libcxx/test/std/algorithms/alg.nonmodifying/alg.find/ranges.find_if.pass.cpp

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