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/// \file
// Range v3 library
//
// Copyright Eric Niebler 2014-present
//
// Use, modification and distribution is subject to the
// Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Project home: https://github.com/ericniebler/range-v3
//
#ifndef RANGES_V3_ALGORITHM_AUX_EQUAL_RANGE_N_HPP
#define RANGES_V3_ALGORITHM_AUX_EQUAL_RANGE_N_HPP
#include <functional>
#include <range/v3/range_fwd.hpp>
#include <range/v3/algorithm/aux_/lower_bound_n.hpp>
#include <range/v3/algorithm/aux_/upper_bound_n.hpp>
#include <range/v3/functional/comparisons.hpp>
#include <range/v3/functional/identity.hpp>
#include <range/v3/functional/invoke.hpp>
#include <range/v3/functional/reference_wrapper.hpp>
#include <range/v3/iterator/operations.hpp>
#include <range/v3/range/access.hpp>
#include <range/v3/range/concepts.hpp>
#include <range/v3/range/traits.hpp>
#include <range/v3/utility/static_const.hpp>
#include <range/v3/view/subrange.hpp>
#include <range/v3/detail/prologue.hpp>
namespace ranges
{
namespace aux
{
struct equal_range_n_fn
{
template(typename I, typename V, typename R = less, typename P = identity)(
requires forward_iterator<I> AND
indirect_strict_weak_order<R, V const *, projected<I, P>>)
constexpr subrange<I> operator()(I first,
iter_difference_t<I> dist,
V const & val,
R pred = R{},
P proj = P{}) const
{
if(0 < dist)
{
do
{
auto half = dist / 2;
auto middle = ranges::next(first, half);
auto && v = *middle;
auto && pv = invoke(proj, (decltype(v) &&)v);
if(invoke(pred, pv, val))
{
first = std::move(++middle);
dist -= half + 1;
}
else if(invoke(pred, val, pv))
{
dist = half;
}
else
{
return {lower_bound_n(std::move(first),
half,
val,
ranges::ref(pred),
ranges::ref(proj)),
upper_bound_n(ranges::next(middle),
dist - (half + 1),
val,
ranges::ref(pred),
ranges::ref(proj))};
}
} while(0 != dist);
}
return {first, first};
}
};
RANGES_INLINE_VARIABLE(equal_range_n_fn, equal_range_n)
} // namespace aux
} // namespace ranges
#include <range/v3/detail/epilogue.hpp>
#endif
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