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-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 // UNSUPPORTED: c++03, c++11, c++14, c++17
10
11 // <algorithm>
12
13 // template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
14 // indirect_unary_predicate<projected<I, Proj>> Pred>
15 // constexpr I partition_point(I first, S last, Pred pred, Proj proj = {}); // Since C++20
16 //
17 // template<forward_range R, class Proj = identity,
18 // indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
19 // constexpr borrowed_iterator_t<R>
20 // partition_point(R&& r, Pred pred, Proj proj = {}); // Since C++20
21
22 #include <algorithm>
23 #include <array>
24 #include <concepts>
25 #include <functional>
26 #include <ranges>
27 #include <utility>
28
29 #include "almost_satisfies_types.h"
30 #include "test_iterators.h"
31
32 struct UnaryPred { bool operator()(int) const; };
33
34 // Test constraints of the (iterator, sentinel) overload.
35 // ======================================================
36
37 template <class Iter = int*, class Sent = int*, class Pred = UnaryPred>
38 concept HasPartitionPointIter =
39 requires(Iter&& iter, Sent&& sent, Pred&& pred) {
40 std::ranges::partition_point(std::forward<Iter>(iter), std::forward<Sent>(sent), std::forward<Pred>(pred));
41 };
42
43 static_assert(HasPartitionPointIter<int*, int*, UnaryPred>);
44
45 // !forward_iterator<I>
46 static_assert(!HasPartitionPointIter<ForwardIteratorNotDerivedFrom>);
47 static_assert(!HasPartitionPointIter<ForwardIteratorNotIncrementable>);
48
49 // !sentinel_for<S, I>
50 static_assert(!HasPartitionPointIter<int*, SentinelForNotSemiregular>);
51 static_assert(!HasPartitionPointIter<int*, SentinelForNotWeaklyEqualityComparableWith>);
52
53 // !indirect_unary_predicate<projected<I, Proj>>
54 static_assert(!HasPartitionPointIter<int*, int*, IndirectUnaryPredicateNotPredicate>);
55 static_assert(!HasPartitionPointIter<int*, int*, IndirectUnaryPredicateNotCopyConstructible>);
56
57 // Test constraints of the (range) overload.
58 // =========================================
59
60 template <class Range, class Pred>
61 concept HasPartitionPointRange =
62 requires(Range&& range, Pred&& pred) {
63 std::ranges::partition_point(std::forward<Range>(range), std::forward<Pred>(pred));
64 };
65
66 template <class T>
67 using R = UncheckedRange<T>;
68
69 static_assert(HasPartitionPointRange<R<int*>, UnaryPred>);
70
71 // !forward_range<R>
72 static_assert(!HasPartitionPointRange<ForwardRangeNotDerivedFrom, UnaryPred>);
73 static_assert(!HasPartitionPointRange<ForwardRangeNotIncrementable, UnaryPred>);
74
75 // !indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
76 static_assert(!HasPartitionPointRange<R<int*>, IndirectUnaryPredicateNotPredicate>);
77 static_assert(!HasPartitionPointRange<R<int*>, IndirectUnaryPredicateNotCopyConstructible>);
78
79 template <class Iter, class Sent, std::size_t N, class Pred>
test_one(std::array<int,N> input,Pred pred,std::size_t partition_point)80 constexpr void test_one(std::array<int, N> input, Pred pred, std::size_t partition_point) {
81 assert(std::ranges::is_partitioned(input, pred));
82
83 auto begin = Iter(input.data());
84 auto end = Sent(Iter(input.data() + input.size()));
85 auto neg_pred = [&](int x) { return !pred(x); };
86
87 { // (iterator, sentinel) overload.
88 std::same_as<Iter> decltype(auto) result = std::ranges::partition_point(begin, end, pred);
89
90 assert(base(result) == input.data() + partition_point);
91 assert(std::ranges::all_of(begin, result, pred));
92 assert(std::ranges::all_of(result, end, neg_pred));
93 }
94
95 { // (range) overload.
96 auto range = std::ranges::subrange(begin, end);
97 std::same_as<Iter> decltype(auto) result = std::ranges::partition_point(range, pred);
98
99 assert(base(result) == input.data() + partition_point);
100 assert(std::ranges::all_of(begin, result, pred));
101 assert(std::ranges::all_of(result, end, neg_pred));
102 }
103 }
104
105 template <class Iter, class Sent>
test_iterators_2()106 constexpr void test_iterators_2() {
107 auto is_odd = [](int x) { return x % 2 != 0; };
108
109 // Empty sequence.
110 test_one<Iter, Sent, 0>({}, is_odd, 0);
111 // 1-element sequence, the element satisfies the predicate.
112 test_one<Iter, Sent, 1>({1}, is_odd, 1);
113 // 1-element sequence, the element doesn't satisfy the predicate.
114 test_one<Iter, Sent, 1>({2}, is_odd, 0);
115 // 2-element sequence.
116 test_one<Iter, Sent, 2>({1, 2}, is_odd, 1);
117 // 3-element sequence.
118 test_one<Iter, Sent, 3>({3, 1, 2}, is_odd, 2);
119 // Longer sequence.
120 test_one<Iter, Sent, 8>({1, 3, 11, 5, 6, 2, 8, 4}, is_odd, 4);
121 // Longer sequence with duplicates.
122 test_one<Iter, Sent, 8>({1, 3, 3, 4, 6, 2, 8, 2}, is_odd, 3);
123 // All elements are the same and satisfy the predicate.
124 test_one<Iter, Sent, 3>({1, 1, 1}, is_odd, 3);
125 // All elements are the same and don't satisfy the predicate.
126 test_one<Iter, Sent, 3>({2, 2, 2}, is_odd, 0);
127 // All non-satisfying and all satisfying elements are the same.
128 test_one<Iter, Sent, 6>({1, 1, 1, 2, 2, 2}, is_odd, 3);
129
130 auto is_negative = [](int x) { return x < 0; };
131 // Different comparator.
132 test_one<Iter, Sent, 5>({-3, -6, 5, 7, 2}, is_negative, 2);
133 }
134
135 template <class Iter>
test_iterators_1()136 constexpr void test_iterators_1() {
137 test_iterators_2<Iter, Iter>();
138 test_iterators_2<Iter, sentinel_wrapper<Iter>>();
139 }
140
test_iterators()141 constexpr void test_iterators() {
142 test_iterators_1<forward_iterator<int*>>();
143 test_iterators_1<bidirectional_iterator<int*>>();
144 test_iterators_1<random_access_iterator<int*>>();
145 test_iterators_1<contiguous_iterator<int*>>();
146 test_iterators_1<int*>();
147 }
148
test()149 constexpr bool test() {
150 test_iterators();
151
152 { // A custom projection works.
153 const std::array in = {1, 3, 4, 6, 8};
154 auto is_odd = [](int x) { return x % 2 != 0; };
155 auto x2 = [](int x) { return x * 2; };
156 auto expected_no_proj = in.begin() + 2;
157 auto expected_with_proj = in.begin();
158
159 { // (iterator, sentinel) overload.
160 auto result_no_proj = std::ranges::partition_point(in.begin(), in.end(), is_odd);
161 assert(result_no_proj == expected_no_proj);
162 auto result_with_proj = std::ranges::partition_point(in.begin(), in.end(), is_odd, x2);
163 assert(result_with_proj == expected_with_proj);
164 }
165
166 { // (range) overload.
167 auto result_no_proj = std::ranges::partition_point(in, is_odd);
168 assert(result_no_proj == expected_no_proj);
169 auto result_with_proj = std::ranges::partition_point(in, is_odd, x2);
170 assert(result_with_proj == expected_with_proj);
171 }
172 }
173
174 return true;
175 }
176
main(int,char **)177 int main(int, char**) {
178 test();
179 static_assert(test());
180
181 return 0;
182 }
183