#| -*-Scheme-*-

$Id$

Copyright 2006 Massachusetts Institute of Technology

This program 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 2 of the License, or (at
your option) any later version.

This program 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
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301,
USA.

|#

;;;; Equality constraints make two connectors hold the same values.

(declare (usual-integrations))

(define cp:B=A
  (cp:make-constraint-type 'B=A
    (lambda (constraint)
      (let ((connectors (cp:constraint-connectors constraint)))
	(for-each (lambda (c1)
		    (if (cp:has-value? c1)
			(for-each (lambda (c2)
				    (if (not (eq? c2 c1))
					(cp:set-value c2
						      (cp:value-of c1)
						      (list c1)
						      constraint)))
				  connectors)))
		  connectors)))
    (lambda (connectors)
      (if (not (>= (length connectors) 2))
	  (error "B=A: Too few connectors:" connectors)))))