// The -*- C++ -*- type traits classes for internal use in libstdc++
// Copyright (C) 2000-2001 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING. If not, write to the Free
// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
// USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
// Written by Gabriel Dos Reis <dosreis@cmla.ens-cachan.fr>
#ifndef _CPP_BITS_CPP_TYPE_TRAITS_H
#define _CPP_BITS_CPP_TYPE_TRAITS_H 1
#pragma GCC system_header
//
// This file provides some compile-time information about various types.
// These representations were designed, on purpose, to be constant-expressions
// and not types as found in <stl/bits/type_traits.h>. In particular, they
// can be used in control structures and the optimizer hopefully will do
// the obvious thing.
//
// Why integral expressions, and not functions nor types?
// Firstly, these compile-time entities are used as template-arguments
// so function return values won't work: We need compile-time entities.
// We're left with types and constant integral expressions.
// Secondly, from the point of view of ease of use, type-based compile-time
// information is -not- *that* convenient. On has to write lots of
// overloaded functions and to hope that the compiler will select the right
// one. As a net effect, the overall structure isn't very clear at first
// glance.
// Thirdly, partial ordering and overload resolution (of function templates)
// is highly costly in terms of compiler-resource. It is a Good Thing to
// keep these resource consumption as least as possible.
//
// See valarray_array.h for a case use.
//
// -- Gaby (dosreis@cmla.ens-cachan.fr) 2000-03-06.
//
namespace std
{
template<typename _Tp>
struct __is_void
{
enum
{
_M_type = 0
};
};
template<>
struct __is_void<void>
{
enum
{
_M_type = 1
};
};
//
// Integer types
//
template<typename _Tp>
struct __is_integer
{
enum
{
_M_type = 0
};
};
// Thirteen specializations (yes there are eleven standard integer
// types; 'long long' and 'unsigned long long' are supported as
// extensions)
template<>
struct __is_integer<bool>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<char>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<signed char>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<unsigned char>
{
enum
{
_M_type = 1
};
};
# ifdef _GLIBCPP_USE_WCHAR_T
template<>
struct __is_integer<wchar_t>
{
enum
{
_M_type = 1
};
};
# endif
template<>
struct __is_integer<short>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<unsigned short>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<int>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<unsigned int>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<long>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<unsigned long>
{
enum
{
_M_type = 1
};
};
# ifdef _GLIBCPP_USE_LONG_LONG
template<>
struct __is_integer<long long>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_integer<unsigned long long>
{
enum
{
_M_type = 1
};
};
# endif
//
// Floating point types
//
template<typename _Tp>
struct __is_floating
{
enum
{
_M_type = 0
};
};
// three specializations (float, double and 'long double')
template<>
struct __is_floating<float>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_floating<double>
{
enum
{
_M_type = 1
};
};
template<>
struct __is_floating<long double>
{
enum
{
_M_type = 1
};
};
//
// An arithmetic type is an integer type or a floating point type
//
template<typename _Tp>
struct __is_arithmetic
{
enum
{
_M_type = __is_integer<_Tp>::_M_type || __is_floating<_Tp>::_M_type
};
};
//
// A fundamental type is `void' or and arithmetic type
//
template<typename _Tp>
struct __is_fundamental
{
enum
{
_M_type = __is_void<_Tp>::_M_type || __is_arithmetic<_Tp>::_M_type
};
};
//
// For the immediate use, the following is a good approximation
//
template<typename _Tp>
struct __is_pod
{
enum
{
_M_type = __is_fundamental<_Tp>::_M_type
};
};
} // namespace std
#endif //_CPP_BITS_CPP_TYPE_TRAITS_H