| //===----------------------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // <algorithm> |
| |
| // UNSUPPORTED: c++03, c++11, c++14, c++17 |
| |
| // template<input_iterator I, class Proj = identity, |
| // indirectly_unary_invocable<projected<I, Proj>> Fun> |
| // constexpr ranges::for_each_n_result<I, Fun> |
| // ranges::for_each_n(I first, iter_difference_t<I> n, Fun f, Proj proj = {}); |
| |
| #include <algorithm> |
| #include <array> |
| #include <ranges> |
| |
| #include "almost_satisfies_types.h" |
| #include "test_iterators.h" |
| |
| struct Callable { |
| void operator()(int); |
| }; |
| |
| template <class Iter> |
| concept HasForEachN = requires (Iter iter) { std::ranges::for_each_n(iter, 0, Callable{}); }; |
| |
| static_assert(HasForEachN<int*>); |
| static_assert(!HasForEachN<InputIteratorNotDerivedFrom>); |
| static_assert(!HasForEachN<InputIteratorNotIndirectlyReadable>); |
| static_assert(!HasForEachN<InputIteratorNotInputOrOutputIterator>); |
| |
| template <class Func> |
| concept HasForEachItFunc = requires(int* a, int b, Func func) { std::ranges::for_each_n(a, b, func); }; |
| |
| static_assert(HasForEachItFunc<Callable>); |
| static_assert(!HasForEachItFunc<IndirectUnaryPredicateNotPredicate>); |
| static_assert(!HasForEachItFunc<IndirectUnaryPredicateNotCopyConstructible>); |
| |
| template <class Iter> |
| constexpr void test_iterator() { |
| { // simple test |
| auto func = [i = 0](int& a) mutable { a += i++; }; |
| int a[] = {1, 6, 3, 4}; |
| std::same_as<std::ranges::for_each_result<Iter, decltype(func)>> auto ret = |
| std::ranges::for_each_n(Iter(a), 4, func); |
| assert(a[0] == 1); |
| assert(a[1] == 7); |
| assert(a[2] == 5); |
| assert(a[3] == 7); |
| assert(base(ret.in) == a + 4); |
| int i = 0; |
| ret.fun(i); |
| assert(i == 4); |
| } |
| |
| { // check that an empty range works |
| std::array<int, 0> a = {}; |
| std::ranges::for_each_n(Iter(a.data()), 0, [](auto&) { assert(false); }); |
| } |
| } |
| |
| constexpr bool test() { |
| test_iterator<cpp17_input_iterator<int*>>(); |
| test_iterator<cpp20_input_iterator<int*>>(); |
| test_iterator<forward_iterator<int*>>(); |
| test_iterator<bidirectional_iterator<int*>>(); |
| test_iterator<random_access_iterator<int*>>(); |
| test_iterator<contiguous_iterator<int*>>(); |
| test_iterator<int*>(); |
| |
| { // check that std::invoke is used |
| struct S { |
| int check; |
| int other; |
| }; |
| |
| S a[] = {{1, 2}, {3, 4}, {5, 6}}; |
| std::ranges::for_each_n(a, 3, [](int& i) { i = 0; }, &S::check); |
| assert(a[0].check == 0); |
| assert(a[0].other == 2); |
| assert(a[1].check == 0); |
| assert(a[1].other == 4); |
| assert(a[2].check == 0); |
| assert(a[2].other == 6); |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |