Function parseHunk

src/patch/parse.ts:440–518

()

  // Parses a hunk
  // This assumes that we are at the start of a hunk.
  function parseHunk() {
    const chunkHeaderIndex = i,
        chunkHeaderLine = diffstr[i++],
        chunkHeader = chunkHeaderLine.split(/@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@/);

    const hunk = {
      oldStart: +chunkHeader[1],
      oldLines: typeof chunkHeader[2] === 'undefined' ? 1 : +chunkHeader[2],
      newStart: +chunkHeader[3],
      newLines: typeof chunkHeader[4] === 'undefined' ? 1 : +chunkHeader[4],
      lines: [] as string[]
    };

    // Unified Diff Format quirk: If the chunk size is 0,
    // the first number is one lower than one would expect.
    // https://www.artima.com/weblogs/viewpost.jsp?thread=164293
    if (hunk.oldLines === 0) {
      hunk.oldStart += 1;
    }
    if (hunk.newLines === 0) {
      hunk.newStart += 1;
    }

    let addCount = 0,
        removeCount = 0;
    for (
      ;
      i < diffstr.length && (removeCount < hunk.oldLines || addCount < hunk.newLines || diffstr[i]?.startsWith('\\'));
      i++
    ) {
      const operation = (diffstr[i].length == 0 && i != (diffstr.length - 1)) ? ' ' : diffstr[i][0];
      if (operation === '+' || operation === '-' || operation === ' ' || operation === '\\') {
        hunk.lines.push(diffstr[i]);

        if (operation === '+') {
          addCount++;
        } else if (operation === '-') {
          removeCount++;
        } else if (operation === ' ') {
          addCount++;
          removeCount++;
        }
      } else {
        throw new Error(`Hunk at line ${chunkHeaderIndex + 1} contained invalid line ${diffstr[i]}`);
      }
    }

    // Handle the empty block count case
    if (!addCount && hunk.newLines === 1) {
      hunk.newLines = 0;
    }
    if (!removeCount && hunk.oldLines === 1) {
      hunk.oldLines = 0;
    }

    // Perform sanity checking
    if (addCount !== hunk.newLines) {
      throw new Error('Added line count did not match for hunk at line ' + (chunkHeaderIndex + 1));