Blame · stringify.ts

b69ab31	1	/**
b69ab31	2	* Copyright (c) Meta Platforms, Inc. and affiliates.
b69ab31	3	*
b69ab31	4	* This source code is licensed under the MIT license found in the
b69ab31	5	* LICENSE file in the root directory of this source tree.
b69ab31	6	*/
b69ab31	7
b69ab31	8	import type {Hunk, ParsedDiff} from './types';
b69ab31	9	import {DiffType} from './types';
b69ab31	10
b69ab31	11	/**
b69ab31	12	* Convert a parsed diff back to git diff format string.
b69ab31	13	*
b69ab31	14	* This is the reverse operation of parsePatch in parse.ts.
b69ab31	15	*/
b69ab31	16	export function stringifyPatch(parsedDiffs: ParsedDiff[]): string {
b69ab31	17	return parsedDiffs.map(stringifyDiff).join('');
b69ab31	18	}
b69ab31	19
b69ab31	20	function stringifyDiff(diff: ParsedDiff): string {
b69ab31	21	const parts: string[] = [];
b69ab31	22
b69ab31	23	// diff header
b69ab31	24	if (diff.oldFileName && diff.newFileName) {
b69ab31	25	parts.push(`diff --git ${diff.oldFileName} ${diff.newFileName}\n`);
b69ab31	26	}
b69ab31	27
b69ab31	28	// extended header lines
b69ab31	29	if (diff.type === DiffType.Renamed) {
b69ab31	30	const oldName = diff.oldFileName?.replace(/^a\//, '') ?? '';
b69ab31	31	const newName = diff.newFileName?.replace(/^b\//, '') ?? '';
b69ab31	32	parts.push(`rename from ${oldName}\n`);
b69ab31	33	parts.push(`rename to ${newName}\n`);
b69ab31	34	}
b69ab31	35
b69ab31	36	if (diff.type === DiffType.Copied) {
b69ab31	37	const oldName = diff.oldFileName?.replace(/^a\//, '') ?? '';
b69ab31	38	const newName = diff.newFileName?.replace(/^b\//, '') ?? '';
b69ab31	39	parts.push(`copy from ${oldName}\n`);
b69ab31	40	parts.push(`copy to ${newName}\n`);
b69ab31	41	}
b69ab31	42
b69ab31	43	if (diff.oldMode && diff.newMode && diff.oldMode !== diff.newMode) {
b69ab31	44	parts.push(`old mode ${diff.oldMode}\n`);
b69ab31	45	parts.push(`new mode ${diff.newMode}\n`);
b69ab31	46	}
b69ab31	47
b69ab31	48	if (diff.type === DiffType.Added && diff.newMode) {
b69ab31	49	parts.push(`new file mode ${diff.newMode}\n`);
b69ab31	50	}
b69ab31	51
b69ab31	52	if (diff.type === DiffType.Removed && diff.newMode) {
b69ab31	53	parts.push(`deleted file mode ${diff.newMode}\n`);
b69ab31	54	}
b69ab31	55
b69ab31	56	// file headers
b69ab31	57	if (diff.hunks.length > 0) {
b69ab31	58	const oldFile = diff.type === DiffType.Added ? '/dev/null' : (diff.oldFileName ?? '/dev/null');
b69ab31	59	const newFile =
b69ab31	60	diff.type === DiffType.Removed ? '/dev/null' : (diff.newFileName ?? '/dev/null');
b69ab31	61	parts.push(`--- ${oldFile}\n`);
b69ab31	62	parts.push(`+++ ${newFile}\n`);
b69ab31	63	}
b69ab31	64
b69ab31	65	// hunks
b69ab31	66	diff.hunks.forEach(hunk => {
b69ab31	67	parts.push(stringifyHunk(hunk));
b69ab31	68	});
b69ab31	69
b69ab31	70	return parts.join('');
b69ab31	71	}
b69ab31	72
b69ab31	73	function stringifyHunk(hunk: Hunk): string {
b69ab31	74	const parts: string[] = [];
b69ab31	75
b69ab31	76	// Handle the Unified Diff Format quirk:
b69ab31	77	// If the hunk size is 0, the start line is one higher than stored
b69ab31	78	let oldStart = hunk.oldStart;
b69ab31	79	let newStart = hunk.newStart;
b69ab31	80
b69ab31	81	if (hunk.oldLines === 0) {
b69ab31	82	oldStart -= 1;
b69ab31	83	}
b69ab31	84	if (hunk.newLines === 0) {
b69ab31	85	newStart -= 1;
b69ab31	86	}
b69ab31	87
b69ab31	88	// hunk header - always include line count
b69ab31	89	const oldRange = `${oldStart},${hunk.oldLines}`;
b69ab31	90	const newRange = `${newStart},${hunk.newLines}`;
b69ab31	91	parts.push(`@@ -${oldRange} +${newRange} @@\n`);
b69ab31	92
b69ab31	93	// hunk lines
b69ab31	94	hunk.lines.forEach((line, index) => {
b69ab31	95	const delimiter = hunk.linedelimiters[index] ?? '\n';
b69ab31	96	parts.push(line + delimiter);
b69ab31	97	});
b69ab31	98
b69ab31	99	return parts.join('');
b69ab31	100	}