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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// <iterator>
// reverse_iterator
// template <RandomAccessIterator Iter1, RandomAccessIterator Iter2>
// requires HasMinus<Iter2, Iter1>
// constexpr auto operator-(const reverse_iterator<Iter1>& x, const reverse_iterator<Iter2>& y)
// -> decltype(y.base() - x.base());
//
// constexpr in C++17
#include <iterator>
#include <cstddef>
#include <cassert>
#include "test_macros.h"
#include "test_iterators.h"
template <class It1, class It2>
void
test(It1 l, It2 r, std::ptrdiff_t x)
{
const std::reverse_iterator<It1> r1(l);
const std::reverse_iterator<It2> r2(r);
assert((r1 - r2) == x);
}
int main()
{
char s[3] = {0};
test(random_access_iterator<const char*>(s), random_access_iterator<char*>(s), 0);
test(random_access_iterator<char*>(s), random_access_iterator<const char*>(s+1), 1);
test(random_access_iterator<const char*>(s+1), random_access_iterator<char*>(s), -1);
test(s, s, 0);
test(s, s+1, 1);
test(s+1, s, -1);
#if TEST_STD_VER > 14
{
constexpr const char *p = "123456789";
typedef std::reverse_iterator<const char *> RI;
constexpr RI it1 = std::make_reverse_iterator(p);
constexpr RI it2 = std::make_reverse_iterator(p+1);
static_assert( it1 - it2 == 1, "");
static_assert( it2 - it1 == -1, "");
}
#endif
}
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