range/adaptor/ref_unwrapped.hpp

0001 // Boost.Range library
0002 //
0003 //  Copyright Robin Eckert 2015.
0004 //  Copyright Thorsten Ottosen, Neil Groves 2006 - 2008. Use, modification and
0005 //  distribution is subject to the Boost Software License, Version
0006 //  1.0. (See accompanying file LICENSE_1_0.txt or copy at
0007 //  http://www.boost.org/LICENSE_1_0.txt)
0008 //
0009 // For more information, see http://www.boost.org/libs/range/
0010 //
0011
0012 #ifndef BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
0013 #define BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
0014
0015 #include <boost/range/adaptor/transformed.hpp>
0016 #include <boost/range/reference.hpp>
0017 #include <boost/range/concepts.hpp>
0018 #include <boost/type_traits/declval.hpp>
0019 #include <utility>
0020
0021 #if !defined(BOOST_NO_CXX11_DECLTYPE)
0022
0023 namespace boost
0024 {
0025     namespace range_detail
0026     {
0027         struct ref_unwrapped_forwarder {};
0028
0029         template<class SinglePassRange>
0030         struct unwrap_ref
0031         {
0032             typedef BOOST_DEDUCED_TYPENAME
0033                           range_reference<SinglePassRange>::type argument_type;
0034
0035             typedef decltype( boost::declval<argument_type>().get() ) result_type;
0036
0037             result_type operator()( argument_type &&r ) const
0038             {
0039                 return r.get();
0040             }
0041         };
0042
0043
0044         template<class SinglePassRange>
0045         class unwrap_ref_range
0046             : public transformed_range<unwrap_ref<SinglePassRange>,
0047                                        SinglePassRange>
0048         {
0049             typedef transformed_range<unwrap_ref<SinglePassRange>,
0050                                            SinglePassRange> base;
0051         public:
0052             typedef unwrap_ref<SinglePassRange> transform_fn_type;
0053             typedef SinglePassRange source_range_type;
0054
0055             unwrap_ref_range(transform_fn_type fn, source_range_type &rng)
0056                 : base(fn, rng)
0057             {
0058             }
0059
0060             unwrap_ref_range(const base &other) : base(other) {}
0061         };
0062
0063         template<class SinglePassRange>
0064         inline unwrap_ref_range<SinglePassRange>
0065         operator|(SinglePassRange& r, ref_unwrapped_forwarder)
0066         {
0067             BOOST_RANGE_CONCEPT_ASSERT((
0068                 SinglePassRangeConcept<SinglePassRange>));
0069
0070             return operator|( r,
0071                 boost::adaptors::transformed(unwrap_ref<SinglePassRange>()));
0072         }
0073
0074     }
0075
0076     using range_detail::unwrap_ref_range;
0077
0078     namespace adaptors
0079     {
0080         namespace
0081         {
0082             const range_detail::ref_unwrapped_forwarder ref_unwrapped =
0083                                        range_detail::ref_unwrapped_forwarder();
0084         }
0085
0086         template<class SinglePassRange>
0087         inline unwrap_ref_range<SinglePassRange>
0088         ref_unwrap(SinglePassRange& rng)
0089         {
0090             BOOST_RANGE_CONCEPT_ASSERT((
0091                 SinglePassRangeConcept<SinglePassRange>));
0092
0093             return unwrap_ref_range<SinglePassRange>(
0094                 range_detail::unwrap_ref<SinglePassRange>(), rng );
0095         }
0096     } // 'adaptors'
0097
0098 }
0099
0100 #endif
0101
0102 #endif