109 lines
3.1 KiB
C++
109 lines
3.1 KiB
C++
//===----------------------------------------------------------------------===//
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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++03, c++11, c++14, c++17
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// constexpr auto begin() requires (!simple-view<V>)
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// { return ranges::begin(base_); }
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//
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// constexpr auto begin() const
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// requires range<const V> &&
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// indirect_unary_predicate<const Pred, iterator_t<const V>>
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// { return ranges::begin(base_); }
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#include <cassert>
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#include <ranges>
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#include <type_traits>
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#include <utility>
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#include "types.h"
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// Test Constraints
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template <class T>
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concept HasConstBegin = requires(const T& ct) { ct.begin(); };
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template <class T>
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concept HasBegin = requires(T& t) { t.begin(); };
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template <class T>
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concept HasConstAndNonConstBegin =
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HasConstBegin<T> &&
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requires(T& t, const T& ct) { requires !std::same_as<decltype(t.begin()), decltype(ct.begin())>; };
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template <class T>
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concept HasOnlyNonConstBegin = HasBegin<T> && !HasConstBegin<T>;
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template <class T>
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concept HasOnlyConstBegin = HasConstBegin<T> && !HasConstAndNonConstBegin<T>;
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struct Pred {
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constexpr bool operator()(int i) const { return i > 5; }
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};
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static_assert(HasOnlyConstBegin<std::ranges::take_while_view<SimpleView, Pred>>);
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static_assert(HasOnlyNonConstBegin<std::ranges::take_while_view<ConstNotRange, Pred>>);
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static_assert(HasConstAndNonConstBegin<std::ranges::take_while_view<NonSimple, Pred>>);
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struct NotPredForConst {
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constexpr bool operator()(int& i) const { return i > 5; }
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};
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static_assert(HasOnlyNonConstBegin<std::ranges::take_while_view<NonSimple, NotPredForConst>>);
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constexpr bool test() {
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// simple-view
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{
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int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1};
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SimpleView v{buffer};
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std::ranges::take_while_view twv(v, Pred{});
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std::same_as<int*> decltype(auto) it1 = twv.begin();
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assert(it1 == buffer);
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std::same_as<int*> decltype(auto) it2 = std::as_const(twv).begin();
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assert(it2 == buffer);
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}
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// const not range
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{
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int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1};
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ConstNotRange v{buffer};
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std::ranges::take_while_view twv(v, Pred{});
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std::same_as<int*> decltype(auto) it1 = twv.begin();
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assert(it1 == buffer);
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}
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// NonSimple
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{
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int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1};
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NonSimple v{buffer};
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std::ranges::take_while_view twv(v, Pred{});
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std::same_as<int*> decltype(auto) it1 = twv.begin();
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assert(it1 == buffer);
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std::same_as<const int*> decltype(auto) it2 = std::as_const(twv).begin();
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assert(it2 == buffer);
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}
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// NotPredForConst
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// LWG 3450: The const overloads of `take_while_view::begin/end` are underconstrained
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{
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int buffer[] = {1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1};
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NonSimple v{buffer};
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std::ranges::take_while_view twv(v, NotPredForConst{});
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std::same_as<int*> decltype(auto) it1 = twv.begin();
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assert(it1 == buffer);
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}
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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