420 lines
9.5 KiB
C++
420 lines
9.5 KiB
C++
// The -*- C++ -*- type traits classes for internal use in libstdc++
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// Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010
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// Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/cpp_type_traits.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{ext/type_traits}
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*/
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// Written by Gabriel Dos Reis <dosreis@cmla.ens-cachan.fr>
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#ifndef _CPP_TYPE_TRAITS_H
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#define _CPP_TYPE_TRAITS_H 1
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#pragma GCC system_header
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#include <bits/c++config.h>
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//
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// This file provides some compile-time information about various types.
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// These representations were designed, on purpose, to be constant-expressions
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// and not types as found in <bits/type_traits.h>. In particular, they
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// can be used in control structures and the optimizer hopefully will do
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// the obvious thing.
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//
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// Why integral expressions, and not functions nor types?
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// Firstly, these compile-time entities are used as template-arguments
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// so function return values won't work: We need compile-time entities.
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// We're left with types and constant integral expressions.
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// Secondly, from the point of view of ease of use, type-based compile-time
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// information is -not- *that* convenient. On has to write lots of
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// overloaded functions and to hope that the compiler will select the right
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// one. As a net effect, the overall structure isn't very clear at first
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// glance.
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// Thirdly, partial ordering and overload resolution (of function templates)
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// is highly costly in terms of compiler-resource. It is a Good Thing to
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// keep these resource consumption as least as possible.
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//
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// See valarray_array.h for a case use.
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//
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// -- Gaby (dosreis@cmla.ens-cachan.fr) 2000-03-06.
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//
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// Update 2005: types are also provided and <bits/type_traits.h> has been
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// removed.
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//
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// Forward declaration hack, should really include this from somewhere.
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_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
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template<typename _Iterator, typename _Container>
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class __normal_iterator;
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_GLIBCXX_END_NAMESPACE
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_GLIBCXX_BEGIN_NAMESPACE(std)
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struct __true_type { };
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struct __false_type { };
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template<bool>
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struct __truth_type
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{ typedef __false_type __type; };
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template<>
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struct __truth_type<true>
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{ typedef __true_type __type; };
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// N.B. The conversions to bool are needed due to the issue
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// explained in c++/19404.
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template<class _Sp, class _Tp>
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struct __traitor
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{
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enum { __value = bool(_Sp::__value) || bool(_Tp::__value) };
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typedef typename __truth_type<__value>::__type __type;
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};
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// Compare for equality of types.
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template<typename, typename>
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struct __are_same
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<typename _Tp>
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struct __are_same<_Tp, _Tp>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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// Holds if the template-argument is a void type.
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template<typename _Tp>
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struct __is_void
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<>
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struct __is_void<void>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// Integer types
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//
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template<typename _Tp>
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struct __is_integer
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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// Thirteen specializations (yes there are eleven standard integer
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// types; <em>long long</em> and <em>unsigned long long</em> are
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// supported as extensions)
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template<>
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struct __is_integer<bool>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<signed char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<unsigned char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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# ifdef _GLIBCXX_USE_WCHAR_T
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template<>
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struct __is_integer<wchar_t>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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# endif
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#ifdef __GXX_EXPERIMENTAL_CXX0X__
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template<>
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struct __is_integer<char16_t>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<char32_t>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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#endif
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template<>
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struct __is_integer<short>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<unsigned short>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<int>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<unsigned int>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<long>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<unsigned long>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<long long>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_integer<unsigned long long>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// Floating point types
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//
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template<typename _Tp>
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struct __is_floating
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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// three specializations (float, double and 'long double')
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template<>
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struct __is_floating<float>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_floating<double>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_floating<long double>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// Pointer types
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//
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template<typename _Tp>
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struct __is_pointer
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<typename _Tp>
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struct __is_pointer<_Tp*>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// Normal iterator type
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//
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template<typename _Tp>
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struct __is_normal_iterator
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<typename _Iterator, typename _Container>
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struct __is_normal_iterator< __gnu_cxx::__normal_iterator<_Iterator,
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_Container> >
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// An arithmetic type is an integer type or a floating point type
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//
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template<typename _Tp>
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struct __is_arithmetic
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: public __traitor<__is_integer<_Tp>, __is_floating<_Tp> >
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{ };
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//
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// A fundamental type is `void' or and arithmetic type
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//
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template<typename _Tp>
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struct __is_fundamental
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: public __traitor<__is_void<_Tp>, __is_arithmetic<_Tp> >
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{ };
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//
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// A scalar type is an arithmetic type or a pointer type
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//
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template<typename _Tp>
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struct __is_scalar
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: public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> >
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{ };
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//
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// For use in std::copy and std::find overloads for streambuf iterators.
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//
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template<typename _Tp>
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struct __is_char
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<>
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struct __is_char<char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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#ifdef _GLIBCXX_USE_WCHAR_T
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template<>
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struct __is_char<wchar_t>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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#endif
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template<typename _Tp>
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struct __is_byte
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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template<>
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struct __is_byte<char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_byte<signed char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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template<>
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struct __is_byte<unsigned char>
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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//
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// Move iterator type
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//
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template<typename _Tp>
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struct __is_move_iterator
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{
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enum { __value = 0 };
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typedef __false_type __type;
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};
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#ifdef __GXX_EXPERIMENTAL_CXX0X__
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template<typename _Iterator>
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class move_iterator;
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template<typename _Iterator>
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struct __is_move_iterator< move_iterator<_Iterator> >
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{
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enum { __value = 1 };
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typedef __true_type __type;
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};
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#endif
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_GLIBCXX_END_NAMESPACE
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#endif //_CPP_TYPE_TRAITS_H
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