b0b022507b
Before this change, each AST node had a 64-byte SourceRange member.
This SourceRange had the following layout:
filename: StringView (16 bytes)
start: Position (24 bytes)
end: Position (24 bytes)
The Position structs have { line, column, offset }, all members size_t.
To reduce memory consumption, AST nodes now only store the following:
source_code: NonnullRefPtr<SourceCode> (8 bytes)
start_offset: u32 (4 bytes)
end_offset: u32 (4 bytes)
SourceCode is a new ref-counted data structure that keeps the filename
and original parsed source code in a single location, and all AST nodes
have a pointer to it.
The start_offset and end_offset can be turned into (line, column) when
necessary by calling SourceCode::range_from_offsets(). This will walk
the source code string and compute line/column numbers on the fly, so
it's not necessarily fast, but it should be rare since this information
is primarily used for diagnostics and exception stack traces.
With this, ASTNode shrinks from 80 bytes to 32 bytes. This gives us a
~23% reduction in memory usage when loading twitter.com/awesomekling
(330 MiB before, 253 MiB after!) :^)
81 lines
1.8 KiB
C++
81 lines
1.8 KiB
C++
/*
|
|
* Copyright (c) 2022, Andreas Kling <kling@serenityos.org>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#include <AK/Utf8View.h>
|
|
#include <LibJS/SourceCode.h>
|
|
#include <LibJS/SourceRange.h>
|
|
#include <LibJS/Token.h>
|
|
|
|
namespace JS {
|
|
|
|
NonnullRefPtr<SourceCode> SourceCode::create(String filename, String code)
|
|
{
|
|
return adopt_ref(*new SourceCode(move(filename), move(code)));
|
|
}
|
|
|
|
SourceCode::SourceCode(String filename, String code)
|
|
: m_filename(move(filename))
|
|
, m_code(move(code))
|
|
{
|
|
}
|
|
|
|
String const& SourceCode::filename() const
|
|
{
|
|
return m_filename;
|
|
}
|
|
|
|
String const& SourceCode::code() const
|
|
{
|
|
return m_code;
|
|
}
|
|
|
|
SourceRange SourceCode::range_from_offsets(u32 start_offset, u32 end_offset) const
|
|
{
|
|
Position start;
|
|
Position end;
|
|
|
|
size_t line = 1;
|
|
size_t column = 1;
|
|
|
|
bool previous_code_point_was_carriage_return = false;
|
|
|
|
Utf8View view(m_code);
|
|
for (auto it = view.begin(); it != view.end(); ++it) {
|
|
|
|
if (start_offset == view.byte_offset_of(it)) {
|
|
start = Position {
|
|
.line = line,
|
|
.column = column,
|
|
.offset = start_offset,
|
|
};
|
|
}
|
|
|
|
if (end_offset == view.byte_offset_of(it)) {
|
|
end = Position {
|
|
.line = line,
|
|
.column = column,
|
|
.offset = end_offset,
|
|
};
|
|
break;
|
|
}
|
|
|
|
u32 code_point = *it;
|
|
|
|
bool is_line_terminator = code_point == '\r' || (code_point == '\n' && !previous_code_point_was_carriage_return) || code_point == LINE_SEPARATOR || code_point == PARAGRAPH_SEPARATOR;
|
|
previous_code_point_was_carriage_return = code_point == '\r';
|
|
|
|
if (is_line_terminator) {
|
|
++line;
|
|
column = 1;
|
|
continue;
|
|
}
|
|
++column;
|
|
}
|
|
|
|
return SourceRange { *this, start, end };
|
|
}
|
|
|
|
}
|