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AK: Implement FlyString for the new String class
This implements a FlyString that will de-duplicate String instances. The FlyString will store the raw encoded data of the String instance: If the String is a short string, FlyString holds the String::ShortString bytes; otherwise FlyString holds a pointer to the Detail::StringData. FlyString itself does not know about String's storage or how to refcount its Detail::StringData. It defers to String to implement these details.
This commit is contained in:
parent
f49a65cb28
commit
1d4f287582
Notes:
sideshowbarker
2024-07-17 01:49:30 +09:00
Author: https://github.com/trflynn89 Commit: https://github.com/SerenityOS/serenity/commit/1d4f287582 Pull-request: https://github.com/SerenityOS/serenity/pull/16958
8 changed files with 445 additions and 1 deletions
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@ -5,6 +5,7 @@ set(AK_SOURCES
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DeprecatedFlyString.cpp
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DeprecatedString.cpp
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FloatingPointStringConversions.cpp
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FlyString.cpp
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Format.cpp
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FuzzyMatch.cpp
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GenericLexer.cpp
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169
AK/FlyString.cpp
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169
AK/FlyString.cpp
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@ -0,0 +1,169 @@
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/*
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* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/FlyString.h>
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#include <AK/HashMap.h>
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#include <AK/Singleton.h>
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#include <AK/StringView.h>
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#include <AK/Utf8View.h>
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namespace AK {
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static auto& all_fly_strings()
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{
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static Singleton<HashMap<StringView, uintptr_t>> table;
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return *table;
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}
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FlyString::FlyString()
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: m_data(String {}.to_fly_string_data({}))
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{
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}
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FlyString::~FlyString()
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{
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String::unref_fly_string_data({}, m_data);
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}
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ErrorOr<FlyString> FlyString::from_utf8(StringView string)
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{
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return FlyString { TRY(String::from_utf8(string)) };
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}
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FlyString::FlyString(String const& string)
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{
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if (string.is_short_string()) {
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m_data = string.to_fly_string_data({});
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return;
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}
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auto it = all_fly_strings().find(string.bytes_as_string_view());
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if (it == all_fly_strings().end()) {
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m_data = string.to_fly_string_data({});
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all_fly_strings().set(string.bytes_as_string_view(), m_data);
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string.did_create_fly_string({});
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} else {
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m_data = it->value;
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}
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String::ref_fly_string_data({}, m_data);
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}
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FlyString::FlyString(FlyString const& other)
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: m_data(other.m_data)
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{
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String::ref_fly_string_data({}, m_data);
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}
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FlyString& FlyString::operator=(FlyString const& other)
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{
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if (this != &other) {
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m_data = other.m_data;
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String::ref_fly_string_data({}, m_data);
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}
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return *this;
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}
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FlyString::FlyString(FlyString&& other)
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: m_data(other.m_data)
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{
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other.m_data = String {}.to_fly_string_data({});
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}
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FlyString& FlyString::operator=(FlyString&& other)
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{
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m_data = other.m_data;
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other.m_data = String {}.to_fly_string_data({});
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return *this;
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}
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bool FlyString::is_empty() const
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{
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return bytes_as_string_view().is_empty();
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}
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unsigned FlyString::hash() const
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{
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return bytes_as_string_view().hash();
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}
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FlyString::operator String() const
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{
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return to_string();
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}
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String FlyString::to_string() const
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{
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return String::fly_string_data_to_string({}, m_data);
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}
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Utf8View FlyString::code_points() const
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{
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return Utf8View { bytes_as_string_view() };
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}
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ReadonlyBytes FlyString::bytes() const
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{
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return bytes_as_string_view().bytes();
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}
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StringView FlyString::bytes_as_string_view() const
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{
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return String::fly_string_data_to_string_view({}, m_data);
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}
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bool FlyString::operator==(FlyString const& other) const
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{
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return m_data == other.m_data;
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}
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bool FlyString::operator==(String const& other) const
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{
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if (m_data == other.to_fly_string_data({}))
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return true;
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return bytes_as_string_view() == other.bytes_as_string_view();
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}
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bool FlyString::operator==(StringView string) const
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{
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return bytes_as_string_view() == string;
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}
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bool FlyString::operator==(char const* string) const
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{
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return bytes_as_string_view() == string;
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}
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void FlyString::did_destroy_fly_string_data(Badge<Detail::StringData>, StringView string_data)
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{
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all_fly_strings().remove(string_data);
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}
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uintptr_t FlyString::data(Badge<String>) const
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{
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return m_data;
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}
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size_t FlyString::number_of_fly_strings()
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{
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return all_fly_strings().size();
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}
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unsigned Traits<FlyString>::hash(FlyString const& fly_string)
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{
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return fly_string.bytes_as_string_view().hash();
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}
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ErrorOr<void> Formatter<FlyString>::format(FormatBuilder& builder, FlyString const& fly_string)
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{
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return Formatter<StringView>::format(builder, fly_string.bytes_as_string_view());
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}
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}
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73
AK/FlyString.h
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73
AK/FlyString.h
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/*
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* Copyright (c) 2023, Tim Flynn <trflynn89@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/Error.h>
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#include <AK/Format.h>
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#include <AK/Platform.h>
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#include <AK/String.h>
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#include <AK/Traits.h>
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#include <AK/Types.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();
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static ErrorOr<FlyString> from_utf8(StringView);
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explicit FlyString(String const&);
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FlyString(FlyString const&);
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FlyString& operator=(FlyString const&);
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FlyString(FlyString&&);
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FlyString& operator=(FlyString&&);
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[[nodiscard]] bool is_empty() const;
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[[nodiscard]] unsigned hash() const;
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explicit operator String() const;
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String to_string() const;
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[[nodiscard]] Utf8View code_points() const;
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[[nodiscard]] ReadonlyBytes bytes() const;
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[[nodiscard]] StringView bytes_as_string_view() const;
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[[nodiscard]] bool operator==(FlyString const& other) const;
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[[nodiscard]] bool operator==(String const&) const;
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[[nodiscard]] bool operator==(StringView) const;
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[[nodiscard]] bool operator==(char const*) const;
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static void did_destroy_fly_string_data(Badge<Detail::StringData>, StringView);
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[[nodiscard]] uintptr_t data(Badge<String>) const;
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// This is primarily interesting to unit tests.
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[[nodiscard]] static size_t number_of_fly_strings();
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private:
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// This will hold either the pointer to the Detail::StringData it represents or the raw bytes of
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// an inlined short string.
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uintptr_t m_data { 0 };
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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(FlyString const&);
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};
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template<>
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struct Formatter<FlyString> : Formatter<StringView> {
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ErrorOr<void> format(FormatBuilder&, FlyString const&);
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};
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}
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#if USING_AK_GLOBALLY
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using AK::FlyString;
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#endif
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@ -21,6 +21,7 @@ class Bitmap;
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using ByteBuffer = Detail::ByteBuffer<32>;
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class CircularBuffer;
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class Error;
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class FlyString;
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class GenericLexer;
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class IPv4Address;
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class JsonArray;
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*/
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#include <AK/Checked.h>
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#include <AK/FlyString.h>
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#include <AK/Format.h>
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#include <AK/String.h>
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#include <AK/StringBuilder.h>
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return m_hash;
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}
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bool is_fly_string() const { return m_is_fly_string; }
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void set_fly_string(bool is_fly_string) { m_is_fly_string = is_fly_string; }
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private:
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explicit StringData(size_t byte_count);
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StringData(StringData const& superstring, size_t start, size_t byte_count);
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mutable unsigned m_hash { 0 };
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mutable bool m_has_hash { false };
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bool m_substring { false };
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bool m_is_fly_string { false };
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u8 m_bytes_or_substring_data[0];
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};
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StringData::~StringData()
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{
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if (m_is_fly_string)
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FlyString::did_destroy_fly_string_data({}, bytes_as_string_view());
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if (m_substring)
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substring_data().superstring->unref();
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}
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@ -255,6 +262,13 @@ bool String::operator==(String const& other) const
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return bytes_as_string_view() == other.bytes_as_string_view();
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}
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bool String::operator==(FlyString const& other) const
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{
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if (reinterpret_cast<uintptr_t>(m_data) == other.data({}))
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return true;
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return bytes_as_string_view() == other.bytes_as_string_view();
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}
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bool String::operator==(StringView other) const
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{
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return bytes_as_string_view() == other;
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@ -307,7 +321,7 @@ ErrorOr<String> String::replace(StringView needle, StringView replacement, Repla
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bool String::is_short_string() const
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{
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return reinterpret_cast<uintptr_t>(m_data) & SHORT_STRING_FLAG;
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return has_short_string_bit(reinterpret_cast<uintptr_t>(m_data));
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}
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ReadonlyBytes String::ShortString::bytes() const
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return string.hash();
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}
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String String::fly_string_data_to_string(Badge<FlyString>, uintptr_t const& data)
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{
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if (has_short_string_bit(data))
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return String { *reinterpret_cast<ShortString const*>(&data) };
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auto const* string_data = reinterpret_cast<Detail::StringData const*>(data);
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return String { NonnullRefPtr<Detail::StringData>(*string_data) };
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}
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StringView String::fly_string_data_to_string_view(Badge<FlyString>, uintptr_t const& data)
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{
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if (has_short_string_bit(data)) {
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auto const* short_string = reinterpret_cast<ShortString const*>(&data);
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return short_string->bytes();
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}
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auto const* string_data = reinterpret_cast<Detail::StringData const*>(data);
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return string_data->bytes_as_string_view();
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}
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uintptr_t String::to_fly_string_data(Badge<FlyString>) const
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{
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return reinterpret_cast<uintptr_t>(m_data);
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}
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void String::ref_fly_string_data(Badge<FlyString>, uintptr_t data)
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{
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if (has_short_string_bit(data))
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return;
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auto const* string_data = reinterpret_cast<Detail::StringData const*>(data);
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string_data->ref();
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}
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void String::unref_fly_string_data(Badge<FlyString>, uintptr_t data)
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{
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if (has_short_string_bit(data))
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return;
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auto const* string_data = reinterpret_cast<Detail::StringData const*>(data);
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string_data->unref();
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}
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void String::did_create_fly_string(Badge<FlyString>) const
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{
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VERIFY(!is_short_string());
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m_data->set_fly_string(true);
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}
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DeprecatedString String::to_deprecated_string() const
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{
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return DeprecatedString(bytes_as_string_view());
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16
AK/String.h
16
AK/String.h
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[[nodiscard]] bool operator==(String const&) const;
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[[nodiscard]] bool operator!=(String const& other) const { return !(*this == other); }
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[[nodiscard]] bool operator==(FlyString const&) const;
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[[nodiscard]] bool operator!=(FlyString const& other) const { return !(*this == other); }
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[[nodiscard]] bool operator==(StringView) const;
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[[nodiscard]] bool operator!=(StringView other) const { return !(*this == other); }
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// NOTE: This is primarily interesting to unit tests.
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[[nodiscard]] bool is_short_string() const;
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[[nodiscard]] static String fly_string_data_to_string(Badge<FlyString>, uintptr_t const&);
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[[nodiscard]] static StringView fly_string_data_to_string_view(Badge<FlyString>, uintptr_t const&);
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[[nodiscard]] uintptr_t to_fly_string_data(Badge<FlyString>) const;
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static void ref_fly_string_data(Badge<FlyString>, uintptr_t);
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static void unref_fly_string_data(Badge<FlyString>, uintptr_t);
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void did_create_fly_string(Badge<FlyString>) const;
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// FIXME: Remove these once all code has been ported to String
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[[nodiscard]] DeprecatedString to_deprecated_string() const;
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static ErrorOr<String> from_deprecated_string(DeprecatedString const&);
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@ -110,6 +121,11 @@ private:
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// NOTE: If the least significant bit of the pointer is set, this is a short string.
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static constexpr uintptr_t SHORT_STRING_FLAG = 1;
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static constexpr bool has_short_string_bit(uintptr_t data)
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{
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return (data & SHORT_STRING_FLAG) != 0;
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}
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struct ShortString {
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ReadonlyBytes bytes() const;
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size_t byte_count() const;
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@ -30,6 +30,7 @@ set(AK_TEST_SOURCES
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TestFixedPoint.cpp
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TestFloatingPoint.cpp
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TestFloatingPointParsing.cpp
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TestFlyString.cpp
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TestFormat.cpp
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TestGenericLexer.cpp
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TestHashFunctions.cpp
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120
Tests/AK/TestFlyString.cpp
Normal file
120
Tests/AK/TestFlyString.cpp
Normal file
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/*
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* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibTest/TestCase.h>
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#include <AK/FlyString.h>
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#include <AK/String.h>
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#include <AK/Try.h>
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TEST_CASE(empty_string)
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{
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FlyString fly {};
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EXPECT(fly.is_empty());
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EXPECT_EQ(fly, ""sv);
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// Short strings do not get stored in the fly string table.
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EXPECT_EQ(FlyString::number_of_fly_strings(), 0u);
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}
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TEST_CASE(short_string)
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{
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FlyString fly1 { MUST(String::from_utf8("foo"sv)) };
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EXPECT_EQ(fly1, "foo"sv);
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FlyString fly2 { MUST(String::from_utf8("foo"sv)) };
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EXPECT_EQ(fly2, "foo"sv);
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FlyString fly3 { MUST(String::from_utf8("bar"sv)) };
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EXPECT_EQ(fly3, "bar"sv);
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EXPECT_EQ(fly1, fly2);
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EXPECT_NE(fly1, fly3);
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EXPECT_NE(fly2, fly3);
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EXPECT(fly1.to_string().is_short_string());
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EXPECT(fly2.to_string().is_short_string());
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EXPECT(fly3.to_string().is_short_string());
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// Short strings do not get stored in the fly string table.
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EXPECT_EQ(FlyString::number_of_fly_strings(), 0u);
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}
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TEST_CASE(long_string)
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{
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FlyString fly1 { MUST(String::from_utf8("thisisdefinitelymorethan7bytes"sv)) };
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EXPECT_EQ(fly1, "thisisdefinitelymorethan7bytes"sv);
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EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
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FlyString fly2 { MUST(String::from_utf8("thisisdefinitelymorethan7bytes"sv)) };
|
||||
EXPECT_EQ(fly2, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
|
||||
FlyString fly3 { MUST(String::from_utf8("thisisalsoforsuremorethan7bytes"sv)) };
|
||||
EXPECT_EQ(fly3, "thisisalsoforsuremorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 2u);
|
||||
|
||||
EXPECT_EQ(fly1, fly2);
|
||||
EXPECT_NE(fly1, fly3);
|
||||
EXPECT_NE(fly2, fly3);
|
||||
|
||||
EXPECT(!fly1.to_string().is_short_string());
|
||||
EXPECT(!fly2.to_string().is_short_string());
|
||||
EXPECT(!fly3.to_string().is_short_string());
|
||||
}
|
||||
|
||||
TEST_CASE(from_string_view)
|
||||
{
|
||||
auto fly1 = MUST(FlyString::from_utf8("thisisdefinitelymorethan7bytes"sv));
|
||||
EXPECT_EQ(fly1, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
|
||||
auto fly2 = MUST(FlyString::from_utf8("thisisdefinitelymorethan7bytes"sv));
|
||||
EXPECT_EQ(fly2, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
|
||||
auto fly3 = MUST(FlyString::from_utf8("foo"sv));
|
||||
EXPECT_EQ(fly3, "foo"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
|
||||
EXPECT_EQ(fly1, fly2);
|
||||
EXPECT_NE(fly1, fly3);
|
||||
EXPECT_NE(fly2, fly3);
|
||||
}
|
||||
|
||||
TEST_CASE(fly_string_keep_string_data_alive)
|
||||
{
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 0u);
|
||||
{
|
||||
FlyString fly {};
|
||||
{
|
||||
auto string = MUST(String::from_utf8("thisisdefinitelymorethan7bytes"sv));
|
||||
fly = FlyString { string };
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
}
|
||||
|
||||
EXPECT_EQ(fly, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
}
|
||||
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 0u);
|
||||
}
|
||||
|
||||
TEST_CASE(moved_fly_string_becomes_empty)
|
||||
{
|
||||
FlyString fly1 {};
|
||||
EXPECT(fly1.is_empty());
|
||||
|
||||
FlyString fly2 { MUST(String::from_utf8("thisisdefinitelymorethan7bytes"sv)) };
|
||||
EXPECT_EQ(fly2, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
|
||||
fly1 = move(fly2);
|
||||
|
||||
EXPECT(fly2.is_empty());
|
||||
EXPECT_EQ(fly1, "thisisdefinitelymorethan7bytes"sv);
|
||||
EXPECT_EQ(FlyString::number_of_fly_strings(), 1u);
|
||||
}
|
Loading…
Reference in a new issue