libcxx/include/__algorithm/unique.h

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

#ifndef _LIBCPP___ALGORITHM_UNIQUE_H
#define _LIBCPP___ALGORITHM_UNIQUE_H

#include <__config>
#include <__algorithm/comp.h>
#include <__algorithm/adjacent_find.h>
#include <__iterator/iterator_traits.h>
#include <__utility/move.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

// unique

template <class _ForwardIterator, class _BinaryPredicate>
_LIBCPP_NODISCARD_EXT _LIBCPP_CONSTEXPR_AFTER_CXX17 _ForwardIterator
unique(_ForwardIterator __first, _ForwardIterator __last, _BinaryPredicate __pred)
{
    __first = _VSTD::adjacent_find<_ForwardIterator, _BinaryPredicate&>(__first, __last, __pred);
    if (__first != __last)
    {
        // ...  a  a  ?  ...
        //      f     i
        _ForwardIterator __i = __first;
        for (++__i; ++__i != __last;)
            if (!__pred(*__first, *__i))
                *++__first = _VSTD::move(*__i);
        ++__first;
    }
    return __first;
}

template <class _ForwardIterator>
_LIBCPP_NODISCARD_EXT inline
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
_ForwardIterator
unique(_ForwardIterator __first, _ForwardIterator __last)
{
    typedef typename iterator_traits<_ForwardIterator>::value_type __v;
    return _VSTD::unique(__first, __last, __equal_to<__v>());
}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___ALGORITHM_UNIQUE_H