mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2024-11-21 23:20:20 +00:00
04920d06f0
Adds a fast path for valid UTF-16 using `simdutf`, and fall back to the slow path for unmatched surrogates.
366 lines
11 KiB
C++
366 lines
11 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <andreas@ladybird.org>
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* Copyright (c) 2023, Liav A. <liavalb@hotmail.co.il>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/ByteBuffer.h>
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#include <AK/ByteString.h>
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#include <AK/Checked.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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#include <AK/StringData.h>
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#include <AK/StringView.h>
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#include <AK/UnicodeUtils.h>
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#include <AK/Utf16View.h>
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#include <AK/Utf32View.h>
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#include <simdutf.h>
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namespace AK {
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static constexpr auto STRING_BASE_PREFIX_SIZE = sizeof(Detail::StringData);
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static ErrorOr<StringBuilder::Buffer> create_buffer(size_t capacity)
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{
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StringBuilder::Buffer buffer;
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if (capacity > StringBuilder::inline_capacity)
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TRY(buffer.try_ensure_capacity(STRING_BASE_PREFIX_SIZE + capacity));
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TRY(buffer.try_resize(STRING_BASE_PREFIX_SIZE));
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return buffer;
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}
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ErrorOr<StringBuilder> StringBuilder::create(size_t initial_capacity)
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{
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auto buffer = TRY(create_buffer(initial_capacity));
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return StringBuilder { move(buffer) };
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}
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StringBuilder::StringBuilder(size_t initial_capacity)
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: m_buffer(MUST(create_buffer(initial_capacity)))
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{
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}
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StringBuilder::StringBuilder(Buffer buffer)
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: m_buffer(move(buffer))
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{
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}
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inline ErrorOr<void> StringBuilder::will_append(size_t size)
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{
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Checked<size_t> needed_capacity = m_buffer.size();
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needed_capacity += size;
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VERIFY(!needed_capacity.has_overflow());
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// Prefer to completely use the existing capacity first
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if (needed_capacity <= m_buffer.capacity())
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return {};
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Checked<size_t> expanded_capacity = needed_capacity;
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expanded_capacity *= 2;
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VERIFY(!expanded_capacity.has_overflow());
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TRY(m_buffer.try_ensure_capacity(expanded_capacity.value()));
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return {};
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}
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size_t StringBuilder::length() const
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{
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return m_buffer.size() - STRING_BASE_PREFIX_SIZE;
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}
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bool StringBuilder::is_empty() const
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{
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return length() == 0;
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}
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void StringBuilder::trim(size_t count)
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{
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auto decrease_count = min(m_buffer.size(), count);
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m_buffer.resize(m_buffer.size() - decrease_count);
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}
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ErrorOr<void> StringBuilder::try_append(StringView string)
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{
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if (string.is_empty())
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return {};
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TRY(will_append(string.length()));
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TRY(m_buffer.try_append(string.characters_without_null_termination(), string.length()));
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return {};
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}
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ErrorOr<void> StringBuilder::try_append(char ch)
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{
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TRY(will_append(1));
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TRY(m_buffer.try_append(ch));
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return {};
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}
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ErrorOr<void> StringBuilder::try_append_repeated(char ch, size_t n)
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{
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TRY(will_append(n));
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for (size_t i = 0; i < n; ++i)
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TRY(try_append(ch));
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return {};
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}
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void StringBuilder::append(StringView string)
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{
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MUST(try_append(string));
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}
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ErrorOr<void> StringBuilder::try_append(char const* characters, size_t length)
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{
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return try_append(StringView { characters, length });
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}
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void StringBuilder::append(char const* characters, size_t length)
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{
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MUST(try_append(characters, length));
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}
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void StringBuilder::append(char ch)
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{
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MUST(try_append(ch));
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}
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void StringBuilder::append_repeated(char ch, size_t n)
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{
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MUST(try_append_repeated(ch, n));
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}
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ErrorOr<ByteBuffer> StringBuilder::to_byte_buffer() const
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{
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return ByteBuffer::copy(data(), length());
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}
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ByteString StringBuilder::to_byte_string() const
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{
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if (is_empty())
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return ByteString::empty();
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return ByteString((char const*)data(), length());
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}
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ErrorOr<String> StringBuilder::to_string()
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{
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if (m_buffer.is_inline())
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return String::from_utf8(string_view());
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return String::from_string_builder({}, *this);
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}
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String StringBuilder::to_string_without_validation()
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{
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if (m_buffer.is_inline())
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return String::from_utf8_without_validation(string_view().bytes());
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return String::from_string_builder_without_validation({}, *this);
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}
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FlyString StringBuilder::to_fly_string_without_validation() const
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{
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return FlyString::from_utf8_without_validation(string_view().bytes());
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}
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ErrorOr<FlyString> StringBuilder::to_fly_string() const
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{
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return FlyString::from_utf8(string_view());
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}
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u8* StringBuilder::data()
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{
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return m_buffer.data() + STRING_BASE_PREFIX_SIZE;
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}
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u8 const* StringBuilder::data() const
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{
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return m_buffer.data() + STRING_BASE_PREFIX_SIZE;
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}
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StringView StringBuilder::string_view() const
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{
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return m_buffer.span().slice(STRING_BASE_PREFIX_SIZE);
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}
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void StringBuilder::clear()
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{
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m_buffer.resize(STRING_BASE_PREFIX_SIZE);
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}
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ErrorOr<void> StringBuilder::try_append_code_point(u32 code_point)
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{
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auto nwritten = TRY(AK::UnicodeUtils::try_code_point_to_utf8(code_point, [this](char c) { return try_append(c); }));
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if (nwritten < 0) {
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TRY(try_append(0xef));
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TRY(try_append(0xbf));
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TRY(try_append(0xbd));
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}
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return {};
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}
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void StringBuilder::append_code_point(u32 code_point)
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{
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if (code_point <= 0x7f) {
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m_buffer.append(static_cast<char>(code_point));
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} else if (code_point <= 0x07ff) {
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(void)will_append(2);
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m_buffer.append(static_cast<char>((((code_point >> 6) & 0x1f) | 0xc0)));
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m_buffer.append(static_cast<char>((((code_point >> 0) & 0x3f) | 0x80)));
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} else if (code_point <= 0xffff) {
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(void)will_append(3);
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m_buffer.append(static_cast<char>((((code_point >> 12) & 0x0f) | 0xe0)));
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m_buffer.append(static_cast<char>((((code_point >> 6) & 0x3f) | 0x80)));
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m_buffer.append(static_cast<char>((((code_point >> 0) & 0x3f) | 0x80)));
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} else if (code_point <= 0x10ffff) {
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(void)will_append(4);
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m_buffer.append(static_cast<char>((((code_point >> 18) & 0x07) | 0xf0)));
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m_buffer.append(static_cast<char>((((code_point >> 12) & 0x3f) | 0x80)));
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m_buffer.append(static_cast<char>((((code_point >> 6) & 0x3f) | 0x80)));
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m_buffer.append(static_cast<char>((((code_point >> 0) & 0x3f) | 0x80)));
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} else {
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(void)will_append(3);
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m_buffer.append(0xef);
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m_buffer.append(0xbf);
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m_buffer.append(0xbd);
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}
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}
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ErrorOr<void> StringBuilder::try_append(Utf16View const& utf16_view)
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{
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if (utf16_view.is_empty())
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return {};
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auto maximum_utf8_length = UnicodeUtils::maximum_utf8_length_from_utf16(utf16_view.span());
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// Possibly over-allocate a little to ensure we don't have to allocate later.
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TRY(will_append(maximum_utf8_length));
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Utf16View remaining_view = utf16_view;
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for (;;) {
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auto uninitialized_data_pointer = static_cast<char*>(m_buffer.end_pointer());
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// Fast path.
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auto result = [&]() {
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switch (remaining_view.endianness()) {
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case Endianness::Host:
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return simdutf::convert_utf16_to_utf8_with_errors(remaining_view.char_data(), remaining_view.length_in_code_units(), uninitialized_data_pointer);
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case Endianness::Big:
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return simdutf::convert_utf16be_to_utf8_with_errors(remaining_view.char_data(), remaining_view.length_in_code_units(), uninitialized_data_pointer);
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case Endianness::Little:
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return simdutf::convert_utf16le_to_utf8_with_errors(remaining_view.char_data(), remaining_view.length_in_code_units(), uninitialized_data_pointer);
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}
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VERIFY_NOT_REACHED();
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}();
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if (result.error == simdutf::SUCCESS) {
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auto bytes_just_written = result.count;
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m_buffer.set_size(m_buffer.size() + bytes_just_written);
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break;
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}
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// Slow path. Found unmatched surrogate code unit.
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auto first_invalid_code_unit = result.count;
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ASSERT(first_invalid_code_unit < remaining_view.length_in_code_units());
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// Unfortunately, `simdutf` does not tell us how many bytes it just wrote in case of an error, so we have to calculate it ourselves.
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auto bytes_just_written = [&]() {
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switch (remaining_view.endianness()) {
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case Endianness::Host:
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return simdutf::utf8_length_from_utf16(remaining_view.char_data(), first_invalid_code_unit);
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case Endianness::Big:
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return simdutf::utf8_length_from_utf16be(remaining_view.char_data(), first_invalid_code_unit);
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case Endianness::Little:
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return simdutf::utf8_length_from_utf16le(remaining_view.char_data(), first_invalid_code_unit);
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}
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VERIFY_NOT_REACHED();
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}();
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do {
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auto code_unit = remaining_view.code_unit_at(first_invalid_code_unit++);
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// Invalid surrogate code units are U+D800 - U+DFFF, so they are always encoded using 3 bytes.
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ASSERT(code_unit >= 0xD800 && code_unit <= 0xDFFF);
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ASSERT(m_buffer.size() + bytes_just_written + 3 < m_buffer.capacity());
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uninitialized_data_pointer[bytes_just_written++] = (((code_unit >> 12) & 0x0f) | 0xe0);
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uninitialized_data_pointer[bytes_just_written++] = (((code_unit >> 6) & 0x3f) | 0x80);
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uninitialized_data_pointer[bytes_just_written++] = (((code_unit >> 0) & 0x3f) | 0x80);
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} while (first_invalid_code_unit < remaining_view.length_in_code_units() && Utf16View::is_low_surrogate(remaining_view.data()[first_invalid_code_unit]));
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// Code unit might no longer be invalid, retry on the remaining data.
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m_buffer.set_size(m_buffer.size() + bytes_just_written);
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remaining_view = remaining_view.substring_view(first_invalid_code_unit);
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}
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return {};
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}
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void StringBuilder::append(Utf16View const& utf16_view)
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{
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MUST(try_append(utf16_view));
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}
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ErrorOr<void> StringBuilder::try_append(Utf32View const& utf32_view)
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{
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for (size_t i = 0; i < utf32_view.length(); ++i) {
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auto code_point = utf32_view.code_points()[i];
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TRY(try_append_code_point(code_point));
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}
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return {};
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}
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void StringBuilder::append(Utf32View const& utf32_view)
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{
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MUST(try_append(utf32_view));
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}
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void StringBuilder::append_as_lowercase(char ch)
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{
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if (ch >= 'A' && ch <= 'Z')
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append(ch + 0x20);
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else
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append(ch);
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}
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void StringBuilder::append_escaped_for_json(StringView string)
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{
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MUST(try_append_escaped_for_json(string));
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}
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ErrorOr<void> StringBuilder::try_append_escaped_for_json(StringView string)
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{
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for (auto ch : string) {
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switch (ch) {
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case '\b':
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TRY(try_append("\\b"sv));
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break;
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case '\n':
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TRY(try_append("\\n"sv));
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break;
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case '\t':
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TRY(try_append("\\t"sv));
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break;
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case '\"':
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TRY(try_append("\\\""sv));
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break;
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case '\\':
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TRY(try_append("\\\\"sv));
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break;
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default:
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if (ch >= 0 && ch <= 0x1f)
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TRY(try_appendff("\\u{:04x}", ch));
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else
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TRY(try_append(ch));
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}
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}
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return {};
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}
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auto StringBuilder::leak_buffer_for_string_construction(Badge<Detail::StringData>) -> Optional<Buffer::OutlineBuffer>
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{
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if (auto buffer = m_buffer.leak_outline_buffer({}); buffer.has_value()) {
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clear();
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return buffer;
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}
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return {};
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}
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}
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