[type]
Parser

[grammar]
grammar T;
myset: ('b'|'c') ;
a: 'a' myset 'd' {<writeln(Append("\"\"","$myset.stop"))>} ; <! bit complicated because of the JavaScript target !>

[start]
a

[input]
aabd

[output]
"""[@2,2:2='b',<1>,1:2]
"""

[errors]
"""line 1:1 extraneous input 'a' expecting {'b', 'c'}
"""