error recovering

  How can i recover from a error which, doesn't have a "terminator"??


Where is the problem:


suppose we have a language which must begin with a 'begin'


so we have the start symbol:


program : BEGIN
                      blah blah
                    END_PROGRAM
                  | error {print msg that says that program MUST begin
with a begin}
                ;


this works, but the program NEVER recovers. it keeps saying, must begin
with BEGIN no matter what is issued.


examples:


ee
begin




doesn't work. :-(


Any thoughts????


                                                  Tiago Umm Pascoal
                                                l41484@alfa.ist.utl.pt
[Yacc's approach to error recovery is to throw tokens away, so you need to
add error rules that provide the tokens you need, e.g.:


end_token: END_PROGRAM | error ;


-John]


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