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

[Andi Clemens]

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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