126 lines
5.2 KiB
C++
126 lines
5.2 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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// Copyright Casey Carter 2016
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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_EQUAL_RANGE_HPP
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#define RANGES_V3_ALGORITHM_EQUAL_RANGE_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/distance.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/iterator_range.hpp>
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#include <range/v3/algorithm/upper_bound.hpp>
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#include <range/v3/algorithm/aux_/equal_range_n.hpp>
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#include <range/v3/algorithm/aux_/lower_bound_n.hpp>
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#include <range/v3/utility/functional.hpp>
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#include <range/v3/utility/iterator.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 equal_range_fn
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{
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template<typename I, typename S, typename V,
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typename C = ordered_less, typename P = ident,
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CONCEPT_REQUIRES_(Sentinel<S, I>() && !SizedSentinel<S, I>() &&
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BinarySearchable<I, V, C, P>())>
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iterator_range<I>
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operator()(I begin, S end, V const &val, C pred = C{}, P proj = P{}) const
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{
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// Probe exponentially for either end-of-range, an iterator that
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// is past the equal range (i.e., denotes an element greater
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// than val), or is in the equal range (denotes an element equal
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// to val).
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auto dist = difference_type_t<I>{1};
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while(true)
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{
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auto mid = begin;
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auto d = advance(mid, dist, end);
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if(d || mid == end)
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{
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// at the end of the input range
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dist -= d;
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return aux::equal_range_n(
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std::move(begin), dist, val, std::ref(pred), std::ref(proj));
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}
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// if val < *mid, mid is after the target range.
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auto && v = *mid;
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auto && pv = invoke(proj, (decltype(v)&&) v);
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if(invoke(pred, val, pv))
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{
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return aux::equal_range_n(
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std::move(begin), dist, val, std::ref(pred), std::ref(proj));
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}
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else if(!invoke(pred, pv, val))
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{
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// *mid == val: the lower bound is <= mid, and the upper bound is > mid.
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return {
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aux::lower_bound_n(std::move(begin), dist, val,
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std::ref(pred), std::ref(proj)),
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upper_bound(std::move(mid), std::move(end), val,
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std::ref(pred), std::ref(proj))
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};
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}
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// *mid < val, mid is before the target range.
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begin = std::move(mid);
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++begin;
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dist *= 2;
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}
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}
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template<typename I, typename S, typename V,
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typename C = ordered_less, typename P = ident,
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CONCEPT_REQUIRES_(SizedSentinel<S, I>() && BinarySearchable<I, V, C, P>())>
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iterator_range<I>
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operator()(I begin, S end, V const &val, C pred = C{}, P proj = P{}) const
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{
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auto const len = distance(begin, end);
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return aux::equal_range_n(std::move(begin), len, val,
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std::move(pred), std::move(proj));
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}
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template<typename Rng, typename V, typename C = ordered_less,
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typename P = ident, typename I = iterator_t<Rng>,
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CONCEPT_REQUIRES_(Range<Rng>() && !SizedRange<Rng>() &&
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BinarySearchable<I, V, C, P>())>
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meta::if_<std::is_lvalue_reference<Rng>, iterator_range<I>, dangling<iterator_range<I>>>
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operator()(Rng &&rng, V const &val, C pred = C{}, P proj = P{}) const
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{
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return (*this)(begin(rng), end(rng), val, std::move(pred), std::move(proj));
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}
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template<typename Rng, typename V, typename C = ordered_less,
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typename P = ident, typename I = iterator_t<Rng>,
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CONCEPT_REQUIRES_(SizedRange<Rng>() && BinarySearchable<I, V, C, P>())>
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meta::if_<std::is_lvalue_reference<Rng>, iterator_range<I>, dangling<iterator_range<I>>>
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operator()(Rng &&rng, V const &val, C pred = C{}, P proj = P{}) const
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{
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auto const len = distance(rng);
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return aux::equal_range_n(begin(rng), len, val, std::move(pred), std::move(proj));
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}
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};
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/// \sa `equal_range_fn`
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/// \ingroup group-algorithms
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RANGES_INLINE_VARIABLE(with_braced_init_args<equal_range_fn>, equal_range)
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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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