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// - std::swap is imported with a using-directive, rather than
17// a using-declaration, because some compilers (including MSVC 7.1,
18// Borland 5.9.3, and Intel 8.1) don't do argument-dependent lookup
19// when it has a 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
33#ifdef BOOST_HAS_PRAGMA_ONCE
34#pragma once
35#endif
36
37#if defined(BOOST_GCC) && (BOOST_GCC < 40700)
38// gcc 4.6 ICEs on noexcept specifications below
39#define BOOST_CORE_SWAP_NOEXCEPT_IF(x)
40#else
41#define BOOST_CORE_SWAP_NOEXCEPT_IF(x) BOOST_NOEXCEPT_IF(x)
42#endif
43
44namespace boost_swap_impl
45{
46 // we can't use type_traits here
47
48 template<class T> struct is_const { enum _vt { value = 0 }; };
49 template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
50
51 // Use std::swap if argument dependent lookup fails.
52 // We need to have this at namespace scope to be able to use unqualified swap() call
53 // in noexcept specification.
54 using namespace std;
55
56 template<class T>
57 BOOST_GPU_ENABLED
58 void swap_impl(T& left, T& right) BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(swap(left, right)))
59 {
60 swap(left, right);
61 }
62
63 template<class T, std::size_t N>
64 BOOST_GPU_ENABLED
65 void swap_impl(T (& left)[N], T (& right)[N])
66 BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::swap_impl(left[0], right[0])))
67 {
68 for (std::size_t i = 0; i < N; ++i)
69 {
70 ::boost_swap_impl::swap_impl(left[i], right[i]);
71 }
72 }
73}
74
75namespace boost
76{
77 template<class T1, class T2>
78 BOOST_GPU_ENABLED
79 typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
80 swap(T1& left, T2& right)
81 BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::swap_impl(left, right)))
82 {
83 ::boost_swap_impl::swap_impl(left, right);
84 }
85}
86
87#undef BOOST_CORE_SWAP_NOEXCEPT_IF
88
89#endif // BOOST_CORE_SWAP_HPP
90