| //===----------------------------------------------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is dual licensed under the MIT and the University of Illinois Open |
| // Source Licenses. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // UNSUPPORTED: c++98, c++03 |
| |
| // <queue> |
| |
| // template <class... Args> decltype(auto) emplace(Args&&... args); |
| // return type is 'decltype(auto)' in C++17; 'void' before |
| // whatever the return type of the underlying container's emplace_back() returns. |
| |
| |
| #include <queue> |
| #include <cassert> |
| #include <list> |
| |
| #include "test_macros.h" |
| |
| #include "../../../Emplaceable.h" |
| |
| template <typename Queue> |
| void test_return_type() { |
| typedef typename Queue::container_type Container; |
| typedef typename Container::value_type value_type; |
| typedef decltype(std::declval<Queue>().emplace(std::declval<value_type &>())) queue_return_type; |
| |
| #if TEST_STD_VER > 14 |
| typedef decltype(std::declval<Container>().emplace_back(std::declval<value_type>())) container_return_type; |
| static_assert(std::is_same<queue_return_type, container_return_type>::value, ""); |
| #else |
| static_assert(std::is_same<queue_return_type, void>::value, ""); |
| #endif |
| } |
| |
| int main() |
| { |
| test_return_type<std::queue<int> > (); |
| test_return_type<std::queue<int, std::list<int> > > (); |
| |
| typedef Emplaceable T; |
| std::queue<Emplaceable> q; |
| #if TEST_STD_VER > 14 |
| T& r1 = q.emplace(1, 2.5); |
| assert(&r1 == &q.back()); |
| T& r2 = q.emplace(2, 3.5); |
| assert(&r2 == &q.back()); |
| T& r3 = q.emplace(3, 4.5); |
| assert(&r3 == &q.back()); |
| assert(&r1 == &q.front()); |
| #else |
| q.emplace(1, 2.5); |
| q.emplace(2, 3.5); |
| q.emplace(3, 4.5); |
| #endif |
| |
| assert(q.size() == 3); |
| assert(q.front() == Emplaceable(1, 2.5)); |
| assert(q.back() == Emplaceable(3, 4.5)); |
| } |