[antlr-interest] Skipping or ignoring whole subtrees in a tree grammar

[Hardy, Stephen]

Maybe you needed

  ^('fun' TYPE ID .+)

since ". ."  would only match two subtrees, which would only be the case
if you had exactly one "param".  As I understand it, the * or +
modifiers create flat lists, not a single root node with * or + number
of subtrees, since the dummy "nil" root gets flattened out by rule
post-processing.

Regards,
SJH



> -----Original Message-----
> From: Frank Smith [mailto:fasmith718 at gmail.com] 
> Sent: Monday, August 13, 2007 10:37 AM
> To: Hardy, Stephen
> Cc: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Skipping or ignoring whole 
> subtrees in a tree grammar
> 
> The wildcard is an interesting beast.
> 
> Only use it on the bare minimum amount of stuff in your 
> grammar (e.g. only the rule you need skipped!), because I had 
> some seemingly unrelated errors crop up in my grammar that I 
> ended up tracing back to overusing the wildcard in some rules. 
> 
> in my case it was:
> 
> ^('fun' TYPE ID param* block)
> 
> worked perfectly with:
> ^('fun' TYPE ID param* .)
> 
> and caused all kinds of heartache with:
> ^('fun' TYPE ID . .)
> 
> so even though i didn't use param in the action that followed 
> i left it in there for the sake of it actually working :)
> 
> good luck with yours