整理

include/boost/algorithm/cxx17/for_each_n.hpp

@@ -0,0 +1,39 @@
+/*
+   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  for_each_n.hpp
+/// \brief Apply a functor to the elements of a sequence
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_FOR_EACH_N_HPP
+#define BOOST_ALGORITHM_FOR_EACH_N_HPP
+
+#include <utility>      // for std::pair
+
+#include <boost/config.hpp>
+
+namespace boost { namespace algorithm {
+
+/// \fn for_each_n(InputIterator first, Size n, Function f);
+/// \return first + n
+///
+/// \param first    The start of the first range.
+/// \param n        One past the end of the first range.
+/// \param f        A functor to apply to the elements of the sequence
+/// \note           If f returns a result, the result is ignored.
+template<class InputIterator, class Size, class Function>
+InputIterator for_each_n(InputIterator first, Size n, Function f)
+{
+    for ( ; n > 0; --n, ++first )
+        f(*first);
+
+    return first;
+}
+
+}} // namespace boost and algorithm
+
+#endif // BOOST_ALGORITHM_FOR_EACH_N_HPP