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/*========================== begin_copyright_notice ============================
Copyright (C) 2019-2021 Intel Corporation
SPDX-License-Identifier: MIT
============================= end_copyright_notice ===========================*/
#ifndef VC_UTILS_GENERAL_STL_EXTRAS_H
#define VC_UTILS_GENERAL_STL_EXTRAS_H
#include <iterator>
namespace vc {
namespace ranges {
template <typename Range>
using iterator_t = decltype(std::begin(std::declval<Range &>()));
template <typename Range>
using range_pointer_t =
typename std::iterator_traits<iterator_t<Range>>::pointer;
template <typename Range>
using range_reference_t =
typename std::iterator_traits<iterator_t<Range>>::reference;
} // namespace ranges
/* Returns the first iterator (let's name it RetIt) such that
* std::accumulate(First, RetIt, 0) > Bound (not full truth, read below).
*
* Arguments:
* \p First, \p Last - considered range
* \p Bound - considered Bound
* \p Op - functor that returns T, takes T and decltype(*First)
* respectively as arguments. It is meant to increment current partial sum.
* First argument is previous partial sum, second argument is upcoming value
* from the range, new partial sum is returned.
*
* Arguments of \p PlusEqualOp may not be equal, so the range may possibly point
* not to T type. In this case partial sum is calculated for transformed range
* (transformation is hidden in \p Op).
*/
template <typename ForwardIt, typename PlusEqualOp, typename T>
ForwardIt upper_partial_sum_bound(ForwardIt First, ForwardIt Last, T Bound,
PlusEqualOp Op) {
T CurSum = 0;
for (; First != Last; ++First) {
CurSum = Op(CurSum, *First);
if (CurSum > Bound)
return First;
}
return Last;
}
} // namespace vc
#endif // VC_UTILS_GENERAL_STL_EXTRAS_H
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