70 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// <iterator>10 11// template <InputIterator Iter>12// Iter next(Iter x, Iter::difference_type n = 1); // constexpr in C++1713 14// LWG #2353 relaxed the requirement on next from ForwardIterator to InputIterator15 16#include <iterator>17#include <cassert>18#include <type_traits>19 20#include "test_macros.h"21#include "test_iterators.h"22 23template <class It>24TEST_CONSTEXPR_CXX17 void25check_next_n(It it, typename std::iterator_traits<It>::difference_type n, It result)26{27 static_assert(std::is_same<decltype(std::next(it, n)), It>::value, "");28 assert(std::next(it, n) == result);29 30 It (*next_ptr)(It, typename std::iterator_traits<It>::difference_type) = std::next;31 assert(next_ptr(it, n) == result);32}33 34template <class It>35TEST_CONSTEXPR_CXX17 void36check_next_1(It it, It result)37{38 static_assert(std::is_same<decltype(std::next(it)), It>::value, "");39 assert(std::next(it) == result);40}41 42TEST_CONSTEXPR_CXX17 bool tests()43{44 const char* s = "1234567890";45 check_next_n(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));46 check_next_n(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));47 check_next_n(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));48 check_next_n(bidirectional_iterator<const char*>(s+10), -10, bidirectional_iterator<const char*>(s));49 check_next_n(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));50 check_next_n(random_access_iterator<const char*>(s+10), -10, random_access_iterator<const char*>(s));51 check_next_n(s, 10, s+10);52 53 check_next_1(cpp17_input_iterator<const char*>(s), cpp17_input_iterator<const char*>(s+1));54 check_next_1(forward_iterator<const char*>(s), forward_iterator<const char*>(s+1));55 check_next_1(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+1));56 check_next_1(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+1));57 check_next_1(s, s+1);58 59 return true;60}61 62int main(int, char**)63{64 tests();65#if TEST_STD_VER >= 1766 static_assert(tests(), "");67#endif68 return 0;69}70