union method

SourceSpan union (SourceSpan other)
override

Creates a new span that's the union of this and other.

The two spans must have the same source URL and may not be disjoint. text is computed by combining this.text and other.text.

Implementation 

SourceSpan union(SourceSpan other) {
  if (sourceUrl != other.sourceUrl) {
    throw new ArgumentError("Source URLs \"${sourceUrl}\" and "
        " \"${other.sourceUrl}\" don't match.");
  }

  var start = min(this.start, other.start);
  var end = max(this.end, other.end);
  var beginSpan = start == this.start ? this : other;
  var endSpan = end == this.end ? this : other;

  if (beginSpan.end.compareTo(endSpan.start) < 0) {
    throw new ArgumentError("Spans $this and $other are disjoint.");
  }

  var text = beginSpan.text +
      endSpan.text.substring(beginSpan.end.distance(endSpan.start));
  return new SourceSpan(start, end, text);
}