ladybird/Userland/Libraries/LibJS/Runtime/Utf16String.cpp
Andreas Kling 206479b2b5 LibJS: Cache UTF-16 strings on the VM
We were already caching UTF-8 and byte strings, so let's add a cache
for UTF-16 strings as well. This is particularly profitable whenever we
run regular expressions, since the output of regex execution is a set of
UTF-16 strings.

Note that this is a weak cache like the other JS string caches, meaning
that strings are removed from the cache as they are garbage collected.

This avoids billions of PrimitiveString allocations across a run of WPT,
significantly reducing GC activity.
2024-10-24 19:00:00 -04:00

137 lines
3 KiB
C++

/*
* Copyright (c) 2021-2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/StringView.h>
#include <LibJS/Runtime/Utf16String.h>
#include <LibJS/Runtime/VM.h>
namespace JS {
namespace Detail {
static NonnullRefPtr<Utf16StringImpl> the_empty_utf16_string()
{
static NonnullRefPtr<Utf16StringImpl> empty_string = Utf16StringImpl::create();
return empty_string;
}
Utf16StringImpl::Utf16StringImpl(Utf16Data string)
: m_string(move(string))
{
}
NonnullRefPtr<Utf16StringImpl> Utf16StringImpl::create()
{
return adopt_ref(*new Utf16StringImpl);
}
NonnullRefPtr<Utf16StringImpl> Utf16StringImpl::create(Utf16Data string)
{
return adopt_ref(*new Utf16StringImpl(move(string)));
}
NonnullRefPtr<Utf16StringImpl> Utf16StringImpl::create(StringView string)
{
return create(MUST(utf8_to_utf16(string)));
}
NonnullRefPtr<Utf16StringImpl> Utf16StringImpl::create(Utf16View const& view)
{
Utf16Data string;
string.ensure_capacity(view.length_in_code_units());
string.unchecked_append(view.data(), view.length_in_code_units());
return create(move(string));
}
Utf16Data const& Utf16StringImpl::string() const
{
return m_string;
}
Utf16View Utf16StringImpl::view() const
{
return Utf16View { m_string };
}
u32 Utf16StringImpl::compute_hash() const
{
if (m_string.is_empty())
return 0;
return string_hash((char const*)m_string.data(), m_string.size() * sizeof(u16));
}
}
Utf16String Utf16String::create()
{
return Utf16String { Detail::the_empty_utf16_string() };
}
Utf16String Utf16String::create(Utf16Data string)
{
return Utf16String { Detail::Utf16StringImpl::create(move(string)) };
}
Utf16String Utf16String::create(StringView string)
{
return Utf16String { Detail::Utf16StringImpl::create(string) };
}
Utf16String Utf16String::create(Utf16View const& string)
{
return Utf16String { Detail::Utf16StringImpl::create(string) };
}
Utf16String::Utf16String(NonnullRefPtr<Detail::Utf16StringImpl> string)
: m_string(move(string))
{
}
Utf16Data const& Utf16String::string() const
{
return m_string->string();
}
Utf16View Utf16String::view() const
{
return m_string->view();
}
Utf16View Utf16String::substring_view(size_t code_unit_offset, size_t code_unit_length) const
{
return view().substring_view(code_unit_offset, code_unit_length);
}
Utf16View Utf16String::substring_view(size_t code_unit_offset) const
{
return view().substring_view(code_unit_offset);
}
String Utf16String::to_utf8() const
{
return MUST(view().to_utf8(Utf16View::AllowInvalidCodeUnits::Yes));
}
ByteString Utf16String::to_byte_string() const
{
return MUST(view().to_byte_string(Utf16View::AllowInvalidCodeUnits::Yes));
}
u16 Utf16String::code_unit_at(size_t index) const
{
return view().code_unit_at(index);
}
size_t Utf16String::length_in_code_units() const
{
return view().length_in_code_units();
}
bool Utf16String::is_empty() const
{
return view().is_empty();
}
}