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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <array>
// reference front(); // constexpr in C++17
// reference back(); // constexpr in C++17
// const_reference front(); // constexpr in C++14
// const_reference back(); // constexpr in C++14
#include <array>
#include <cassert>
#include "test_macros.h"
// std::array is explicitly allowed to be initialized with A a = { init-list };.
// Disable the missing braces warning for this reason.
#include "disable_missing_braces_warning.h"
#if TEST_STD_VER > 14
constexpr bool check_front( double val )
{
std::array<double, 3> arr = {1, 2, 3.5};
return arr.front() == val;
}
constexpr bool check_back( double val )
{
std::array<double, 3> arr = {1, 2, 3.5};
return arr.back() == val;
}
#endif
int main(int, char**)
{
{
typedef double T;
typedef std::array<T, 3> C;
C c = {1, 2, 3.5};
C::reference r1 = c.front();
assert(r1 == 1);
r1 = 5.5;
assert(c[0] == 5.5);
C::reference r2 = c.back();
assert(r2 == 3.5);
r2 = 7.5;
assert(c[2] == 7.5);
}
{
typedef double T;
typedef std::array<T, 3> C;
const C c = {1, 2, 3.5};
C::const_reference r1 = c.front();
assert(r1 == 1);
C::const_reference r2 = c.back();
assert(r2 == 3.5);
}
{
typedef double T;
typedef std::array<T, 0> C;
C c = {};
C const& cc = c;
ASSERT_SAME_TYPE(decltype( c.back()), typename C::reference);
ASSERT_SAME_TYPE(decltype(cc.back()), typename C::const_reference);
LIBCPP_ASSERT_NOEXCEPT( c.back());
LIBCPP_ASSERT_NOEXCEPT( cc.back());
ASSERT_SAME_TYPE(decltype( c.front()), typename C::reference);
ASSERT_SAME_TYPE(decltype(cc.front()), typename C::const_reference);
LIBCPP_ASSERT_NOEXCEPT( c.front());
LIBCPP_ASSERT_NOEXCEPT( cc.front());
if (c.size() > (0)) { // always false
TEST_IGNORE_NODISCARD c.front();
TEST_IGNORE_NODISCARD c.back();
TEST_IGNORE_NODISCARD cc.front();
TEST_IGNORE_NODISCARD cc.back();
}
}
{
typedef double T;
typedef std::array<const T, 0> C;
C c = {{}};
C const& cc = c;
ASSERT_SAME_TYPE(decltype( c.back()), typename C::reference);
ASSERT_SAME_TYPE(decltype(cc.back()), typename C::const_reference);
LIBCPP_ASSERT_NOEXCEPT( c.back());
LIBCPP_ASSERT_NOEXCEPT( cc.back());
ASSERT_SAME_TYPE(decltype( c.front()), typename C::reference);
ASSERT_SAME_TYPE(decltype(cc.front()), typename C::const_reference);
LIBCPP_ASSERT_NOEXCEPT( c.front());
LIBCPP_ASSERT_NOEXCEPT( cc.front());
if (c.size() > (0)) {
TEST_IGNORE_NODISCARD c.front();
TEST_IGNORE_NODISCARD c.back();
TEST_IGNORE_NODISCARD cc.front();
TEST_IGNORE_NODISCARD cc.back();
}
}
#if TEST_STD_VER > 11
{
typedef double T;
typedef std::array<T, 3> C;
constexpr C c = {1, 2, 3.5};
constexpr T t1 = c.front();
static_assert (t1 == 1, "");
constexpr T t2 = c.back();
static_assert (t2 == 3.5, "");
}
#endif
#if TEST_STD_VER > 14
{
static_assert (check_front(1), "");
static_assert (check_back (3.5), "");
}
#endif
return 0;
}
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