mirror of
https://github.com/SerenityOS/serenity
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c7a66882f4
AK::shuffle() doesn't work on these, because their operator[] returns a reference to the pointed-at value, instead of to the NonnullPtr itself.
87 lines
1.9 KiB
C++
87 lines
1.9 KiB
C++
/*
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* Copyright (c) 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/Platform.h>
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#include <AK/StdLibExtras.h>
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#include <AK/Types.h>
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#if defined(AK_OS_SERENITY) || defined(AK_OS_ANDROID)
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# include <stdlib.h>
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#endif
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#if defined(__unix__)
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# include <unistd.h>
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#endif
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#if defined(AK_OS_MACOS)
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# include <sys/random.h>
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#endif
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#if defined(AK_OS_WINDOWS)
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# include <stdlib.h>
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#endif
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namespace AK {
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inline void fill_with_random([[maybe_unused]] void* buffer, [[maybe_unused]] size_t length)
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{
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#if defined(AK_OS_SERENITY) || defined(AK_OS_ANDROID)
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arc4random_buf(buffer, length);
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#elif defined(OSS_FUZZ)
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#elif defined(__unix__) or defined(AK_OS_MACOS)
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[[maybe_unused]] int rc = getentropy(buffer, length);
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#else
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char* char_buffer = static_cast<char*>(buffer);
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for (size_t i = 0; i < length; i++) {
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char_buffer[i] = rand();
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}
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#endif
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}
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template<typename T>
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inline T get_random()
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{
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T t;
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fill_with_random(&t, sizeof(T));
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return t;
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}
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u32 get_random_uniform(u32 max_bounds);
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template<typename Collection>
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inline void shuffle(Collection& collection)
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{
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// Fisher-Yates shuffle
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for (size_t i = collection.size() - 1; i >= 1; --i) {
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size_t j = get_random_uniform(i + 1);
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AK::swap(collection[i], collection[j]);
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}
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}
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// shuffle() implementation for NonnullPtrVector, since its operator[] returns a reference to the pointed-at value
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// instead of the pointer itself.
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template<typename Collection>
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requires(requires(Collection collection) { collection.ptr_at(0); })
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inline void shuffle(Collection& collection)
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{
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// Fisher-Yates shuffle
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for (size_t i = collection.size() - 1; i >= 1; --i) {
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size_t j = get_random_uniform(i + 1);
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AK::swap(collection.ptr_at(i), collection.ptr_at(j));
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}
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}
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}
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#if USING_AK_GLOBALLY
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using AK::fill_with_random;
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using AK::get_random;
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using AK::get_random_uniform;
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using AK::shuffle;
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#endif
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