Merge Boost.Algorithm to release branch

[SVN r78025]

include/boost/algorithm/cxx11/copy_n.hpp

@@ -0,0 +1,44 @@
+/* 
+   Copyright (c) Marshall Clow 2011-2012.
+
+   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  copy_n.hpp
+/// \brief Copy n items from one sequence to another
+/// \author Marshall Clow
+
+#ifndef BOOST_ALGORITHM_COPY_N_HPP
+#define BOOST_ALGORITHM_COPY_N_HPP
+
+#include <algorithm>    // for std::copy_n, if available
+
+namespace boost { namespace algorithm {
+
+#if __cplusplus >= 201103L
+//  Use the C++11 versions of copy_n if it is available
+using std::copy_n;          // Section 25.3.1
+#else
+/// \fn copy_n ( InputIterator first, Size n, OutputIterator result )
+/// \brief Copies exactly n (n > 0) elements from the range starting at first to
+///     the range starting at result.
+/// \return         The updated output iterator
+/// 
+/// \param first    The start of the input sequence
+/// \param n        The number of elements to copy
+/// \param result   An output iterator to write the results into
+/// \note           This function is part of the C++2011 standard library.
+///  We will use the standard one if it is available, 
+///     otherwise we have our own implementation.
+template <typename InputIterator, typename Size, typename OutputIterator>
+OutputIterator copy_n ( InputIterator first, Size n, OutputIterator result )
+{
+    for ( ; n > 0; --n, ++first, ++result )
+        *result = *first;
+    return result;
+}
+#endif
+}} // namespace boost and algorithm
+
+#endif  // BOOST_ALGORITHM_COPY_IF_HPP