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// -*- C++ -*-
//===------------------------------ span ---------------------------------===//
//
// 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
//
//===---------------------------------------------------------------------===//
// UNSUPPORTED: c++03, c++11, c++14, c++17
// <span>
// constexpr reference front() const noexcept;
// Expects: empty() is false.
// Effects: Equivalent to: return *data();
//
#include <span>
#include <cassert>
#include <string>
#include "test_macros.h"
template <typename Span>
constexpr bool testConstexprSpan(Span sp)
{
LIBCPP_ASSERT(noexcept(sp.front()));
return std::addressof(sp.front()) == sp.data();
}
template <typename Span>
void testRuntimeSpan(Span sp)
{
LIBCPP_ASSERT(noexcept(sp.front()));
assert(std::addressof(sp.front()) == sp.data());
}
template <typename Span>
void testEmptySpan(Span sp)
{
if (!sp.empty())
[[maybe_unused]] auto res = sp.front();
}
struct A{};
constexpr int iArr1[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
int iArr2[] = {10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
int main(int, char**)
{
static_assert(testConstexprSpan(std::span<const int>(iArr1, 1)), "");
static_assert(testConstexprSpan(std::span<const int>(iArr1, 2)), "");
static_assert(testConstexprSpan(std::span<const int>(iArr1, 3)), "");
static_assert(testConstexprSpan(std::span<const int>(iArr1, 4)), "");
static_assert(testConstexprSpan(std::span<const int, 1>(iArr1, 1)), "");
static_assert(testConstexprSpan(std::span<const int, 2>(iArr1, 2)), "");
static_assert(testConstexprSpan(std::span<const int, 3>(iArr1, 3)), "");
static_assert(testConstexprSpan(std::span<const int, 4>(iArr1, 4)), "");
testRuntimeSpan(std::span<int>(iArr2, 1));
testRuntimeSpan(std::span<int>(iArr2, 2));
testRuntimeSpan(std::span<int>(iArr2, 3));
testRuntimeSpan(std::span<int>(iArr2, 4));
testRuntimeSpan(std::span<int, 1>(iArr2, 1));
testRuntimeSpan(std::span<int, 2>(iArr2, 2));
testRuntimeSpan(std::span<int, 3>(iArr2, 3));
testRuntimeSpan(std::span<int, 4>(iArr2, 4));
std::string s;
testRuntimeSpan(std::span<std::string> (&s, 1));
testRuntimeSpan(std::span<std::string, 1>(&s, 1));
std::span<int, 0> sp;
testEmptySpan(sp);
return 0;
}
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