[antlr-interest] Tell ANTLR to ignore parsing errors?

[Jim Idle]

No - don’t make whitespace significant unless the language absolutely makes you do so.

What you have to do is left factor:

create
    : CREATE
    (
           cr_table
        | cr_user
        | cr_trigger
    )
 ;

cr_table
 : TABLE .....

Jim

> -----Original Message-----
> From: Andi Clemens [mailto:Andi.Clemens at gmx.net]
> Sent: Thursday, September 09, 2010 9:57 AM
> To: Jim Idle; antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Tell ANTLR to ignore parsing errors?
> 
> Ok, thanks for the answers.
> 
> One final question: Would it be better to have tokens like "CREATE USER"
> and "CREATE TABLE" in the lexer or doesn't this work anyway because of the
> whitespace?
> 
> Andi
> 
> -------- Original-Nachricht --------
> > Datum: Thu, 9 Sep 2010 08:26:59 -0700
> > Von: "Jim Idle" <jimi at temporal-wave.com>
> > An: antlr-interest at antlr.org
> > Betreff: Re: [antlr-interest] Tell ANTLR to ignore parsing errors?
> 
> > When putting things in the parser, you have not enough control over
> > the tokens both in terms of what they are named in code generation
> > time (hence error messages are difficult, and producing a tree parser
> > is difficult), and you cannot see the potential ambiguities in your
> > lexer. It just makes things more difficult for no(IMO) advantage.
> >
> > If you have told the input stream to be case insensitive, then I am
> > afraid that the problem is going to be with your grammar. You will
> > have to single step though the code to find out why.
> >
> > Jim
> >
> > > -----Original Message-----
> > > From: Andi Clemens [mailto:Andi.Clemens at gmx.net]
> > > Sent: Thursday, September 09, 2010 7:32 AM
> > > To: Jim Idle; antlr-interest at antlr.org
> > > Subject: Re: [antlr-interest] Tell ANTLR to ignore parsing errors?
> > >
> > > Yes it is case insensitive. What is the difference if I add "CREATE"
> > > or
> > similar to
> > > the lexer?
> > > Is it more reliable in detecting the right tokens?
> > >
> > > Andi
> > >
> > > -------- Original-Nachricht --------
> > > > Datum: Thu, 9 Sep 2010 07:21:45 -0700
> > > > Von: "Jim Idle" <jimi at temporal-wave.com>
> > > > An: antlr-interest at antlr.org
> > > > Betreff: Re: [antlr-interest] Tell ANTLR to ignore parsing errors?
> > >
> > > > If you are getting errors it is because your grammar is incorrect.
> > > > Oracle SQL is a huge grammar to undertake and you cannot 'hack' it.
> > > > Your token in the parser (which you should move to the lexer
> > > > anyway
> > and
> > > not use 'LITERAL'
> > > > in your parser code) is CREATEE but your input is create. Did you
> > > > tell the runtime to be case insensitive?
> > > >
> > > > Read the API or use antlr.markmail.org to see how to override
> > > > displayRecognitionError(). You cannot just ignore errors though
> > > > because somehow you have to recover. You could just make them
> > > > silent and when the parser returns if the error count is >0 then
> > > > ignore that
> > source
> > > or something.
> > > >
> > > > I will have a commercial version of Oracle SQOL and PLSQL
> > > > available before too long too.
> > > >
> > > > Jim
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> > > > > bounces at antlr.org] On Behalf Of Andi Clemens
> > > > > Sent: Thursday, September 09, 2010 5:45 AM
> > > > > To: antlr-interest at antlr.org
> > > > > Subject: [antlr-interest] Tell ANTLR to ignore parsing errors?
> > > > >
> > > > > Hi,
> > > > >
> > > > > I use this ANTLR grammar file to parse Oracle PL/SQL statements:
> > > > > http://pastebin.com/uy0wZTax
> > > > >
> > > > > But some of the statements produce errors when I try to parse
> > > > > them, for
> > > > > example:
> > > > >
> > > > > "create user u1 identified by p1 account unlock;"
> > > > >
> > > > > I get the following error message:
> > > > >
> > > > > ==============================
> > > > > statementString(1)  : error 3 : , at offset -1
> > > > >     near [Index: 0 (Start: 141054912-Stop: 141054917) ='create',
> > > > type<50> Line:
> > > > > 1 LinePos:-1]
> > > > >      : cannot match to any predicted input...
> > > > > ==============================
> > > > >
> > > > > But why? The rule looks like this:
> > > > > ==============================
> > > > > create_user_statement
> > > > > 	:	'CREATE' 'USER' identifier 'INDENTIFIED' .*
> > > > > 	;
> > > > > ==============================
> > > > >
> > > > > Could the wildcard character be the problem?
> > > > > Actually I just want to parse known Statements with my grammar,
> > > > > all unknown statements (parsing errors) could be ignored.
> > > > >
> > > > > Can I tell ANTLR (for the C target) to ignore those error
> > > > > messages and
> > > > just
> > > > > return FALSE or something like that, so that I can decide wether
> > > > > to take
> > > > an
> > > > > appropiate action?
> > > > >
> > > > > I get a lot of those error messages, and to be honest, the error
> > > > messages are
> > > > > not helping me here. I can not see problems with the grammar.
> > > > > Unfortunately I'm not able to debug the grammar with ANTLRworks.
> > > > >
> > > > > Can someone show me the error or tell me a way to disable those
> > > > > error messages in the ANTLR C target?
> > > > >
> > > > > Andi
> > > > >
> > > > > --
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