ladybird/AK/StringImpl.cpp
Andreas Kling 2dd3b54827 AK: Make CaseInsensitiveStringTraits allocation-free
Instead of calling String::to_lowercase(), do case-insensitive hashing
and comparison.
2022-02-19 14:45:59 +01:00

151 lines
3.9 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/CharacterTypes.h>
#include <AK/FlyString.h>
#include <AK/HashTable.h>
#include <AK/Memory.h>
#include <AK/StdLibExtras.h>
#include <AK/StringHash.h>
#include <AK/StringImpl.h>
#include <AK/kmalloc.h>
namespace AK {
static StringImpl* s_the_empty_stringimpl = nullptr;
StringImpl& StringImpl::the_empty_stringimpl()
{
if (!s_the_empty_stringimpl) {
void* slot = kmalloc(sizeof(StringImpl) + sizeof(char));
s_the_empty_stringimpl = new (slot) StringImpl(ConstructTheEmptyStringImpl);
}
return *s_the_empty_stringimpl;
}
StringImpl::StringImpl(ConstructWithInlineBufferTag, size_t length)
: m_length(length)
{
}
StringImpl::~StringImpl()
{
if (m_fly)
FlyString::did_destroy_impl({}, *this);
}
NonnullRefPtr<StringImpl> StringImpl::create_uninitialized(size_t length, char*& buffer)
{
VERIFY(length);
void* slot = kmalloc(allocation_size_for_stringimpl(length));
VERIFY(slot);
auto new_stringimpl = adopt_ref(*new (slot) StringImpl(ConstructWithInlineBuffer, length));
buffer = const_cast<char*>(new_stringimpl->characters());
buffer[length] = '\0';
return new_stringimpl;
}
RefPtr<StringImpl> StringImpl::create(const char* cstring, size_t length, ShouldChomp should_chomp)
{
if (!cstring)
return nullptr;
if (should_chomp) {
while (length) {
char last_ch = cstring[length - 1];
if (!last_ch || last_ch == '\n' || last_ch == '\r')
--length;
else
break;
}
}
if (!length)
return the_empty_stringimpl();
char* buffer;
auto new_stringimpl = create_uninitialized(length, buffer);
memcpy(buffer, cstring, length * sizeof(char));
return new_stringimpl;
}
RefPtr<StringImpl> StringImpl::create(const char* cstring, ShouldChomp shouldChomp)
{
if (!cstring)
return nullptr;
if (!*cstring)
return the_empty_stringimpl();
return create(cstring, strlen(cstring), shouldChomp);
}
RefPtr<StringImpl> StringImpl::create(ReadonlyBytes bytes, ShouldChomp shouldChomp)
{
return StringImpl::create(reinterpret_cast<const char*>(bytes.data()), bytes.size(), shouldChomp);
}
RefPtr<StringImpl> StringImpl::create_lowercased(char const* cstring, size_t length)
{
if (!cstring)
return nullptr;
if (!length)
return the_empty_stringimpl();
char* buffer;
auto impl = create_uninitialized(length, buffer);
for (size_t i = 0; i < length; ++i)
buffer[i] = (char)to_ascii_lowercase(cstring[i]);
return impl;
}
RefPtr<StringImpl> StringImpl::create_uppercased(char const* cstring, size_t length)
{
if (!cstring)
return nullptr;
if (!length)
return the_empty_stringimpl();
char* buffer;
auto impl = create_uninitialized(length, buffer);
for (size_t i = 0; i < length; ++i)
buffer[i] = (char)to_ascii_uppercase(cstring[i]);
return impl;
}
NonnullRefPtr<StringImpl> StringImpl::to_lowercase() const
{
for (size_t i = 0; i < m_length; ++i) {
if (is_ascii_upper_alpha(characters()[i]))
return create_lowercased(characters(), m_length).release_nonnull();
}
return const_cast<StringImpl&>(*this);
}
NonnullRefPtr<StringImpl> StringImpl::to_uppercase() const
{
for (size_t i = 0; i < m_length; ++i) {
if (is_ascii_lower_alpha(characters()[i]))
return create_uppercased(characters(), m_length).release_nonnull();
}
return const_cast<StringImpl&>(*this);
}
unsigned StringImpl::case_insensitive_hash() const
{
return case_insensitive_string_hash(characters(), length());
}
void StringImpl::compute_hash() const
{
if (!length())
m_hash = 0;
else
m_hash = string_hash(characters(), m_length);
m_has_hash = true;
}
}