[antlr-interest] Problem parsing grammer for a label

[Gary Brown]

Thanks a lot - that was the problem.

I knew it was going to be something simple :(

Regards
Gary


On Sun, Aug 1, 2010 at 9:19 PM, John B. Brodie <jbb at acm.org> wrote:

> Greetings!
>
> On Sun, 2010-08-01 at 20:57 +0100, Gary Brown wrote:
> > Hi
> >
> > I have a stripped down grammer where I want to have a keyword, followed
> by
> > an ID, then ':' and then a block demarcated by '{' and '}'. The grammer
> is:
> >
> > grammar ParserTest;
> >
> > options {
> >     output=AST;
> > }
> >
> > tokens {
> >     PLUS     = '+' ;
> >     MINUS    = '-' ;
> >     MULT    = '*' ;
> >     DIV    = '/' ;
> >     FULLSTOP = '.' ;
> > }
> >
> > @header {
> > package test;
> > }
> >
> > @lexer::header {
> > package test;
> > }
> >
> > recurDef: 'recur'^ labelName ':'! blockDef ;
> > labelName: ID ;
> > blockDef: '{'! '}'! ;
> >
> > ID : ('a'..'z'|'A'..'Z'|'_')('a'..'z'|'A'..'Z'|'0'..'9'|'_')* ;
> > URL : (ID|':'|'?'|'/')+ ;
> > NUMBER    : (DIGIT)+ ;
> > WHITESPACE : ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+     { $channel =
> > HIDDEN; } ;
> > fragment DIGIT    : '0'..'9' ;
> >
> >
> > When I used the generated parser against the following:
> >
> > recur Transaction: {
> > }
> >
> >
> > I get the following error:
> >
> > line 1:6 mismatched input 'Transaction:' expecting ID
> >
> > Shouldn't the lexical analyser recognize the 'Transaction' part as an ID,
> > and then the colon as a separate character. If the ':'! is removed from
> the
> > rule, and the content changes to
> >
> > recur Transaction{
> > }
> >
> > it correctly detects the ID as being distinct from the following '{'
> > character. So why is the ':' being treated as a special case?
>
> the input string `Transaction:` is a URL under your rules.
>
> try `Transaction :`
>
> it is probably just this stripped down example example, but since URL is
> not used, just remove that rule...
>
> >
> > Any guidance would be appreciated.
> >
>
> Hope this helps...
>    -jbb
>
>
>