diff_match_patch.prototype.patch_fromText = function()

in kitsune/sumo/static/sumo/js/libs/diff_match_patch_uncompressed.js [2057:2125]
67 lines of code
15 McCabe index (conditional complexity)

diff_match_patch.prototype.patch_fromText = function(textline) {
  var patches = [];
  if (!textline) {
    return patches;
  }
  var text = textline.split('\n');
  var textPointer = 0;
  var patchHeader = /^@@ -(\d+),?(\d*) \+(\d+),?(\d*) @@$/;
  while (textPointer < text.length) {
    var m = text[textPointer].match(patchHeader);
    if (!m) {
      throw new Error('Invalid patch string: ' + text[textPointer]);
    }
    var patch = new diff_match_patch.patch_obj();
    patches.push(patch);
    patch.start1 = parseInt(m[1], 10);
    if (m[2] === '') {
      patch.start1--;
      patch.length1 = 1;
    } else if (m[2] == '0') {
      patch.length1 = 0;
    } else {
      patch.start1--;
      patch.length1 = parseInt(m[2], 10);
    }

    patch.start2 = parseInt(m[3], 10);
    if (m[4] === '') {
      patch.start2--;
      patch.length2 = 1;
    } else if (m[4] == '0') {
      patch.length2 = 0;
    } else {
      patch.start2--;
      patch.length2 = parseInt(m[4], 10);
    }
    textPointer++;

    while (textPointer < text.length) {
      var sign = text[textPointer].charAt(0);
      try {
        var line = decodeURI(text[textPointer].substring(1));
      } catch (ex) {
        // Malformed URI sequence.
        throw new Error('Illegal escape in patch_fromText: ' + line);
      }
      if (sign == '-') {
        // Deletion.
        patch.diffs.push([DIFF_DELETE, line]);
      } else if (sign == '+') {
        // Insertion.
        patch.diffs.push([DIFF_INSERT, line]);
      } else if (sign == ' ') {
        // Minor equality.
        patch.diffs.push([DIFF_EQUAL, line]);
      } else if (sign == '@') {
        // Start of next patch.
        break;
      } else if (sign === '') {
        // Blank line?  Whatever.
      } else {
        // WTF?
        throw new Error('Invalid patch mode "' + sign + '" in: ' + line);
      }
      textPointer++;
    }
  }
  return patches;
};