1 | #ifndef BOOST_REF_HPP_INCLUDED
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2 | #define BOOST_REF_HPP_INCLUDED
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3 |
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4 | // MS compatible compilers support #pragma once
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5 |
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6 | #if defined(_MSC_VER) && (_MSC_VER >= 1020)
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7 | # pragma once
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8 | #endif
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9 |
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10 | #include <boost/config.hpp>
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11 | #include <boost/utility/addressof.hpp>
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12 | #include <boost/mpl/bool.hpp>
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13 | #include <boost/detail/workaround.hpp>
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14 | #include <boost/type_traits/is_base_of.hpp>
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15 | #include <boost/utility/enable_if.hpp>
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16 |
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17 | //
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18 | // ref.hpp - ref/cref, useful helper functions
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19 | //
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20 | // Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
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21 | // Copyright (C) 2001, 2002 Peter Dimov
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22 | // Copyright (C) 2002 David Abrahams
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23 | //
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24 | // Distributed under the Boost Software License, Version 1.0. (See
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25 | // accompanying file LICENSE_1_0.txt or copy at
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26 | // http://www.boost.org/LICENSE_1_0.txt)
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27 | //
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28 | // See http://www.boost.org/libs/bind/ref.html for documentation.
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29 | //
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30 |
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31 | namespace boost
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32 | {
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33 |
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34 | template<class T> class reference_wrapper
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35 | {
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36 | public:
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37 | typedef T type;
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38 |
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39 | #if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, < 1300 )
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40 |
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41 | explicit reference_wrapper(T& t): t_(&t) {}
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42 |
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43 | #else
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44 |
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45 | explicit reference_wrapper(T& t): t_(boost::addressof(t)) {}
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46 |
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47 | #endif
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48 |
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49 | // Implicit conversion from child-type reference_wrapper
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50 | template <typename FromT>
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51 | reference_wrapper(reference_wrapper<FromT> const& wrapper,typename boost::enable_if<boost::is_base_of<T,FromT> >::type* =0): t_(wrapper.t_) {}
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52 |
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53 | operator T& () const { return *t_; }
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54 |
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55 | T& get() const { return *t_; }
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56 |
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57 | T* get_pointer() const { return t_; }
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58 |
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59 | // Implicit conversion to parent-type references
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60 | template <typename ToT>
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61 | operator typename boost::enable_if<boost::is_base_of<ToT,T>,ToT>::type () const { return *t_ ; }
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62 |
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63 | private:
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64 |
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65 | T* t_;
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66 | template <typename OtherT> friend class reference_wrapper;
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67 | };
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68 |
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69 | # if defined( __BORLANDC__ ) && BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) )
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70 | # define BOOST_REF_CONST
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71 | # else
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72 | # define BOOST_REF_CONST const
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73 | # endif
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74 |
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75 | template<class T> inline reference_wrapper<T> BOOST_REF_CONST ref(T & t)
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76 | {
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77 | return reference_wrapper<T>(t);
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78 | }
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79 |
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80 | template<class T> inline reference_wrapper<T const> BOOST_REF_CONST cref(T const & t)
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81 | {
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82 | return reference_wrapper<T const>(t);
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83 | }
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84 |
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85 | # undef BOOST_REF_CONST
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86 |
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87 | # ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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88 |
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89 | template<typename T>
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90 | class is_reference_wrapper
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91 | : public mpl::false_
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92 | {
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93 | };
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94 |
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95 | template<typename T>
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96 | class unwrap_reference
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97 | {
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98 | public:
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99 | typedef T type;
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100 | };
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101 |
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102 | # define AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(X) \
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103 | template<typename T> \
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104 | class is_reference_wrapper< X > \
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105 | : public mpl::true_ \
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106 | { \
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107 | }; \
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108 | \
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109 | template<typename T> \
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110 | class unwrap_reference< X > \
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111 | { \
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112 | public: \
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113 | typedef T type; \
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114 | }; \
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115 | /**/
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116 |
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117 | AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T>)
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118 | #if !defined(BOOST_NO_CV_SPECIALIZATIONS)
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119 | AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> const)
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120 | AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> volatile)
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121 | AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> const volatile)
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122 | #endif
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123 |
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124 | # undef AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF
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125 |
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126 | # else // no partial specialization
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127 |
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128 | } // namespace boost
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129 |
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130 | #include <boost/type.hpp>
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131 |
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132 | namespace boost
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133 | {
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134 |
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135 | namespace detail
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136 | {
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137 | typedef char (&yes_reference_wrapper_t)[1];
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138 | typedef char (&no_reference_wrapper_t)[2];
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139 |
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140 | no_reference_wrapper_t is_reference_wrapper_test(...);
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141 |
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142 | template<typename T>
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143 | yes_reference_wrapper_t is_reference_wrapper_test(type< reference_wrapper<T> >);
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144 |
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145 | template<bool wrapped>
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146 | struct reference_unwrapper
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147 | {
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148 | template <class T>
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149 | struct apply
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150 | {
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151 | typedef T type;
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152 | };
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153 | };
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154 |
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155 | template<>
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156 | struct reference_unwrapper<true>
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157 | {
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158 | template <class T>
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159 | struct apply
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160 | {
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161 | typedef typename T::type type;
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162 | };
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163 | };
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164 | }
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165 |
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166 | template<typename T>
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167 | class is_reference_wrapper
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168 | {
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169 | public:
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170 | BOOST_STATIC_CONSTANT(
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171 | bool, value = (
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172 | sizeof(detail::is_reference_wrapper_test(type<T>()))
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173 | == sizeof(detail::yes_reference_wrapper_t)));
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174 |
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175 | typedef ::boost::mpl::bool_<value> type;
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176 | };
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177 |
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178 | template <typename T>
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179 | class unwrap_reference
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180 | : public detail::reference_unwrapper<
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181 | is_reference_wrapper<T>::value
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182 | >::template apply<T>
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183 | {};
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184 |
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185 | # endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
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186 |
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187 | template <class T> inline typename unwrap_reference<T>::type&
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188 | unwrap_ref(T& t)
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189 | {
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190 | return t;
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191 | }
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192 |
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193 | template<class T> inline T* get_pointer( reference_wrapper<T> const & r )
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194 | {
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195 | return r.get_pointer();
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196 | }
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197 |
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198 | } // namespace boost
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199 |
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200 | #endif // #ifndef BOOST_REF_HPP_INCLUDED
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