boost_mirror/core
1
0
Fork 0
mirror of https://github.com/boostorg/core.git synced 2025-05-09 23:03:54 +00:00
Code Issues Packages Projects Releases Wiki Activity

Simplify exchange implementation for pre-C++11

Browse Source
This commit is contained in:
Glen Fernandes 2018-07-09 08:48:40 -04:00
parent 75ae238d0c
commit 19ec659a91
3 changed files with 58 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
include/boost/core/exchange.hpp
View File

@ -15,18 +15,10 @@ Distributed under the Boost Software License, Version 1.0.
#endif
namespace boost {
namespace detail {
template<class T>
struct exchange_type {
typedef T type;
};
} /* detail */
#if defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
template<class T>
inline T exchange(T& t, const typename detail::exchange_type<T>::type& u)
template<class T, class U>
inline T exchange(T& t, const U& u)
{
T v = t;
t = u;
@ -34,19 +26,11 @@ inline T exchange(T& t, const typename detail::exchange_type<T>::type& u)
}
#else
#if BOOST_WORKAROUND(BOOST_MSVC, < 1800)
template<class T>
inline T exchange(T& t, const typename detail::exchange_type<T>::type& u)
template<class T, class U>
inline T exchange(T& t, U&& u)
{
T v = std::move(t);
t = u;
return v;
}
template<class T>
inline T exchange(T& t, typename detail::exchange_type<T>::type&& u)
{
T v = std::move(t);
t = std::move(u);
t = std::forward<U>(u);
return v;
}
#else

27
test/exchange_move_test.cpp
View File

@ -59,10 +59,37 @@ void test2()
BOOST_TEST(x.i() == 2);
}
class C3 {
public:
explicit C3(int i)
: i_(i) { }
C3(C3&& c)
: i_(c.i_) { }
C3& operator=(C1&& c) {
i_ = c.i();
return *this;
}
int i() const {
return i_;
}
private:
C3(const C3&);
C3& operator=(const C3&);
int i_;
};
void test3()
{
C3 x(1);
BOOST_TEST(boost::exchange(x, C1(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
int main()
{
test1();
test2();
test3();
return boost::report_errors();
}
#else

26
test/exchange_test.cpp
View File

@ -56,10 +56,36 @@ void test3()
BOOST_TEST(x.i() == 2);
}
class C3 {
public:
explicit C3(int i)
: i_(i) { }
C3(const C3& c)
: i_(c.i_) { }
C3& operator=(const C1& c) {
i_ = c.i();
return *this;
}
int i() const {
return i_;
}
private:
C3& operator=(const C3&);
int i_;
};
void test4()
{
C3 x(1);
BOOST_TEST(boost::exchange(x, C1(2)).i() == 1);
BOOST_TEST(x.i() == 2);
}
int main()
{
test1();
test2();
test3();
test4();
return boost::report_errors();
}