type_traits.h revision 169691
1169691Skan// -*- C++ -*- 2169691Skan 3169691Skan// Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc. 4169691Skan// 5169691Skan// This file is part of the GNU ISO C++ Library. This library is free 6169691Skan// software; you can redistribute it and/or modify it under the terms 7169691Skan// of the GNU General Public License as published by the Free Software 8169691Skan// Foundation; either version 2, or (at your option) any later 9169691Skan// version. 10169691Skan 11169691Skan// This library is distributed in the hope that it will be useful, but 12169691Skan// WITHOUT ANY WARRANTY; without even the implied warranty of 13169691Skan// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14169691Skan// General Public License for more details. 15169691Skan 16169691Skan// You should have received a copy of the GNU General Public License along 17169691Skan// with this library; see the file COPYING. If not, write to the Free 18169691Skan// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 19169691Skan// USA. 20169691Skan 21169691Skan// As a special exception, you may use this file as part of a free 22169691Skan// software library without restriction. Specifically, if other files 23169691Skan// instantiate templates or use macros or inline functions from this 24169691Skan// file, or you compile this file and link it with other files to 25169691Skan// produce an executable, this file does not by itself cause the 26169691Skan// resulting executable to be covered by the GNU General Public 27169691Skan// License. This exception does not however invalidate any other 28169691Skan// reasons why the executable file might be covered by the GNU General 29169691Skan// Public License. 30169691Skan 31169691Skan/** @file ext/type_traits.h 32169691Skan * This file is a GNU extension to the Standard C++ Library. 33169691Skan */ 34169691Skan 35169691Skan#ifndef _EXT_TYPE_TRAITS 36169691Skan#define _EXT_TYPE_TRAITS 1 37169691Skan 38169691Skan#pragma GCC system_header 39169691Skan 40169691Skan#include <cstddef> 41169691Skan#include <utility> 42169691Skan#include <bits/cpp_type_traits.h> 43169691Skan 44169691Skan_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 45169691Skan 46169691Skan // Define a nested type if some predicate holds. 47169691Skan template<bool, typename> 48169691Skan struct __enable_if 49169691Skan { }; 50169691Skan 51169691Skan template<typename _Tp> 52169691Skan struct __enable_if<true, _Tp> 53169691Skan { typedef _Tp __type; }; 54169691Skan 55169691Skan 56169691Skan // Conditional expression for types. If true, first, if false, second. 57169691Skan template<bool _Cond, typename _Iftrue, typename _Iffalse> 58169691Skan struct __conditional_type 59169691Skan { typedef _Iftrue __type; }; 60169691Skan 61169691Skan template<typename _Iftrue, typename _Iffalse> 62169691Skan struct __conditional_type<false, _Iftrue, _Iffalse> 63169691Skan { typedef _Iffalse __type; }; 64169691Skan 65169691Skan 66169691Skan // Given an integral builtin type, return the corresponding unsigned type. 67169691Skan template<typename _Tp> 68169691Skan struct __add_unsigned 69169691Skan { 70169691Skan private: 71169691Skan typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 72169691Skan 73169691Skan public: 74169691Skan typedef typename __if_type::__type __type; 75169691Skan }; 76169691Skan 77169691Skan template<> 78169691Skan struct __add_unsigned<char> 79169691Skan { typedef unsigned char __type; }; 80169691Skan 81169691Skan template<> 82169691Skan struct __add_unsigned<signed char> 83169691Skan { typedef unsigned char __type; }; 84169691Skan 85169691Skan template<> 86169691Skan struct __add_unsigned<short> 87169691Skan { typedef unsigned short __type; }; 88169691Skan 89169691Skan template<> 90169691Skan struct __add_unsigned<int> 91169691Skan { typedef unsigned int __type; }; 92169691Skan 93169691Skan template<> 94169691Skan struct __add_unsigned<long> 95169691Skan { typedef unsigned long __type; }; 96169691Skan 97169691Skan template<> 98169691Skan struct __add_unsigned<long long> 99169691Skan { typedef unsigned long long __type; }; 100169691Skan 101169691Skan // Declare but don't define. 102169691Skan template<> 103169691Skan struct __add_unsigned<bool>; 104169691Skan 105169691Skan template<> 106169691Skan struct __add_unsigned<wchar_t>; 107169691Skan 108169691Skan 109169691Skan // Given an integral builtin type, return the corresponding signed type. 110169691Skan template<typename _Tp> 111169691Skan struct __remove_unsigned 112169691Skan { 113169691Skan private: 114169691Skan typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 115169691Skan 116169691Skan public: 117169691Skan typedef typename __if_type::__type __type; 118169691Skan }; 119169691Skan 120169691Skan template<> 121169691Skan struct __remove_unsigned<char> 122169691Skan { typedef signed char __type; }; 123169691Skan 124169691Skan template<> 125169691Skan struct __remove_unsigned<unsigned char> 126169691Skan { typedef signed char __type; }; 127169691Skan 128169691Skan template<> 129169691Skan struct __remove_unsigned<unsigned short> 130169691Skan { typedef short __type; }; 131169691Skan 132169691Skan template<> 133169691Skan struct __remove_unsigned<unsigned int> 134169691Skan { typedef int __type; }; 135169691Skan 136169691Skan template<> 137169691Skan struct __remove_unsigned<unsigned long> 138169691Skan { typedef long __type; }; 139169691Skan 140169691Skan template<> 141169691Skan struct __remove_unsigned<unsigned long long> 142169691Skan { typedef long long __type; }; 143169691Skan 144169691Skan // Declare but don't define. 145169691Skan template<> 146169691Skan struct __remove_unsigned<bool>; 147169691Skan 148169691Skan template<> 149169691Skan struct __remove_unsigned<wchar_t>; 150169691Skan 151169691Skan_GLIBCXX_END_NAMESPACE 152169691Skan 153169691Skan#endif 154