opt-prop.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, 2009
 *
 *  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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#include <algorithm>

namespace Gecode { namespace Int { namespace Unary {

  template<class OptTask, class PL>
  forceinline
  OptProp<OptTask,PL>::OptProp(Home home, TaskArray<OptTask>& t)
    : TaskProp<OptTask,PL>(home,t) {}

  template<class OptTask, class PL>
  forceinline
  OptProp<OptTask,PL>::OptProp(Space& home, bool shared,
                               OptProp<OptTask,PL>& p)
    : TaskProp<OptTask,PL>(home,shared,p) {}

  template<class OptTask, class PL>
  ExecStatus
  OptProp<OptTask,PL>::post(Home home, TaskArray<OptTask>& t) {
    int m=0, o=0;
    for (int i=t.size(); i--; ) {
      if (t[i].mandatory())
        m++;
      else if (t[i].optional())
        o++;
    }
    if (m == t.size()) {
      TaskArray<typename TaskTraits<OptTask>::ManTask> mt(home,m);
      for (int i=m; i--; )
        mt[i].init(t[i]);
      return ManProp<typename TaskTraits<OptTask>::ManTask,PL>::post(home,mt);
    }
    if (o+m > 1)
      (void) new (home) OptProp<OptTask,PL>(home,t);
    return ES_OK;
  }

  template<class OptTask, class PL>
  Actor*
  OptProp<OptTask,PL>::copy(Space& home, bool share) {
    return new (home) OptProp<OptTask,PL>(home,share,*this);
  }

  template<class OptTask, class PL>
  ExecStatus
  OptProp<OptTask,PL>::propagate(Space& home, const ModEventDelta& med) {
    // Did one of the Boolean views change?
    if (BoolView::me(med) == ME_BOOL_VAL)
      GECODE_ES_CHECK((purge<OptTask,PL>(home,*this,t)));

    GECODE_ES_CHECK((overload<OptTask,PL>(home,*this,t)));

    if (PL::basic)
      GECODE_ES_CHECK(timetabling(home,*this,t));

    if (PL::advanced) {
      GECODE_ES_CHECK((detectable<OptTask,PL>(home,*this,t)));
      GECODE_ES_CHECK((notfirstnotlast<OptTask,PL>(home,*this,t)));

      // Partition into mandatory and optional activities
      int n = t.size();
      int i=0, j=n-1;
      while (true) {
        while ((i < n) && t[i].mandatory()) i++;
        while ((j >= 0) && !t[j].mandatory()) j--;
        if (i >= j) break;
        std::swap(t[i],t[j]);
      }

      if (i > 1) {
        // Truncate array to only contain mandatory tasks
        t.size(i);
        GECODE_ES_CHECK(edgefinding(home,t));
        // Restore to also include optional tasks
        t.size(n);
      }
    }

    if (!PL::basic)
      GECODE_ES_CHECK(subsumed(home,*this,t));

    return ES_NOFIX;
  }

}}}

// STATISTICS: int-prop