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https://github.com/LadybirdBrowser/ladybird.git
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AK: Add FlyString, a simple flyweight string class
FlyString is a flyweight string class that wraps a RefPtr<StringImpl> known to be unique among the set of FlyStrings. The class is very unoptimized at the moment. When to use FlyString: - When you want O(1) string comparison - When you want to deduplicate a lot of identical strings When not to use FlyString: - For strings that don't need either of the above features - For strings that are likely to be unique
This commit is contained in:
parent
0395b25e3f
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4f72f6b886
Notes:
sideshowbarker
2024-07-19 08:11:13 +09:00
Author: https://github.com/awesomekling Commit: https://github.com/SerenityOS/serenity/commit/4f72f6b8866
91
AK/FlyString.cpp
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91
AK/FlyString.cpp
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@ -0,0 +1,91 @@
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/*
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* Copyright (c) 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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#include <AK/FlyString.h>
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#include <AK/HashTable.h>
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#include <AK/String.h>
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#include <AK/StringUtils.h>
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namespace AK {
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struct FlyStringImplTraits : public AK::Traits<StringImpl*> {
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static unsigned hash(const StringImpl* s) { return s ? s->hash() : 0; }
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static bool equals(const StringImpl* a, const StringImpl* b)
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{
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ASSERT(a);
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ASSERT(b);
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if (a == b)
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return true;
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if (a->length() != b->length())
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return false;
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return !__builtin_memcmp(a->characters(), b->characters(), a->length());
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}
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};
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static HashTable<StringImpl*, FlyStringImplTraits>& fly_impls()
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{
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static HashTable<StringImpl*, FlyStringImplTraits>* table;
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if (!table)
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table = new HashTable<StringImpl*, FlyStringImplTraits>;
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return *table;
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}
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void FlyString::did_destroy_impl(Badge<StringImpl>, StringImpl& impl)
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{
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fly_impls().remove(&impl);
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}
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FlyString::FlyString(const String& string)
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{
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if (string.is_null())
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return;
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auto it = fly_impls().find(const_cast<StringImpl*>(string.impl()));
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if (it == fly_impls().end()) {
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fly_impls().set(const_cast<StringImpl*>(string.impl()));
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string.impl()->set_fly({}, true);
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m_impl = string.impl();
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} else {
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ASSERT((*it)->is_fly());
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m_impl = *it;
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}
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}
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FlyString::FlyString(const StringView& string)
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: FlyString(static_cast<String>(string))
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{
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}
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FlyString::FlyString(const char* string)
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: FlyString(static_cast<String>(string))
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{
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}
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int FlyString::to_int(bool& ok) const
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{
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return StringUtils::convert_to_int(view(), ok);
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}
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}
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64
AK/FlyString.h
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64
AK/FlyString.h
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@ -0,0 +1,64 @@
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/*
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* Copyright (c) 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/String.h>
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namespace AK {
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class FlyString {
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public:
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FlyString() {}
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FlyString(const String&);
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FlyString(const StringView&);
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FlyString(const char*);
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bool operator==(const FlyString& other) const { return m_impl == other.m_impl; }
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bool operator!=(const FlyString& other) const { return m_impl != other.m_impl; }
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const StringImpl* impl() const { return m_impl; }
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const char* characters() const { return m_impl ? m_impl->characters() : nullptr; }
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size_t length() const { return m_impl ? m_impl->length() : 0; }
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StringView view() const { return { characters(), length() }; }
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int to_int(bool& ok) const;
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static void did_destroy_impl(Badge<StringImpl>, StringImpl&);
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private:
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RefPtr<StringImpl> m_impl;
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};
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template<>
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struct Traits<FlyString> : public GenericTraits<FlyString> {
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static unsigned hash(const FlyString& s) { return s.impl() ? s.impl()->hash() : 0; }
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};
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}
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using AK::FlyString;
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@ -45,6 +45,7 @@ class StringBuilder;
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class StringImpl;
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class StringView;
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class URL;
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class FlyString;
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class Utf8View;
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template<typename T>
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@ -137,5 +138,6 @@ using AK::StringImpl;
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using AK::StringView;
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using AK::Traits;
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using AK::URL;
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using AK::FlyString;
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using AK::Utf8View;
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using AK::Vector;
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@ -24,6 +24,7 @@
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/FlyString.h>
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#include <AK/HashTable.h>
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#include <AK/Memory.h>
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#include <AK/StdLibExtras.h>
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@ -72,6 +73,8 @@ StringImpl::StringImpl(ConstructWithInlineBufferTag, size_t length)
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StringImpl::~StringImpl()
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{
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if (m_fly)
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FlyString::did_destroy_impl({}, *this);
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#ifdef DEBUG_STRINGIMPL
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--g_stringimpl_count;
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g_all_live_stringimpls->remove(this);
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@ -26,6 +26,7 @@
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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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@ -70,11 +71,15 @@ public:
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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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@ -89,6 +94,7 @@ private:
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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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@ -28,6 +28,7 @@
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#include <AK/Memory.h>
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#include <AK/String.h>
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#include <AK/StringView.h>
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#include <AK/FlyString.h>
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#include <AK/Vector.h>
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namespace AK {
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@ -39,6 +40,13 @@ StringView::StringView(const String& string)
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{
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}
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StringView::StringView(const FlyString& string)
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: m_impl(string.impl())
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, m_characters(string.characters())
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, m_length(string.length())
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{
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}
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StringView::StringView(const ByteBuffer& buffer)
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: m_characters((const char*)buffer.data())
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, m_length(buffer.size())
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StringView(const ByteBuffer&);
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StringView(const String&);
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StringView(const FlyString&);
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bool is_null() const { return !m_characters; }
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bool is_empty() const { return m_length == 0; }
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@ -7,6 +7,7 @@ SHARED_TEST_SOURCES = \
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../LogStream.cpp \
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../JsonValue.cpp \
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../JsonParser.cpp \
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../FlyString.cpp \
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../FileSystemPath.cpp \
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../URL.cpp \
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../Utf8View.cpp
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#include <AK/TestSuite.h>
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#include <AK/FlyString.h>
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#include <AK/String.h>
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#include <AK/StringBuilder.h>
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TEST_CASE(construct_empty)
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{
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@ -137,4 +139,24 @@ TEST_CASE(to_uppercase)
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EXPECT(String("AbC").to_uppercase() == "ABC");
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}
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TEST_CASE(flystring)
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{
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{
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FlyString a("foo");
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FlyString b("foo");
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EXPECT_EQ(a.impl(), b.impl());
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}
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{
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String a = "foo";
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FlyString b = a;
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StringBuilder builder;
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builder.append('f');
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builder.append("oo");
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FlyString c = builder.to_string();
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EXPECT_EQ(a.impl(), b.impl());
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EXPECT_EQ(a.impl(), c.impl());
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}
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}
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TEST_MAIN(String)
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@ -4,14 +4,15 @@ PROGRAM = FormCompiler
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OBJS = \
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main.o \
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../../AK/String.o \
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../../AK/StringImpl.o \
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../../AK/StringBuilder.o \
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../../AK/StringView.o \
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../../AK/StringUtils.o \
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../../AK/JsonValue.o \
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../../AK/FlyString.o \
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../../AK/JsonParser.o \
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../../AK/JsonValue.o \
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../../AK/LogStream.o \
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../../AK/String.o \
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../../AK/StringBuilder.o \
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../../AK/StringImpl.o \
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../../AK/StringUtils.o \
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../../AK/StringView.o \
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../../Libraries/LibCore/IODevice.o \
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../../Libraries/LibCore/File.o \
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../../Libraries/LibCore/Object.o \
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@ -4,14 +4,15 @@ PROGRAM = IPCCompiler
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OBJS = \
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main.o \
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../../AK/String.o \
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../../AK/StringImpl.o \
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../../AK/StringBuilder.o \
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../../AK/StringView.o \
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../../AK/StringUtils.o \
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../../AK/JsonValue.o \
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../../AK/FlyString.o \
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../../AK/JsonParser.o \
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../../AK/JsonValue.o \
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../../AK/LogStream.o \
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../../AK/String.o \
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../../AK/StringBuilder.o \
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../../AK/StringImpl.o \
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../../AK/StringUtils.o \
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../../AK/StringView.o \
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../../Libraries/LibCore/IODevice.o \
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../../Libraries/LibCore/File.o \
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../../Libraries/LibCore/Object.o \
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@ -1,13 +1,14 @@
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OBJS = \
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../AK/FileSystemPath.o \
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../AK/FlyString.o \
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../AK/JsonParser.o \
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../AK/JsonValue.o \
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../AK/LogStream.o \
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../AK/String.o \
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../AK/StringBuilder.o \
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../AK/StringImpl.o \
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../AK/StringView.o \
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../AK/StringUtils.o \
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../AK/StringView.o \
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../Libraries/LibELF/ELFImage.o \
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../Libraries/LibELF/ELFLoader.o \
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../Libraries/LibBareMetal/Output/Console.o \
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@ -1,16 +1,17 @@
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AK_OBJS = \
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../../AK/StringImpl.o \
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../../AK/String.o \
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../../AK/StringView.o \
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../../AK/StringBuilder.o \
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../../AK/StringUtils.o \
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../../AK/FileSystemPath.o \
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../../AK/URL.o \
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../../AK/JsonValue.o \
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../../AK/FlyString.o \
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../../AK/JsonParser.o \
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../../AK/JsonValue.o \
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../../AK/LogStream.o \
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../../AK/MappedFile.o \
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../../AK/SharedBuffer.o \
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../../AK/String.o \
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../../AK/StringBuilder.o \
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../../AK/StringImpl.o \
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../../AK/StringUtils.o \
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../../AK/StringView.o \
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../../AK/URL.o \
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../../AK/Utf8View.o
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LIBC_OBJS = \
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OBJS = \
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Generate_CSS_PropertyID_cpp.o \
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../../../../AK/String.o \
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../../../../AK/StringImpl.o \
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../../../../AK/StringBuilder.o \
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../../../../AK/StringView.o \
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../../../../AK/StringUtils.o \
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../../../../AK/JsonValue.o \
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../../../../AK/FlyString.o \
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../../../../AK/JsonParser.o \
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../../../../AK/JsonValue.o \
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../../../../AK/LogStream.o \
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../../../../AK/String.o \
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../../../../AK/StringBuilder.o \
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../../../../AK/StringImpl.o \
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../../../../AK/StringUtils.o \
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../../../../AK/StringView.o \
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../../../../Libraries/LibCore/IODevice.o \
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../../../../Libraries/LibCore/File.o \
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../../../../Libraries/LibCore/Object.o \
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@ -4,14 +4,15 @@ PROGRAM = Generate_CSS_PropertyID_h
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OBJS = \
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Generate_CSS_PropertyID_h.o \
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../../../../AK/StringUtils.o \
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../../../../AK/String.o \
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../../../../AK/StringImpl.o \
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../../../../AK/StringBuilder.o \
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../../../../AK/StringView.o \
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../../../../AK/JsonValue.o \
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../../../../AK/FlyString.o \
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../../../../AK/JsonParser.o \
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../../../../AK/JsonValue.o \
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../../../../AK/LogStream.o \
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../../../../AK/String.o \
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../../../../AK/StringBuilder.o \
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../../../../AK/StringImpl.o \
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../../../../AK/StringUtils.o \
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../../../../AK/StringView.o \
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../../../../Libraries/LibCore/IODevice.o \
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../../../../Libraries/LibCore/File.o \
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../../../../Libraries/LibCore/Object.o \
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