Merge pull request #41 from robin-eckert/adaptor_ref_unwrapped

add a new range adaptor boost::adaptors::ref_unwrapped
2016-01-04 16:38:36 +00:00
parent 5196baa1b0 3225aaf82b
commit 5a37aa4e98
6 changed files with 285 additions and 0 deletions
@@ -0,0 +1,102 @@
+// Boost.Range library
+//
+//  Copyright Robin Eckert 2015.
+//  Copyright Thorsten Ottosen, Neil Groves 2006 - 2008. 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)
+//
+// For more information, see http://www.boost.org/libs/range/
+//
+
+#ifndef BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
+#define BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
+
+#include <boost/range/adaptor/transformed.hpp>
+#include <boost/range/reference.hpp>
+#include <boost/range/concepts.hpp>
+
+#include <utility>
+
+#if !defined(BOOST_NO_CXX11_DECLTYPE)
+
+namespace boost
+{
+    namespace range_detail
+    {
+        struct ref_unwrapped_forwarder {};
+
+        template<class SinglePassRange>
+        struct unwrap_ref
+        {
+            typedef BOOST_DEDUCED_TYPENAME
+                          range_reference<SinglePassRange>::type argument_type;
+
+            using result_type = decltype(std::declval<argument_type>().get() );
+
+            result_type operator()( argument_type &&r ) const
+            {
+                return r.get();
+            }
+        };
+
+
+        template<class SinglePassRange>
+        class unwrap_ref_range
+            : public transformed_range<unwrap_ref<SinglePassRange>,
+                                       SinglePassRange>
+        {
+            using base = transformed_range<unwrap_ref<SinglePassRange>,
+                                           SinglePassRange>;
+        public:
+            using transform_fn_type = unwrap_ref<SinglePassRange>;
+            using source_range_type = SinglePassRange;
+
+            unwrap_ref_range(transform_fn_type fn, source_range_type &rng)
+                : base(fn, rng)
+            {
+            }
+
+            unwrap_ref_range(const base &other) : base(other) {}
+        };
+
+        template<class SinglePassRange>
+        inline unwrap_ref_range<SinglePassRange>
+        operator|(SinglePassRange& r, ref_unwrapped_forwarder)
+        {
+            BOOST_RANGE_CONCEPT_ASSERT((
+                SinglePassRangeConcept<SinglePassRange>));
+
+            return operator|( r,
+                boost::adaptors::transformed(unwrap_ref<SinglePassRange>()));
+        }
+
+    }
+
+    using range_detail::unwrap_ref_range;
+
+    namespace adaptors
+    {
+        namespace
+        {
+            const range_detail::ref_unwrapped_forwarder ref_unwrapped =
+                                       range_detail::ref_unwrapped_forwarder();
+        }
+
+        template<class SinglePassRange>
+        inline unwrap_ref_range<SinglePassRange>
+        ref_unwrap(SinglePassRange& rng)
+        {
+            BOOST_RANGE_CONCEPT_ASSERT((
+                SinglePassRangeConcept<SinglePassRange>));
+
+            return unwrap_ref_range<SinglePassRange>(
+                range_detail::unwrap_ref<SinglePassRange>(), rng );
+        }
+    } // 'adaptors'
+
+}
+
+#endif
+
+#endif