整理

include/boost/algorithm/cxx17/transform_exclusive_scan.hpp

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+/*
+   Copyright (c) Marshall Clow 2017.
+
+   Distributed under the Boost Software License, Version 1.0. (See accompanying
+   file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+*/
+
+/// \file  transform_exclusive_scan.hpp
+/// \brief ????
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_TRANSFORM_EXCLUSIVE_SCAN_HPP
+#define BOOST_ALGORITHM_TRANSFORM_EXCLUSIVE_SCAN_HPP
+
+#include <functional>     // for std::plus
+#include <iterator>       // for std::iterator_traits
+
+#include <boost/config.hpp>
+#include <boost/range/begin.hpp>
+#include <boost/range/end.hpp>
+#include <boost/range/value_type.hpp>
+
+namespace boost { namespace algorithm {
+
+/// \fn transform_exclusive_scan ( InputIterator first, InputIterator last, OutputIterator result, BinaryOperation bOp, UnaryOperation uOp, T init )
+/// \brief Transforms elements from the input range with uOp and then combines
+/// those transformed elements with bOp such that the n-1th element and the nth
+/// element are combined. Exclusivity means that the nth element is not
+/// included in the nth combination.
+/// \return The updated output iterator
+///
+/// \param first  The start of the input sequence
+/// \param last   The end of the input sequence
+/// \param result The output iterator to write the results into
+/// \param bOp    The operation for combining transformed input elements
+/// \param uOp    The operation for transforming input elements
+/// \param init   The initial value
+///
+/// \note This function is part of the C++17 standard library
+template<class InputIterator, class OutputIterator, class T,
+         class BinaryOperation, class UnaryOperation>
+OutputIterator transform_exclusive_scan(InputIterator first, InputIterator last,
+                                        OutputIterator result, T init,
+                                        BinaryOperation bOp, UnaryOperation uOp)
+{
+    if (first != last)
+    {
+        T saved = init;
+        do
+        {
+            init = bOp(init, uOp(*first));
+            *result = saved;
+            saved = init;
+            ++result;
+        } while (++first != last);
+    }
+    return result;
+}
+
+}} // namespace boost and algorithm
+
+#endif // BOOST_ALGORITHM_TRANSFORM_EXCLUSIVE_SCAN_HPP