1// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
2//
3// Distributed under the Boost Software License, Version 1.0. (See
4// accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6// For more information, see http://www.boost.org
7
8
9#ifndef BOOST_CORE_SWAP_HPP
10#define BOOST_CORE_SWAP_HPP
11
12// Note: the implementation of this utility contains various workarounds:
13// - swap_impl is put outside the boost namespace, to avoid infinite
14// recursion (causing stack overflow) when swapping objects of a primitive
15// type.
16// - swap_impl has a using-directive, rather than a using-declaration,
17// because some compilers (including MSVC 7.1, Borland 5.9.3, and
18// Intel 8.1) don't do argument-dependent lookup when it has a
19// using-declaration instead.
20// - boost::swap has two template arguments, instead of one, to
21// avoid ambiguity when swapping objects of a Boost type that does
22// not have its own boost::swap overload.
23
24#include <boost/core/enable_if.hpp>
25#include <boost/config.hpp>
26#if __cplusplus >= 201103L || defined(BOOST_DINKUMWARE_STDLIB)
27#include <utility> // for std::swap (C++11)
28#else
29#include <algorithm> // for std::swap (C++98)
30#endif
31#include <cstddef> // for std::size_t
32
33namespace boost_swap_impl
34{
35 // we can't use type_traits here
36
37 template<class T> struct is_const { enum _vt { value = 0 }; };
38 template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
39
40 template<class T>
41 BOOST_GPU_ENABLED
42 void swap_impl(T& left, T& right)
43 {
44 using namespace std;//use std::swap if argument dependent lookup fails
45 swap(left,right);
46 }
47
48 template<class T, std::size_t N>
49 BOOST_GPU_ENABLED
50 void swap_impl(T (& left)[N], T (& right)[N])
51 {
52 for (std::size_t i = 0; i < N; ++i)
53 {
54 ::boost_swap_impl::swap_impl(left[i], right[i]);
55 }
56 }
57}
58
59namespace boost
60{
61 template<class T1, class T2>
62 BOOST_GPU_ENABLED
63 typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
64 swap(T1& left, T2& right)
65 {
66 ::boost_swap_impl::swap_impl(left, right);
67 }
68}
69
70#endif
71

source code of include/boost/core/swap.hpp