1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
|
//===----------------------------------------------------------------------===//
//
// 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));
}
|
