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_BEGIN_NAMESPACE_STD
  22
  23 template <class _InputIterator, class _OutputIterator>
  24 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  25 _OutputIterator
  26 partial_sum(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
  27 {
  28     if (__first != __last)
  29     {
  30         typename iterator_traits<_InputIterator>::value_type __t(*__first);
  31         *__result = __t;
  32         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  33         {
  34 #if _LIBCPP_STD_VER > 17
  35             __t = _VSTD::move(__t) + *__first;
  36 #else
  37             __t = __t + *__first;
  38 #endif
  39             *__result = __t;
  40         }
  41     }
  42     return __result;
  43 }
  44
  45 template <class _InputIterator, class _OutputIterator, class _BinaryOperation>
  46 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
  47 _OutputIterator
  48 partial_sum(_InputIterator __first, _InputIterator __last, _OutputIterator __result,
  49               _BinaryOperation __binary_op)
  50 {
  51     if (__first != __last)
  52     {
  53         typename iterator_traits<_InputIterator>::value_type __t(*__first);
  54         *__result = __t;
  55         for (++__first, (void) ++__result; __first != __last; ++__first, (void) ++__result)
  56         {
  57 #if _LIBCPP_STD_VER > 17
  58             __t = __binary_op(_VSTD::move(__t), *__first);
  59 #else
  60             __t = __binary_op(__t, *__first);
  61 #endif
  62             *__result = __t;
  63         }
  64     }
  65     return __result;
  66 }
  67
  68 _LIBCPP_END_NAMESPACE_STD
  69
  70 #endif // _LIBCPP___NUMERIC_PARTIAL_SUM_H