libcxx/include/__numeric/partial_sum.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_PARTIAL_SUM_H
  11 #define _LIBCPP___NUMERIC_PARTIAL_SUM_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_PUSH_MACROS
  22 #include <__undef_macros>
  23
  24 _LIBCPP_BEGIN_NAMESPACE_STD
  25
  26 template <class _InputIterator, class _OutputIterator>
  27 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  28 _OutputIterator
  29 partial_sum(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
  30 {
  31     if (__first != __last)
  32     {
  33         typename iterator_traits<_InputIterator>::value_type __t(*__first);
  34         *__result = __t;
  35         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  36         {
  37 #if _LIBCPP_STD_VER >= 20
  38             __t = _VSTD::move(__t) + *__first;
  39 #else
  40             __t = __t + *__first;
  41 #endif
  42             *__result = __t;
  43         }
  44     }
  45     return __result;
  46 }
  47
  48 template <class _InputIterator, class _OutputIterator, class _BinaryOperation>
  49 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  50 _OutputIterator
  51 partial_sum(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
  52               _BinaryOperation __binary_op)
  53 {
  54     if (__first != __last)
  55     {
  56         typename iterator_traits<_InputIterator>::value_type __t(*__first);
  57         *__result = __t;
  58         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  59         {
  60 #if _LIBCPP_STD_VER >= 20
  61             __t = __binary_op(_VSTD::move(__t), *__first);
  62 #else
  63             __t = __binary_op(__t, *__first);
  64 #endif
  65             *__result = __t;
  66         }
  67     }
  68     return __result;
  69 }
  70
  71 _LIBCPP_END_NAMESPACE_STD
  72
  73 _LIBCPP_POP_MACROS
  74
  75 #endif // _LIBCPP___NUMERIC_PARTIAL_SUM_H