292 lines
12 KiB
C++
292 lines
12 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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//===-------------------------- algorithm ---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef RANGES_V3_ALGORITHM_PERMUTATION_HPP
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#define RANGES_V3_ALGORITHM_PERMUTATION_HPP
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#include <meta/meta.hpp>
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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/distance.hpp>
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#include <range/v3/utility/iterator.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/swap.hpp>
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#include <range/v3/utility/functional.hpp>
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#include <range/v3/algorithm/reverse.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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/// \ingroup group-concepts
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template<typename I1, typename I2, typename C = equal_to, typename P1 = ident,
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typename P2 = ident>
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using IsPermutationable = meta::strict_and<
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ForwardIterator<I1>,
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ForwardIterator<I2>,
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Comparable<I1, I2, C, P1, P2>>;
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/// \addtogroup group-algorithms
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/// @{
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struct is_permutation_fn
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{
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private:
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template<typename I1, typename S1, typename I2, typename S2, typename C, typename P1,
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typename P2>
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static bool four_iter_impl(I1 begin1, S1 end1, I2 begin2, S2 end2, C pred, P1 proj1,
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P2 proj2)
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{
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// shorten sequences as much as possible by lopping off any equal parts
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for(; begin1 != end1 && begin2 != end2; ++begin1, ++begin2)
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if(!invoke(pred, invoke(proj1, *begin1), invoke(proj2, *begin2)))
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goto not_done;
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return begin1 == end1 && begin2 == end2;
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not_done:
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// begin1 != end1 && begin2 != end2 && *begin1 != *begin2
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auto l1 = distance(begin1, end1);
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auto l2 = distance(begin2, end2);
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if(l1 != l2)
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return false;
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// For each element in [f1, l1) see if there are the same number of
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// equal elements in [f2, l2)
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for(I1 i = begin1; i != end1; ++i)
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{
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// Have we already counted the number of *i in [f1, l1)?
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for(I1 j = begin1; j != i; ++j)
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if(invoke(pred, invoke(proj1, *j), invoke(proj1, *i)))
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goto next_iter;
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{
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// Count number of *i in [f2, l2)
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difference_type_t<I2> c2 = 0;
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for(I2 j = begin2; j != end2; ++j)
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if(invoke(pred, invoke(proj1, *i), invoke(proj2, *j)))
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++c2;
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if(c2 == 0)
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return false;
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// Count number of *i in [i, l1) (we can start with 1)
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difference_type_t<I1> c1 = 1;
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for(I1 j = next(i); j != end1; ++j)
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if(invoke(pred, invoke(proj1, *i), invoke(proj1, *j)))
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++c1;
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if(c1 != c2)
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return false;
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}
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next_iter:;
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}
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return true;
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}
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public:
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template<typename I1, typename S1, typename I2, typename C = equal_to,
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typename P1 = ident, typename P2 = ident,
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CONCEPT_REQUIRES_(Sentinel<S1, I1>() && IsPermutationable<I1, I2, C, P1, P2>())>
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bool operator()(I1 begin1, S1 end1, I2 begin2, C pred = C{}, P1 proj1 = P1{},
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P2 proj2 = P2{}) const
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{
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// shorten sequences as much as possible by lopping off any equal parts
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for(; begin1 != end1; ++begin1, ++begin2)
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if(!invoke(pred, invoke(proj1, *begin1), invoke(proj2, *begin2)))
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goto not_done;
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return true;
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not_done:
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// begin1 != end1 && *begin1 != *begin2
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auto l1 = distance(begin1, end1);
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if(l1 == 1)
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return false;
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I2 end2 = next(begin2, l1);
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// For each element in [f1, l1) see if there are the same number of
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// equal elements in [f2, l2)
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for(I1 i = begin1; i != end1; ++i)
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{
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// Have we already counted the number of *i in [f1, l1)?
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for(I1 j = begin1; j != i; ++j)
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if(invoke(pred, invoke(proj1, *j), invoke(proj1, *i)))
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goto next_iter;
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{
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// Count number of *i in [f2, l2)
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difference_type_t<I2> c2 = 0;
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for(I2 j = begin2; j != end2; ++j)
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if(invoke(pred, invoke(proj1, *i), invoke(proj2, *j)))
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++c2;
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if(c2 == 0)
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return false;
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// Count number of *i in [i, l1) (we can start with 1)
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difference_type_t<I1> c1 = 1;
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for(I1 j = next(i); j != end1; ++j)
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if(invoke(pred, invoke(proj1, *i), invoke(proj1, *j)))
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++c1;
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if(c1 != c2)
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return false;
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}
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next_iter:;
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}
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return true;
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}
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template<typename I1, typename S1, typename I2, typename S2,
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typename C = equal_to, typename P1 = ident, typename P2 = ident,
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CONCEPT_REQUIRES_(Sentinel<S1, I1>() && Sentinel<S2, I2>() &&
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IsPermutationable<I1, I2, C, P1, P2>())>
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bool operator()(I1 begin1, S1 end1, I2 begin2, S2 end2, C pred = C{},
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P1 proj1 = P1{}, P2 proj2 = P2{}) const
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{
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if(SizedSentinel<S1, I1>() && SizedSentinel<S2, I2>())
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return distance(begin1, end1) == distance(begin2, end2) &&
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(*this)(std::move(begin1), std::move(end1), std::move(begin2),
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std::move(pred), std::move(proj1), std::move(proj2));
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return is_permutation_fn::four_iter_impl(std::move(begin1), std::move(end1),
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std::move(begin2), std::move(end2), std::move(pred), std::move(proj1),
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std::move(proj2));
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}
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template<typename Rng1, typename I2Ref, typename C = equal_to, typename P1 = ident,
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typename P2 = ident, typename I1 = iterator_t<Rng1>,
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typename I2 = uncvref_t<I2Ref>,
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CONCEPT_REQUIRES_(ForwardRange<Rng1>() && Iterator<I2>() &&
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IsPermutationable<I1, I2, C, P1, P2>())>
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bool operator()(Rng1 &&rng1, I2Ref &&begin2,
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C pred = C{}, P1 proj1 = P1{}, P2 proj2 = P2{}) const
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{
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return (*this)(begin(rng1), end(rng1), (I2Ref &&) begin2, std::move(pred),
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std::move(proj1), std::move(proj2));
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}
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template<typename Rng1, typename Rng2, typename C = equal_to, typename P1 = ident,
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typename P2 = ident, typename I1 = iterator_t<Rng1>,
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typename I2 = iterator_t<Rng2>,
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CONCEPT_REQUIRES_(ForwardRange<Rng1>() && ForwardRange<Rng2>() &&
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IsPermutationable<I1, I2, C, P1, P2>())>
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bool operator()(Rng1 &&rng1, Rng2 &&rng2,
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C pred = C{}, P1 proj1 = P1{}, P2 proj2 = P2{}) const
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{
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if(SizedRange<Rng1>() && SizedRange<Rng2>())
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return distance(rng1) == distance(rng2) &&
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(*this)(begin(rng1), end(rng1), begin(rng2), std::move(pred),
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std::move(proj1), std::move(proj2));
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return is_permutation_fn::four_iter_impl(begin(rng1), end(rng1), begin(rng2),
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end(rng2), std::move(pred), std::move(proj1), std::move(proj2));
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}
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};
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/// \sa `is_permutation_fn`
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/// \ingroup group-algorithms
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RANGES_INLINE_VARIABLE(with_braced_init_args<is_permutation_fn>,
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is_permutation)
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struct next_permutation_fn
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{
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template<typename I, typename S, typename C = ordered_less, typename P = ident,
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CONCEPT_REQUIRES_(BidirectionalIterator<I>() && Sentinel<S, I>() && Sortable<I, C, P>())>
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bool operator()(I begin, S end_, C pred = C{}, P proj = P{}) const
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{
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if(begin == end_)
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return false;
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I end = ranges::next(begin, end_), i = end;
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if(begin == --i)
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return false;
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while(true)
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{
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I ip1 = i;
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if(invoke(pred, invoke(proj, *--i), invoke(proj, *ip1)))
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{
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I j = end;
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while(!invoke(pred, invoke(proj, *i), invoke(proj, *--j)))
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;
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ranges::iter_swap(i, j);
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ranges::reverse(ip1, end);
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return true;
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}
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if(i == begin)
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{
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ranges::reverse(begin, end);
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return false;
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}
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}
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}
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template<typename Rng, typename C = ordered_less, typename P = ident,
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typename I = iterator_t<Rng>,
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CONCEPT_REQUIRES_(BidirectionalRange<Rng>() && Sortable<I, C, P>())>
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bool operator()(Rng &&rng, C pred = C{}, P proj = P{}) const
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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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};
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/// \sa `next_permutation_fn`
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/// \ingroup group-algorithms
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RANGES_INLINE_VARIABLE(with_braced_init_args<next_permutation_fn>,
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next_permutation)
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struct prev_permutation_fn
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{
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template<typename I, typename S, typename C = ordered_less, typename P = ident,
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CONCEPT_REQUIRES_(BidirectionalIterator<I>() && Sentinel<S, I>() && Sortable<I, C, P>())>
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bool operator()(I begin, S end_, C pred = C{}, P proj = P{}) const
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{
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if(begin == end_)
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return false;
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I end = ranges::next(begin, end_), i = end;
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if(begin == --i)
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return false;
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while(true)
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{
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I ip1 = i;
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if(invoke(pred, invoke(proj, *ip1), invoke(proj, *--i)))
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{
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I j = end;
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while(!invoke(pred, invoke(proj, *--j), invoke(proj, *i)))
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;
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ranges::iter_swap(i, j);
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ranges::reverse(ip1, end);
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return true;
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}
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if(i == begin)
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{
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ranges::reverse(begin, end);
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return false;
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}
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}
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}
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template<typename Rng, typename C = ordered_less, typename P = ident,
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typename I = iterator_t<Rng>,
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CONCEPT_REQUIRES_(BidirectionalRange<Rng>() && Sortable<I, C, P>())>
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bool operator()(Rng &&rng, C pred = C{}, P proj = P{}) const
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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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};
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/// \sa `prev_permutation_fn`
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/// \ingroup group-algorithms
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RANGES_INLINE_VARIABLE(with_braced_init_args<prev_permutation_fn>,
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prev_permutation)
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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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