89 lines
3.0 KiB
C++
89 lines
3.0 KiB
C++
/// \file
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// Range v3 library
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//
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// Copyright Andrey Diduh 2019
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// Copyright Casey Carter 2019
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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_UNSTABLE_REMOVE_IF_HPP
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#define RANGES_V3_ALGORITHM_UNSTABLE_REMOVE_IF_HPP
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#include <functional>
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#include <utility>
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#include <concepts/concepts.hpp>
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#include <range/v3/range_fwd.hpp>
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#include <range/v3/algorithm/find_if.hpp>
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#include <range/v3/algorithm/find_if_not.hpp>
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#include <range/v3/functional/identity.hpp>
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#include <range/v3/iterator/concepts.hpp>
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#include <range/v3/iterator/reverse_iterator.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/utility/move.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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/// unstable_remove have O(1) complexity for each element remove, unlike remove O(n)
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/// [for worst case]. Each erased element overwritten (moved in) with last one.
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/// unstable_remove_if does not preserve relative element order.
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RANGES_FUNC_BEGIN(unstable_remove_if)
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/// \brief function template \c unstable_remove_if
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template(typename I, typename C, typename P = identity)(
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/// \pre
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requires bidirectional_iterator<I> AND permutable<I> AND
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indirect_unary_predicate<C, projected<I, P>>)
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I RANGES_FUNC(unstable_remove_if)(I first, I last, C pred, P proj = {})
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{
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while(true)
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{
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first = find_if(std::move(first), last, std::ref(pred), std::ref(proj));
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last = find_if_not(make_reverse_iterator(std::move(last)),
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make_reverse_iterator(first),
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std::ref(pred),
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std::ref(proj))
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.base();
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if(first == last)
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return first;
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*first = iter_move(--last);
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// discussion here: https://github.com/ericniebler/range-v3/issues/988
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++first;
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}
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}
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/// \overload
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template(typename Rng, typename C, typename P = identity)(
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/// \pre
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requires bidirectional_range<Rng> AND common_range<Rng> AND
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permutable<iterator_t<Rng>> AND
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indirect_unary_predicate<C, projected<iterator_t<Rng>, P>>)
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borrowed_iterator_t<Rng> //
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RANGES_FUNC(unstable_remove_if)(Rng && rng, C pred, P proj = P{}) //
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{
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return (*this)(begin(rng), end(rng), std::move(pred), std::move(proj));
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}
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RANGES_FUNC_END(unstable_remove_if)
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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 // RANGES_V3_ALGORITHM_UNSTABLE_REMOVE_IF_HPP
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