296 lines
5.7 KiB
C++
296 lines
5.7 KiB
C++
// The -*- C++ -*- type traits classes for internal use in libstdc++
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// Copyright (C) 2000 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 2, 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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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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// Written by Gabriel Dos Reis <dosreis@cmla.ens-cachan.fr>
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#ifndef _CPP_BITS_CPP_TYPE_TRAITS_H
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#define _CPP_BITS_CPP_TYPE_TRAITS_H 1
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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 <stl/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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namespace std
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{
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template<typename _Tp>
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struct __is_void
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{
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enum
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{
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_M_type = 0
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 0
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};
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};
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// Thirteen specializations (yes there are eleven standard integer
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// types; 'long long' and 'unsigned long long' are supported as
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// extensions)
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template<>
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struct __is_integer<bool>
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{
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enum
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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};
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# ifdef _GLIBCPP_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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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};
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# ifdef _GLIBCPP_USE_LONG_LONG
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template<>
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struct __is_integer<long long>
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{
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enum
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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};
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# endif
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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
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{
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_M_type = 0
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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
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{
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_M_type = 1
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};
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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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{
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enum
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{
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_M_type = __is_integer<_Tp>::_M_type || __is_floating<_Tp>::_M_type
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};
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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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{
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enum
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{
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_M_type = __is_void<_Tp>::_M_type || __is_arithmetic<_Tp>::_M_type
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};
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};
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//
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// For the immediate use, the following is a good approximation
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//
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template<typename _Tp>
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struct __is_pod
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{
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enum
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{
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_M_type = __is_fundamental<_Tp>::_M_type
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};
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};
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} // namespace std
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#endif //_CPP_BITS_CPP_TYPE_TRAITS_H
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