@pierre/diffs/dist/utils/computeFileOffsets.js

//#region src/utils/computeFileOffsets.ts
const LINE_FEED = 10;
const CARRIAGE_RETURN = 13;
const DENSE_LINE_BREAK_BLOCK_SIZE = 4;
const DENSE_LINE_BREAK_BLOCK_SPAN = 40;
/**
* Computes line start offsets for a string.
*/
function computeLineOffsets(contents) {
	const offsets = [0];
	let carriageReturn = contents.indexOf("\r");
	let lineFeed = contents.indexOf("\n");
	let blockStart = 0;
	let blockBreaks = 0;
	while (carriageReturn !== -1 || lineFeed !== -1) {
		let nextOffset;
		if (carriageReturn !== -1 && (lineFeed === -1 || carriageReturn < lineFeed)) if (lineFeed === carriageReturn + 1) {
			nextOffset = lineFeed + 1;
			carriageReturn = contents.indexOf("\r", nextOffset);
			lineFeed = contents.indexOf("\n", nextOffset);
		} else {
			nextOffset = carriageReturn + 1;
			carriageReturn = contents.indexOf("\r", nextOffset);
		}
		else {
			nextOffset = lineFeed + 1;
			lineFeed = contents.indexOf("\n", nextOffset);
		}
		offsets.push(nextOffset);
		if (++blockBreaks === DENSE_LINE_BREAK_BLOCK_SIZE) {
			if (nextOffset - blockStart <= DENSE_LINE_BREAK_BLOCK_SPAN) {
				for (let i = nextOffset; i < contents.length; i++) {
					const char = contents.charCodeAt(i);
					if (char === LINE_FEED || char === CARRIAGE_RETURN) {
						if (char === CARRIAGE_RETURN && i + 1 < contents.length && contents.charCodeAt(i + 1) === LINE_FEED) i++;
						offsets.push(i + 1);
					}
				}
				return offsets;
			}
			blockStart = nextOffset;
			blockBreaks = 0;
		}
	}
	return offsets;
}
/**
* Counts line breaks in a string, treating `\n`, `\r`, and `\r\n` the same way
* {@link computeLineOffsets} does (a `\r\n` pair is one break). Mirrors that
* scan but counts in a single pass instead of building and discarding an
* offsets array, so sizing the changed-line range for large edits stays cheap.
* A unit test asserts it stays in lockstep with `computeLineOffsets`.
*/
function countLineBreaks(contents) {
	let count = 0;
	for (let i = 0; i < contents.length; i++) {
		const char = contents.charCodeAt(i);
		if (char === LINE_FEED || char === CARRIAGE_RETURN) {
			if (char === CARRIAGE_RETURN && i + 1 < contents.length && contents.charCodeAt(i + 1) === LINE_FEED) i++;
			count++;
		}
	}
	return count;
}
/**
* Splits file contents into lines aligned with {@link computeLineOffsets}.
* Unlike splitFileContents, a trailing newline produces a final empty line.
*/
function linesFromFileContents(contents) {
	const offsets = computeLineOffsets(contents);
	return Array.from({ length: offsets.length }, (_, i) => {
		const start = offsets[i];
		const end = offsets[i + 1] ?? contents.length;
		return contents.slice(start, end);
	});
}
//#endregion
export { computeLineOffsets, countLineBreaks, linesFromFileContents };

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