onMatch method
Processes match, adding nodes to parser and possibly advancing
parser.
Returns whether the caller should advance parser by match[0].length.
Implementation
@override
bool onMatch(InlineParser parser, Match match) {
var url = match[1]!;
var text = parser._encodeHtml ? escapeHtml(url) : url;
var anchor = Element.text('a', text);
anchor.attributes['href'] = Uri.encodeFull(url);
parser.addNode(anchor);
return true;
}