forked from OSchip/llvm-project
118 lines
3.3 KiB
C++
118 lines
3.3 KiB
C++
// -*- C++ -*-
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//===------------------------------ span ---------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===---------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
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// <span>
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// template<class Container>
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// constexpr span(Container& cont);
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// template<class Container>
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// constexpr span(const Container& cont);
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//
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// Remarks: These constructors shall not participate in overload resolution unless:
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// — extent == dynamic_extent,
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// — Container is not a specialization of span,
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// — Container is not a specialization of array,
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// — is_array_v<Container> is false,
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// — data(cont) and size(cont) are both well-formed, and
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// — remove_pointer_t<decltype(data(cont))>(*)[] is convertible to ElementType(*)[].
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//
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#include <span>
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#include <cassert>
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#include <string>
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#include <vector>
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#include "test_macros.h"
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// Look ma - I'm a container!
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template <typename T>
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struct IsAContainer {
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constexpr IsAContainer() : v_{} {}
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constexpr size_t size() const {return 1;}
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constexpr T *data() {return &v_;}
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constexpr const T *data() const {return &v_;}
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constexpr T *begin() {return &v_;}
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constexpr const T *begin() const {return &v_;}
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constexpr T *end() {return &v_ + 1;}
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constexpr const T *end() const {return &v_ + 1;}
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constexpr T const *getV() const {return &v_;} // for checking
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T v_;
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};
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void checkCV()
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{
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std::vector<int> v = {1,2,3};
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// Types the same
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{
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std::span< int> s1{v}; // a span< int> pointing at int.
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}
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// types different
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{
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std::span<const int> s1{v}; // a span<const int> pointing at int.
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std::span< volatile int> s2{v}; // a span< volatile int> pointing at int.
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std::span< volatile int> s3{v}; // a span< volatile int> pointing at const int.
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std::span<const volatile int> s4{v}; // a span<const volatile int> pointing at int.
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}
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// Constructing a const view from a temporary
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{
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std::span<const int> s1{IsAContainer<int>()};
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std::span<const int> s3{std::vector<int>()};
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(void) s1;
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(void) s3;
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}
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}
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template <typename T>
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constexpr bool testConstexprSpan()
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{
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constexpr IsAContainer<const T> val{};
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std::span<const T> s1{val};
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return s1.data() == val.getV() && s1.size() == 1;
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}
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template <typename T>
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void testRuntimeSpan()
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{
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IsAContainer<T> val{};
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const IsAContainer<T> cVal;
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std::span<T> s1{val};
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std::span<const T> s2{cVal};
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assert(s1.data() == val.getV() && s1.size() == 1);
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assert(s2.data() == cVal.getV() && s2.size() == 1);
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}
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struct A{};
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int main(int, char**)
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{
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static_assert(testConstexprSpan<int>(), "");
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static_assert(testConstexprSpan<long>(), "");
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static_assert(testConstexprSpan<double>(), "");
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static_assert(testConstexprSpan<A>(), "");
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testRuntimeSpan<int>();
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testRuntimeSpan<long>();
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testRuntimeSpan<double>();
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testRuntimeSpan<std::string>();
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testRuntimeSpan<A>();
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checkCV();
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return 0;
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}
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