boost_core/include/boost/core/swap.hpp

// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
// For more information, see http://www.boost.org


#ifndef BOOST_CORE_SWAP_HPP
#define BOOST_CORE_SWAP_HPP

// Note: the implementation of this utility contains various workarounds:
// - swap_impl is put outside the boost namespace, to avoid infinite
// recursion (causing stack overflow) when swapping objects of a primitive
// type.
// - swap_impl has a using-directive, rather than a using-declaration,
// because some compilers (including MSVC 7.1, Borland 5.9.3, and
// Intel 8.1) don't do argument-dependent lookup when it has a
// using-declaration instead.
// - boost::swap has two template arguments, instead of one, to
// avoid ambiguity when swapping objects of a Boost type that does
// not have its own boost::swap overload.

#include <boost/core/enable_if.hpp>
#include <boost/config.hpp>
#include <cstddef> //for std::size_t

// try to include std::swap from the most lightweight header
#if defined(BOOST_DINKUMWARE_STDLIB)
# include <utility>
#elif defined(_LIBCPP_VERSION) // since the first commit
# include <type_traits>
#elif defined(__GLIBCXX__) && __GLIBCXX__ > 20080621 // GCC 4.4
# include <bits/move.h>
#elif defined(__GLIBCXX__) && __GLIBCXX__ > 20071010 // GCC 4.3
# include <bits/stl_move.h>
#elif defined(__GLIBCXX__) || defined(__GLIBCPP__) // && __GLIBCPP__ > 20001005 // GCC 2.97
# include <bits/stl_algobase.h>
#elif __cplusplus >= 201103L
# include <utility>
#else // C++98/03 fallback
# include <algorithm>
#endif

namespace boost_swap_impl
{
  // we can't use type_traits here

  template<class T> struct is_const { enum _vt { value = 0 }; };
  template<class T> struct is_const<T const> { enum _vt { value = 1 }; };

  template<class T>
  BOOST_GPU_ENABLED
  void swap_impl(T& left, T& right)
  {
    using namespace std;//use std::swap if argument dependent lookup fails
    swap(left,right);
  }

  template<class T, std::size_t N>
  BOOST_GPU_ENABLED
  void swap_impl(T (& left)[N], T (& right)[N])
  {
    for (std::size_t i = 0; i < N; ++i)
    {
      ::boost_swap_impl::swap_impl(left[i], right[i]);
    }
  }
}

namespace boost
{
  template<class T1, class T2>
  BOOST_GPU_ENABLED
  typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
  swap(T1& left, T2& right)
  {
    ::boost_swap_impl::swap_impl(left, right);
  }
}

#endif