[antlr-interest] fragments..

Gavin Lambert antlr at mirality.co.nz
Mon Mar 26 05:23:54 PDT 2007

At 22:20 26/03/2007, Tobias Pape wrote:
 >BinarySelector :
 >( Equal ) =>
 >   Equal {$type=Equal;}
 >fragment Equal : '=' ;
 >My problem is, when I change the Equal Rule, to be 
 >antlr warns me about Token Equal not beeing accessible.
 >h248:~/dev/parsertest tobias$ antlr_ SOM.g
 >no such locale file org/antlr/tool/templates/messages/languages/ 

 >de.stg retrying with English locale
 >ANTLR Parser Generator  Version 3.0b7 (??, 2007)  1989-2007
 >warning(208): SOM.g:461:1: The following token definitions are
 >unreachable: Equal
 >weird, huh?

Not really, that makes sense.  It *is* inaccessible, because the 
BinarySelector rule will match it first.  You should probably list 
your 'primitive' tokens first, giving them the chance to match and 
output first, and most of them probably shouldn't be fragments, 
since you're actually trying to output them.  (You shouldn't use 
{$type = x;} for any x that is a fragment.)

Actually I don't really see the point of the whole BinarySelector 
rule.  It seems too disconnected to be a useful rule.  Especially 
since it doesn't even seem to be an output token in itself.

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