Re: Unable to use error recovery with bison

f.tomassetti@gmail.com (Federico Tomassetti) wrote:


> I spent the last days trying to make error recovery working but I
> can't catch one and yyerror is always invoked:
>
> I report a portion from the lex source, yacc source and file parsed.
>
> I always obtain the message "syntax error, unexpected NEWLINE,
> expecting SPACE"


Looking at your grammar, you have
    voidspace: SPACE | TAB | NEWLINE
    ;
thus only admitting eaxctly one of the three, for example in your rule
    class_decl_header:
                    KWCLASS SPACE CLASSNAME
You probably want any number of these.


It is common to let the lexer zip out the whitespace by .l rules:
    [ \f\r\t\v]+ {}
    \n+ {}
The idea here is to also break up longer rule matches, as the Flex
generated lexer otherwise may get into buffer problems, slowing it down.


--
    Hans Aberg

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