mirror of
https://github.com/LadybirdBrowser/ladybird.git
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290 lines
8.3 KiB
C++
290 lines
8.3 KiB
C++
/*
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* Copyright (c) 2021, Tim Flynn <trflynn89@pm.me>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/StringBuilder.h>
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#include <AK/StringView.h>
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#include <AK/Utf16View.h>
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#include <AK/Utf32View.h>
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#include <AK/Utf8View.h>
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namespace AK {
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static constexpr u16 high_surrogate_min = 0xd800;
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static constexpr u16 high_surrogate_max = 0xdbff;
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static constexpr u16 low_surrogate_min = 0xdc00;
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static constexpr u16 low_surrogate_max = 0xdfff;
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static constexpr u32 replacement_code_point = 0xfffd;
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static constexpr u32 first_supplementary_plane_code_point = 0x10000;
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template<typename UtfViewType>
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static Vector<u16, 1> to_utf16_impl(UtfViewType const& view) requires(IsSame<UtfViewType, Utf8View> || IsSame<UtfViewType, Utf32View>)
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{
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Vector<u16, 1> utf16_data;
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utf16_data.ensure_capacity(view.length());
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for (auto code_point : view)
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code_point_to_utf16(utf16_data, code_point);
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return utf16_data;
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}
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Vector<u16, 1> utf8_to_utf16(StringView const& utf8_view)
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{
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return to_utf16_impl(Utf8View { utf8_view });
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}
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Vector<u16, 1> utf8_to_utf16(Utf8View const& utf8_view)
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{
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return to_utf16_impl(utf8_view);
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}
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Vector<u16, 1> utf32_to_utf16(Utf32View const& utf32_view)
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{
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return to_utf16_impl(utf32_view);
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}
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void code_point_to_utf16(Vector<u16, 1>& string, u32 code_point)
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{
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VERIFY(is_unicode(code_point));
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if (code_point < first_supplementary_plane_code_point) {
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string.append(static_cast<u16>(code_point));
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} else {
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code_point -= first_supplementary_plane_code_point;
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string.append(static_cast<u16>(high_surrogate_min | (code_point >> 10)));
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string.append(static_cast<u16>(low_surrogate_min | (code_point & 0x3ff)));
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}
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}
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bool Utf16View::is_high_surrogate(u16 code_unit)
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{
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return (code_unit >= high_surrogate_min) && (code_unit <= high_surrogate_max);
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}
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bool Utf16View::is_low_surrogate(u16 code_unit)
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{
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return (code_unit >= low_surrogate_min) && (code_unit <= low_surrogate_max);
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}
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u32 Utf16View::decode_surrogate_pair(u16 high_surrogate, u16 low_surrogate)
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{
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VERIFY(is_high_surrogate(high_surrogate));
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VERIFY(is_low_surrogate(low_surrogate));
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return ((high_surrogate - high_surrogate_min) << 10) + (low_surrogate - low_surrogate_min) + first_supplementary_plane_code_point;
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}
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String Utf16View::to_utf8(AllowInvalidCodeUnits allow_invalid_code_units) const
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{
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StringBuilder builder;
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if (allow_invalid_code_units == AllowInvalidCodeUnits::Yes) {
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for (auto const* ptr = begin_ptr(); ptr < end_ptr(); ++ptr) {
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if (is_high_surrogate(*ptr)) {
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auto const* next = ptr + 1;
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if ((next < end_ptr()) && is_low_surrogate(*next)) {
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auto code_point = decode_surrogate_pair(*ptr, *next);
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builder.append_code_point(code_point);
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++ptr;
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continue;
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}
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}
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builder.append_code_point(static_cast<u32>(*ptr));
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}
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} else {
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for (auto code_point : *this)
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builder.append_code_point(code_point);
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}
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return builder.build();
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}
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size_t Utf16View::length_in_code_points() const
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{
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if (!m_length_in_code_points.has_value())
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m_length_in_code_points = calculate_length_in_code_points();
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return *m_length_in_code_points;
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}
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u16 Utf16View::code_unit_at(size_t index) const
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{
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VERIFY(index < length_in_code_units());
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return m_code_units[index];
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}
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u32 Utf16View::code_point_at(size_t index) const
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{
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VERIFY(index < length_in_code_units());
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u32 code_point = code_unit_at(index);
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if (!is_high_surrogate(code_point) && !is_low_surrogate(code_point))
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return code_point;
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if (is_low_surrogate(code_point) || (index + 1 == length_in_code_units()))
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return code_point;
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auto second = code_unit_at(index + 1);
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if (!is_low_surrogate(second))
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return code_point;
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return decode_surrogate_pair(code_point, second);
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}
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size_t Utf16View::code_point_offset_of(size_t code_unit_offset) const
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{
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size_t code_point_offset = 0;
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for (auto it = begin(); it != end(); ++it) {
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if (code_unit_offset == 0)
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return code_point_offset;
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code_unit_offset -= it.length_in_code_units();
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++code_point_offset;
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}
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return code_point_offset;
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}
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size_t Utf16View::code_unit_offset_of(size_t code_point_offset) const
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{
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size_t code_unit_offset = 0;
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for (auto it = begin(); it != end(); ++it) {
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if (code_point_offset == 0)
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return code_unit_offset;
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code_unit_offset += it.length_in_code_units();
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--code_point_offset;
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}
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return code_unit_offset;
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}
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Utf16View Utf16View::substring_view(size_t code_unit_offset, size_t code_unit_length) const
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{
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VERIFY(!Checked<size_t>::addition_would_overflow(code_unit_offset, code_unit_length));
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VERIFY(code_unit_offset + code_unit_length <= length_in_code_units());
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return Utf16View { m_code_units.slice(code_unit_offset, code_unit_length) };
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}
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Utf16View Utf16View::unicode_substring_view(size_t code_point_offset, size_t code_point_length) const
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{
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if (code_point_length == 0)
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return {};
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auto code_unit_offset_of = [&](Utf16CodePointIterator const& it) { return it.m_ptr - begin_ptr(); };
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size_t code_point_index = 0;
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size_t code_unit_offset = 0;
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for (auto it = begin(); it != end(); ++it) {
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if (code_point_index == code_point_offset)
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code_unit_offset = code_unit_offset_of(it);
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if (code_point_index == (code_point_offset + code_point_length - 1)) {
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size_t code_unit_length = code_unit_offset_of(++it) - code_unit_offset;
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return substring_view(code_unit_offset, code_unit_length);
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}
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++code_point_index;
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}
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VERIFY_NOT_REACHED();
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}
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bool Utf16View::validate(size_t& valid_code_units) const
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{
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valid_code_units = 0;
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for (auto const* ptr = begin_ptr(); ptr < end_ptr(); ++ptr) {
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if (is_high_surrogate(*ptr)) {
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if ((++ptr >= end_ptr()) || !is_low_surrogate(*ptr))
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return false;
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++valid_code_units;
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} else if (is_low_surrogate(*ptr)) {
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return false;
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}
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++valid_code_units;
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}
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return true;
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}
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size_t Utf16View::calculate_length_in_code_points() const
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{
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size_t code_points = 0;
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for ([[maybe_unused]] auto code_point : *this)
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++code_points;
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return code_points;
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}
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bool Utf16View::equals_ignoring_case(Utf16View const& other) const
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{
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if (length_in_code_units() == 0)
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return other.length_in_code_units() == 0;
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if (length_in_code_units() != other.length_in_code_units())
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return false;
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for (size_t i = 0; i < length_in_code_units(); ++i) {
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// FIXME: Handle non-ASCII case insensitive comparisons.
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if (to_ascii_lowercase(m_code_units[i]) != to_ascii_lowercase(other.m_code_units[i]))
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return false;
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}
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return true;
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}
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Utf16CodePointIterator& Utf16CodePointIterator::operator++()
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{
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size_t code_units = length_in_code_units();
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if (code_units > m_remaining_code_units) {
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// If there aren't enough code units remaining, skip to the end.
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m_ptr += m_remaining_code_units;
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m_remaining_code_units = 0;
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} else {
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m_ptr += code_units;
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m_remaining_code_units -= code_units;
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}
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return *this;
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}
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u32 Utf16CodePointIterator::operator*() const
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{
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VERIFY(m_remaining_code_units > 0);
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if (Utf16View::is_high_surrogate(*m_ptr)) {
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if ((m_remaining_code_units > 1) && Utf16View::is_low_surrogate(*(m_ptr + 1)))
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return Utf16View::decode_surrogate_pair(*m_ptr, *(m_ptr + 1));
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return replacement_code_point;
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} else if (Utf16View::is_low_surrogate(*m_ptr)) {
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return replacement_code_point;
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}
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return static_cast<u32>(*m_ptr);
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}
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size_t Utf16CodePointIterator::length_in_code_units() const
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{
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VERIFY(m_remaining_code_units > 0);
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if (Utf16View::is_high_surrogate(*m_ptr)) {
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if ((m_remaining_code_units > 1) && Utf16View::is_low_surrogate(*(m_ptr + 1)))
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return 2;
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}
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// If this return is reached, either the encoded code point is a valid single code unit, or that
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// code point is invalid (e.g. began with a low surrogate, or a low surrogate did not follow a
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// high surrogate). In the latter case, a single replacement code unit will be used.
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return 1;
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}
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}
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