整理

include/boost/pointee.hpp

@@ -0,0 +1,62 @@
+#ifndef BOOST_POINTEE_DWA200415_HPP
+#define BOOST_POINTEE_DWA200415_HPP
+
+//
+// Copyright David Abrahams 2004. Use, modification and distribution is
+// subject to 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)
+//
+// typename pointee<P>::type provides the pointee type of P.
+//
+// For example, it is T for T* and X for shared_ptr<X>.
+//
+// http://www.boost.org/libs/iterator/doc/pointee.html
+//
+
+#include <iterator>
+#include <type_traits>
+
+#include <boost/detail/is_incrementable.hpp>
+
+namespace boost {
+namespace detail {
+
+template< typename P >
+struct smart_ptr_pointee
+{
+    using type = typename P::element_type;
+};
+
+template<
+    typename Iterator,
+    typename = typename std::remove_reference< decltype(*std::declval< Iterator& >()) >::type
+>
+struct iterator_pointee
+{
+    using type = typename std::iterator_traits< Iterator >::value_type;
+};
+
+template< typename Iterator, typename Reference >
+struct iterator_pointee< Iterator, const Reference >
+{
+    using type = typename std::add_const< typename std::iterator_traits< Iterator >::value_type >::type;
+};
+
+} // namespace detail
+
+template< typename P >
+struct pointee :
+    public std::conditional<
+        detail::is_incrementable< P >::value,
+        detail::iterator_pointee< P >,
+        detail::smart_ptr_pointee< P >
+    >::type
+{
+};
+
+template< typename P >
+using pointee_t = typename pointee< P >::type;
+
+} // namespace boost
+
+#endif // BOOST_POINTEE_DWA200415_HPP