;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; This file is part of "NOVA":  NOVA = search + COCOMO tools
; Copyright, 2008, Tim Menzies tim@menzies.us
;
; NOVA is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; NOVA is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; You should have received a copy of the GNU General Public License
; a long with NOVA.  If not, see <http://www.gnu.org/licenses/>.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defsearch seesaw ((smart% 0.95))
  (save-state)
  (if *debug-search* (print-state (first-state? path)))
  (loop

   ;; if the solution is fully constrained, return
   (if (= (constrained% (first-state? path)) 1) (return))

   ;; constrain a random feature to its min or max value
   (let* ((treatment (?elt (coalesce-treatments (non-singletons? open))))
	  (feature   (car treatment))
	  (range     (cdr treatment)))

     ;; create new states with the min and max ranges
     (with-new-path
       (move-elts (separate-treatments (list treatment)) open closed)
       (move-elt (list feature (apply #'min range)) closed open)
       (save-state)
       (push path paths))
     (with-new-path
       (move-elts (separate-treatments (list treatment)) open closed)
       (move-elt (list feature (apply #'max range)) closed open)
       (save-state)
       (push path paths))

     ;; choose the better of the two states
     ;; possibly stay at the current state if better than the two new states
     (let ((path2 (pop paths))
	   (path1 (pop paths)))
       (when (or (< smart% (my-random 1))
		 (< (min (energy? (first-state? path1)) (energy? (first-state? path2)))
		    (energy? (first-state? path))))
	 (if (< (energy? (first-state? path1)) (energy? (first-state? path2)))
	     (switch-path path1)
	     (switch-path path2))
	 (if *debug-search* (print-state (first-state? path)))))))
  (if *debug-search* (terpri)))