[antlr-interest] null pointer to ADAPTOR->setTokenBoundaries

[Jim Idle]

Ah, hang on. Why have you got (segment+)? And you are discarding yoru line number and rewriting in the subrule.

Try this first:

line
   : line_number? segment* K_NEWLINE
	
        ->^(STMT line_number? segment*)

   | oword_stmt

        ->^(STMT oword_stmt)
;

The problem is that your telling me that the cardinality of segment is + but it is in fact *. I am pretty sure that this will work then.

Jim


> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Alan Condit
> Sent: Thursday, May 20, 2010 8:05 AM
> To: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] null pointer to ADAPTOR-
> >setTokenBoundaries
> 
> I can put two of the productions in separate rules but the first two
> productions are really one split for simplicity of writing the rewrite
> rules.
> 
> Without the rewrite rules it is this
> line	:	line_number? segment* K_NEWLINE
> 	| 	oword_stmt
> 	;
> 
> With the rewrite rules you can get to this
> line	:	line_number? ((segment+)? -> ^(STMT segment+)?) K_NEWLINE
> 	| 	oword_stmt
> 		-> ^(STMT oword_stmt)
> 	;
> 
> You can split those two productions into two separate rules but they
> ultimately have to be combined. Like shown below:
> program	:	stmt
> 	;
> 
> stmt	:	line+
> 	;
> 
> line	:	line_number? ((segment+)? -> ^(STMT segment+)?) K_NEWLINE
> 	| 	oword_stmt
> 		-> ^(STMT oword_stmt)
> 	;
> 
> So by splitting them you would get something like this:
> program	:	stmt
> 	;
> 
> stmt	:	line+
> 		    ;
> 
> line	:	sline
> 	| 	oline
> 	;
> 
> 		// a segment line can have 0 to several segments
> 		// but segment lines with 0 segments should not be in the
> AST tree
> sline	:	line_number? ((segment+)? -> ^(STMT segment+)?) K_NEWLINE
> 	;
> 
> oline
> 	| 	oword_stmt
> 		-> ^(STMT oword_stmt)
> 	;
> 
> The line_number and the K_NEWLINE token are never in the tree. Bottom
> line is you still have to deal with an empty rewrite rule.
> 
> Alan
> 
> jim wrote:
> 
> I think you will have to put those three productions in separate rules,
> but I will look into it more.
> 
> Jim
> 
> > -----Original Message-----
> > From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> > bounces at antlr.org] On Behalf Of Alan Condit
> > Sent: Wednesday, May 19, 2010 2:06 PM
> > To: antlr-interest at antlr.org
> > Subject: Re: [antlr-interest] null pointer to ADAPTOR-
> >> setTokenBoundaries
> >
> > Jim,
> >
> > Here is what I have set in options:
> > options {
> > 	backtrack 	= 	true;
> > 	memoize		= 	true;
> > 	language	=	C;
> > 	output		=	AST;
> > 	ASTLabelType	=	pANTLR3_BASE_TREE;
> > 	}
> >
> > The null is inside 'ctx' inside 'adaptor' at 'setTokenBoundaries'.
> >
> > It is inside a function
> > /**
> > * $ANTLR start line
> > *
> >
> /Users/acondit/source/GCCnv/LatheBranch/trunk/Parser/RS274ngc.g:184:1:
> > line : ( ( line_number )? ( segment )+ K_NEWLINE -> ^( STMT ( segment
> > )+ ) | ( line_number )? K_NEWLINE -> | oword_stmt -> ^( STMT
> oword_stmt
> > ) );
> > */
> > static RS274ngcParser_line_return
> > line(pRS274ngcParser ctx)
> > {
> > ...
> > }
> >
> > which I assume, based on the comment, is generated from this rule:
> > line	:	line_number? segment+ K_NEWLINE
> > 		-> ^(STMT segment+)
> > 	|	line_number? K_NEWLINE
> > 		->
> > 	|	oword_stmt
> > 		-> ^(STMT oword_stmt)
> > 	;
> >
> > The grammar is for parsing an existing language not one of my
> > invention, and grammatically the newlines delineate a semantic block
> > therefore must be known by the parser, but empty lines are discarded
> > and therefore should not be in the tree.
> >
> > Alan
> > ---
> >
> > Alan's MachineWorks
> > 1085 Tierra Ct.
> > Woodburn, OR 97071
> >
> > Email -- acondit at alansmachineworks.com
> > www.alansmachineworks.com
> >
> > Jim wrote--
> > Please post more information about your grammar, what the null
> pointer
> > is, etc. It is hard to interpolate, but the common mistake is not
> > adding output=AST; to the options, so you do not get a tree adaptor
> > created.
> >
> > Jim
> >> -----Original Message-----
> >> From: antlr-interest-bounces at antlr.org
> > [mailto:antlr-interest-
> >> bounces at antlr.org
> > ] On Behalf Of Alan Condit
> >
> >> Sent: Wednesday, May 19, 2010 11:25 AM
> >> To: antlr-interest at antlr.org
> >> Subject: [antlr-interest] null pointer to ADAPTOR-
> >setTokenBoundaries
> >>
> >> Help!!!
> >>
> >> I am getting a null pointer to setTokenBoundaries in the following
> > line
> >> of generated code.
> >> "ADAPTOR->setTokenBoundaries(ADAPTOR, retval.tree, retval.start,
> >> retval.stop);"
> >>
> >> The grammar works under Java.  In moving it back to 'C', I changed
> > the
> >> language option to 'C', added option ASTLabelType=pANTLR3_BASE_TREE;
> >> and added the necessary includes to compile and link under
> Objective-
> > C.
> >>
> >> Is there anything obvious that I am doing wrong?
> >>
> >> Thanks,
> >> Alan
> >>
> 
> 
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