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https://github.com/SerenityOS/serenity
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1682f0b760
SPDX License Identifiers are a more compact / standardized way of representing file license information. See: https://spdx.dev/resources/use/#identifiers This was done with the `ambr` search and replace tool. ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
71 lines
1.4 KiB
C++
71 lines
1.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/StdLibExtras.h>
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#include <AK/Types.h>
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namespace AK {
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struct DefaultComparator {
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template<typename T, typename S>
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constexpr int operator()(T& lhs, S& rhs)
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{
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if (lhs > rhs)
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return 1;
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if (lhs < rhs)
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return -1;
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return 0;
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}
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};
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template<typename Container, typename Needle, typename Comparator = DefaultComparator>
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constexpr auto binary_search(
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Container&& haystack,
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Needle&& needle,
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size_t* nearby_index = nullptr,
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Comparator comparator = Comparator {}) -> decltype(&haystack[0])
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{
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if (haystack.size() == 0) {
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if (nearby_index)
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*nearby_index = 0;
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return nullptr;
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}
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size_t low = 0;
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size_t high = haystack.size() - 1;
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while (low <= high) {
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size_t middle = low + (high - low) / 2;
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int comparison = comparator(needle, haystack[middle]);
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if (comparison < 0)
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if (middle != 0)
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high = middle - 1;
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else
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break;
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else if (comparison > 0)
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low = middle + 1;
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else {
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if (nearby_index)
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*nearby_index = middle;
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return &haystack[middle];
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}
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}
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if (nearby_index)
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*nearby_index = min(low, high);
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return nullptr;
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}
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}
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using AK::binary_search;
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