[antlr-interest] the ^ character in an ANTLR grammar

David Richards masterxor at rcn.com
Sun Dec 10 12:06:08 PST 2006

Hello -
I'm an ANTLR newbie and was wondering about the calc.g grammar file in
examples/java/calc that came with version 2.7.7. The online tutorial (An
Introduction to ANTLR by Terence Paar) states the following grammar rule for
an expression:

expr:   mexpr ((PLUS|MINUS) mexpr)*

But the rule that I see in examples/java/calc/calc.g states it as follows:

	:	mexpr (PLUS^ mexpr)* SEMI!

What exactly does the '^' character mean in an ANTLR grammar? I searched
high and low with out success...
Many Thanks!

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