits into integral n, of type Res
69 // Returns : n
70 template<class Res, class Iter, class Facet>
71 Iter str2int (const Iter & start, const Iter & last, Res & res,
72 const Facet& fac)
73 {
74 using namespace std;
75 Iter it;
76 res=0;
77 for(it=start; it != last && wrap_isdigit(fac, *it); ++it ) {
78 char cur_ch = wrap_narrow(fac, *it, 0); // cant fail.
79 res *= 10;
80 res += cur_ch - '0'; // 22.2.1.1.2.13 of the C++ standard
81 }
82 return it;
83 }
84
85 // auxiliary func called by parse_printf_directive
86 // for centralising error handling
87 // it either throws if user sets the corresponding flag, or does nothing.
88 inline void maybe_throw_exception(unsigned char exceptions,
89 std::size_t pos, std::size_t size)
90 {
91 if(exceptions & io::bad_format_string_bit)
92 boost::throw_exception(e: io::bad_format_string(pos, size) );
93 }
94
95
96 // Input: the position of a printf-directive in the format-string
97 // a basic_ios& merely to use its widen/narrow member function
98 // a bitset'exceptions' telling whether to throw exceptions on errors.
99 // Returns:
100 // true if parse succeeded (ignore some errors if exceptions disabled)
101 // false if it failed so bad that the directive should be printed verbatim
102 // Effects:
103 // start is incremented so that *start is the first char after
104 // this directive
105 // *fpar is set with the parameters read in the directive
106 template<class Ch, class Tr, class Alloc, class Iter, class Facet>
107 bool parse_printf_directive(Iter & start, const Iter& last,
108 detail::format_item<Ch, Tr, Alloc> * fpar,
109 const Facet& fac,
110 std::size_t offset, unsigned char exceptions)
111 {
112 typedef typename basic_format<Ch, Tr, Alloc>::format_item_t format_item_t;
113
114 fpar->argN_ = format_item_t::argN_no_posit; // if no positional-directive
115 bool precision_set = false;
116 bool in_brackets=false;
117 Iter start0 = start;
118 std::size_t fstring_size = last-start0+offset;
119 char mssiz = 0;
120
121 if(start>= last) { // empty directive : this is a trailing %
122 maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
123 return false;
124 }
125
126 if(*start== const_or_not(fac).widen( '|')) {
127 in_brackets=true;
128 if( ++start >= last ) {
129 maybe_throw_exception(exceptions, start-start0 + offset, fstring_size);
130 return false;
131 }
132 }
133
134 // the flag '0' would be picked as a digit for argument order, but here it's a flag :
135 if(*start== const_or_not(fac).widen( '0'))
136 goto parse_flags;
137
138 // handle argument order (%2$d) or possibly width specification: %2d
139 if(wrap_isdigit(fac, *start)) {
140 int n;
141 start = str2int(start, last, n, fac);
142 if( start >= last ) {
143 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
144 return false;
145 }
146
147 // %N% case : this is already the end of the directive
148 if( *start == const_or_not(fac).widen( '%') ) {
149 fpar->argN_ = n-1;
150 ++start;
151 if( in_brackets)
152 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
153 return true;
154 }
155
156 if ( *start== const_or_not(fac).widen( '$') ) {
157 fpar->argN_ = n-1;
158 ++start;
159 }
160 else {
161 // non-positional directive
162 fpar->fmtstate_.width_ = n;
163 fpar->argN_ = format_item_t::argN_no_posit;
164 goto parse_precision;
165 }
166 }
167
168 parse_flags:
169 // handle flags
170 while (start != last) { // as long as char is one of + - = _ # 0 or ' '
171 switch ( wrap_narrow(fac, *start, 0)) {
172 case '\'':
173 break; // no effect yet. (painful to implement)
174 case '-':
175 fpar->fmtstate_.flags_ |= std::ios_base::left;
176 break;
177 case '=':
178 fpar->pad_scheme_ |= format_item_t::centered;
179 break;
180 case '_':
181 fpar->fmtstate_.flags_ |= std::ios_base::internal;
182 break;
183 case ' ':
184 fpar->pad_scheme_ |= format_item_t::spacepad;
185 break;
186 case '+':
187 fpar->fmtstate_.flags_ |= std::ios_base::showpos;
188 break;
189 case '0':
190 fpar->pad_scheme_ |= format_item_t::zeropad;
191 // need to know alignment before really setting flags,
192 // so just add 'zeropad' flag for now, it will be processed later.
193 break;
194 case '#':
195 fpar->fmtstate_.flags_ |= std::ios_base::showpoint | std::ios_base::showbase;
196 break;
197 default:
198 goto parse_width;
199 }
200 ++start;
201 } // loop on flag.
202
203 if( start>=last) {
204 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
205 return true;
206 }
207
208 // first skip 'asterisk fields' : * or num (length)
209 parse_width:
210 if(*start == const_or_not(fac).widen( '*') )
211 ++start;
212 else if(start!=last && wrap_isdigit(fac, *start))
213 start = str2int(start, last, fpar->fmtstate_.width_, fac);
214
215 parse_precision:
216 if( start>= last) {
217 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
218 return true;
219 }
220 // handle precision spec
221 if (*start== const_or_not(fac).widen( '.')) {
222 ++start;
223 if(start != last && *start == const_or_not(fac).widen( '*') )
224 ++start;
225 else if(start != last && wrap_isdigit(fac, *start)) {
226 start = str2int(start, last, fpar->fmtstate_.precision_, fac);
227 precision_set = true;
228 }
229 else
230 fpar->fmtstate_.precision_ =0;
231 }
232
233 // argument type modifiers
234 while (start != last) {
235 switch (wrap_narrow(fac, *start, 0)) {
236 case 'h':
237 case 'l':
238 case 'j':
239 case 'z':
240 case 'L':
241 // boost::format ignores argument type modifiers as it relies on
242 // the type of the argument fed into it by operator %
243 break;
244
245 // Note that the ptrdiff_t argument type 't' from C++11 is not honored
246 // because it was already in use as the tabulation specifier in boost::format
247 // case 't':
248
249 // Microsoft extensions:
250 // https://msdn.microsoft.com/en-us/library/tcxf1dw6.aspx
251
252 case 'w':
253 break;
254 case 'I':
255 mssiz = 'I';
256 break;
257 case '3':
258 if (mssiz != 'I') {
259 maybe_throw_exception(exceptions, start - start0 + offset, fstring_size);
260 return true;
261 }
262 mssiz = '3';
263 break;
264 case '2':
265 if (mssiz != '3') {
266 maybe_throw_exception(exceptions, start - start0 + offset, fstring_size);
267 return true;
268 }
269 mssiz = 0x00;
270 break;
271 case '6':
272 if (mssiz != 'I') {
273 maybe_throw_exception(exceptions, start - start0 + offset, fstring_size);
274 return true;
275 }
276 mssiz = '6';
277 break;
278 case '4':
279 if (mssiz != '6') {
280 maybe_throw_exception(exceptions, start - start0 + offset, fstring_size);
281 return true;
282 }
283 mssiz = 0x00;
284 break;
285 default:
286 if (mssiz && mssiz == 'I') {
287 mssiz = 0;
288 }
289 goto parse_conversion_specification;
290 }
291 ++start;
292 } // loop on argument type modifiers to pick up 'hh', 'll', and the more complex microsoft ones
293
294 parse_conversion_specification:
295 if (start >= last || mssiz) {
296 maybe_throw_exception(exceptions, start - start0 + offset, fstring_size);
297 return true;
298 }
299
300 if( in_brackets && *start== const_or_not(fac).widen( '|') ) {
301 ++start;
302 return true;
303 }
304
305 // The default flags are "dec" and "skipws"
306 // so if changing the base, need to unset basefield first
307
308 switch (wrap_narrow(fac, *start, 0))
309 {
310 // Boolean
311 case 'b':
312 fpar->fmtstate_.flags_ |= std::ios_base::boolalpha;
313 break;
314
315 // Decimal
316 case 'u':
317 case 'd':
318 case 'i':
319 // Defaults are sufficient
320 break;
321
322 // Hex
323 case 'X':
324 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
325 BOOST_FALLTHROUGH;
326 case 'x':
327 case 'p': // pointer => set hex.
328 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
329 fpar->fmtstate_.flags_ |= std::ios_base::hex;
330 break;
331
332 // Octal
333 case 'o':
334 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
335 fpar->fmtstate_.flags_ |= std::ios_base::oct;
336 break;
337
338 // Floating
339 case 'A':
340 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
341 BOOST_FALLTHROUGH;
342 case 'a':
343 fpar->fmtstate_.flags_ &= ~std::ios_base::basefield;
344 fpar->fmtstate_.flags_ |= std::ios_base::fixed;
345 fpar->fmtstate_.flags_ |= std::ios_base::scientific;
346 break;
347 case 'E':
348 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
349 BOOST_FALLTHROUGH;
350 case 'e':
351 fpar->fmtstate_.flags_ |= std::ios_base::scientific;
352 break;
353 case 'F':
354 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
355 BOOST_FALLTHROUGH;
356 case 'f':
357 fpar->fmtstate_.flags_ |= std::ios_base::fixed;
358 break;
359 case 'G':
360 fpar->fmtstate_.flags_ |= std::ios_base::uppercase;
361 BOOST_FALLTHROUGH;
362 case 'g':
363 // default flags are correct here
364 break;
365
366 // Tabulation (a boost::format extension)
367 case 'T':
368 ++start;
369 if( start >= last) {
370 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
371 return false;
372 } else {
373 fpar->fmtstate_.fill_ = *start;
374 }
375 fpar->pad_scheme_ |= format_item_t::tabulation;
376 fpar->argN_ = format_item_t::argN_tabulation;
377 break;
378 case 't':
379 fpar->fmtstate_.fill_ = const_or_not(fac).widen( ' ');
380 fpar->pad_scheme_ |= format_item_t::tabulation;
381 fpar->argN_ = format_item_t::argN_tabulation;
382 break;
383
384 // Character
385 case 'C':
386 case 'c':
387 fpar->truncate_ = 1;
388 break;
389
390 // String
391 case 'S':
392 case 's':
393 if(precision_set) // handle truncation manually, with own parameter.
394 fpar->truncate_ = fpar->fmtstate_.precision_;
395 fpar->fmtstate_.precision_ = 6; // default stream precision.
396 break;
397
398 // %n is insecure and ignored by boost::format
399 case 'n' :
400 fpar->argN_ = format_item_t::argN_ignored;
401 break;
402
403 default:
404 maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
405 }
406 ++start;
407
408 if( in_brackets ) {
409 if( start != last && *start== const_or_not(fac).widen( '|') ) {
410 ++start;
411 return true;
412 }
413 else maybe_throw_exception(exceptions, start-start0+offset, fstring_size);
414 }
415 return true;
416 }
417 // -end parse_printf_directive()
418
419 template<class String, class Facet>
420 int upper_bound_from_fstring(const String& buf,
421 const typename String::value_type arg_mark,
422 const Facet& fac,
423 unsigned char exceptions)
424 {
425 // quick-parsing of the format-string to count arguments mark (arg_mark, '%')
426 // returns : upper bound on the number of format items in the format strings
427 using namespace boost::io;
428 typename String::size_type i1=0;
429 int num_items=0;
430 while( (i1=buf.find(arg_mark,i1)) != String::npos ) {
431 if( i1+1 >= buf.size() ) {
432 if(exceptions & bad_format_string_bit)
433 boost::throw_exception(e: bad_format_string(i1, buf.size() )); // must not end in ".. %"
434 else {
435 ++num_items;
436 break;
437 }
438 }
439 if(buf[i1+1] == buf[i1] ) {// escaped "%%"
440 i1+=2; continue;
441 }
442
443 ++i1;
444 // in case of %N% directives, dont count it double (wastes allocations..) :
445 i1 = detail::wrap_scan_notdigit(fac, buf.begin()+i1, buf.end()) - buf.begin();
446 if( i1 < buf.size() && buf[i1] == arg_mark )
447 ++i1;
448 ++num_items;
449 }
450 return num_items;
451 }
452 template<class String> inline
453 void append_string(String& dst, const String& src,
454 const typename String::size_type beg,
455 const typename String::size_type end) {
456 dst.append(src.begin()+beg, src.begin()+end);
457 }
458
459} // detail namespace
460} // io namespace
461
462
463
464// -----------------------------------------------
465// format :: parse(..)
466
467 template<class Ch, class Tr, class Alloc>
468 basic_format<Ch, Tr, Alloc>& basic_format<Ch, Tr, Alloc>::
469 parse (const string_type& buf) {
470 // parse the format-string
471 using namespace std;
472#if !defined(BOOST_NO_STD_LOCALE)
473 const std::ctype<Ch> & fac = BOOST_USE_FACET( std::ctype<Ch>, getloc());
474#else
475 io::basic_oaltstringstream<Ch, Tr, Alloc> fac;
476 //has widen and narrow even on compilers without locale
477#endif
478
479 const Ch arg_mark = io::detail::const_or_not(fac).widen( '%');
480 bool ordered_args=true;
481 int max_argN=-1;
482
483 // A: find upper_bound on num_items and allocates arrays
484 int num_items = io::detail::upper_bound_from_fstring(buf, arg_mark, fac, exceptions());
485 make_or_reuse_data(nbitems: num_items);
486
487 // B: Now the real parsing of the format string :
488 num_items=0;
489 typename string_type::size_type i0=0, i1=0;
490 typename string_type::const_iterator it;
491 bool special_things=false;
492 int cur_item=0;
493 while( (i1=buf.find(arg_mark,i1)) != string_type::npos ) {
494 string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
495 if( buf[i1+1] == buf[i1] ) { // escaped mark, '%%'
496 io::detail::append_string(piece, buf, i0, i1+1);
497 i1+=2; i0=i1;
498 continue;
499 }
500 BOOST_ASSERT( static_cast<unsigned int>(cur_item) < items_.size() || cur_item==0);
501
502 if(i1!=i0) {
503 io::detail::append_string(piece, buf, i0, i1);
504 i0=i1;
505 }
506 ++i1;
507 it = buf.begin()+i1;
508 bool parse_ok = io::detail::parse_printf_directive(
509 it, buf.end(), &items_[cur_item], fac, i1, exceptions());
510 i1 = it - buf.begin();
511 if( ! parse_ok ) // the directive will be printed verbatim
512 continue;
513 i0=i1;
514 items_[cur_item].compute_states(); // process complex options, like zeropad, into params
515
516 int argN=items_[cur_item].argN_;
517 if(argN == format_item_t::argN_ignored)
518 continue;
519 if(argN ==format_item_t::argN_no_posit)
520 ordered_args=false;
521 else if(argN == format_item_t::argN_tabulation) special_things=true;
522 else if(argN > max_argN) max_argN = argN;
523 ++num_items;
524 ++cur_item;
525 } // loop on %'s
526 BOOST_ASSERT(cur_item == num_items);
527
528 // store the final piece of string
529 {
530 string_type & piece = (cur_item==0) ? prefix_ : items_[cur_item-1].appendix_;
531 io::detail::append_string(piece, buf, i0, buf.size());
532 }
533
534 if( !ordered_args) {
535 if(max_argN >= 0 ) { // dont mix positional with non-positionnal directives
536 if(exceptions() & io::bad_format_string_bit)
537 boost::throw_exception(
538 e: io::bad_format_string(static_cast<std::size_t>(max_argN), 0));
539 // else do nothing. => positionnal arguments are processed as non-positionnal
540 }
541 // set things like it would have been with positional directives :
542 int non_ordered_items = 0;
543 for(int i=0; i< num_items; ++i)
544 if(items_[i].argN_ == format_item_t::argN_no_posit) {
545 items_[i].argN_ = non_ordered_items;
546 ++non_ordered_items;
547 }
548 max_argN = non_ordered_items-1;
549 }
550
551 // C: set some member data :
552 items_.resize(num_items, format_item_t(io::detail::const_or_not(fac).widen( ' ')) );
553
554 if(special_things) style_ |= special_needs;
555 num_args_ = max_argN + 1;
556 if(ordered_args) style_ |= ordered;
557 else style_ &= ~ordered;
558 return *this;
559 }
560
561} // namespace boost
562
563
564#endif // BOOST_FORMAT_PARSING_HPP
565

source code of include/boost/format/parsing.hpp