diff_match_patch.prototype.patch_splitMax = function()

in pontoon/base/static/js/lib/diff.js [1947:2031]
85 lines of code
20 McCabe index (conditional complexity)

diff_match_patch.prototype.patch_splitMax = function(patches) {
  var patch_size = this.Match_MaxBits;
  for (var x = 0; x < patches.length; x++) {
    if (patches[x].length1 <= patch_size) {
      continue;
    }
    var bigpatch = patches[x];
    // Remove the big old patch.
    patches.splice(x--, 1);
    var start1 = bigpatch.start1;
    var start2 = bigpatch.start2;
    var precontext = '';
    while (bigpatch.diffs.length !== 0) {
      // Create one of several smaller patches.
      var patch = new diff_match_patch.patch_obj();
      var empty = true;
      patch.start1 = start1 - precontext.length;
      patch.start2 = start2 - precontext.length;
      if (precontext !== '') {
        patch.length1 = patch.length2 = precontext.length;
        patch.diffs.push([DIFF_EQUAL, precontext]);
      }
      while (bigpatch.diffs.length !== 0 &&
             patch.length1 < patch_size - this.Patch_Margin) {
        var diff_type = bigpatch.diffs[0][0];
        var diff_text = bigpatch.diffs[0][1];
        if (diff_type === DIFF_INSERT) {
          // Insertions are harmless.
          patch.length2 += diff_text.length;
          start2 += diff_text.length;
          patch.diffs.push(bigpatch.diffs.shift());
          empty = false;
        } else if (diff_type === DIFF_DELETE && patch.diffs.length == 1 &&
                   patch.diffs[0][0] == DIFF_EQUAL &&
                   diff_text.length > 2 * patch_size) {
          // This is a large deletion.  Let it pass in one chunk.
          patch.length1 += diff_text.length;
          start1 += diff_text.length;
          empty = false;
          patch.diffs.push([diff_type, diff_text]);
          bigpatch.diffs.shift();
        } else {
          // Deletion or equality.  Only take as much as we can stomach.
          diff_text = diff_text.substring(0,
              patch_size - patch.length1 - this.Patch_Margin);
          patch.length1 += diff_text.length;
          start1 += diff_text.length;
          if (diff_type === DIFF_EQUAL) {
            patch.length2 += diff_text.length;
            start2 += diff_text.length;
          } else {
            empty = false;
          }
          patch.diffs.push([diff_type, diff_text]);
          if (diff_text == bigpatch.diffs[0][1]) {
            bigpatch.diffs.shift();
          } else {
            bigpatch.diffs[0][1] =
                bigpatch.diffs[0][1].substring(diff_text.length);
          }
        }
      }
      // Compute the head context for the next patch.
      precontext = this.diff_text2(patch.diffs);
      precontext =
          precontext.substring(precontext.length - this.Patch_Margin);
      // Append the end context for this patch.
      var postcontext = this.diff_text1(bigpatch.diffs)
                            .substring(0, this.Patch_Margin);
      if (postcontext !== '') {
        patch.length1 += postcontext.length;
        patch.length2 += postcontext.length;
        if (patch.diffs.length !== 0 &&
            patch.diffs[patch.diffs.length - 1][0] === DIFF_EQUAL) {
          patch.diffs[patch.diffs.length - 1][1] += postcontext;
        } else {
          patch.diffs.push([DIFF_EQUAL, postcontext]);
        }
      }
      if (!empty) {
        patches.splice(++x, 0, patch);
      }
    }
  }
};