;;; This code was based on Arthur Lemmens' in
;;; <URL:http://groups.google.com/groups?as_umsgid=39F36F1A.B8F19D20%40simplex.nl>;

(in-package :cxml)

(defun split-sequence-if (predicate seq &key (count nil) (remove-empty-subseqs nil) (from-end nil) (start 0) (end nil) (key nil key-supplied))
  (let ((len (length seq))
        (other-keys (when key-supplied 
		      (list :key key))))
    (unless end (setq end len))
    (if from-end
        (loop for right = end then left
              for left = (max (or (apply #'position-if predicate seq 
					 :end right
					 :from-end t
					 other-keys)
				  -1)
			      (1- start))
              unless (and (= right (1+ left))
                          remove-empty-subseqs) ; empty subseq we don't want
              if (and count (>= nr-elts count))
              ;; We can't take any more. Return now.
              return (values (nreverse subseqs) right)
              else 
              collect (subseq seq (1+ left) right) into subseqs
              and sum 1 into nr-elts
              until (< left start)
              finally (return (values (nreverse subseqs) (1+ left))))
      (loop for left = start then (+ right 1)
            for right = (min (or (apply #'position-if predicate seq 
					:start left
					other-keys)
				 len)
			     end)
            unless (and (= right left) 
                        remove-empty-subseqs) ; empty subseq we don't want
            if (and count (>= nr-elts count))
            ;; We can't take any more. Return now.
            return (values subseqs left)
            else
            collect (subseq seq left right) into subseqs
            and sum 1 into nr-elts
            until (>= right end)
            finally (return (values subseqs right))))))