[vox-tech] how to get yacc/bison to say "i'm confused"

[Peter Jay Salzman]

newbie here.

i'm using flex/bison for processing a program's user input, and have a
list of rules that define the user input grammar.

after bison processes all it's input, is there a way of telling it:

   if no rule matched the input, take your input and feed it to
   ParseError(const char *error)?

the problem i'm having is typically:

	ruleset:    TOK_RULESET NUMBER    { ChangeRuleset($2); }
		|        TOK_RULESET           { ChangeRuleset(-1); }

if the user types something like "ruleset asdf", it'll match
"TOK_RULESET", and (i think) "asdf" gets put back into the buffer since
it's not a NUMBER, and is processed the next time the user inputs
something.  in other words, bison gets out of sync and confused.

i have a rule like:

	(snip)
	WORD    { ParseError($1); }
	;

and this handles truly garbled input, like "qwerty", but doesn't handle
the situation i outlined above.


thanks,
pete

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