val.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, 2007
 *
 *  Last modified:
 *     $Date: 2011-05-25 16:56:41 +0200 (Wed, 25 May 2011) $ by $Author: schulte $
 *     $Revision: 12022 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  Permission is hereby granted, free of charge, to any person obtaining
 *  a copy of this software and associated documentation files (the
 *  "Software"), to deal in the Software without restriction, including
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 *  permit persons to whom the Software is furnished to do so, subject to
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namespace Gecode { namespace Int { namespace Circuit {

  /*
   * The actual propagator
   *
   */
  template<class View, class Offset>
  forceinline
  Val<View,Offset>::Val(Home home, ViewArray<View>& x, Offset& o)
    : Base<View,Offset>(home,x,o) {}

  template<class View, class Offset>
  forceinline
  Val<View,Offset>::Val(Space& home, bool share, Val<View,Offset>& p)
    : Base<View,Offset>(home,share,p) {}

  template<class View, class Offset>
  Actor*
  Val<View,Offset>::copy(Space& home, bool share) {
    return new (home) Val<View,Offset>(home,share,*this);
  }

  template<class View, class Offset>
  PropCost
  Val<View,Offset>::cost(const Space&, const ModEventDelta&) const {
    return PropCost::linear(PropCost::HI, x.size());
  }

  template<class View, class Offset>
  ExecStatus
  Val<View,Offset>::propagate(Space& home, const ModEventDelta&) {
    GECODE_ES_CHECK((Int::Distinct::prop_val<View,true>(home,y)));
    ExecStatus esc = connected(home);
    if (esc != ES_FIX)
      return esc;
    /*
     * One cannot have a single unassigned view as the views constitute
     * a permutation.
     */
    if (y.size() < 2)
      return home.ES_SUBSUMED(*this);
    return path(home);
  }

  template<class View, class Offset>
  ExecStatus
  Val<View,Offset>::post(Home home, ViewArray<View>& x, Offset& o) {
    int n = x.size();
    if (n == 1) {
      GECODE_ME_CHECK(o(x[0]).eq(home,0));
    } else if (n == 2) {
      GECODE_ME_CHECK(o(x[0]).eq(home,1));
      GECODE_ME_CHECK(o(x[1]).eq(home,0));
    } else {
      for (int i=n; i--; ) {
        GECODE_ME_CHECK(o(x[i]).gq(home,0));
        GECODE_ME_CHECK(o(x[i]).le(home,n));
        GECODE_ME_CHECK(o(x[i]).nq(home,i));
      }
      (void) new (home) Val<View,Offset>(home,x,o);
    }
    return ES_OK;
  }

}}}

// STATISTICS: int-prop