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Implement boost::exchange

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This commit is contained in:
Glen Fernandes 2018-07-07 23:13:03 -04:00
parent 9445d08ea7
commit 2cd4753a02
4 changed files with 188 additions and 0 deletions
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47
include/boost/core/exchange.hpp Normal file
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@ -0,0 +1,47 @@
/*
Copyright 2018 Glen Joseph Fernandes
(glenjofe@gmail.com)
Distributed under the Boost Software License, Version 1.0.
(http://www.boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_CORE_EXCHANGE_HPP
#define BOOST_CORE_EXCHANGE_HPP
#include <boost/config.hpp>
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
#include <utility>
#endif
namespace boost {
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
template<class T, class U = T>
BOOST_CXX14_CONSTEXPR inline T exchange(T& t, U&& u)
{
T v = std::move(t);
t = std::forward<U>(u);
return v;
}
#else
namespace detail {
template<class T>
struct exchanger {
typedef T type;
};
} /* detail */
template<class T>
inline T exchange(T& t, const typename detail::exchanger<T>::type& u)
{
T v = t;
t = u;
return v;
}
#endif
} /* boost */
#endif

3
test/Jamfile.v2
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@ -121,5 +121,8 @@ run pointer_traits_rebind_test.cpp ;
run pointer_traits_pointer_to_test.cpp ;
run to_address_test.cpp ;
run exchange_test.cpp ;
run exchange_move_test.cpp ;
use-project /boost/core/swap : ./swap ;
build-project ./swap ;

73
test/exchange_move_test.cpp Normal file
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/*
Copyright 2018 Glen Joseph Fernandes
(glenjofe@gmail.com)
Distributed under the Boost Software License, Version 1.0.
(http://www.boost.org/LICENSE_1_0.txt)
*/
#include <boost/config.hpp>
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
#include <boost/core/exchange.hpp>
#include <boost/core/lightweight_test.hpp>
class C1 {
public:
explicit C1(int i)
: i_(i) { }
C1(C1&& c)
: i_(c.i_) { }
C1& operator=(C1&& c) {
i_ = c.i_;
return *this;
}
int i() const {
return i_;
}
private:
C1(const C1&);
C1& operator=(const C1&);
int i_;
};
void test1()
{
C1 x(1);
BOOST_TEST(boost::exchange(x, C1(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
class C2 {
public:
explicit C2(int i)
: i_(i) { }
operator C1() const {
return C1(i_);
}
int i() const {
return i_;
}
private:
C2(const C2&);
C2& operator=(const C2&);
int i_;
};
void test2()
{
C1 x(1);
BOOST_TEST(boost::exchange(x, C2(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
int main()
{
test1();
test2();
return boost::report_errors();
}
#else
int main()
{
return 0;
}
#endif

65
test/exchange_test.cpp Normal file
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/*
Copyright 2018 Glen Joseph Fernandes
(glenjofe@gmail.com)
Distributed under the Boost Software License, Version 1.0.
(http://www.boost.org/LICENSE_1_0.txt)
*/
#include <boost/core/exchange.hpp>
#include <boost/core/lightweight_test.hpp>
void test1()
{
int i = 1;
BOOST_TEST(boost::exchange(i, 2) == 1);
BOOST_TEST(i == 2);
}
class C1 {
public:
explicit C1(int i)
: i_(i) { }
int i() const {
return i_;
}
private:
int i_;
};
void test2()
{
C1 x(1);
BOOST_TEST(boost::exchange(x, C1(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
class C2 {
public:
explicit C2(int i)
: i_(i) { }
operator C1() const {
return C1(i_);
}
int i() const {
return i_;
}
private:
C2(const C2&);
C2& operator=(const C2&);
int i_;
};
void test3()
{
C1 x(1);
BOOST_TEST(boost::exchange(x, C2(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
int main()
{
test1();
test2();
test3();
return boost::report_errors();
}