[antlr-interest] Are ANTLR grammars space sensitive?

[Terence Parr]

Howdy...yeah, the action parser "sucks" at the moment...sorry. careful  
of spaces in args, actions.
Ter
On Apr 9, 2008, at 9:26 AM, Edson Tirelli wrote:

>
>    All,
>
>    While playing with ANTLR during the weekend in my quest for  
> learning AST/Tree grammars I found an odd situation. The following  
> rule generates compilation errors:
>
> key_sentence
> @init {
>         String text = "";
> }
>     : variable_definition
>     | cb=key_chunk { text = $cb.text; }
>     -> ^(VT_LITERAL[ $cb.start, text ] )
>     ;
>
>    Errors are:
>
> [13:15:53] /tmp/antlrworks/DSLMapParser.java:1313: illegal start of  
> expression
> [13:15:53]                         root_1 =  
> (Object)adaptor.becomeRoot(adaptor.create(VT_LITERAL,  ,  
> ((Token)cb.start),  text ), root_1);
> [13 
> : 
> 15 
> : 
> 53 
> ]                                                                                         ^
> [13:15:53] /tmp/antlrworks/DSLMapParser.java:1313: ')' expected
> [13:15:53]                         root_1 =  
> (Object)adaptor.becomeRoot(adaptor.create(VT_LITERAL,  ,  
> ((Token)cb.start),  text ), root_1);
> [13 
> : 
> 15 
> : 
> 53 
> ]                                                                                                                              ^
> [13:15:53] 2 errors
>
>    Removing the spaces from inside the [], fixes the problem:
>
>     -> ^(VT_LITERAL[$cb.start, text] )
>
>    Is this known behavior? bug? I found no reference about it.
>
>    Also, on a related question, as you can see in the rule, I'm  
> using a dummy "text" variable to capture the text matched by the  
> "key_chunk" rule. That is because simply writing:
>
>     -> ^(VT_LITERAL[$cb.start, $cb.text] )
>
>    Also generate compilation errors:
>
> [13:23:12] /tmp/antlrworks/DSLMapParser.java:1313: illegal start of  
> expression
> [13:23:12]                         root_1 =  
> (Object)adaptor.becomeRoot(adaptor.create(VT_LITERAL,  
> ((Token)cb.start),  , input.toString(cb.start,cb.stop)), root_1);
> [13 
> : 
> 23 
> : 
> 12 
> ]                                                                                                            ^
> [13:23:12] /tmp/antlrworks/DSLMapParser.java:1313: ')' expected
> [13:23:12]                         root_1 =  
> (Object)adaptor.becomeRoot(adaptor.create(VT_LITERAL,  
> ((Token)cb.start),  , input.toString(cb.start,cb.stop)), root_1);
> [13 
> : 
> 23 
> : 
> 12 
> ]                                                                                                                                                        ^
> [13:23:12] 2 errors
>
>
>     Any idea if it is possible to avoid creating the dummy variable?  
> I just prefer to keep the grammar as clean as possible...
>
>     Thanks
>            Edson
>
> -- 
> Edson Tirelli
> JBoss Drools Core Development
> Office: +55 11 3529-6000
> Mobile: +55 11 9287-5646
> JBoss, a division of Red Hat @ www.jboss.com

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