mirror of
https://github.com/RGBCube/serenity
synced 2025-05-14 08:24:58 +00:00
54d149bc25
The idea is to eventually get rid of protected state in StringBase. To do this, we first need to remove all references to m_data and m_short_string from String.
76 lines
2 KiB
C++
76 lines
2 KiB
C++
/*
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* Copyright (c) 2023, Dan Klishch <danilklishch@gmail.com>
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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/Endian.h>
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#include <AK/Forward.h>
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namespace AK::Detail {
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class StringData;
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static constexpr size_t MAX_SHORT_STRING_BYTE_COUNT = sizeof(StringData*) - 1;
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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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// NOTE: This is the byte count shifted left 1 step and or'ed with a 1 (the SHORT_STRING_FLAG)
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u8 byte_count_and_short_string_flag { 0 };
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u8 storage[MAX_SHORT_STRING_BYTE_COUNT] = { 0 };
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};
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static_assert(HostIsLittleEndian, "Order of fields in ShortString assumes LE.");
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static_assert(sizeof(ShortString) >= sizeof(StringData*));
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static_assert(__builtin_offsetof(ShortString, byte_count_and_short_string_flag) == 0);
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class StringBase {
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public:
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StringBase(StringBase const&);
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constexpr StringBase(StringBase&& other)
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: m_short_string(other.m_short_string)
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{
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other.m_short_string = ShortString {};
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other.m_short_string.byte_count_and_short_string_flag = SHORT_STRING_FLAG;
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}
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StringBase& operator=(StringBase&&);
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StringBase& operator=(StringBase const&);
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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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// Returns the underlying UTF-8 encoded bytes.
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// NOTE: There is no guarantee about null-termination.
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[[nodiscard]] ReadonlyBytes bytes() const;
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[[nodiscard]] bool operator==(StringBase const&) const;
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protected:
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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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explicit StringBase(NonnullRefPtr<Detail::StringData const>);
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explicit constexpr StringBase(ShortString short_string)
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: m_short_string(short_string)
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{
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}
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union {
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ShortString m_short_string;
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Detail::StringData const* m_data { nullptr };
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};
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};
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}
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