/*
 *  Authors:
 *    Christian Schulte <schulte@gecode.dev>
 *
 *  Copyright:
 *    Christian Schulte, 2008-2026
 *
 *  Permission is hereby granted, free of charge, to any person obtaining
 *  a copy of this software, to deal in the software without restriction,
 *  including without limitation the rights to use, copy, modify, merge,
 *  publish, distribute, sublicense, and/or sell copies of the software,
 *  and to permit persons to whom the software is furnished to do so, subject
 *  to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be
 *  included in all copies or substantial portions of the software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <gecode/int.hh>

using namespace Gecode;

class Disequal : public Propagator {
protected:
  Int::IntView x0, x1;
public:
  Disequal(Home home, Int::IntView y0, Int::IntView y1) 
    : Propagator(home), x0(y0), x1(y1) {
    x0.subscribe(home,*this,Int::PC_INT_VAL);
    x1.subscribe(home,*this,Int::PC_INT_VAL);
  }
  static ExecStatus post(Home home, 
                         Int::IntView x0, Int::IntView x1) {
    if (x0 == x1)
      return ES_FAILED;
    (void) new (home) Disequal(home,x0,x1);
    return ES_OK;
  }
  virtual size_t dispose(Space& home) {
    x0.cancel(home,*this,Int::PC_INT_VAL);
    x1.cancel(home,*this,Int::PC_INT_VAL);
    (void) Propagator::dispose(home);
    return sizeof(*this);
  }
  Disequal(Space& home, Disequal& p) 
    : Propagator(home,p) {
    x0.update(home,p.x0);
    x1.update(home,p.x1);
  }
  virtual Propagator* copy(Space& home) {
    return new (home) Disequal(home,*this);
  }
  virtual PropCost cost(const Space&, const ModEventDelta&) const {
    return PropCost::binary(PropCost::LO);
  }
  virtual void reschedule(Space& home) {
    x0.reschedule(home,*this,Int::PC_INT_VAL);
    x1.reschedule(home,*this,Int::PC_INT_VAL);
  }
  virtual ExecStatus propagate(Space& home, const ModEventDelta&) {
    if (x0.assigned())  
      GECODE_ME_CHECK(x1.nq(home,x0.val()));
    else
      GECODE_ME_CHECK(x0.nq(home,x1.val()));
    return home.ES_SUBSUMED(*this);
  }
};

void disequal(Home home, IntVar x0, IntVar x1) {
  if (home.failed()) return;
  PostInfo pi(home);
  GECODE_ES_FAIL(Disequal::post(home,x0,x1));
}