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