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) {
final alias = match[1]!;
final emoji = emojis[alias];
if (emoji == null) {
parser.advanceBy(1);
return false;
}
parser.addNode(Text(emoji));
return true;
}