libcxx/test/std/iterators/predef.iterators/reverse.iterators/reverse.iter.ops/reverse.iter.op-=/difference_type.pass.cpp

//===----------------------------------------------------------------------===//
//
//                     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

// requires RandomAccessIterator<Iter>
//   reverse_iterator& operator-=(difference_type n);

#include <iterator>
#include <cassert>

#include "test_iterators.h"

template <class It>
void
test(It i, typename std::iterator_traits<It>::difference_type n, It x)
{
    std::reverse_iterator<It> r(i);
    std::reverse_iterator<It>& rr = r -= n;
    assert(r.base() == x);
    assert(&rr == &r);
}

int main()
{
    const char* s = "1234567890";
    test(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
    test(s+5, 5, s+10);
}