整理

include/boost/algorithm/cxx17/transform_reduce.hpp

@@ -0,0 +1,56 @@
+/*
+   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_reduce.hpp
+/// \brief Combine the (transformed) elements of a sequence (or two) into a single value.
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_TRANSFORM_REDUCE_HPP
+#define BOOST_ALGORITHM_TRANSFORM_REDUCE_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 {
+
+template<class InputIterator1, class InputIterator2, class T,
+         class BinaryOperation1, class BinaryOperation2>
+T transform_reduce(InputIterator1 first1, InputIterator1 last1,
+                   InputIterator2 first2, T init,
+                 BinaryOperation1 bOp1, BinaryOperation2 bOp2)
+{
+    for (; first1 != last1; ++first1, (void) ++first2)
+        init = bOp1(init, bOp2(*first1, *first2));
+    return init;
+}
+
+template<class InputIterator, class T,
+         class BinaryOperation, class UnaryOperation>
+T transform_reduce(InputIterator first, InputIterator last,
+                   T init, BinaryOperation bOp, UnaryOperation uOp)
+{
+    for (; first != last; ++first)
+        init = bOp(init, uOp(*first));
+    return init;
+}
+
+template<class InputIterator1, class InputIterator2, class T>
+T transform_reduce(InputIterator1 first1, InputIterator1 last1,
+                   InputIterator2 first2, T init)
+{
+    return boost::algorithm::transform_reduce(first1, last1, first2, init,
+                            std::plus<T>(), std::multiplies<T>());
+}
+
+}} // namespace boost and algorithm
+
+#endif // BOOST_ALGORITHM_TRANSFORM_REDUCE_HPP