perf: memoize Rope::from_str(source_text)

[Boshen]

oxc/crates/oxc_transformer/src/react/utils.rs

Lines 3 to 19 in a96866d

	/// Get line and column from offset and source text.
	///
	/// Line number starts at 1.
	/// Column number is in UTF-16 characters, and starts at 1.
	///
	/// This matches Babel's output.
	pub fn get_line_column(offset: u32, source_text: &str) -> (usize, usize) {
	let offset = offset as usize;
	let rope = Rope::from_str(source_text);
	// Get line number and byte offset of start of line
	let line_index = rope.byte_to_line(offset);
	let line_offset = rope.line_to_byte(line_index);
	// Get column number
	let column_index = source_text[line_offset..offset].encode_utf16().count();
	// line and column are zero-indexed, but we want 1-indexed
	(line_index + 1, column_index + 1)
	}

oxc/crates/oxc_language_server/src/linter.rs

Lines 373 to 381 in 2514cc9

	fn offset_to_position(offset: usize, source_text: &str) -> Option<Position> {
	let rope = Rope::from_str(source_text);
	let line = rope.try_byte_to_line(offset).ok()?;
	let first_char_of_line = rope.try_line_to_char(line).ok()?;
	// Original offset is byte, but Rope uses char offset
	let offset = rope.try_byte_to_char(offset).ok()?;
	let column = offset - first_char_of_line;
	Some(Position::new(line as u32, column as u32))
	}

Rope::from_str(source_text) is too expensive.

[IWANABETHATGUY]

You could just use lineArray, if you don't need incremental remove and add a string.

[IWANABETHATGUY]

This remind me a blog long time ago, https://code.visualstudio.com/blogs/2018/03/23/text-buffer-reimplementation