forked from boostorg/range
3225aaf82b
The new adaptor is like boost::adaptors::indirected, but for std::reference_wrapper values (instead of pointer). It calls .get() on every value and returns the result. It is useful for range-based iteration of ranges of std::reference_wrapper (or related) types.
103 lines
2.8 KiB
C++
103 lines
2.8 KiB
C++
// Boost.Range library
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//
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// Copyright Robin Eckert 2015.
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// Copyright Thorsten Ottosen, Neil Groves 2006 - 2008. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// For more information, see http://www.boost.org/libs/range/
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//
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#ifndef BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
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#define BOOST_RANGE_ADAPTOR_REF_UNWRAPPED_HPP
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#include <boost/range/adaptor/transformed.hpp>
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#include <boost/range/reference.hpp>
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#include <boost/range/concepts.hpp>
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#include <utility>
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#if !defined(BOOST_NO_CXX11_DECLTYPE)
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namespace boost
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{
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namespace range_detail
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{
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struct ref_unwrapped_forwarder {};
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template<class SinglePassRange>
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struct unwrap_ref
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{
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typedef BOOST_DEDUCED_TYPENAME
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range_reference<SinglePassRange>::type argument_type;
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using result_type = decltype(std::declval<argument_type>().get() );
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result_type operator()( argument_type &&r ) const
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{
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return r.get();
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}
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};
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template<class SinglePassRange>
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class unwrap_ref_range
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: public transformed_range<unwrap_ref<SinglePassRange>,
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SinglePassRange>
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{
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using base = transformed_range<unwrap_ref<SinglePassRange>,
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SinglePassRange>;
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public:
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using transform_fn_type = unwrap_ref<SinglePassRange>;
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using source_range_type = SinglePassRange;
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unwrap_ref_range(transform_fn_type fn, source_range_type &rng)
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: base(fn, rng)
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{
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}
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unwrap_ref_range(const base &other) : base(other) {}
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};
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template<class SinglePassRange>
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inline unwrap_ref_range<SinglePassRange>
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operator|(SinglePassRange& r, ref_unwrapped_forwarder)
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{
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BOOST_RANGE_CONCEPT_ASSERT((
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SinglePassRangeConcept<SinglePassRange>));
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return operator|( r,
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boost::adaptors::transformed(unwrap_ref<SinglePassRange>()));
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}
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}
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using range_detail::unwrap_ref_range;
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namespace adaptors
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{
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namespace
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{
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const range_detail::ref_unwrapped_forwarder ref_unwrapped =
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range_detail::ref_unwrapped_forwarder();
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}
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template<class SinglePassRange>
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inline unwrap_ref_range<SinglePassRange>
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ref_unwrap(SinglePassRange& rng)
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{
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BOOST_RANGE_CONCEPT_ASSERT((
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SinglePassRangeConcept<SinglePassRange>));
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return unwrap_ref_range<SinglePassRange>(
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range_detail::unwrap_ref<SinglePassRange>(), rng );
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}
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} // 'adaptors'
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}
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#endif
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#endif
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