Processing child nodes with variable start index in visitor

[raffian]

I am building an AST model for C.g4 using visitor strategy but having some difficulty modeling postfixExpression rule.

postfixExpression
    :
    (   primaryExpression  | '(' typeName ')' '{' initializerList '}' )
    (   '[' expression ']'
      | '(' argumentExpressionList? ')'
      | ('.' | '->') Identifier
      | '++'
      | '--'
    )*
    ;

postfixExpression is a two-part production; I added some comments to highlight these parts.

• [1] primaryExpression OR compound literal (typeName/initializerList)
• [2] list of postfix expressions/operators 0..*

postfixExpression
    : // [1] 
      // primary expression OR compound literal
    ( primaryExpression | '('typeName')' '{'initializerList'}' )
    
      // [2]
     //arbitrary list of postfix expressions or operators 0..*
    ('[' expression ']'
     | '(' argumentExpressionList? ')'
     | ('.' | '->') Identifier
     | '++'
     | '--'
    )*
    ;

When [1] produces primaryExpression, accumulate remaining child nodes in [2] to produce the list of postfix expressions. The for loop starts at 1 to account for the first child in the context at index 0 - primaryExpression; this works fine.

    postfixExpression.setPrimaryExprNode(visit(ctx.primaryExpression()));
    List<Expression> postfixExprList;
    //i starts at 1 for [1]->primaryExpression
    for (int i = 1; i < ctx.getChildCount(); i++) {
        postfixExprList.add(visit(ctx.getChild(i)));
    }

PROBLEM
When [1] produces a compound literal (typeName/initializerList), accumulate remaining child nodes in [2] but offset i to 6 in the for loop since '('typeName')' '{'initializerList'}' accounts for the first 6 child nodes in the context. While this solution works, it's brittle and doesn't feel right; any minor change to this rule in the future breaks the logic.

Is there a cleaner way to iterate child nodes in a context when the start index is variable?

    postfixExpression.setCompoundLiteralNode(visit(ctx.typeName()), visit(ctx.initializerList()));
    List<Expression> postfixExprList;
    //i starts at 6 for [1]->typeName/initializerList
    for (int i = 6; i < ctx.getChildCount(); i++) {
        postfixExprList.add(visit(ctx.getChild(i)));
    }