test/std/iterators/iterator.primitives/iterator.operations/distance.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// <iterator>

// template <InputIterator Iter>
//   Iter::difference_type
//   distance(Iter first, Iter last);
//
// template <RandomAccessIterator Iter>
//   Iter::difference_type
//   distance(Iter first, Iter last);

#include <iterator>
#include <cassert>

#include "test_macros.h"
#include "test_iterators.h"

template <class It>
void
test(It first, It last, typename std::iterator_traits<It>::difference_type x)
{
    assert(std::distance(first, last) == x);
}

#if TEST_STD_VER > 14
template <class It>
constexpr bool
constexpr_test(It first, It last, typename std::iterator_traits<It>::difference_type x)
{
    return std::distance(first, last) == x;
}
#endif

int main(int, char**)
{
    {
    const char* s = "1234567890";
    test(input_iterator<const char*>(s), input_iterator<const char*>(s+10), 10);
    test(forward_iterator<const char*>(s), forward_iterator<const char*>(s+10), 10);
    test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+10), 10);
    test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+10), 10);
    test(s, s+10, 10);
    }
#if TEST_STD_VER > 14
    {
    constexpr const char* s = "1234567890";
    static_assert( constexpr_test(input_iterator<const char*>(s), input_iterator<const char*>(s+10), 10), "");
    static_assert( constexpr_test(forward_iterator<const char*>(s), forward_iterator<const char*>(s+10), 10), "");
    static_assert( constexpr_test(bidirectional_iterator<const char*>(s), bidirectional_iterator<const char*>(s+10), 10), "");
    static_assert( constexpr_test(random_access_iterator<const char*>(s), random_access_iterator<const char*>(s+10), 10), "");
    static_assert( constexpr_test(s, s+10, 10), "");
    }
#endif

  return 0;
}