view-eq.hpp

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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2003
 *
 *  Last modified:
 *     $Date: 2016-04-19 17:19:45 +0200 (Tue, 19 Apr 2016) $ by $Author: schulte $
 *     $Revision: 14967 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
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namespace Gecode { namespace Int { namespace Count {

  template<class VX, class VY, class VZ, bool shr, bool dom>
  forceinline
  EqView<VX,VY,VZ,shr,dom>::EqView(Home home,
                                   ViewArray<VX>& x, VY y, VZ z, int c)
    : ViewBase<VX,VY,VZ>(home,x,y,z,c) {}

  template<class VX, class VY, class VZ, bool shr, bool dom>
  ExecStatus
  EqView<VX,VY,VZ,shr,dom>::post(Home home,
                                 ViewArray<VX>& x, VY y, VZ z, int c) {
    GECODE_ME_CHECK(z.gq(home,-c));
    GECODE_ME_CHECK(z.lq(home,x.size()-c));
    if (isval(y) && z.assigned())
      return EqInt<VX,VY>::post(home,x,y,z.val()+c);
    if (sharing(x,y,z))
      (void) new (home) EqView<VX,VY,VZ,true,dom>(home,x,y,z,c);
    else
      (void) new (home) EqView<VX,VY,VZ,false,dom>(home,x,y,z,c);
    return ES_OK;
  }

  template<class VX, class VY, class VZ, bool shr, bool dom>
  forceinline
  EqView<VX,VY,VZ,shr,dom>::EqView(Space& home, bool share,
                                   EqView<VX,VY,VZ,shr,dom>& p)
    : ViewBase<VX,VY,VZ>(home,share,p) {}

  template<class VX, class VY, class VZ, bool shr, bool dom>
  Actor*
  EqView<VX,VY,VZ,shr,dom>::copy(Space& home, bool share) {
    return new (home) EqView<VX,VY,VZ,shr,dom>(home,share,*this);
  }

  template<class VX, class VY, class VZ, bool shr, bool dom>
  ExecStatus
  EqView<VX,VY,VZ,shr,dom>::propagate(Space& home, const ModEventDelta&) {
    count(home);

    GECODE_ME_CHECK(z.gq(home,atleast()));
    GECODE_ME_CHECK(z.lq(home,atmost()));

    if (z.assigned()) {
      if (z.val() == atleast()) {
        GECODE_ES_CHECK(post_false(home,x,y));
        return home.ES_SUBSUMED(*this);
      }
      if (z.val() == atmost()) {
        GECODE_ES_CHECK(post_true(home,x,y));
        return home.ES_SUBSUMED(*this);
      }
      if (!dom || isval(y)) {
        VY yc(y);
        GECODE_REWRITE(*this,(EqInt<VX,VY>
                              ::post(home(*this),x,yc,z.val()+c)));
      }
    }


    if (dom && !isval(y) && (z.min() > 0)) {
      /*
       * Only if the propagator is at fixpoint here, continue
       * when things are shared: the reason is that prune
       * requires that the views in x overlap with y!
       */
      if (shr && (VX::me(Propagator::modeventdelta()) != ME_INT_NONE))
        return ES_NOFIX;

      GECODE_ES_CHECK(prune(home,x,y));

      return ES_NOFIX;
    }

    return shr ? ES_NOFIX : ES_FIX;
  }

}}}

// STATISTICS: int-prop