[type]
Parser

[grammar]
grammar T;
s
@init {
<BuildParseTrees()>
}
@after {
<ToStringTree("$r.ctx"):writeln()>
}
  : r=a ;
a : 'x' 'y'* '!'
  ;
Z : 'z'
  ;

[start]
s

[input]
xzyy!

[output]
"""(a x z y y !)
"""

[errors]
"""line 1:1 extraneous input 'z' expecting {'y', '!'}
"""