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73 lines
2.1 KiB
C++
73 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-present
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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/functional/identity.hpp>
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#include <range/v3/functional/invoke.hpp>
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#include <range/v3/iterator/concepts.hpp>
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#include <range/v3/iterator/traits.hpp>
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#include <range/v3/range/access.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/static_const.hpp>
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#include <range/v3/detail/prologue.hpp>
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namespace ranges
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{
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/// \addtogroup group-algorithms
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/// @{
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RANGES_FUNC_BEGIN(count)
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/// \brief function template \c count
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template(typename I, typename S, typename V, typename P = identity)(
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requires input_iterator<I> AND sentinel_for<S, I> AND
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indirect_relation<equal_to, projected<I, P>, V const *>)
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constexpr iter_difference_t<I> //
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RANGES_FUNC(count)(I first, S last, V const & val, P proj = P{})
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{
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iter_difference_t<I> n = 0;
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for(; first != last; ++first)
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if(invoke(proj, *first) == val)
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++n;
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return n;
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}
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/// \overload
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template(typename Rng, typename V, typename P = identity)(
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requires input_range<Rng> AND
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indirect_relation<equal_to, projected<iterator_t<Rng>, P>, V const *>)
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constexpr iter_difference_t<iterator_t<Rng>> //
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RANGES_FUNC(count)(Rng && rng, V const & val, P proj = P{})
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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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RANGES_FUNC_END(count)
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namespace cpp20
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{
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using ranges::count;
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}
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/// @}
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} // namespace ranges
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#include <range/v3/detail/epilogue.hpp>
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#endif
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