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, size_t N, class Pred>
80 constexpr void test_one(std::array<int, N> input, Pred pred, 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>
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>
136 constexpr void test_iterators_1() {
137   test_iterators_2<Iter, Iter>();
138   test_iterators_2<Iter, sentinel_wrapper<Iter>>();
139 }
140 
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 
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 
177 int main(int, char**) {
178   test();
179   static_assert(test());
180 
181   return 0;
182 }
183