1// Copyright (C) 2007, 2008 Steven Watanabe, Joseph Gauterin, Niels Dekker
2// Copyright (C) 2023 Andrey Semashev
3//
4// Distributed under the Boost Software License, Version 1.0. (See
5// accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt)
7// For more information, see http://www.boost.org
8
9#ifndef BOOST_CORE_INVOKE_SWAP_HPP
10#define BOOST_CORE_INVOKE_SWAP_HPP
11
12// Note: the implementation of this utility contains various workarounds:
13// - invoke_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// - The main entry function is called invoke_swap rather than swap
21// to avoid forming an infinite recursion when the arguments are not
22// swappable.
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
48template<class T> struct is_const { enum _vt { value = 0 }; };
49template<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.
54using namespace std;
55
56template<class T>
57BOOST_GPU_ENABLED
58inline void invoke_swap_impl(T& left, T& right) BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(swap(left, right)))
59{
60 swap(left, right);
61}
62
63template<class T, std::size_t N>
64BOOST_GPU_ENABLED
65inline void invoke_swap_impl(T (& left)[N], T (& right)[N])
66 BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::invoke_swap_impl(left[0], right[0])))
67{
68 for (std::size_t i = 0; i < N; ++i)
69 {
70 ::boost_swap_impl::invoke_swap_impl(left[i], right[i]);
71 }
72}
73
74} // namespace boost_swap_impl
75
76namespace boost {
77namespace core {
78
79template<class T>
80BOOST_GPU_ENABLED
81inline typename enable_if_c< !::boost_swap_impl::is_const<T>::value >::type
82invoke_swap(T& left, T& right)
83 BOOST_CORE_SWAP_NOEXCEPT_IF(BOOST_NOEXCEPT_EXPR(::boost_swap_impl::invoke_swap_impl(left, right)))
84{
85 ::boost_swap_impl::invoke_swap_impl(left, right);
86}
87
88} // namespace core
89} // namespace boost
90
91#undef BOOST_CORE_SWAP_NOEXCEPT_IF
92
93#endif // BOOST_CORE_INVOKE_SWAP_HPP
94

source code of boost/libs/core/include/boost/core/invoke_swap.hpp