[antlr-interest] NullPointerException in actions for recurring rules
Terence Parr
parrt at cs.usfca.edu
Sun Jun 26 09:57:34 PDT 2011
did you give token stream to the tree parser?
Ter
On Jun 26, 2011, at 6:03 AM, Dariusz Dwornikowski wrote:
> Hello Again,
>
> What is the proper way to handle expression on abstract symbols (instead of
> 1+2+3+4, ive got only a+b+c etc)
>
>
> rmdef returns [ProcessDef process]
> : ^(PEPADEF pan=IDENT a=expression)
> {
> process = new ProcessDef();
> process.setLHS($pan.text);
> }
> ;
>
> expression
> : ^(COOP a=expression b=expression)
> | ^(PREFIX a=expression b=expression) { print($a.text); }
> | ^(CHOICE a=expression b=expression)
> | procek=IDENT
> ;
>
>
>
> In this case print($a.text); causes NullPointerException,
>
>
> --
> Pozdrawiam,
> -----------------------------------------------------------------------------
> Dariusz Dwornikowski,
> Institute of Computing Science, Poznań University of Technology
> www.cs.put.poznan.pl/ddwornikowski/
> room 421 WE | tel. +48 61 665 21 24 | mobile: +48 533 890 600
> -----------------------------------------------------------------------------
>
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