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1 // Copyright Kevlin Henney, 2000-2005.
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2 // Copyright Alexander Nasonov, 2006-2010.
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3 // Copyright Antony Polukhin, 2011-2014.
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4 //
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5 // Distributed under the Boost Software License, Version 1.0. (See
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6 // accompanying file LICENSE_1_0.txt or copy at
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7 // http://www.boost.org/LICENSE_1_0.txt)
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8 //
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9 // what: lexical_cast custom keyword cast
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10 // who: contributed by Kevlin Henney,
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11 // enhanced with contributions from Terje Slettebo,
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12 // with additional fixes and suggestions from Gennaro Prota,
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13 // Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
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14 // Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
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15 // Cheng Yang, Matthew Bradbury, David W. Birdsall, Pavel Korzh and other Boosters
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16 // when: November 2000, March 2003, June 2005, June 2006, March 2011 - 2014
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17
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18 #ifndef BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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19 #define BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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20
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21 #include <boost/config.hpp>
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22 #ifdef BOOST_HAS_PRAGMA_ONCE
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23 # pragma once
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24 #endif
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25
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26 #if defined(BOOST_NO_STRINGSTREAM) || defined(BOOST_NO_STD_WSTRING)
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27 #define BOOST_LCAST_NO_WCHAR_T
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28 #endif
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29
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30 #include <climits>
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31 #include <cstddef>
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32 #include <string>
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33 #include <cstring>
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34 #include <cstdio>
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35 #include <boost/limits.hpp>
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36 #include <boost/mpl/if.hpp>
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37 #include <boost/type_traits/ice.hpp>
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38 #include <boost/type_traits/is_pointer.hpp>
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39 #include <boost/static_assert.hpp>
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40 #include <boost/detail/lcast_precision.hpp>
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41 #include <boost/detail/workaround.hpp>
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42
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43 #ifdef BOOST_NO_STRINGSTREAM
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44 #include <strstream>
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45 #else
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46 #include <sstream>
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47 #endif
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48
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49 #include <boost/lexical_cast/bad_lexical_cast.hpp>
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50 #include <boost/lexical_cast/detail/widest_char.hpp>
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51
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52 namespace boost {
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53 namespace detail
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54 {
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55
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56 // selectors for choosing stream character type
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57 template<typename Type>
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58 struct stream_char
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59 {
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60 typedef char type;
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61 };
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62
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63 #ifndef BOOST_LCAST_NO_WCHAR_T
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64 #ifndef BOOST_NO_INTRINSIC_WCHAR_T
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65 template<>
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66 struct stream_char<wchar_t>
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67 {
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68 typedef wchar_t type;
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69 };
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70 #endif
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71
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72 template<>
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73 struct stream_char<wchar_t *>
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74 {
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75 typedef wchar_t type;
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76 };
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77
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78 template<>
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79 struct stream_char<const wchar_t *>
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80 {
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81 typedef wchar_t type;
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82 };
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83
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84 template<>
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85 struct stream_char<std::wstring>
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86 {
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87 typedef wchar_t type;
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88 };
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89 #endif
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90
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91 // stream wrapper for handling lexical conversions
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92 template<typename Target, typename Source, typename Traits>
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93 class lexical_stream
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94 {
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95 private:
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96 typedef typename widest_char<
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97 typename stream_char<Target>::type,
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98 typename stream_char<Source>::type>::type char_type;
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99
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100 typedef Traits traits_type;
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101
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102 public:
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103 lexical_stream(char_type* = 0, char_type* = 0)
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104 {
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105 stream.unsetf(std::ios::skipws);
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106 lcast_set_precision(stream, static_cast<Source*>(0), static_cast<Target*>(0) );
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107 }
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108 ~lexical_stream()
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109 {
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110 #if defined(BOOST_NO_STRINGSTREAM)
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111 stream.freeze(false);
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112 #endif
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113 }
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114 bool operator<<(const Source &input)
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115 {
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116 return !(stream << input).fail();
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117 }
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118 template<typename InputStreamable>
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119 bool operator>>(InputStreamable &output)
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120 {
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121 return !is_pointer<InputStreamable>::value &&
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122 stream >> output &&
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123 stream.get() == traits_type::eof();
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124 }
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125
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126 bool operator>>(std::string &output)
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127 {
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128 #if defined(BOOST_NO_STRINGSTREAM)
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129 stream << '\0';
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130 #endif
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131 stream.str().swap(output);
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132 return true;
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133 }
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134 #ifndef BOOST_LCAST_NO_WCHAR_T
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135 bool operator>>(std::wstring &output)
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136 {
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137 stream.str().swap(output);
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138 return true;
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139 }
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140 #endif
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141
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142 private:
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143 #if defined(BOOST_NO_STRINGSTREAM)
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144 std::strstream stream;
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145 #elif defined(BOOST_NO_STD_LOCALE)
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146 std::stringstream stream;
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147 #else
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148 std::basic_stringstream<char_type,traits_type> stream;
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149 #endif
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150 };
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151 }
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152
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153 // call-by-value fallback version (deprecated)
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154
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155 template<typename Target, typename Source>
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156 Target lexical_cast(Source arg)
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157 {
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158 typedef typename detail::widest_char<
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159 BOOST_DEDUCED_TYPENAME detail::stream_char<Target>::type
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160 , BOOST_DEDUCED_TYPENAME detail::stream_char<Source>::type
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161 >::type char_type;
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162
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163 typedef std::char_traits<char_type> traits;
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164 detail::lexical_stream<Target, Source, traits> interpreter;
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165 Target result;
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166
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167 if(!(interpreter << arg && interpreter >> result))
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168 boost::conversion::detail::throw_bad_cast<Source, Target>();
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169 return result;
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170 }
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171
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172 } // namespace boost
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173
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174 #undef BOOST_LCAST_NO_WCHAR_T
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175
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176 #endif // BOOST_LEXICAL_CAST_LEXICAL_CAST_OLD_HPP
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177
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