libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/ranges.copy_n.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, weakly_incrementable O>
  14 //   requires indirectly_copyable<I, O>
  15 //   constexpr ranges::copy_n_result<I, O>
  16 //     ranges::copy_n(I first, iter_difference_t<I> n, O result);
  17
  18 #include <algorithm>
  19 #include <array>
  20 #include <cassert>
  21 #include <ranges>
  22
  23 #include "almost_satisfies_types.h"
  24 #include "test_iterators.h"
  25
  26 template <class In, class Out = In, class Count = std::size_t>
  27 concept HasCopyNIt = requires(In in, Count count, Out out) { std::ranges::copy_n(in, count, out); };
  28
  29 static_assert(HasCopyNIt<int*>);
  30 static_assert(!HasCopyNIt<InputIteratorNotDerivedFrom>);
  31 static_assert(!HasCopyNIt<InputIteratorNotIndirectlyReadable>);
  32 static_assert(!HasCopyNIt<InputIteratorNotInputOrOutputIterator>);
  33 static_assert(!HasCopyNIt<int*, WeaklyIncrementableNotMovable>);
  34 struct NotIndirectlyCopyable {};
  35 static_assert(!HasCopyNIt<int*, NotIndirectlyCopyable*>);
  36 static_assert(!HasCopyNIt<int*, int*, SentinelForNotSemiregular>);
  37 static_assert(!HasCopyNIt<int*, int*, SentinelForNotWeaklyEqualityComparableWith>);
  38
  39 static_assert(std::is_same_v<std::ranges::copy_result<int, long>, std::ranges::in_out_result<int, long>>);
  40
  41 template <class In, class Out, class Sent = In>
  42 constexpr void test_iterators() {
  43   { // simple test
  44     std::array in {1, 2, 3, 4};
  45     std::array<int, 4> out;
  46     std::same_as<std::ranges::in_out_result<In, Out>> auto ret =
  47       std::ranges::copy_n(In(in.data()), in.size(), Out(out.data()));
  48     assert(in == out);
  49     assert(base(ret.in) == in.data() + in.size());
  50     assert(base(ret.out) == out.data() + out.size());
  51   }
  52
  53   { // check that an empty range works
  54     std::array<int, 0> in;
  55     std::array<int, 0> out;
  56     auto ret = std::ranges::copy_n(In(in.data()), in.size(), Out(out.begin()));
  57     assert(base(ret.in) == in.data());
  58     assert(base(ret.out) == out.data());
  59   }
  60 }
  61
  62 template <class Out>
  63 constexpr void test_in_iterators() {
  64   test_iterators<cpp20_input_iterator<int*>, Out, sentinel_wrapper<cpp20_input_iterator<int*>>>();
  65   test_iterators<forward_iterator<int*>, Out>();
  66   test_iterators<bidirectional_iterator<int*>, Out>();
  67   test_iterators<random_access_iterator<int*>, Out>();
  68   test_iterators<contiguous_iterator<int*>, Out>();
  69 }
  70
  71 template <class Out>
  72 constexpr void test_proxy_in_iterators() {
  73   test_iterators<ProxyIterator<cpp20_input_iterator<int*>>, Out, sentinel_wrapper<ProxyIterator<cpp20_input_iterator<int*>>>>();
  74   test_iterators<ProxyIterator<forward_iterator<int*>>, Out>();
  75   test_iterators<ProxyIterator<bidirectional_iterator<int*>>, Out>();
  76   test_iterators<ProxyIterator<random_access_iterator<int*>>, Out>();
  77   test_iterators<ProxyIterator<contiguous_iterator<int*>>, Out>();
  78 }
  79
  80 constexpr bool test() {
  81   test_in_iterators<cpp20_input_iterator<int*>>();
  82   test_in_iterators<forward_iterator<int*>>();
  83   test_in_iterators<bidirectional_iterator<int*>>();
  84   test_in_iterators<random_access_iterator<int*>>();
  85   test_in_iterators<contiguous_iterator<int*>>();
  86
  87   test_proxy_in_iterators<ProxyIterator<cpp20_input_iterator<int*>>>();
  88   test_proxy_in_iterators<ProxyIterator<forward_iterator<int*>>>();
  89   test_proxy_in_iterators<ProxyIterator<bidirectional_iterator<int*>>>();
  90   test_proxy_in_iterators<ProxyIterator<random_access_iterator<int*>>>();
  91   test_proxy_in_iterators<ProxyIterator<contiguous_iterator<int*>>>();
  92
  93   { // check that every element is copied exactly once
  94     struct CopyOnce {
  95       bool copied = false;
  96       constexpr CopyOnce() = default;
  97       constexpr CopyOnce(const CopyOnce& other) = delete;
  98       constexpr CopyOnce& operator=(const CopyOnce& other) {
  99         assert(!other.copied);
 100         copied = true;
 101         return *this;
 102       }
 103     };
 104     std::array<CopyOnce, 4> in {};
 105     std::array<CopyOnce, 4> out {};
 106     auto ret = std::ranges::copy_n(in.data(), in.size(), out.begin());
 107     assert(ret.in == in.end());
 108     assert(ret.out == out.end());
 109     assert(std::all_of(out.begin(), out.end(), [](const auto& e) { return e.copied; }));
 110   }
 111
 112   return true;
 113 }
 114
 115 int main(int, char**) {
 116   test();
 117   static_assert(test());
 118
 119   return 0;
 120 }