libcxx/test/std/iterators/iterator.primitives/iterator.operations/distance.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 // <iterator>
  10
  11 // template <InputIterator Iter>
  12 //   Iter::difference_type
  13 //   distance(Iter first, Iter last); // constexpr in C++17
  14 //
  15 // template <RandomAccessIterator Iter>
  16 //   Iter::difference_type
  17 //   distance(Iter first, Iter last); // constexpr in C++17
  18
  19 #include <iterator>
  20 #include <cassert>
  21 #include <type_traits>
  22
  23 #include "test_macros.h"
  24 #include "test_iterators.h"
  25
  26 template <class It>
  27 TEST_CONSTEXPR_CXX17
  28 void check_distance(It first, It last, typename std::iterator_traits<It>::difference_type dist)
  29 {
  30     typedef typename std::iterator_traits<It>::difference_type Difference;
  31     static_assert(std::is_same<decltype(std::distance(first, last)), Difference>::value, "");
  32     assert(std::distance(first, last) == dist);
  33 }
  34
  35 TEST_CONSTEXPR_CXX17 bool tests()
  36 {
  37     const char* s = "1234567890";
  38     check_distance(cpp17_input_iterator<const char*>(s), cpp17_input_iterator<const char*>(s+10), 10);
  39     check_distance(forward_iterator<const char*>(s), forward_iterator<const char*>(s+10), 10);
  40     check_distance(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+10), 10);
  41     check_distance(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+10), 10);
  42     check_distance(s, s+10, 10);
  43     return true;
  44 }
  45
  46 int main(int, char**)
  47 {
  48     tests();
  49 #if TEST_STD_VER >= 17
  50     static_assert(tests(), "");
  51 #endif
  52     return 0;
  53 }