[antlr-interest] Re: Newbie Question

[Praveen Ray]

Do u have a corresponding Lexer rule to identify the keywords?
Simply defining tokens in the Parser is not enough until there is
a Lexer rule to recognize the keywords in input stream. Also, the
corresponsing Lexer must have 'testLiteral' option set to true.

Try in Lexer (assuming your keywords begin with $ and Uppercase
Letter ):

KEYWORDS 
options
{
   testLiterals = true;
}
: '$' ('A'..'Z' | 'a'..'z')+ ;
and in Parser (wherever u need keywords accessed):
my_rule : "$Begin" (..other production elements etc)

Any literal in Parser is automatically a Lexer Keyword so you dont
need 'tokens' section.
Hope this helps.

--- In antlr-interest at y..., harshadpatel at t... wrote:
> Hi All !
> Im new to antlr and I am struggling to get my simple parser working
> my question is How do I write a grammer 
> to parse keywords beginning with the dollor character
> e.g
> $BeginA
> $BeginB
> $EndB
> $EndA
> 
> 
> I've tried to define tokens such as this -->
> tokens
> {
> BEGIN="$Begin";
> END="$End";
> }
> 
> But I get 
> exception: antlr.TokenStreamRecognitionException: unexpected char: $
> 
> When I run the Parser ???
> 
> Any suggestions anyone 
> Thanks in advance 
> Harshad


 

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