在AST访问者中，我如何知道我正在访问哪个节点的属性？

Question

I'm programming an AST Visitor (eclipse JDT).

An EnumDeclaration node contains the following structural properties:

JAVADOC , MODIFIERS , NAME , SUPER_INTERFACE_TYPES , ENUM_CONSTANTS and BODY_DECLARATIONS .

When I visit a child node of EnumDeclaration (a SimpleName node, for instance), is it possible to know which of the lists of nodes I'm visiting? Is it possible to differentiate?

I'd like to process a node differently, depending on whether I found it in ENUM_CONSTANTS or BODY_DECLARATIONS .

Answer 1

I found a solution. Explicitly visiting the nodes in the list (WITH accept() , not visit() ). Something like (for visiting the super interfaces):

List<Type> superInterfaces = enumDecNode.superInterfaceTypes();
for( Type superInterface: superInterfaces)
    superInterface.accept( this);

Note that it is not possible to use:

    this.visit( superInterface);

because Type is an umbrella abstract class for which no visit( Type node) implementation exists.

This also forces the children of the nodes in the superInterfaces list to be visited as soon as their parent is visited. Problem solved.

On a side note, if you already process all the children of a node via these lists, you can forbid the visitor from re-visiting its children, by returning false.

Answer 2

Your nodes should invoke corresponding methods.

MODIFIERS -> visitModifiers 
NAME -> visitNAME

and so on

Answer 3

Another alternative solution (thanks to Markus Keller @ eclipse JDT forum):

Use "node.getLocationInParent() == EnumDeclaration.NAME_PROPERTY" or other *_PROPERTY constants.

Markus