(in-package :cl-user)

;; defines a function that creates a function that iterates using the
;; visitor pattern. Name is the name of the function, args has two keywords:
;; CALLER: Initialization form for the think that does the walking
;; INVOKER: Function that is called on the CALLER and the visitor to do the iteration.
;; The visitor java instance is created automatically.
;; Created function needs to have the first argument be a function that will be called for each visit.
;; Arguments to that function are: (caller-java-instance visitor-java-instance &rest arguments-the-visit-function-is-called-with)

(defmacro define-owl-visitor (name args keys)
  (destructuring-bind (&key caller invoker) keys
    (let ((callername (make-symbol "CALLER"))
	  (visitorname (make-symbol "VISITOR")))
      `(defun ,name ,args
	 (let ((,callername ,caller)
	       (,visitorname nil))
	   (setq ,visitorname
		 (jinterface-safe-implementation
		  (find-java-class 'org.semanticweb.owl.model.OWLObjectVisitorEx)
		  "visit"
		  (lambda(&rest args)
		    (Apply ,(car args) ,callername ,visitorname args)
		    (make-immediate-object nil :ref))))
	   (,invoker ,callername ,visitorname)
	   )))))