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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>
// template <BidirectionalIterator Iter>
// Iter prev(Iter x, Iter::difference_type n = 1);
#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)
{
assert(std::prev(i, n) == x);
It (*prev)(It, typename std::iterator_traits<It>::difference_type) = std::prev;
assert(prev(i, n) == x);
}
template <class It>
void
test(It i, It x)
{
assert(std::prev(i) == x);
}
#if TEST_STD_VER > 14
template <class It>
constexpr bool
constexpr_test(It i, typename std::iterator_traits<It>::difference_type n, It x)
{
return std::prev(i, n) == x;
}
template <class It>
constexpr bool
constexpr_test(It i, It x)
{
return std::prev(i) == x;
}
#endif
int main()
{
{
const char* s = "1234567890";
test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s));
test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s));
test(s+10, 10, s);
test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s));
test(s+1, s);
}
#if TEST_STD_VER > 14
{
constexpr const char* s = "1234567890";
static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s)), "" );
static_assert( constexpr_test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s)), "" );
static_assert( constexpr_test(s+10, 10, s), "" );
static_assert( constexpr_test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s)), "" );
static_assert( constexpr_test(random_access_iterator<const char*>(s+1), random_access_iterator<const char*>(s)), "" );
static_assert( constexpr_test(s+1, s), "" );
}
#endif
}
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