gcc/libstdc++-v3/include/tr1/common.h

// Internal header for TR1 complex -*- C++ -*-

// Copyright (C) 2006 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// 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.

/** @file 
 *  This is a TR1 C++ Library header. 
 */

#ifndef _TR1_COMMON_H
#define _TR1_COMMON_H 1

#include <tr1/type_traits>

// namespace std::tr1
namespace std
{
_GLIBCXX_BEGIN_NAMESPACE(tr1)

  template<typename _Tp, bool = is_integral<_Tp>::value>
    struct __promote
    { typedef double __type; };

  template<typename _Tp>
    struct __promote<_Tp, false>
    { typedef _Tp __type; };

  template<typename _Tp, typename _Up>
    struct __promote_2
    {
    private:
      typedef typename __promote<_Tp>::__type __type1;
      typedef typename __promote<_Up>::__type __type2;

    public:
      typedef __typeof__(__type1() + __type2()) __type;
    };

  template<typename _Tp, typename _Up, typename _Vp>
    struct __promote_3
    {
    private:
      typedef typename __promote<_Tp>::__type __type1;
      typedef typename __promote<_Up>::__type __type2;
      typedef typename __promote<_Vp>::__type __type3;

    public:
      typedef __typeof__(__type1() + __type2() + __type3()) __type;
    };

_GLIBCXX_END_NAMESPACE
} // namespace std

#endif