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, c++20
12
13 // template<input_iterator I1, sentinel_for<I1> S1, input_iterator I2, sentinel_for<I2> S2,
14 // class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
15 // requires indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
16 // constexpr bool ranges::starts_with(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
17 // Proj1 proj1 = {}, Proj2 proj2 = {});
18 // template<input_range R1, input_range R2, class Pred = ranges::equal_to, class Proj1 = identity,
19 // class Proj2 = identity>
20 // requires indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
21 // constexpr bool ranges::starts_with(R1&& r1, R2&& r2, Pred pred = {},
22 // Proj1 proj1 = {}, Proj2 proj2 = {});
23
24 #include <algorithm>
25 #include <array>
26 #include <ranges>
27
28 #include "almost_satisfies_types.h"
29 #include "test_iterators.h"
30
31 template <class Iter1, class Sent1 = Iter1, class Iter2 = int*, class Sent2 = Iter2>
32 concept HasStartsWithIt = requires(Iter1 first1, Sent1 last1, Iter2 first2, Sent2 last2) {
33 std::ranges::starts_with(first1, last1, first2, last2);
34 };
35
36 static_assert(HasStartsWithIt<int*>);
37 static_assert(HasStartsWithIt<ForwardIteratorNotDerivedFrom>);
38 static_assert(HasStartsWithIt<ForwardIteratorNotIncrementable>);
39 static_assert(!HasStartsWithIt<int*, SentinelForNotSemiregular>);
40 static_assert(!HasStartsWithIt<int*, int*, int**>); // not indirectly comparable
41 static_assert(!HasStartsWithIt<int*, SentinelForNotWeaklyEqualityComparableWith>);
42 static_assert(HasStartsWithIt<int*, int*, ForwardIteratorNotDerivedFrom>);
43 static_assert(HasStartsWithIt<int*, int*, ForwardIteratorNotIncrementable>);
44 static_assert(!HasStartsWithIt<int*, int*, int*, SentinelForNotSemiregular>);
45 static_assert(!HasStartsWithIt<int*, int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
46
47 template <class Range1, class Range2 = UncheckedRange<int*>>
48 concept HasStartsWithR = requires(Range1 range1, Range2 range2) { std::ranges::starts_with(range1, range2); };
49
50 static_assert(HasStartsWithR<UncheckedRange<int*>>);
51 static_assert(HasStartsWithR<ForwardRangeNotDerivedFrom>);
52 static_assert(!HasStartsWithR<ForwardIteratorNotIncrementable>);
53 static_assert(!HasStartsWithR<ForwardRangeNotSentinelSemiregular>);
54 static_assert(!HasStartsWithR<ForwardRangeNotSentinelEqualityComparableWith>);
55 static_assert(!HasStartsWithR<UncheckedRange<int*>, UncheckedRange<int**>>); // not indirectly comparable
56 static_assert(HasStartsWithR<UncheckedRange<int*>, ForwardRangeNotDerivedFrom>);
57 static_assert(HasStartsWithR<UncheckedRange<int*>, ForwardRangeNotIncrementable>);
58 static_assert(!HasStartsWithR<UncheckedRange<int*>, ForwardRangeNotSentinelSemiregular>);
59 static_assert(!HasStartsWithR<UncheckedRange<int*>, ForwardRangeNotSentinelEqualityComparableWith>);
60
61 // clang-format off
62 template <class Iter1, class Sent1 = Iter1, class Iter2, class Sent2 = Iter2>
test_iterators()63 constexpr void test_iterators() {
64 { // simple tests
65 {
66 int a[] = {1, 2, 3, 4, 5, 6};
67 int p[] = {1, 2};
68 std::same_as<bool> decltype(auto) ret =
69 std::ranges::starts_with(Iter1(a), Sent1(Iter1(a + 6)), Iter2(p), Sent2(Iter2(p + 2)));
70 assert(ret);
71 }
72 {
73 int a[] = {1, 2, 3, 4, 5, 6};
74 int p[] = {1, 2};
75 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
76 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 2)));
77 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
78 assert(ret);
79 }
80 }
81
82 { // prefix doesn't match
83 {
84 int a[] = {1, 2, 3, 4, 5, 6};
85 int p[] = {4, 5, 6};
86 std::same_as<bool> decltype(auto) ret =
87 std::ranges::starts_with(Iter1(a), Sent1(Iter1(a + 6)), Iter2(p), Sent2(Iter2(p + 3)));
88 assert(!ret);
89 }
90 {
91 int a[] = {1, 2, 3, 4, 5, 6};
92 int p[] = {4, 5, 6};
93 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
94 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
95 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
96 assert(!ret);
97 }
98 }
99
100 { // range and prefix are identical
101 {
102 int a[] = {1, 2, 3, 4, 5, 6};
103 int p[] = {1, 2, 3, 4, 5, 6};
104 std::same_as<bool> decltype(auto) ret =
105 std::ranges::starts_with(Iter1(a), Sent1(Iter1(a + 6)), Iter2(p), Sent2(Iter2(p + 6)));
106 assert(ret);
107 }
108 {
109 int a[] = {1, 2, 3, 4, 5, 6};
110 int p[] = {1, 2, 3, 4, 5, 6};
111 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
112 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 6)));
113 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
114 assert(ret);
115 }
116 }
117
118 { // prefix is longer than range
119 {
120 int a[] = {1, 2, 3, 4, 5, 6};
121 int p[] = {1, 2, 3, 4, 5, 6, 7, 8};
122 std::same_as<bool> decltype(auto) ret =
123 std::ranges::starts_with(Iter1(a), Sent1(Iter1(a + 6)), Iter2(p), Sent2(Iter2(p + 8)));
124 assert(!ret);
125 }
126 {
127 int a[] = {1, 2, 3, 4, 5, 6};
128 int p[] = {1, 2, 3, 4, 5, 6, 7, 8};
129 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
130 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 8)));
131 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
132 assert(!ret);
133 }
134 }
135
136 { // prefix has zero length
137 {
138 int a[] = {1, 2, 3, 4, 5, 6};
139 std::array<int, 0> p = {};
140 std::same_as<bool> decltype(auto) ret =
141 std::ranges::starts_with(Iter1(a), Sent1(Iter1(a + 6)), Iter2(p.data()), Sent2(Iter2(p.data())));
142 assert(ret);
143 }
144 {
145 int a[] = {1, 2, 3, 4, 5, 6};
146 std::array<int, 0> p = {};
147 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
148 auto prefix = std::ranges::subrange(Iter2(p.data()), Sent2(Iter2(p.data())));
149 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
150 assert(ret);
151 }
152 }
153
154 { // range has zero length
155 {
156 std::array<int, 0> a = {};
157 int p[] = {1, 2, 3, 4, 5, 6, 7, 8};
158 std::same_as<bool> decltype(auto) ret =
159 std::ranges::starts_with(Iter1(a.data()), Sent1(Iter1(a.data())), Iter2(p), Sent2(Iter2(p + 8)));
160 assert(!ret);
161 }
162 {
163 std::array<int, 0> a = {};
164 int p[] = {1, 2, 3, 4, 5, 6, 7, 8};
165 auto whole = std::ranges::subrange(Iter1(a.data()), Sent1(Iter1(a.data())));
166 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 8)));
167 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix);
168 assert(!ret);
169 }
170 }
171
172 { // check that the predicate is used
173 {
174 int a[] = {11, 8, 3, 4, 0, 6};
175 int p[] = {1, 12};
176 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(
177 Iter1(a), Sent1(Iter1(a + 6)), Iter2(p), Sent2(Iter2(p + 2)), [](int l, int r) { return l > r; });
178 assert(!ret);
179 }
180 {
181 int a[] = {11, 8, 3, 4, 0, 6};
182 int p[] = {1, 12};
183 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
184 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 2)));
185 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(whole, prefix, [](int l, int r) { return l > r; });
186 assert(!ret);
187 }
188 }
189
190 { // check that the projections are used
191 {
192 int a[] = {1, 3, 5, 1, 5, 6};
193 int p[] = {2, 3, 4};
194 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(
195 Iter1(a),
196 Sent1(Iter1(a + 6)),
197 Iter2(p),
198 Sent2(Iter2(p + 3)),
199 {},
200 [](int i) { return i + 3; },
201 [](int i) { return i * 2; });
202 assert(ret);
203 }
204 {
205 int a[] = {1, 3, 5, 1, 5, 6};
206 int p[] = {2, 3, 4};
207 auto whole = std::ranges::subrange(Iter1(a), Sent1(Iter1(a + 6)));
208 auto prefix = std::ranges::subrange(Iter2(p), Sent2(Iter2(p + 3)));
209 std::same_as<bool> decltype(auto) ret = std::ranges::starts_with(
210 whole, prefix, {}, [](int i) { return i + 3; }, [](int i) { return i * 2; });
211 assert(ret);
212 }
213 }
214 }
215
test()216 constexpr bool test() {
217 types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter2>() {
218 types::for_each(types::cpp20_input_iterator_list<int*>{}, []<class Iter1>() {
219 if constexpr (std::forward_iterator<Iter1> && std::forward_iterator<Iter2>)
220 test_iterators<Iter1, Iter1, Iter2, Iter2>();
221 if constexpr (std::forward_iterator<Iter2>)
222 test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, Iter2>();
223 if constexpr (std::forward_iterator<Iter1>)
224 test_iterators<Iter1, Iter1, Iter2, sized_sentinel<Iter2>>();
225 test_iterators<Iter1, sized_sentinel<Iter1>, Iter2, sized_sentinel<Iter2>>();
226 });
227 });
228
229 { // check that std::invoke is used
230 struct S {
231 int i;
232
233 constexpr S identity() { return *this; }
234
235 constexpr bool compare(const S& s) { return i == s.i; }
236 };
237 {
238 S a[] = {{1}, {2}, {3}, {4}};
239 S p[] = {{1}, {2}};
240 auto ret = std::ranges::starts_with(a, a + 4, p, p + 2, &S::compare, &S::identity, &S::identity);
241 assert(ret);
242 }
243 {
244 S a[] = {{1}, {2}, {3}, {4}};
245 S p[] = {{1}, {2}};
246 auto ret = std::ranges::starts_with(a, p, &S::compare, &S::identity, &S::identity);
247 assert(ret);
248 }
249 }
250
251 return true;
252 }
253
main(int,char **)254 int main(int, char**) {
255 test();
256 static_assert(test());
257
258 return 0;
259 }
260