1// Copyright Kevlin Henney, 2000-2005.
2// Copyright Alexander Nasonov, 2006-2010.
3// Copyright Antony Polukhin, 2011-2014.
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#endif
32
33#include <string>
34#include <boost/mpl/bool.hpp>
35#include <boost/mpl/identity.hpp>
36#include <boost/mpl/if.hpp>
37#include <boost/type_traits/is_same.hpp>
38#include <boost/type_traits/is_arithmetic.hpp>
39
40#include <boost/lexical_cast/detail/is_character.hpp>
41#include <boost/lexical_cast/detail/converter_numeric.hpp>
42#include <boost/lexical_cast/detail/converter_lexical.hpp>
43
44#include <boost/range/iterator_range_core.hpp>
45#include <boost/container/container_fwd.hpp>
46
47namespace boost {
48 namespace detail
49 {
50 template<typename T>
51 struct is_stdstring
52 : boost::false_type
53 {};
54
55 template<typename CharT, typename Traits, typename Alloc>
56 struct is_stdstring< std::basic_string<CharT, Traits, Alloc> >
57 : boost::true_type
58 {};
59
60 template<typename CharT, typename Traits, typename Alloc>
61 struct is_stdstring< boost::container::basic_string<CharT, Traits, Alloc> >
62 : boost::true_type
63 {};
64
65 template<typename Target, typename Source>
66 struct is_arithmetic_and_not_xchars
67 {
68 typedef boost::mpl::bool_<
69 !(boost::detail::is_character<Target>::value) &&
70 !(boost::detail::is_character<Source>::value) &&
71 boost::is_arithmetic<Source>::value &&
72 boost::is_arithmetic<Target>::value
73 > type;
74
75 BOOST_STATIC_CONSTANT(bool, value = (
76 type::value
77 ));
78 };
79
80 /*
81 * is_xchar_to_xchar<Target, Source>::value is true,
82 * Target and Souce are char types of the same size 1 (char, signed char, unsigned char).
83 */
84 template<typename Target, typename Source>
85 struct is_xchar_to_xchar
86 {
87 typedef boost::mpl::bool_<
88 sizeof(Source) == sizeof(Target) &&
89 sizeof(Source) == sizeof(char) &&
90 boost::detail::is_character<Target>::value &&
91 boost::detail::is_character<Source>::value
92 > type;
93
94 BOOST_STATIC_CONSTANT(bool, value = (
95 type::value
96 ));
97 };
98
99 template<typename Target, typename Source>
100 struct is_char_array_to_stdstring
101 : boost::false_type
102 {};
103
104 template<typename CharT, typename Traits, typename Alloc>
105 struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, CharT* >
106 : boost::true_type
107 {};
108
109 template<typename CharT, typename Traits, typename Alloc>
110 struct is_char_array_to_stdstring< std::basic_string<CharT, Traits, Alloc>, const CharT* >
111 : boost::true_type
112 {};
113
114 template<typename CharT, typename Traits, typename Alloc>
115 struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, CharT* >
116 : boost::true_type
117 {};
118
119 template<typename CharT, typename Traits, typename Alloc>
120 struct is_char_array_to_stdstring< boost::container::basic_string<CharT, Traits, Alloc>, const CharT* >
121 : boost::true_type
122 {};
123
124 template <typename Target, typename Source>
125 struct copy_converter_impl
126 {
127// MSVC fail to forward an array (DevDiv#555157 "SILENT BAD CODEGEN triggered by perfect forwarding",
128// fixed in 2013 RTM).
129#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && (!defined(BOOST_MSVC) || BOOST_MSVC >= 1800)
130 template <class T>
131 static inline bool try_convert(T&& arg, Target& result) {
132 result = static_cast<T&&>(arg); // eqaul to `result = std::forward<T>(arg);`
133 return true;
134 }
135#else
136 static inline bool try_convert(const Source& arg, Target& result) {
137 result = arg;
138 return true;
139 }
140#endif
141 };
142 }
143
144 namespace conversion { namespace detail {
145
146 template <typename Target, typename Source>
147 inline bool try_lexical_convert(const Source& arg, Target& result)
148 {
149 typedef BOOST_DEDUCED_TYPENAME boost::detail::array_to_pointer_decay<Source>::type src;
150
151 typedef boost::mpl::bool_<
152 boost::detail::is_xchar_to_xchar<Target, src >::value ||
153 boost::detail::is_char_array_to_stdstring<Target, src >::value ||
154 (
155 boost::is_same<Target, src >::value &&
156 boost::detail::is_stdstring<Target >::value
157 ) ||
158 (
159 boost::is_same<Target, src >::value &&
160 boost::detail::is_character<Target >::value
161 )
162 > shall_we_copy_t;
163
164 typedef boost::detail::is_arithmetic_and_not_xchars<Target, src >
165 shall_we_copy_with_dynamic_check_t;
166
167 // We do evaluate second `if_` lazily to avoid unnecessary instantiations
168 // of `shall_we_copy_with_dynamic_check_t` and improve compilation times.
169 typedef BOOST_DEDUCED_TYPENAME boost::mpl::if_c<
170 shall_we_copy_t::value,
171 boost::mpl::identity<boost::detail::copy_converter_impl<Target, src > >,
172 boost::mpl::if_<
173 shall_we_copy_with_dynamic_check_t,
174 boost::detail::dynamic_num_converter_impl<Target, src >,
175 boost::detail::lexical_converter_impl<Target, src >
176 >
177 >::type caster_type_lazy;
178
179 typedef BOOST_DEDUCED_TYPENAME caster_type_lazy::type caster_type;
180
181 return caster_type::try_convert(arg, result);
182 }
183
184 template <typename Target, typename CharacterT>
185 inline bool try_lexical_convert(const CharacterT* chars, std::size_t count, Target& result)
186 {
187 BOOST_STATIC_ASSERT_MSG(
188 boost::detail::is_character<CharacterT>::value,
189 "This overload of try_lexical_convert is meant to be used only with arrays of characters."
190 );
191 return ::boost::conversion::detail::try_lexical_convert(
192 ::boost::iterator_range<const CharacterT*>(chars, chars + count), result
193 );
194 }
195
196 }} // namespace conversion::detail
197
198 namespace conversion {
199 // ADL barrier
200 using ::boost::conversion::detail::try_lexical_convert;
201 }
202
203} // namespace boost
204
205#if defined(__clang__) || (defined(__GNUC__) && \
206 !(defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)) && \
207 (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)))
208#pragma GCC diagnostic pop
209#endif
210
211#endif // BOOST_LEXICAL_CAST_TRY_LEXICAL_CONVERT_HPP
212
213

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