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https://github.com/LadybirdBrowser/ladybird.git
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02e0fab19a
Since the FlyString deduplication mechanism uses a HashTable, we know that any StringImpl inside a non-null FlyString will already have its lazily computed hash.
124 lines
3.6 KiB
C++
124 lines
3.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <AK/Badge.h>
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <AK/Types.h>
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#include <AK/kmalloc.h>
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namespace AK {
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enum ShouldChomp {
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NoChomp,
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Chomp
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};
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class StringImpl : public RefCounted<StringImpl> {
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public:
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static NonnullRefPtr<StringImpl> create_uninitialized(size_t length, char*& buffer);
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static RefPtr<StringImpl> create(const char* cstring, ShouldChomp = NoChomp);
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static RefPtr<StringImpl> create(const char* cstring, size_t length, ShouldChomp = NoChomp);
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NonnullRefPtr<StringImpl> to_lowercase() const;
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NonnullRefPtr<StringImpl> to_uppercase() const;
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void operator delete(void* ptr)
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{
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kfree(ptr);
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}
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static StringImpl& the_empty_stringimpl();
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~StringImpl();
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size_t length() const { return m_length; }
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const char* characters() const { return &m_inline_buffer[0]; }
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const char& operator[](size_t i) const
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{
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ASSERT(i < m_length);
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return characters()[i];
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}
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unsigned hash() const
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{
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if (!m_has_hash)
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compute_hash();
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return m_hash;
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}
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unsigned existing_hash() const
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{
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return m_hash;
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}
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bool is_fly() const { return m_fly; }
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void set_fly(Badge<FlyString>, bool fly) const { m_fly = fly; }
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private:
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enum ConstructTheEmptyStringImplTag {
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ConstructTheEmptyStringImpl
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};
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explicit StringImpl(ConstructTheEmptyStringImplTag)
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: m_fly(true)
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{
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m_inline_buffer[0] = '\0';
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}
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enum ConstructWithInlineBufferTag {
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ConstructWithInlineBuffer
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};
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StringImpl(ConstructWithInlineBufferTag, size_t length);
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void compute_hash() const;
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size_t m_length { 0 };
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mutable unsigned m_hash { 0 };
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mutable bool m_has_hash { false };
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mutable bool m_fly { false };
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char m_inline_buffer[0];
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};
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inline constexpr u32 string_hash(const char* characters, size_t length)
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{
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u32 hash = 0;
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for (size_t i = 0; i < length; ++i) {
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hash += (u32)characters[i];
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hash += (hash << 10);
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hash ^= (hash >> 6);
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}
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hash += hash << 3;
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hash ^= hash >> 11;
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hash += hash << 15;
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return hash;
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}
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}
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using AK::Chomp;
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using AK::string_hash;
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using AK::StringImpl;
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