Visit a parse tree, and return a user-defined result of the operation.
Visit the children of a node, and return a user-defined result of the operation.
Visit an error node, and return a user-defined result of the operation.
Visit a terminal node, and return a user-defined result of the operation.
This interface defines the basic notion of a parse tree visitor. Generated visitors implement this interface and the {@code XVisitor} interface for grammar {@code X}.
@param <T> The return type of the visit operation. Use {@link Void} for operations with no return type.