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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>
// template<class Container>
// constexpr span(Container& cont);
// template<class Container>
// constexpr span(const Container& cont);
//
// Remarks: These constructors shall not participate in overload resolution unless:
// — extent == dynamic_extent,
// — Container is not a specialization of span,
// — Container is not a specialization of array,
// — is_array_v<Container> is false,
// — data(cont) and size(cont) are both well-formed, and
// — remove_pointer_t<decltype(data(cont))>(*)[] is convertible to ElementType(*)[].
//
#include <span>
#include <cassert>
#include <string>
#include <vector>
#include "test_macros.h"
// Look ma - I'm a container!
template <typename T>
struct IsAContainer {
constexpr IsAContainer() : v_{} {}
constexpr size_t size() const {return 1;}
constexpr T *data() {return &v_;}
constexpr const T *data() const {return &v_;}
constexpr T *begin() {return &v_;}
constexpr const T *begin() const {return &v_;}
constexpr T *end() {return &v_ + 1;}
constexpr const T *end() const {return &v_ + 1;}
constexpr T const *getV() const {return &v_;} // for checking
T v_;
};
void checkCV()
{
std::vector<int> v = {1,2,3};
// Types the same
{
std::span< int> s1{v}; // a span< int> pointing at int.
}
// types different
{
std::span<const int> s1{v}; // a span<const int> pointing at int.
std::span< volatile int> s2{v}; // a span< volatile int> pointing at int.
std::span< volatile int> s3{v}; // a span< volatile int> pointing at const int.
std::span<const volatile int> s4{v}; // a span<const volatile int> pointing at int.
}
// Constructing a const view from a temporary
{
std::span<const int> s1{IsAContainer<int>()};
std::span<const int> s3{std::vector<int>()};
(void) s1;
(void) s3;
}
}
template <typename T>
constexpr bool testConstexprSpan()
{
constexpr IsAContainer<const T> val{};
std::span<const T> s1{val};
return s1.data() == val.getV() && s1.size() == 1;
}
template <typename T>
constexpr bool testConstexprSpanStatic()
{
constexpr IsAContainer<const T> val{};
std::span<const T, 1> s1{val};
return s1.data() == val.getV() && s1.size() == 1;
}
template <typename T>
void testRuntimeSpan()
{
IsAContainer<T> val{};
const IsAContainer<T> cVal;
std::span<T> s1{val};
std::span<const T> s2{cVal};
assert(s1.data() == val.getV() && s1.size() == 1);
assert(s2.data() == cVal.getV() && s2.size() == 1);
}
template <typename T>
void testRuntimeSpanStatic()
{
IsAContainer<T> val{};
const IsAContainer<T> cVal;
std::span<T, 1> s1{val};
std::span<const T, 1> s2{cVal};
assert(s1.data() == val.getV() && s1.size() == 1);
assert(s2.data() == cVal.getV() && s2.size() == 1);
}
struct A{};
int main(int, char**)
{
static_assert(testConstexprSpan<int>(), "");
static_assert(testConstexprSpan<long>(), "");
static_assert(testConstexprSpan<double>(), "");
static_assert(testConstexprSpan<A>(), "");
static_assert(testConstexprSpanStatic<int>(), "");
static_assert(testConstexprSpanStatic<long>(), "");
static_assert(testConstexprSpanStatic<double>(), "");
static_assert(testConstexprSpanStatic<A>(), "");
testRuntimeSpan<int>();
testRuntimeSpan<long>();
testRuntimeSpan<double>();
testRuntimeSpan<std::string>();
testRuntimeSpan<A>();
testRuntimeSpanStatic<int>();
testRuntimeSpanStatic<long>();
testRuntimeSpanStatic<double>();
testRuntimeSpanStatic<std::string>();
testRuntimeSpanStatic<A>();
checkCV();
return 0;
}
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