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 // <algorithm>
10 
11 // UNSUPPORTED: c++03, c++11, c++14, c++17
12 // UNSUPPORTED: libcpp-has-no-incomplete-ranges
13 
14 // template<input_iterator I, sentinel_for<I> S, class Proj = identity,
15 //          indirect_unary_predicate<projected<I, Proj>> Pred>
16 //   constexpr I ranges::find_if(I first, S last, Pred pred, Proj proj = {});
17 // template<input_range R, class Proj = identity,
18 //          indirect_unary_predicate<projected<iterator_t<R>, Proj>> Pred>
19 //   constexpr borrowed_iterator_t<R>
20 //     ranges::find_if(R&& r, Pred pred, Proj proj = {});
21 
22 #include <algorithm>
23 #include <array>
24 #include <cassert>
25 #include <ranges>
26 
27 #include "almost_satisfies_types.h"
28 #include "boolean_testable.h"
29 #include "test_iterators.h"
30 
31 struct Predicate {
32   bool operator()(int);
33 };
34 
35 template <class It, class Sent = It>
36 concept HasFindIfIt = requires(It it, Sent sent) { std::ranges::find_if(it, sent, Predicate{}); };
37 static_assert(HasFindIfIt<int*>);
38 static_assert(!HasFindIfIt<InputIteratorNotDerivedFrom>);
39 static_assert(!HasFindIfIt<InputIteratorNotIndirectlyReadable>);
40 static_assert(!HasFindIfIt<InputIteratorNotInputOrOutputIterator>);
41 static_assert(!HasFindIfIt<cpp20_input_iterator<int*>, SentinelForNotSemiregular>);
42 static_assert(!HasFindIfIt<cpp20_input_iterator<int*>, InputRangeNotSentinelEqualityComparableWith>);
43 
44 static_assert(!HasFindIfIt<int*, int>);
45 static_assert(!HasFindIfIt<int, int*>);
46 
47 template <class Pred>
48 concept HasFindIfPred = requires(int* it, Pred pred) {std::ranges::find_if(it, it, pred); };
49 
50 static_assert(!HasFindIfPred<IndirectUnaryPredicateNotCopyConstructible>);
51 static_assert(!HasFindIfPred<IndirectUnaryPredicateNotPredicate>);
52 
53 template <class R>
54 concept HasFindIfR = requires(R r) { std::ranges::find_if(r, Predicate{}); };
55 static_assert(HasFindIfR<std::array<int, 0>>);
56 static_assert(!HasFindIfR<int>);
57 static_assert(!HasFindIfR<InputRangeNotDerivedFrom>);
58 static_assert(!HasFindIfR<InputRangeNotIndirectlyReadable>);
59 static_assert(!HasFindIfR<InputRangeNotInputOrOutputIterator>);
60 static_assert(!HasFindIfR<InputRangeNotSentinelSemiregular>);
61 static_assert(!HasFindIfR<InputRangeNotSentinelEqualityComparableWith>);
62 
63 template <class It, class Sent = It>
test_iterators()64 constexpr void test_iterators() {
65   {
66     int a[] = {1, 2, 3, 4};
67     std::same_as<It> auto ret = std::ranges::find_if(It(a), Sent(It(a + 4)), [](int x) mutable { return x == 4; });
68     assert(base(ret) == a + 3);
69     assert(*ret == 4);
70   }
71   {
72     int a[] = {1, 2, 3, 4};
73     auto range = std::ranges::subrange(It(a), Sent(It(a + 4)));
74     std::same_as<It> auto ret = std::ranges::find_if(range, [](int x) mutable { return x == 4; });
75     assert(base(ret) == a + 3);
76     assert(*ret == 4);
77   }
78 }
79 
80 struct NonConstComparable {
operator ==(const NonConstComparable &,const NonConstComparable &)81   friend constexpr bool operator==(const NonConstComparable&, const NonConstComparable&) { return false; }
operator ==(NonConstComparable &,NonConstComparable &)82   friend constexpr bool operator==(NonConstComparable&, NonConstComparable&) { return false; }
operator ==(const NonConstComparable &,NonConstComparable &)83   friend constexpr bool operator==(const NonConstComparable&, NonConstComparable&) { return false; }
operator ==(NonConstComparable &,const NonConstComparable &)84   friend constexpr bool operator==(NonConstComparable&, const NonConstComparable&) { return true; }
85 };
86 
test()87 constexpr bool test() {
88   test_iterators<int*>();
89   test_iterators<const int*>();
90   test_iterators<cpp20_input_iterator<int*>, sentinel_wrapper<cpp20_input_iterator<int*>>>();
91   test_iterators<bidirectional_iterator<int*>>();
92   test_iterators<forward_iterator<int*>>();
93   test_iterators<random_access_iterator<int*>>();
94   test_iterators<contiguous_iterator<int*>>();
95 
96   {
97     // check that projections are used properly and that they are called with the iterator directly
98     {
99       int a[] = {1, 2, 3, 4};
100       auto ret = std::ranges::find_if(a, a + 4, [&](int* i) { return i == a + 3; }, [](int& i) { return &i; });
101       assert(ret == a + 3);
102     }
103     {
104       int a[] = {1, 2, 3, 4};
105       auto ret = std::ranges::find_if(a, [&](int* i) { return i == a + 3; }, [](int& i) { return &i; });
106       assert(ret == a + 3);
107     }
108   }
109 
110   {
111     // check that the first element is returned
112     {
113       struct S {
114         int comp;
115         int other;
116       };
117       S a[] = { {0, 0}, {0, 2}, {0, 1} };
118       auto ret = std::ranges::find_if(a, [](int i){ return i == 0; }, &S::comp);
119       assert(ret == a);
120       assert(ret->comp == 0);
121       assert(ret->other == 0);
122     }
123     {
124       struct S {
125         int comp;
126         int other;
127       };
128       S a[] = { {0, 0}, {0, 2}, {0, 1} };
129       auto ret = std::ranges::find_if(a, a + 3, [](int i) { return i == 0; }, &S::comp);
130       assert(ret == a);
131       assert(ret->comp == 0);
132       assert(ret->other == 0);
133     }
134   }
135 
136   {
137     // check that end + 1 iterator is returned with no match
138     {
139       int a[] = {1, 1, 1};
140       auto ret = std::ranges::find_if(a, a + 3, [](int) { return false; });
141       assert(ret == a + 3);
142     }
143     {
144       int a[] = {1, 1, 1};
145       auto ret = std::ranges::find_if(a, [](int){ return false; });
146       assert(ret == a + 3);
147     }
148   }
149 
150   {
151     // check that ranges::dangling is returned
152     [[maybe_unused]] std::same_as<std::ranges::dangling> auto ret =
153       std::ranges::find_if(std::array{1, 2}, [](int){ return false; });
154   }
155 
156   {
157     // check that an iterator is returned with a borrowing range
158     int a[] = {1, 2, 3, 4};
159     std::same_as<int*> auto ret = std::ranges::find_if(std::views::all(a), [](int){ return true; });
160     assert(ret == a);
161     assert(*ret == 1);
162   }
163 
164   {
165     // check that std::invoke is used
166     struct S { int i; };
167     S a[] = { S{1}, S{3}, S{2} };
168     std::same_as<S*> auto ret = std::ranges::find_if(a, [](int) { return false; }, &S::i);
169     assert(ret == a + 3);
170   }
171 
172   {
173     // count projection and predicate invocation count
174     {
175       int a[] = {1, 2, 3, 4};
176       int predicate_count = 0;
177       int projection_count = 0;
178       auto ret = std::ranges::find_if(a, a + 4,
179                                       [&](int i) { ++predicate_count; return i == 2; },
180                                       [&](int i) { ++projection_count; return i; });
181       assert(ret == a + 1);
182       assert(*ret == 2);
183       assert(predicate_count == 2);
184       assert(projection_count == 2);
185     }
186     {
187       int a[] = {1, 2, 3, 4};
188       int predicate_count = 0;
189       int projection_count = 0;
190       auto ret = std::ranges::find_if(a,
191                                       [&](int i) { ++predicate_count; return i == 2; },
192                                       [&](int i) { ++projection_count; return i; });
193       assert(ret == a + 1);
194       assert(*ret == 2);
195       assert(predicate_count == 2);
196       assert(projection_count == 2);
197     }
198   }
199 
200   {
201     // check that the return type of `iter::operator*` doesn't change
202     {
203       NonConstComparable a[] = { NonConstComparable{} };
204       auto ret = std::ranges::find_if(a, a + 1, [](auto&& e) { return e == NonConstComparable{}; });
205       assert(ret == a);
206     }
207     {
208       NonConstComparable a[] = { NonConstComparable{} };
209       auto ret = std::ranges::find_if(a, [](auto&& e) { return e == NonConstComparable{}; });
210       assert(ret == a);
211     }
212   }
213 
214   {
215     // check that an empty range works
216     {
217       std::array<int ,0> a = {};
218       auto ret = std::ranges::find_if(a.begin(), a.end(), [](int) { return true; });
219       assert(ret == a.begin());
220     }
221     {
222       std::array<int, 0> a = {};
223       auto ret = std::ranges::find_if(a, [](int) { return true; });
224       assert(ret == a.begin());
225     }
226   }
227 
228   {
229     // check that the implicit conversion to bool works
230     {
231       int a[] = {1, 2, 3, 4};
232       auto ret = std::ranges::find_if(a, a + 4, [](const int& i) { return BooleanTestable{i == 3}; });
233       assert(ret == a + 2);
234     }
235     {
236       int a[] = {1, 2, 3, 4};
237       auto ret = std::ranges::find_if(a, [](const int& b) { return BooleanTestable{b == 3}; });
238       assert(ret == a + 2);
239     }
240   }
241 
242   return true;
243 }
244 
main(int,char **)245 int main(int, char**) {
246   test();
247   static_assert(test());
248 
249   return 0;
250 }
251