canParse method
Implementation
@override
bool canParse(BlockParser parser) {
// Check if it matches `hrPattern`, otherwise it will produce an infinite
// loop if put `UnorderedListSyntax` or `UnorderedListWithCheckboxSyntax`
// bofore `HorizontalRuleSyntax` and parse:
// ```
// * * *
// ```
if (hrPattern.hasMatch(parser.current.content)) {
return false;
}
return pattern.hasMatch(parser.current.content);
}