1// Copyright Kevlin Henney, 2000-2005.
2// Copyright Alexander Nasonov, 2006-2010.
3// Copyright Antony Polukhin, 2011-2020.
4//
5// Distributed under the Boost Software License, Version 1.0. (See
6// accompanying file LICENSE_1_0.txt or copy at
7// http://www.boost.org/LICENSE_1_0.txt)
8//
9// what: lexical_cast custom keyword cast
10// who: contributed by Kevlin Henney,
11// enhanced with contributions from Terje Slettebo,
12// with additional fixes and suggestions from Gennaro Prota,
13// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
14// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
15// Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
16// when: November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
17
18#ifndef BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
19#define BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
20
21#include <boost/config.hpp>
22#ifdef BOOST_HAS_PRAGMA_ONCE
23# pragma once
24#endif
25
26#if defined(__clang__) || (defined(__GNUC__) && \
27 !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && \
28 (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
29#pragma GCC diagnostic push
30#pragma GCC diagnostic ignored "-Wuninitialized"
31#pragma GCC diagnostic ignored "-Wsign-conversion"
32#endif
33
34
35#include <string>
36#include <boost/type_traits/is_integral.hpp>
37#include <boost/type_traits/type_identity.hpp>
38#include <boost/type_traits/conditional.hpp>
39#include <boost/type_traits/is_same.hpp>
40#include <boost/type_traits/is_arithmetic.hpp>
41
42#include <boost/lexical_cast/detail/is_character.hpp>
43#include <boost/lexical_cast/detail/converter_numeric.hpp>
44#include <boost/lexical_cast/detail/converter_lexical.hpp>
45
46#include <boost/range/iterator_range_core.hpp>
47#include <boost/container/container_fwd.hpp>
48
49namespace boost {
50 namespace detail
51 {
52 template<typename T>
53 struct is_stdstring
54 : boost::false_type
55 {};
56
57 template<typename CharT, typename Traits, typename Alloc>
58 struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
59 : boost::true_type
60 {};
61
62 // Sun Studio has problem with partial specialization of templates differing only in namespace.
63 // We workaround that by making `is_booststring` trait, instead of specializing `is_stdstring` for `boost::container::basic_string`.
64 template<typename T>
65 struct is_booststring
66 : boost::false_type
67 {};
68
69 template<typename CharT, typename Traits, typename Alloc>
70 struct is_booststring< boost::container::basic_string<CharT, Traits, Alloc> >
71 : boost::true_type
72 {};
73
74 template<typename Target, typename Source>
75 struct is_arithmetic_and_not_xchars
76 {
77 typedef boost::integral_constant<
78 bool,
79 !(boost::detail::is_character<Target>::value) &&
80 !(boost::detail::is_character<Source>::value) &&
81 boost::is_arithmetic<Source>::value &&
82 boost::is_arithmetic<Target>::value
83 > type;
84
85 BOOST_STATIC_CONSTANT(bool, value = (
86 type::value
87 ));
88 };
89
90 /*
91 * is_xchar_to_xchar<Target, Source>::value is true,
92 * Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
93 */
94 template<typename Target, typename Source>
95 struct is_xchar_to_xchar
96 {
97 typedef boost::integral_constant<
98 bool,
99 sizeof(Source) == sizeof(Target) &&
100 sizeof(Source) == sizeof(char) &&
101 boost::detail::is_character<Target>::value &&
102 boost::detail::is_character<Source>::value
103 > type;
104
105 BOOST_STATIC_CONSTANT(bool, value = (
106 type::value
107 ));
108 };
109
110 template<typename Target, typename Source>
111 struct is_char_array_to_stdstring
112 : boost::false_type
113 {};
114
115 template<typename CharT, typename Traits, typename Alloc>
116 struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
117 : boost::true_type
118 {};
119
120 template<typename CharT, typename Traits, typename Alloc>
121 struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
122 : boost::true_type
123 {};
124
125 // Sun Studio has problem with partial specialization of templates differing only in namespace.
126 // We workaround that by making `is_char_array_to_booststring` trait, instead of specializing `is_char_array_to_stdstring` for `boost::container::basic_string`.
127 template<typename Target, typename Source>
128 struct is_char_array_to_booststring
129 : boost::false_type
130 {};
131
132 template<typename CharT, typename Traits, typename Alloc>
133 struct is_char_array_to_booststring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
134 : boost::true_type
135 {};
136
137 template<typename CharT, typename Traits, typename Alloc>
138 struct is_char_array_to_booststring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
139 : boost::true_type
140 {};
141
142 template <typename Target, typename Source>
143 struct copy_converter_impl
144 {
145// MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
146// fixed in 2013 RTM).
147#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
148 template <class T>
149 static inline bool try_convert(T&& arg, Target& result) {
150 result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
151 return true;
152 }
153#else
154 static inline bool try_convert(const Source& arg, Target& result) {
155 result = arg;
156 return true;
157 }
158#endif
159 };
160 }
161
162 namespace conversion { namespace detail {
163
164 template <typename Target, typename Source>
165 inline bool try_lexical_convert(const Source& arg, Target& result)
166 {
167 typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
168
169 typedef boost::integral_constant<
170 bool,
171 boost::detail::is_xchar_to_xchar<Target, src >::value ||
172 boost::detail::is_char_array_to_stdstring<Target, src >::value ||
173 boost::detail::is_char_array_to_booststring<Target, src >::value ||
174 (
175 boost::is_same<Target, src >::value &&
176 (boost::detail::is_stdstring<Target >::value || boost::detail::is_booststring<Target >::value)
177 ) ||
178 (
179 boost::is_same<Target, src >::value &&
180 boost::detail::is_character<Target >::value
181 )
182 > shall_we_copy_t;
183
184 typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
185 shall_we_copy_with_dynamic_check_t;
186
187 // We do evaluate second `if_` lazily to avoid unnecessary instantiations
188 // of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
189 typedef BOOST_DEDUCED_TYPENAME boost::conditional<
190 shall_we_copy_t::value,
191 boost::type_identity<boost::detail::copy_converter_impl<Target, src > >,
192 boost::conditional<
193 shall_we_copy_with_dynamic_check_t::value,
194 boost::detail::dynamic_num_converter_impl<Target, src >,
195 boost::detail::lexical_converter_impl<Target, src >
196 >
197 >::type caster_type_lazy;
198
199 typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
200
201 return caster_type::try_convert(arg, result);
202 }
203
204 template <typename Target, typename CharacterT>
205 inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
206 {
207 BOOST_STATIC_ASSERT_MSG(
208 boost::detail::is_character<CharacterT>::value,
209 "This overload of try_lexical_convert is meant to be used only with arrays of characters."
210 );
211 return ::boost::conversion::detail::try_lexical_convert(
212 ::boost::iterator_range<const CharacterT*>(chars, chars + count), result
213 );
214 }
215
216 }} // namespace conversion::detail
217
218 namespace conversion {
219 // ADL barrier
220 using ::boost::conversion::detail::try_lexical_convert;
221 }
222
223} // namespace boost
224
225#if defined(__clang__) || (defined(__GNUC__) && \
226 !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && \
227 (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
228#pragma GCC diagnostic pop
229#endif
230
231#endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
232
233

source code of include/boost/lexical_cast/try_lexical_convert.hpp