<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/> <meta http-equiv="X-UA-Compatible" content="IE=9"/> <meta name="generator" content="Doxygen 1.8.15"/> <meta name="viewport" content="width=device-width, initial-scale=1"/> <title>libstdc++: type_traits.h Source File</title> <link href="tabs.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="jquery.js"></script> <script type="text/javascript" src="dynsections.js"></script> <link href="navtree.css" rel="stylesheet" type="text/css"/> <script type="text/javascript" src="resize.js"></script> <script type="text/javascript" src="navtreedata.js"></script> <script type="text/javascript" src="navtree.js"></script> <script type="text/javascript"> /* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ $(document).ready(initResizable); /* @license-end */</script> <link href="doxygen.css" rel="stylesheet" type="text/css" /> </head> <body> <div id="top"><!-- do not remove this div, it is closed by doxygen! --> <div id="titlearea"> <table cellspacing="0" cellpadding="0"> <tbody> <tr style="height: 56px;"> <td id="projectalign" style="padding-left: 0.5em;"> <div id="projectname">libstdc++ </div> </td> </tr> </tbody> </table> </div> <!-- end header part --> <!-- Generated by Doxygen 1.8.15 --> </div><!-- top --> <div id="side-nav" class="ui-resizable side-nav-resizable"> <div id="nav-tree"> <div id="nav-tree-contents"> <div id="nav-sync" class="sync"></div> </div> </div> <div id="splitbar" style="-moz-user-select:none;" class="ui-resizable-handle"> </div> </div> <script type="text/javascript"> /* @license magnet:?xt=urn:btih:cf05388f2679ee054f2beb29a391d25f4e673ac3&dn=gpl-2.0.txt GPL-v2 */ $(document).ready(function(){initNavTree('a01088_source.html','');}); /* @license-end */ </script> <div id="doc-content"> <div class="header"> <div class="headertitle"> <div class="title">type_traits.h</div> </div> </div><!--header--> <div class="contents"> <a href="a01088.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span> <span class="comment">// -*- C++ -*-</span></div><div class="line"><a name="l00002"></a><span class="lineno"> 2</span> </div><div class="line"><a name="l00003"></a><span class="lineno"> 3</span> <span class="comment">// Copyright (C) 2005-2018 Free Software Foundation, Inc.</span></div><div class="line"><a name="l00004"></a><span class="lineno"> 4</span> <span class="comment">//</span></div><div class="line"><a name="l00005"></a><span class="lineno"> 5</span> <span class="comment">// This file is part of the GNU ISO C++ Library. This library is free</span></div><div class="line"><a name="l00006"></a><span class="lineno"> 6</span> <span class="comment">// software; you can redistribute it and/or modify it under the terms</span></div><div class="line"><a name="l00007"></a><span class="lineno"> 7</span> <span class="comment">// of the GNU General Public License as published by the Free Software</span></div><div class="line"><a name="l00008"></a><span class="lineno"> 8</span> <span class="comment">// Foundation; either version 3, or (at your option) any later</span></div><div class="line"><a name="l00009"></a><span class="lineno"> 9</span> <span class="comment">// version.</span></div><div class="line"><a name="l00010"></a><span class="lineno"> 10</span> </div><div class="line"><a name="l00011"></a><span class="lineno"> 11</span> <span class="comment">// This library is distributed in the hope that it will be useful, but</span></div><div class="line"><a name="l00012"></a><span class="lineno"> 12</span> <span class="comment">// WITHOUT ANY WARRANTY; without even the implied warranty of</span></div><div class="line"><a name="l00013"></a><span class="lineno"> 13</span> <span class="comment">// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</span></div><div class="line"><a name="l00014"></a><span class="lineno"> 14</span> <span class="comment">// General Public License for more details.</span></div><div class="line"><a name="l00015"></a><span class="lineno"> 15</span> </div><div class="line"><a name="l00016"></a><span class="lineno"> 16</span> <span class="comment">// Under Section 7 of GPL version 3, you are granted additional</span></div><div class="line"><a name="l00017"></a><span class="lineno"> 17</span> <span class="comment">// permissions described in the GCC Runtime Library Exception, version</span></div><div class="line"><a name="l00018"></a><span class="lineno"> 18</span> <span class="comment">// 3.1, as published by the Free Software Foundation.</span></div><div class="line"><a name="l00019"></a><span class="lineno"> 19</span> </div><div class="line"><a name="l00020"></a><span class="lineno"> 20</span> <span class="comment">// You should have received a copy of the GNU General Public License and</span></div><div class="line"><a name="l00021"></a><span class="lineno"> 21</span> <span class="comment">// a copy of the GCC Runtime Library Exception along with this program;</span></div><div class="line"><a name="l00022"></a><span class="lineno"> 22</span> <span class="comment">// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see</span></div><div class="line"><a name="l00023"></a><span class="lineno"> 23</span> <span class="comment">// <http://www.gnu.org/licenses/>.</span></div><div class="line"><a name="l00024"></a><span class="lineno"> 24</span> <span class="comment"></span></div><div class="line"><a name="l00025"></a><span class="lineno"> 25</span> <span class="comment">/** @file ext/type_traits.h</span></div><div class="line"><a name="l00026"></a><span class="lineno"> 26</span> <span class="comment"> * This file is a GNU extension to the Standard C++ Library.</span></div><div class="line"><a name="l00027"></a><span class="lineno"> 27</span> <span class="comment"> */</span></div><div class="line"><a name="l00028"></a><span class="lineno"> 28</span> </div><div class="line"><a name="l00029"></a><span class="lineno"> 29</span> <span class="preprocessor">#ifndef _EXT_TYPE_TRAITS</span></div><div class="line"><a name="l00030"></a><span class="lineno"> 30</span> <span class="preprocessor">#define _EXT_TYPE_TRAITS 1</span></div><div class="line"><a name="l00031"></a><span class="lineno"> 31</span> </div><div class="line"><a name="l00032"></a><span class="lineno"> 32</span> <span class="preprocessor">#pragma GCC system_header</span></div><div class="line"><a name="l00033"></a><span class="lineno"> 33</span> </div><div class="line"><a name="l00034"></a><span class="lineno"> 34</span> <span class="preprocessor">#include <<a class="code" href="a00656.html">bits/c++config.h</a>></span></div><div class="line"><a name="l00035"></a><span class="lineno"> 35</span> <span class="preprocessor">#include <<a class="code" href="a00311.html">bits/cpp_type_traits.h</a>></span></div><div class="line"><a name="l00036"></a><span class="lineno"> 36</span> </div><div class="line"><a name="l00037"></a><span class="lineno"> 37</span> <span class="keyword">extern</span> <span class="stringliteral">"C++"</span> {</div><div class="line"><a name="l00038"></a><span class="lineno"> 38</span> </div><div class="line"><a name="l00039"></a><span class="lineno"> 39</span> <span class="keyword">namespace </span><a class="code" href="a01544.html">__gnu_cxx</a> _GLIBCXX_VISIBILITY(default)</div><div class="line"><a name="l00040"></a><span class="lineno"> 40</span> {</div><div class="line"><a name="l00041"></a><span class="lineno"> 41</span> _GLIBCXX_BEGIN_NAMESPACE_VERSION</div><div class="line"><a name="l00042"></a><span class="lineno"> 42</span> </div><div class="line"><a name="l00043"></a><span class="lineno"> 43</span>  <span class="comment">// Define a nested type if some predicate holds.</span></div><div class="line"><a name="l00044"></a><span class="lineno"> 44</span>  <span class="keyword">template</span><<span class="keywordtype">bool</span>, <span class="keyword">typename</span>></div><div class="line"><a name="l00045"></a><span class="lineno"> 45</span>  <span class="keyword">struct </span>__enable_if </div><div class="line"><a name="l00046"></a><span class="lineno"> 46</span>  { };</div><div class="line"><a name="l00047"></a><span class="lineno"> 47</span> </div><div class="line"><a name="l00048"></a><span class="lineno"> 48</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Tp></div><div class="line"><a name="l00049"></a><span class="lineno"> 49</span>  <span class="keyword">struct </span>__enable_if<true, _Tp></div><div class="line"><a name="l00050"></a><span class="lineno"> 50</span>  { <span class="keyword">typedef</span> _Tp __type; };</div><div class="line"><a name="l00051"></a><span class="lineno"> 51</span> </div><div class="line"><a name="l00052"></a><span class="lineno"> 52</span> </div><div class="line"><a name="l00053"></a><span class="lineno"> 53</span>  <span class="comment">// Conditional expression for types. If true, first, if false, second.</span></div><div class="line"><a name="l00054"></a><span class="lineno"> 54</span>  <span class="keyword">template</span><<span class="keywordtype">bool</span> _Cond, <span class="keyword">typename</span> _Iftrue, <span class="keyword">typename</span> _Iffalse></div><div class="line"><a name="l00055"></a><span class="lineno"> 55</span>  <span class="keyword">struct </span>__conditional_type</div><div class="line"><a name="l00056"></a><span class="lineno"> 56</span>  { <span class="keyword">typedef</span> _Iftrue __type; };</div><div class="line"><a name="l00057"></a><span class="lineno"> 57</span> </div><div class="line"><a name="l00058"></a><span class="lineno"> 58</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Iftrue, <span class="keyword">typename</span> _Iffalse></div><div class="line"><a name="l00059"></a><span class="lineno"> 59</span>  <span class="keyword">struct </span>__conditional_type<false, _Iftrue, _Iffalse></div><div class="line"><a name="l00060"></a><span class="lineno"> 60</span>  { <span class="keyword">typedef</span> _Iffalse __type; };</div><div class="line"><a name="l00061"></a><span class="lineno"> 61</span> </div><div class="line"><a name="l00062"></a><span class="lineno"> 62</span> </div><div class="line"><a name="l00063"></a><span class="lineno"> 63</span>  <span class="comment">// Given an integral builtin type, return the corresponding unsigned type.</span></div><div class="line"><a name="l00064"></a><span class="lineno"> 64</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Tp></div><div class="line"><a name="l00065"></a><span class="lineno"> 65</span>  <span class="keyword">struct </span>__add_unsigned</div><div class="line"><a name="l00066"></a><span class="lineno"> 66</span>  { </div><div class="line"><a name="l00067"></a><span class="lineno"> 67</span>  <span class="keyword">private</span>:</div><div class="line"><a name="l00068"></a><span class="lineno"> 68</span>  <span class="keyword">typedef</span> __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;</div><div class="line"><a name="l00069"></a><span class="lineno"> 69</span>  </div><div class="line"><a name="l00070"></a><span class="lineno"> 70</span>  <span class="keyword">public</span>:</div><div class="line"><a name="l00071"></a><span class="lineno"> 71</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> __if_type::__type __type; </div><div class="line"><a name="l00072"></a><span class="lineno"> 72</span>  };</div><div class="line"><a name="l00073"></a><span class="lineno"> 73</span> </div><div class="line"><a name="l00074"></a><span class="lineno"> 74</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00075"></a><span class="lineno"> 75</span>  <span class="keyword">struct </span>__add_unsigned<char></div><div class="line"><a name="l00076"></a><span class="lineno"> 76</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> __type; };</div><div class="line"><a name="l00077"></a><span class="lineno"> 77</span> </div><div class="line"><a name="l00078"></a><span class="lineno"> 78</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00079"></a><span class="lineno"> 79</span>  <span class="keyword">struct </span>__add_unsigned<signed char></div><div class="line"><a name="l00080"></a><span class="lineno"> 80</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> __type; };</div><div class="line"><a name="l00081"></a><span class="lineno"> 81</span> </div><div class="line"><a name="l00082"></a><span class="lineno"> 82</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00083"></a><span class="lineno"> 83</span>  <span class="keyword">struct </span>__add_unsigned<short></div><div class="line"><a name="l00084"></a><span class="lineno"> 84</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> __type; };</div><div class="line"><a name="l00085"></a><span class="lineno"> 85</span> </div><div class="line"><a name="l00086"></a><span class="lineno"> 86</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00087"></a><span class="lineno"> 87</span>  <span class="keyword">struct </span>__add_unsigned<int></div><div class="line"><a name="l00088"></a><span class="lineno"> 88</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> __type; };</div><div class="line"><a name="l00089"></a><span class="lineno"> 89</span> </div><div class="line"><a name="l00090"></a><span class="lineno"> 90</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00091"></a><span class="lineno"> 91</span>  <span class="keyword">struct </span>__add_unsigned<long></div><div class="line"><a name="l00092"></a><span class="lineno"> 92</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> __type; };</div><div class="line"><a name="l00093"></a><span class="lineno"> 93</span> </div><div class="line"><a name="l00094"></a><span class="lineno"> 94</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00095"></a><span class="lineno"> 95</span>  <span class="keyword">struct </span>__add_unsigned<long long></div><div class="line"><a name="l00096"></a><span class="lineno"> 96</span>  { <span class="keyword">typedef</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> <span class="keywordtype">long</span> __type; };</div><div class="line"><a name="l00097"></a><span class="lineno"> 97</span> </div><div class="line"><a name="l00098"></a><span class="lineno"> 98</span>  <span class="comment">// Declare but don't define.</span></div><div class="line"><a name="l00099"></a><span class="lineno"> 99</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00100"></a><span class="lineno"> 100</span>  <span class="keyword">struct </span>__add_unsigned<bool>;</div><div class="line"><a name="l00101"></a><span class="lineno"> 101</span> </div><div class="line"><a name="l00102"></a><span class="lineno"> 102</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00103"></a><span class="lineno"> 103</span>  <span class="keyword">struct </span>__add_unsigned<wchar_t>;</div><div class="line"><a name="l00104"></a><span class="lineno"> 104</span> </div><div class="line"><a name="l00105"></a><span class="lineno"> 105</span> </div><div class="line"><a name="l00106"></a><span class="lineno"> 106</span>  <span class="comment">// Given an integral builtin type, return the corresponding signed type.</span></div><div class="line"><a name="l00107"></a><span class="lineno"> 107</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Tp></div><div class="line"><a name="l00108"></a><span class="lineno"> 108</span>  <span class="keyword">struct </span>__remove_unsigned</div><div class="line"><a name="l00109"></a><span class="lineno"> 109</span>  { </div><div class="line"><a name="l00110"></a><span class="lineno"> 110</span>  <span class="keyword">private</span>:</div><div class="line"><a name="l00111"></a><span class="lineno"> 111</span>  <span class="keyword">typedef</span> __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;</div><div class="line"><a name="l00112"></a><span class="lineno"> 112</span>  </div><div class="line"><a name="l00113"></a><span class="lineno"> 113</span>  <span class="keyword">public</span>:</div><div class="line"><a name="l00114"></a><span class="lineno"> 114</span>  <span class="keyword">typedef</span> <span class="keyword">typename</span> __if_type::__type __type; </div><div class="line"><a name="l00115"></a><span class="lineno"> 115</span>  };</div><div class="line"><a name="l00116"></a><span class="lineno"> 116</span> </div><div class="line"><a name="l00117"></a><span class="lineno"> 117</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00118"></a><span class="lineno"> 118</span>  <span class="keyword">struct </span>__remove_unsigned<char></div><div class="line"><a name="l00119"></a><span class="lineno"> 119</span>  { <span class="keyword">typedef</span> <span class="keywordtype">signed</span> <span class="keywordtype">char</span> __type; };</div><div class="line"><a name="l00120"></a><span class="lineno"> 120</span> </div><div class="line"><a name="l00121"></a><span class="lineno"> 121</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00122"></a><span class="lineno"> 122</span>  <span class="keyword">struct </span>__remove_unsigned<unsigned char></div><div class="line"><a name="l00123"></a><span class="lineno"> 123</span>  { <span class="keyword">typedef</span> <span class="keywordtype">signed</span> <span class="keywordtype">char</span> __type; };</div><div class="line"><a name="l00124"></a><span class="lineno"> 124</span> </div><div class="line"><a name="l00125"></a><span class="lineno"> 125</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00126"></a><span class="lineno"> 126</span>  <span class="keyword">struct </span>__remove_unsigned<unsigned short></div><div class="line"><a name="l00127"></a><span class="lineno"> 127</span>  { <span class="keyword">typedef</span> <span class="keywordtype">short</span> __type; };</div><div class="line"><a name="l00128"></a><span class="lineno"> 128</span> </div><div class="line"><a name="l00129"></a><span class="lineno"> 129</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00130"></a><span class="lineno"> 130</span>  <span class="keyword">struct </span>__remove_unsigned<unsigned int></div><div class="line"><a name="l00131"></a><span class="lineno"> 131</span>  { <span class="keyword">typedef</span> <span class="keywordtype">int</span> __type; };</div><div class="line"><a name="l00132"></a><span class="lineno"> 132</span> </div><div class="line"><a name="l00133"></a><span class="lineno"> 133</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00134"></a><span class="lineno"> 134</span>  <span class="keyword">struct </span>__remove_unsigned<unsigned long></div><div class="line"><a name="l00135"></a><span class="lineno"> 135</span>  { <span class="keyword">typedef</span> <span class="keywordtype">long</span> __type; };</div><div class="line"><a name="l00136"></a><span class="lineno"> 136</span> </div><div class="line"><a name="l00137"></a><span class="lineno"> 137</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00138"></a><span class="lineno"> 138</span>  <span class="keyword">struct </span>__remove_unsigned<unsigned long long></div><div class="line"><a name="l00139"></a><span class="lineno"> 139</span>  { <span class="keyword">typedef</span> <span class="keywordtype">long</span> <span class="keywordtype">long</span> __type; };</div><div class="line"><a name="l00140"></a><span class="lineno"> 140</span> </div><div class="line"><a name="l00141"></a><span class="lineno"> 141</span>  <span class="comment">// Declare but don't define.</span></div><div class="line"><a name="l00142"></a><span class="lineno"> 142</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00143"></a><span class="lineno"> 143</span>  <span class="keyword">struct </span>__remove_unsigned<bool>;</div><div class="line"><a name="l00144"></a><span class="lineno"> 144</span> </div><div class="line"><a name="l00145"></a><span class="lineno"> 145</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00146"></a><span class="lineno"> 146</span>  <span class="keyword">struct </span>__remove_unsigned<wchar_t>;</div><div class="line"><a name="l00147"></a><span class="lineno"> 147</span> </div><div class="line"><a name="l00148"></a><span class="lineno"> 148</span> </div><div class="line"><a name="l00149"></a><span class="lineno"> 149</span>  <span class="comment">// For use in string and vstring.</span></div><div class="line"><a name="l00150"></a><span class="lineno"> 150</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Type></div><div class="line"><a name="l00151"></a><span class="lineno"> 151</span>  <span class="keyword">inline</span> <span class="keywordtype">bool</span></div><div class="line"><a name="l00152"></a><span class="lineno"> 152</span>  __is_null_pointer(_Type* __ptr)</div><div class="line"><a name="l00153"></a><span class="lineno"> 153</span>  { <span class="keywordflow">return</span> __ptr == 0; }</div><div class="line"><a name="l00154"></a><span class="lineno"> 154</span> </div><div class="line"><a name="l00155"></a><span class="lineno"> 155</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Type></div><div class="line"><a name="l00156"></a><span class="lineno"> 156</span>  <span class="keyword">inline</span> <span class="keywordtype">bool</span></div><div class="line"><a name="l00157"></a><span class="lineno"> 157</span>  __is_null_pointer(_Type)</div><div class="line"><a name="l00158"></a><span class="lineno"> 158</span>  { <span class="keywordflow">return</span> <span class="keyword">false</span>; }</div><div class="line"><a name="l00159"></a><span class="lineno"> 159</span> </div><div class="line"><a name="l00160"></a><span class="lineno"> 160</span> <span class="preprocessor">#if __cplusplus >= 201103L</span></div><div class="line"><a name="l00161"></a><span class="lineno"> 161</span>  <span class="keyword">inline</span> <span class="keywordtype">bool</span></div><div class="line"><a name="l00162"></a><span class="lineno"> 162</span>  __is_null_pointer(std::nullptr_t)</div><div class="line"><a name="l00163"></a><span class="lineno"> 163</span>  { <span class="keywordflow">return</span> <span class="keyword">true</span>; }</div><div class="line"><a name="l00164"></a><span class="lineno"> 164</span> <span class="preprocessor">#endif</span></div><div class="line"><a name="l00165"></a><span class="lineno"> 165</span> </div><div class="line"><a name="l00166"></a><span class="lineno"> 166</span>  <span class="comment">// For complex and cmath</span></div><div class="line"><a name="l00167"></a><span class="lineno"> 167</span>  template<typename _Tp, bool = std::__is_integer<_Tp>::__value></div><div class="line"><a name="l00168"></a><span class="lineno"> 168</span>  <span class="keyword">struct </span>__promote</div><div class="line"><a name="l00169"></a><span class="lineno"> 169</span>  { <span class="keyword">typedef</span> <span class="keywordtype">double</span> __type; };</div><div class="line"><a name="l00170"></a><span class="lineno"> 170</span> </div><div class="line"><a name="l00171"></a><span class="lineno"> 171</span>  <span class="comment">// No nested __type member for non-integer non-floating point types,</span></div><div class="line"><a name="l00172"></a><span class="lineno"> 172</span>  <span class="comment">// allows this type to be used for SFINAE to constrain overloads in</span></div><div class="line"><a name="l00173"></a><span class="lineno"> 173</span>  <span class="comment">// <cmath> and <complex> to only the intended types.</span></div><div class="line"><a name="l00174"></a><span class="lineno"> 174</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Tp></div><div class="line"><a name="l00175"></a><span class="lineno"> 175</span>  <span class="keyword">struct </span>__promote<_Tp, false></div><div class="line"><a name="l00176"></a><span class="lineno"> 176</span>  { };</div><div class="line"><a name="l00177"></a><span class="lineno"> 177</span> </div><div class="line"><a name="l00178"></a><span class="lineno"> 178</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00179"></a><span class="lineno"> 179</span>  <span class="keyword">struct </span>__promote<long double></div><div class="line"><a name="l00180"></a><span class="lineno"> 180</span>  { <span class="keyword">typedef</span> <span class="keywordtype">long</span> <span class="keywordtype">double</span> __type; };</div><div class="line"><a name="l00181"></a><span class="lineno"> 181</span> </div><div class="line"><a name="l00182"></a><span class="lineno"> 182</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00183"></a><span class="lineno"> 183</span>  <span class="keyword">struct </span>__promote<double></div><div class="line"><a name="l00184"></a><span class="lineno"> 184</span>  { <span class="keyword">typedef</span> <span class="keywordtype">double</span> __type; };</div><div class="line"><a name="l00185"></a><span class="lineno"> 185</span> </div><div class="line"><a name="l00186"></a><span class="lineno"> 186</span>  <span class="keyword">template</span><></div><div class="line"><a name="l00187"></a><span class="lineno"> 187</span>  <span class="keyword">struct </span>__promote<float></div><div class="line"><a name="l00188"></a><span class="lineno"> 188</span>  { <span class="keyword">typedef</span> <span class="keywordtype">float</span> __type; };</div><div class="line"><a name="l00189"></a><span class="lineno"> 189</span> </div><div class="line"><a name="l00190"></a><span class="lineno"> 190</span>  <span class="keyword">template</span><<span class="keyword">typename</span> _Tp, <span class="keyword">typename</span> _Up,</div><div class="line"><a name="l00191"></a><span class="lineno"> 191</span>  <span class="keyword">typename</span> _Tp2 = <span class="keyword">typename</span> __promote<_Tp>::__type,</div><div class="line"><a name="l00192"></a><span class="lineno"> 192</span>  <span class="keyword">typename</span> _Up2 = <span class="keyword">typename</span> __promote<_Up>::__type></div><div class="line"><a name="l00193"></a><span class="lineno"> 193</span>  <span class="keyword">struct </span>__promote_2</div><div class="line"><a name="l00194"></a><span class="lineno"> 194</span>  {</div><div class="line"><a name="l00195"></a><span class="lineno"> 195</span>  <span class="keyword">typedef</span> __typeof__(_Tp2() + _Up2()) __type;</div><div class="line"><a name="l00196"></a><span class="lineno"> 196</span>  };</div><div class="line"><a name="l00197"></a><span class="lineno"> 197</span> </div><div class="line"><a name="l00198"></a><span class="lineno"> 198</span>  template<typename _Tp, typename _Up, typename _Vp,</div><div class="line"><a name="l00199"></a><span class="lineno"> 199</span>  typename _Tp2 = typename __promote<_Tp>::__type,</div><div class="line"><a name="l00200"></a><span class="lineno"> 200</span>  typename _Up2 = typename __promote<_Up>::__type,</div><div class="line"><a name="l00201"></a><span class="lineno"> 201</span>  typename _Vp2 = typename __promote<_Vp>::__type></div><div class="line"><a name="l00202"></a><span class="lineno"> 202</span>  struct __promote_3</div><div class="line"><a name="l00203"></a><span class="lineno"> 203</span>  {</div><div class="line"><a name="l00204"></a><span class="lineno"> 204</span>  <span class="keyword">typedef</span> __typeof__(_Tp2() + _Up2() + _Vp2()) __type;</div><div class="line"><a name="l00205"></a><span class="lineno"> 205</span>  };</div><div class="line"><a name="l00206"></a><span class="lineno"> 206</span> </div><div class="line"><a name="l00207"></a><span class="lineno"> 207</span>  template<typename _Tp, typename _Up, typename _Vp, typename _Wp,</div><div class="line"><a name="l00208"></a><span class="lineno"> 208</span>  typename _Tp2 = typename __promote<_Tp>::__type,</div><div class="line"><a name="l00209"></a><span class="lineno"> 209</span>  typename _Up2 = typename __promote<_Up>::__type,</div><div class="line"><a name="l00210"></a><span class="lineno"> 210</span>  typename _Vp2 = typename __promote<_Vp>::__type,</div><div class="line"><a name="l00211"></a><span class="lineno"> 211</span>  typename _Wp2 = typename __promote<_Wp>::__type></div><div class="line"><a name="l00212"></a><span class="lineno"> 212</span>  struct __promote_4</div><div class="line"><a name="l00213"></a><span class="lineno"> 213</span>  {</div><div class="line"><a name="l00214"></a><span class="lineno"> 214</span>  <span class="keyword">typedef</span> __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type;</div><div class="line"><a name="l00215"></a><span class="lineno"> 215</span>  };</div><div class="line"><a name="l00216"></a><span class="lineno"> 216</span> </div><div class="line"><a name="l00217"></a><span class="lineno"> 217</span> _GLIBCXX_END_NAMESPACE_VERSION</div><div class="line"><a name="l00218"></a><span class="lineno"> 218</span> } <span class="comment">// namespace</span></div><div class="line"><a name="l00219"></a><span class="lineno"> 219</span> } <span class="comment">// extern "C++"</span></div><div class="line"><a name="l00220"></a><span class="lineno"> 220</span> </div><div class="line"><a name="l00221"></a><span class="lineno"> 221</span> <span class="preprocessor">#endif </span></div><div class="ttc" id="a00656_html"><div class="ttname"><a href="a00656.html">c++config.h</a></div></div> <div class="ttc" id="a01544_html"><div class="ttname"><a href="a01544.html">__gnu_cxx</a></div><div class="ttdoc">GNU extensions for public use.</div></div> <div class="ttc" id="a00311_html"><div class="ttname"><a href="a00311.html">cpp_type_traits.h</a></div></div> </div><!-- fragment --></div><!-- contents --> </div><!-- doc-content --> <!-- start 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