[antlr-interest] Java Grammar

[Simon]

hi

I'm trying to build an AST for a Java like language. The hardest part  
(if you want to built a meaningful AST) is the section of  
unaryExpressionNotPlusMinus (see grammar fragments at end or the  
Java.g grammar on antlr.org).

I have successfully built ASTs for the following constructs (using  
semantic predicates based on a symbol table)

   ^(FIELD_ACCESS target Identifier)
   ^(INVOKE target Identifier arguments)
   ^(ARRAY_ACCESS target expr)

However, I'm struggling with fully qualified type names, such as those  
in

   java.lang.Integer.parseInt("123")

Of course, I want something like

   ^(INVOKE ^(TYPE_REFERENCE ...) arguments)

The problem is that I somehow have to look ahead to detect whether it  
is a qualified type name (don't know how the precedence is if there is  
a variable named java with a field named lang that has a field named  
Integer that has method named parseInt, but that's another problem). I  
could write my own semantic predicate method that looks ahead in the  
input to detect a qualified type name. Is there an easier way to do  
that? Or am I approaching the problem from the wrong side?

I've tried to look at the Java grammar from langtools recently posted  
in this list, but didn't get any smarter (they rely heavily on the  
existing javac classes).

Thanks
Simon



unaryExpressionNotPlusMinus
     :   ...
     |   primary selector* ('++'|'--')?
     ;

primary
     :   parExpression
     |   literal
     |   'new' creator
     |   Identifier ('.' Identifier)* identifierSuffix?   // this is  
the hard / interesting part
     |   primitiveType ('[' ']')* '.' 'class'
     |   'void' '.' 'class'
     ;

identifierSuffix
     :   ('[' ']')+ '.' 'class'
     |   ('[' expression ']')+ // can also be matched by selector, but  
do here
     |   arguments
     |   '.' 'class'
     ;

selector
     :   '.' Identifier arguments?
     |   '[' expression ']'
     ;