(match-element?)

[Chris Maden <crism@xxxxxxx>]

I needed this procedure, and couldn't find an implementation.  This is
public, but if anyone has a better way to do it, please share!  (It
relies on (cadr), implementation of which is left as an exercise for
the reader...)

Thanks,
Chris

;; (match-element?) is defined in ISO/IEC 10179, but no implementation
;; is given.
(define (match-element? pattern
			snl)
  (if (list? pattern)
      (let pattern-loop
	((gi-list (reverse pattern))
	 (att-list '())
	 (this-node snl)
	 (matches #t))
	(if matches
	    (if (or (= (length gi-list)
		       0)
		    (node-list-empty? this-node))
		matches
	        (pattern-loop (list-tail gi-list
					 1)
			      (if (list? (car gi-list))
				  (car gi-list)
				  '())
			      (if (list? (car gi-list))
				  this-node
				  (origin this-node))
			      (and matches
				   (if (list? (car gi-list))
				       #t
				       (equal? (car gi-list)
					       (gi this-node)))
				   (if (= (length att-list)
					  0)
				       #t
				       (equal? (cadr att-list)
					       (attribute-string (car att-list)
								 this-node))))))
	    #f))
      (equal? pattern
	      (gi snl))))

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