lookup method Null safety

LookupResult lookup(
  1. int offset,
  2. {bool inclusive = false}

Looks up a child Node at specified character offset in this container.

Returns LookupResult. The result may contain found node or null if no node is found at specified offset.

LookupResult.offset is set to relative offset within returned child node which points at the same character position in the document as the original offset.


LookupResult lookup(int offset, {bool inclusive = false}) {
  assert(offset >= 0 && offset <= length);

  for (final node in children) {
    final length = node.length;
    if (offset < length || (inclusive && offset == length && (node.isLast))) {
      return LookupResult(node, offset);
    offset -= length;
  return LookupResult(null, 0);