[antlr-interest] Code translation: Is it possible to bring the TreeParser back?

[luciano mantuaneli]

Greetings!
I'm developing a Java2C# parser, and I'm having some trouble trying to translate constructors that call the supar class constructor.... In Java, we make that thing like this:

class MyClass extends MyOtherClass{
   public MyClass(Object param){
      super(param);
      /*...*/
   }
}

The corresponding C# code would be like this:

class MyClass: MyOtherClass{
   public MyClass(Object param): base(param){
     /*...*/
   }
}


The tree grammar I using to translate the code from Java to C# have the folowing rules to treat the constructor definition and invocation:

ctorDef :
    CTOR_DEF modifiers 
    ( typeParameters )? 
    methodHead 
    ( slist )? 
    ;

slist :
    SLIST 
    ( stat )* 
    ;

stat :
    typeDefinition 
    | variableDef 
    | expression 
    | //... 
    ;

expression :
    EXPR expr 
    ;

expr :
    conditionalExpr 
    | //...
    ;

conditionalExpr :
    //...
    | primaryExpression 
    ;

primaryExpression :
    //...
    | ctorCall 
    | //...
    ;

ctorCall :
    CTOR_CALL elist 
    | SUPER_CTOR_CALL 
    ( elist | primaryExpression elist ) 
    ;

elist :
    ELIST 
    ( expression )* 
    ;

Well, in C#, the super-constructor invocation is made before the statement list. In Java, that invocations, when exists, is the first statement in the statement list.
My question is: looking to the ctorDef rule, how can I know if the super-constructor was invoked before enter the slist rule?
I need it that way because I'm constructing the translation text like this:

ctorDef{
    MethodHead mh;
    ArrayList<String> mods = new ArrayList<String>();
}
    :    #(ctor:CTOR_DEF 
            mods=modifiers 
            (typeParameters)? 
            mh=methodHead {
                GSB.tab();
                for(String mod: mods)
                    GSB.app(mod + " ");
                GSB.app(mh);
                //if invokes super constructor then GSB.app(":base(" + ??? + ")");
                GSB.app("{");
            }
            (slist)?{
                GSB.less().tab("}").nl();
            }
        )
    ;
GSB is a class of mine that just represents an improved version of StringBuilder (Global String Builder) that have only static methods, which returns an sigleton instance of GSB. I use this clas to mount the C# code.
As you can see, after I append the String returned by the methodHead rule in my GSB, I need to know, before enter the slist rule, if the current constructor invokes the super-constructor...
I tried to do this manipulating directly the "ctor" AST node defined above, in order to find an AST node of type SUPER_CTOR_CALL, and then call directly the method corresponding to ctorCall rule. Obviously, it doesn't work, because I'm not sure if there is a way to walk "two times" over a same tree path...
So, how can I know if there is a super-constructor call, before entering in the slist rule?

Thanks in advance
 

Luciano Mantuaneli
Analist-Programmer
 		
---------------------------------
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