[antlr-interest] Why BANG after rule id ?

Graham Wideman gwlist at grahamwideman.com
Tue Oct 6 03:15:05 PDT 2009


Hi folks:

I see in the ANTLR grammar that you can place a BANG (exclamation point) after the initial rule id in a rule. Indeed it's used in the ANTLR v3 grammar itself:

----------------------------
range!
  :  c1=CHAR_LITERAL RANGE c2=CHAR_LITERAL elementOptions?
    -> ^(CHAR_RANGE[$c1,".."] $c1 $c2 elementOptions?)
;
----------------------------

Could someone illuminate what this ! does? 

Thanks,   Graham





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