Function swapPrefix

src/patch/reverse.ts:3–14

(fileName: string | undefined)

import type { StructuredPatch } from '../types.js';

function swapPrefix(fileName: string | undefined): string | undefined {
  if (fileName === undefined || fileName === '/dev/null') {
    return fileName;
  }
  if (fileName.startsWith('a/')) {
    return 'b/' + fileName.slice(2);
  }
  if (fileName.startsWith('b/')) {
    return 'a/' + fileName.slice(2);
  }
  return fileName;
}

/**
 * Returns a new structured patch which when applied will undo the original `patch`.