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 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
11 
12 // <algorithm>
13 
14 // template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
15 //          indirect_unary_predicate<projected<I, Proj>> Pred>
16 //   constexpr I partition_point(I first, S last, Pred pred, Proj proj = {});                       // Since C++20
17 //
18 // template<forward_range R, class Proj = identity,
19 //          indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
20 //   constexpr borrowed_iterator_t<R>
21 //     partition_point(R&& r, Pred pred, Proj proj = {});                                           // Since C++20
22 
23 #include <algorithm>
24 #include <array>
25 #include <concepts>
26 #include <functional>
27 #include <ranges>
28 #include <utility>
29 
30 #include "almost_satisfies_types.h"
31 #include "test_iterators.h"
32 
33 struct UnaryPred { bool operator()(int) const; };
34 
35 // Test constraints of the (iterator, sentinel) overload.
36 // ======================================================
37 
38 template <class Iter = int*, class Sent = int*, class Pred = UnaryPred>
39 concept HasPartitionPointIter =
40     requires(Iter&& iter, Sent&& sent, Pred&& pred) {
41       std::ranges::partition_point(std::forward<Iter>(iter), std::forward<Sent>(sent), std::forward<Pred>(pred));
42     };
43 
44 static_assert(HasPartitionPointIter<int*, int*, UnaryPred>);
45 
46 // !forward_iterator<I>
47 static_assert(!HasPartitionPointIter<ForwardIteratorNotDerivedFrom>);
48 static_assert(!HasPartitionPointIter<ForwardIteratorNotIncrementable>);
49 
50 // !sentinel_for<S, I>
51 static_assert(!HasPartitionPointIter<int*, SentinelForNotSemiregular>);
52 static_assert(!HasPartitionPointIter<int*, SentinelForNotWeaklyEqualityComparableWith>);
53 
54 // !indirect_unary_predicate<projected<I, Proj>>
55 static_assert(!HasPartitionPointIter<int*, int*, IndirectUnaryPredicateNotPredicate>);
56 static_assert(!HasPartitionPointIter<int*, int*, IndirectUnaryPredicateNotCopyConstructible>);
57 
58 // Test constraints of the (range) overload.
59 // =========================================
60 
61 template <class Range, class Pred>
62 concept HasPartitionPointRange =
63     requires(Range&& range, Pred&& pred) {
64       std::ranges::partition_point(std::forward<Range>(range), std::forward<Pred>(pred));
65     };
66 
67 template <class T>
68 using R = UncheckedRange<T>;
69 
70 static_assert(HasPartitionPointRange<R<int*>, UnaryPred>);
71 
72 // !forward_range<R>
73 static_assert(!HasPartitionPointRange<ForwardRangeNotDerivedFrom, UnaryPred>);
74 static_assert(!HasPartitionPointRange<ForwardRangeNotIncrementable, UnaryPred>);
75 
76 // !indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
77 static_assert(!HasPartitionPointRange<R<int*>, IndirectUnaryPredicateNotPredicate>);
78 static_assert(!HasPartitionPointRange<R<int*>, IndirectUnaryPredicateNotCopyConstructible>);
79 
80 template <class Iter, class Sent, size_t N, class Pred>
81 constexpr void test_one(std::array<int, N> input, Pred pred, size_t partition_point) {
82   assert(std::ranges::is_partitioned(input, pred));
83 
84   auto begin = Iter(input.data());
85   auto end = Sent(Iter(input.data() + input.size()));
86   auto neg_pred = [&](int x) { return !pred(x); };
87 
88   { // (iterator, sentinel) overload.
89     std::same_as<Iter> decltype(auto) result = std::ranges::partition_point(begin, end, pred);
90 
91     assert(base(result) == input.data() + partition_point);
92     assert(std::ranges::all_of(begin, result, pred));
93     assert(std::ranges::all_of(result, end, neg_pred));
94   }
95 
96   { // (range) overload.
97     auto range = std::ranges::subrange(begin, end);
98     std::same_as<Iter> decltype(auto) result = std::ranges::partition_point(range, pred);
99 
100     assert(base(result) == input.data() + partition_point);
101     assert(std::ranges::all_of(begin, result, pred));
102     assert(std::ranges::all_of(result, end, neg_pred));
103   }
104 }
105 
106 template <class Iter, class Sent>
107 constexpr void test_iterators_2() {
108   auto is_odd = [](int x) { return x % 2 != 0; };
109 
110   // Empty sequence.
111   test_one<Iter, Sent, 0>({}, is_odd, 0);
112   // 1-element sequence, the element satisfies the predicate.
113   test_one<Iter, Sent, 1>({1}, is_odd, 1);
114   // 1-element sequence, the element doesn't satisfy the predicate.
115   test_one<Iter, Sent, 1>({2}, is_odd, 0);
116   // 2-element sequence.
117   test_one<Iter, Sent, 2>({1, 2}, is_odd, 1);
118   // 3-element sequence.
119   test_one<Iter, Sent, 3>({3, 1, 2}, is_odd, 2);
120   // Longer sequence.
121   test_one<Iter, Sent, 8>({1, 3, 11, 5, 6, 2, 8, 4}, is_odd, 4);
122   // Longer sequence with duplicates.
123   test_one<Iter, Sent, 8>({1, 3, 3, 4, 6, 2, 8, 2}, is_odd, 3);
124   // All elements are the same and satisfy the predicate.
125   test_one<Iter, Sent, 3>({1, 1, 1}, is_odd, 3);
126   // All elements are the same and don't satisfy the predicate.
127   test_one<Iter, Sent, 3>({2, 2, 2}, is_odd, 0);
128   // All non-satisfying and all satisfying elements are the same.
129   test_one<Iter, Sent, 6>({1, 1, 1, 2, 2, 2}, is_odd, 3);
130 
131   auto is_negative = [](int x) { return x < 0; };
132   // Different comparator.
133   test_one<Iter, Sent, 5>({-3, -6, 5, 7, 2}, is_negative, 2);
134 }
135 
136 template <class Iter>
137 constexpr void test_iterators_1() {
138   test_iterators_2<Iter, Iter>();
139   test_iterators_2<Iter, sentinel_wrapper<Iter>>();
140 }
141 
142 constexpr void test_iterators() {
143   test_iterators_1<forward_iterator<int*>>();
144   test_iterators_1<bidirectional_iterator<int*>>();
145   test_iterators_1<random_access_iterator<int*>>();
146   test_iterators_1<contiguous_iterator<int*>>();
147   test_iterators_1<int*>();
148 }
149 
150 constexpr bool test() {
151   test_iterators();
152 
153   { // A custom projection works.
154     const std::array in = {1, 3, 4, 6, 8};
155     auto is_odd = [](int x) { return x % 2 != 0; };
156     auto x2 = [](int x) { return x * 2; };
157     auto expected_no_proj = in.begin() + 2;
158     auto expected_with_proj = in.begin();
159 
160     { // (iterator, sentinel) overload.
161       auto result_no_proj = std::ranges::partition_point(in.begin(), in.end(), is_odd);
162       assert(result_no_proj == expected_no_proj);
163       auto result_with_proj = std::ranges::partition_point(in.begin(), in.end(), is_odd, x2);
164       assert(result_with_proj == expected_with_proj);
165     }
166 
167     { // (range) overload.
168       auto result_no_proj = std::ranges::partition_point(in, is_odd);
169       assert(result_no_proj == expected_no_proj);
170       auto result_with_proj = std::ranges::partition_point(in, is_odd, x2);
171       assert(result_with_proj == expected_with_proj);
172     }
173   }
174 
175   return true;
176 }
177 
178 int main(int, char**) {
179   test();
180   static_assert(test());
181 
182   return 0;
183 }
184