ladybird/AK/Utf8View.cpp
Andreas Kling 391352c112 AK: Inline all the trivial Utf8View functions
This improves parsing time on a large chunk of JS by ~3%.
2021-09-18 19:54:24 +02:00

290 lines
8.3 KiB
C++

/*
* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
* Copyright (c) 2021, Max Wipfli <mail@maxwipfli.ch>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/Format.h>
#include <AK/Utf8View.h>
namespace AK {
Utf8CodePointIterator Utf8View::iterator_at_byte_offset(size_t byte_offset) const
{
size_t current_offset = 0;
for (auto iterator = begin(); !iterator.done(); ++iterator) {
if (current_offset >= byte_offset)
return iterator;
current_offset += iterator.underlying_code_point_length_in_bytes();
}
return end();
}
size_t Utf8View::byte_offset_of(const Utf8CodePointIterator& it) const
{
VERIFY(it.m_ptr >= begin_ptr());
VERIFY(it.m_ptr <= end_ptr());
return it.m_ptr - begin_ptr();
}
size_t Utf8View::byte_offset_of(size_t code_point_offset) const
{
size_t byte_offset = 0;
for (auto it = begin(); !it.done(); ++it) {
if (code_point_offset == 0)
return byte_offset;
byte_offset += it.underlying_code_point_length_in_bytes();
--code_point_offset;
}
return byte_offset;
}
Utf8View Utf8View::unicode_substring_view(size_t code_point_offset, size_t code_point_length) const
{
if (code_point_length == 0)
return {};
size_t code_point_index = 0, offset_in_bytes = 0;
for (auto iterator = begin(); !iterator.done(); ++iterator) {
if (code_point_index == code_point_offset)
offset_in_bytes = byte_offset_of(iterator);
if (code_point_index == code_point_offset + code_point_length - 1) {
size_t length_in_bytes = byte_offset_of(++iterator) - offset_in_bytes;
return substring_view(offset_in_bytes, length_in_bytes);
}
++code_point_index;
}
VERIFY_NOT_REACHED();
}
static inline bool decode_first_byte(
unsigned char byte,
size_t& out_code_point_length_in_bytes,
u32& out_value)
{
if ((byte & 128) == 0) {
out_value = byte;
out_code_point_length_in_bytes = 1;
return true;
}
if ((byte & 64) == 0) {
return false;
}
if ((byte & 32) == 0) {
out_value = byte & 31;
out_code_point_length_in_bytes = 2;
return true;
}
if ((byte & 16) == 0) {
out_value = byte & 15;
out_code_point_length_in_bytes = 3;
return true;
}
if ((byte & 8) == 0) {
out_value = byte & 7;
out_code_point_length_in_bytes = 4;
return true;
}
return false;
}
bool Utf8View::validate(size_t& valid_bytes) const
{
valid_bytes = 0;
for (auto ptr = begin_ptr(); ptr < end_ptr(); ptr++) {
size_t code_point_length_in_bytes;
u32 value;
bool first_byte_makes_sense = decode_first_byte(*ptr, code_point_length_in_bytes, value);
if (!first_byte_makes_sense)
return false;
for (size_t i = 1; i < code_point_length_in_bytes; i++) {
ptr++;
if (ptr >= end_ptr())
return false;
if (*ptr >> 6 != 2)
return false;
}
valid_bytes += code_point_length_in_bytes;
}
return true;
}
size_t Utf8View::calculate_length() const
{
size_t length = 0;
for ([[maybe_unused]] auto code_point : *this) {
++length;
}
return length;
}
bool Utf8View::starts_with(const Utf8View& start) const
{
if (start.is_empty())
return true;
if (is_empty())
return false;
if (start.length() > length())
return false;
if (begin_ptr() == start.begin_ptr())
return true;
for (auto k = begin(), l = start.begin(); l != start.end(); ++k, ++l) {
if (*k != *l)
return false;
}
return true;
}
bool Utf8View::contains(u32 needle) const
{
for (u32 code_point : *this) {
if (code_point == needle)
return true;
}
return false;
}
Utf8View Utf8View::trim(const Utf8View& characters, TrimMode mode) const
{
size_t substring_start = 0;
size_t substring_length = byte_length();
if (mode == TrimMode::Left || mode == TrimMode::Both) {
for (auto code_point = begin(); code_point != end(); ++code_point) {
if (substring_length == 0)
return {};
if (!characters.contains(*code_point))
break;
substring_start += code_point.underlying_code_point_length_in_bytes();
substring_length -= code_point.underlying_code_point_length_in_bytes();
}
}
if (mode == TrimMode::Right || mode == TrimMode::Both) {
size_t seen_whitespace_length = 0;
for (auto code_point = begin(); code_point != end(); ++code_point) {
if (characters.contains(*code_point))
seen_whitespace_length += code_point.underlying_code_point_length_in_bytes();
else
seen_whitespace_length = 0;
}
if (seen_whitespace_length >= substring_length)
return {};
substring_length -= seen_whitespace_length;
}
return substring_view(substring_start, substring_length);
}
Utf8CodePointIterator& Utf8CodePointIterator::operator++()
{
VERIFY(m_length > 0);
size_t code_point_length_in_bytes = underlying_code_point_length_in_bytes();
if (code_point_length_in_bytes > m_length) {
// We don't have enough data for the next code point. Skip one character and try again.
// The rest of the code will output replacement characters as needed for any eventual extension bytes we might encounter afterwards.
dbgln("Expected code point size {} is too big for the remaining length {}. Moving forward one byte.", code_point_length_in_bytes, m_length);
m_ptr += 1;
m_length -= 1;
return *this;
}
m_ptr += code_point_length_in_bytes;
m_length -= code_point_length_in_bytes;
return *this;
}
size_t Utf8CodePointIterator::underlying_code_point_length_in_bytes() const
{
VERIFY(m_length > 0);
size_t code_point_length_in_bytes = 0;
u32 value;
bool first_byte_makes_sense = decode_first_byte(*m_ptr, code_point_length_in_bytes, value);
// If any of these tests fail, we will output a replacement character for this byte and treat it as a code point of size 1.
if (!first_byte_makes_sense)
return 1;
if (code_point_length_in_bytes > m_length)
return 1;
for (size_t offset = 1; offset < code_point_length_in_bytes; offset++) {
if (m_ptr[offset] >> 6 != 2)
return 1;
}
return code_point_length_in_bytes;
}
ReadonlyBytes Utf8CodePointIterator::underlying_code_point_bytes() const
{
return { m_ptr, underlying_code_point_length_in_bytes() };
}
u32 Utf8CodePointIterator::operator*() const
{
VERIFY(m_length > 0);
u32 code_point_value_so_far = 0;
size_t code_point_length_in_bytes = 0;
bool first_byte_makes_sense = decode_first_byte(m_ptr[0], code_point_length_in_bytes, code_point_value_so_far);
if (!first_byte_makes_sense) {
// The first byte of the code point doesn't make sense: output a replacement character
dbgln("First byte doesn't make sense: {:#02x}.", m_ptr[0]);
return 0xFFFD;
}
if (code_point_length_in_bytes > m_length) {
// There is not enough data left for the full code point: output a replacement character
dbgln("Not enough bytes (need {}, have {}), first byte is: {:#02x}.", code_point_length_in_bytes, m_length, m_ptr[0]);
return 0xFFFD;
}
for (size_t offset = 1; offset < code_point_length_in_bytes; offset++) {
if (m_ptr[offset] >> 6 != 2) {
// One of the extension bytes of the code point doesn't make sense: output a replacement character
dbgln("Extension byte {:#02x} in {} position after first byte {:#02x} doesn't make sense.", m_ptr[offset], offset, m_ptr[0]);
return 0xFFFD;
}
code_point_value_so_far <<= 6;
code_point_value_so_far |= m_ptr[offset] & 63;
}
return code_point_value_so_far;
}
Optional<u32> Utf8CodePointIterator::peek(size_t offset) const
{
if (offset == 0) {
if (this->done())
return {};
return this->operator*();
}
auto new_iterator = *this;
for (size_t index = 0; index < offset; ++index) {
++new_iterator;
if (new_iterator.done())
return {};
}
return *new_iterator;
}
}