[antlr-interest] Reusing grammars

[Ian McDonagh]

Hi all

I want to implement my own template language (like Velocity, JSP or ASP) and reuse an existing ANTLR 3.0 grammar I've written for evaluating expressions.

I might have something like this:
________________________________________
Contacts:
@foreach( getPeople(lastName) )
Name: ${Name}
@end
________________________________________

This input would be parsed to construct a template, which is made up of various nodes, which could in turn be merged with a context to produce the template output.  The parsed template structure would look something like this:
#Text:"Contacts:"
#ForEach: getPeople(lastName)
|----#Text:"Name: "
|----#Expression: Name

My problem is that my expression language uses some of the same tokens I want to use in my template language, so it's difficult to use a lexical filter only (which is pretty simple with tags like '<%' and '%>').

Is it possible to parse the entire input in one pass, switching between different parsers?

With ANTLR 2.7 I could just use grammar inheritance.  What to do in ANTLR 3?

Any advice would be greatly appreciated.
Thanks.






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