libcxx/include/__numeric/adjacent_difference.h

   1 // -*- C++ -*-
   2 //===----------------------------------------------------------------------===//
   3 //
   4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5 // See https://llvm.org/LICENSE.txt for license information.
   6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef _LIBCPP___NUMERIC_ADJACENT_DIFFERENCE_H
  11 #define _LIBCPP___NUMERIC_ADJACENT_DIFFERENCE_H
  12
  13 #include <__config>
  14 #include <__iterator/iterator_traits.h>
  15 #include <__utility/move.h>
  16
  17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  18 #  pragma GCC system_header
  19 #endif
  20
  21 _LIBCPP_BEGIN_NAMESPACE_STD
  22
  23 template <class _InputIterator, class _OutputIterator>
  24 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  25 _OutputIterator
  26 adjacent_difference(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
  27 {
  28     if (__first != __last)
  29     {
  30         typename iterator_traits<_InputIterator>::value_type __acc(*__first);
  31         *__result = __acc;
  32         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  33         {
  34             typename iterator_traits<_InputIterator>::value_type __val(*__first);
  35 #if _LIBCPP_STD_VER > 17
  36             *__result = __val - _VSTD::move(__acc);
  37 #else
  38             *__result = __val - __acc;
  39 #endif
  40             __acc = _VSTD::move(__val);
  41         }
  42     }
  43     return __result;
  44 }
  45
  46 template <class _InputIterator, class _OutputIterator, class _BinaryOperation>
  47 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  48 _OutputIterator
  49 adjacent_difference(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
  50                       _BinaryOperation __binary_op)
  51 {
  52     if (__first != __last)
  53     {
  54         typename iterator_traits<_InputIterator>::value_type __acc(*__first);
  55         *__result = __acc;
  56         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  57         {
  58             typename iterator_traits<_InputIterator>::value_type __val(*__first);
  59 #if _LIBCPP_STD_VER > 17
  60             *__result = __binary_op(__val, _VSTD::move(__acc));
  61 #else
  62             *__result = __binary_op(__val, __acc);
  63 #endif
  64             __acc = _VSTD::move(__val);
  65         }
  66     }
  67     return __result;
  68 }
  69
  70 _LIBCPP_END_NAMESPACE_STD
  71
  72 #endif // _LIBCPP___NUMERIC_ADJACENT_DIFFERENCE_H