122 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// UNSUPPORTED: c++03, c++11, c++14, c++1710 11// template<common_with<I> I2>12// friend constexpr iter_difference_t<I2> operator-(13// const counted_iterator& x, const counted_iterator<I2>& y);14 15#include <iterator>16 17#include "test_macros.h"18#include "test_iterators.h"19 20// This iterator is common_with forward_iterator but NOT comparable with it.21template <class It>22class CommonWithForwardIter23{24 It it_;25 26public:27 typedef std::input_iterator_tag iterator_category;28 typedef typename std::iterator_traits<It>::value_type value_type;29 typedef typename std::iterator_traits<It>::difference_type difference_type;30 typedef It pointer;31 typedef typename std::iterator_traits<It>::reference reference;32 33 constexpr It base() const {return it_;}34 35 CommonWithForwardIter() = default;36 explicit constexpr CommonWithForwardIter(It it) : it_(it) {}37 constexpr CommonWithForwardIter(const forward_iterator<It>& it) : it_(it.base()) {}38 39 constexpr reference operator*() const {return *it_;}40 41 constexpr CommonWithForwardIter& operator++() {++it_; return *this;}42 constexpr CommonWithForwardIter operator++(int)43 {CommonWithForwardIter tmp(*this); ++(*this); return tmp;}44};45 46constexpr bool test() {47 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8};48 49 {50 std::counted_iterator iter1(random_access_iterator<int*>{buffer}, 8);51 std::counted_iterator iter2(random_access_iterator<int*>{buffer + 4}, 4);52 assert(iter1 - iter2 == -4);53 assert(iter2 - iter1 == 4);54 assert(iter1.count() == 8);55 assert(iter2.count() == 4);56 57 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);58 }59 {60 const std::counted_iterator iter1(random_access_iterator<int*>{buffer}, 8);61 const std::counted_iterator iter2(random_access_iterator<int*>{buffer + 4}, 4);62 assert(iter1 - iter2 == -4);63 assert(iter2 - iter1 == 4);64 assert(iter1.count() == 8);65 assert(iter2.count() == 4);66 67 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);68 }69 {70 std::counted_iterator iter1(contiguous_iterator<int*>{buffer}, 8);71 std::counted_iterator iter2(contiguous_iterator<int*>{buffer + 2}, 6);72 assert(iter1 - iter2 == -2);73 assert(iter2 - iter1 == 2);74 assert(iter1.count() == 8);75 assert(iter2.count() == 6);76 77 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);78 }79 {80 const std::counted_iterator iter1(contiguous_iterator<int*>{buffer}, 8);81 const std::counted_iterator iter2(contiguous_iterator<int*>{buffer + 2}, 6);82 assert(iter1 - iter2 == -2);83 assert(iter2 - iter1 == 2);84 assert(iter1.count() == 8);85 assert(iter2.count() == 6);86 87 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);88 }89 // The minus operator works even if Iter is not a random_access_iterator because90 // counted_iterator is able to implement it by subtracting the counts rather than91 // the underlying iterators.92 {93 std::counted_iterator iter1(CommonWithForwardIter<int*>{buffer}, 8);94 std::counted_iterator iter2(forward_iterator<int*>{buffer + 2}, 6);95 assert(iter1 - iter2 == -2);96 assert(iter2 - iter1 == 2);97 assert(iter1.count() == 8);98 assert(iter2.count() == 6);99 100 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);101 }102 {103 const std::counted_iterator iter1(CommonWithForwardIter<int*>{buffer}, 8);104 const std::counted_iterator iter2(forward_iterator<int*>{buffer + 2}, 6);105 assert(iter1 - iter2 == -2);106 assert(iter2 - iter1 == 2);107 assert(iter1.count() == 8);108 assert(iter2.count() == 6);109 110 ASSERT_SAME_TYPE(decltype(iter1 - iter2), std::iter_difference_t<int*>);111 }112 113 return true;114}115 116int main(int, char**) {117 test();118 static_assert(test());119 120 return 0;121}122