67 lines
2.1 KiB
C++
67 lines
2.1 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Eric Niebler 2014
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//
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// Use, modification and distribution is subject to the
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// Boost Software License, Version 1.0. (See accompanying
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// 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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// Project home: https://github.com/ericniebler/range-v3
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//
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#ifndef RANGES_V3_ALGORITHM_COUNT_HPP
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#define RANGES_V3_ALGORITHM_COUNT_HPP
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#include <utility>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/begin_end.hpp>
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#include <range/v3/range_concepts.hpp>
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#include <range/v3/range_traits.hpp>
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#include <range/v3/utility/functional.hpp>
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#include <range/v3/utility/iterator_concepts.hpp>
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#include <range/v3/utility/iterator_traits.hpp>
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#include <range/v3/utility/static_const.hpp>
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namespace ranges
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{
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inline namespace v3
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{
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/// \addtogroup group-algorithms
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/// @{
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struct count_fn
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{
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template<typename I, typename S, typename V, typename P = ident,
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CONCEPT_REQUIRES_(InputIterator<I>() && Sentinel<S, I>() &&
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IndirectRelation<equal_to, projected<I, P>, V const *>())>
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difference_type_t<I>
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operator()(I begin, S end, V const & val, P proj = P{}) const
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{
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difference_type_t<I> n = 0;
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for(; begin != end; ++begin)
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if(invoke(proj, *begin) == val)
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++n;
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return n;
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}
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template<typename Rng, typename V, typename P = ident,
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typename I = iterator_t<Rng>,
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CONCEPT_REQUIRES_(InputRange<Rng>() &&
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IndirectRelation<equal_to, projected<I, P>, V const *>())>
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difference_type_t<I>
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operator()(Rng &&rng, V const & val, P proj = P{}) const
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{
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return (*this)(begin(rng), end(rng), val, std::move(proj));
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}
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};
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/// \sa `count_fn`
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/// \ingroup group-algorithms
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RANGES_INLINE_VARIABLE(with_braced_init_args<with_braced_init_args<count_fn>>,
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count)
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/// @}
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} // namespace v3
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} // namespace ranges
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#endif // include guard
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