unionConst.icc

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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
 *  Main authors:
 *     Guido Tack <tack@gecode.org>
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Guido Tack, 2004,2006,2007
 *     Christian Schulte, 2004
 *
 *  Last modified:
 *     $Date: 2008-05-27 19:24:07 +0200 (Tue, 27 May 2008) $ by $Author: tack $
 *     $Revision: 6982 $
 *
 *  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
 *  without limitation the rights to use, copy, modify, merge, publish,
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 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
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 */

namespace Gecode { namespace Set { namespace Element {

  template <class SView, class RView>
  forceinline
  ElementUnionConst<SView,RView>::
  ElementUnionConst(Space* home, SView y0,
                     SharedArray<IntSet>& iv0,
                     RView y1)
    : Propagator(home), x0(y0), iv(iv0), x1(y1) {
    force(home);
    x0.subscribe(home,this, PC_SET_ANY);
    x1.subscribe(home,this, PC_SET_ANY);
  }

  template <class SView, class RView>
  forceinline
  ElementUnionConst<SView,RView>::
  ElementUnionConst(Space* home, bool share,
                     ElementUnionConst<SView,RView>& p)
    : Propagator(home,share,p) {
    x0.update(home,share,p.x0);
    x1.update(home,share,p.x1);
    iv.update(home,share,p.iv);
  }

  template <class SView, class RView>
  PropCost
  ElementUnionConst<SView,RView>::cost(ModEventDelta) const {
    return PC_LINEAR_HI;
  }

  template <class SView, class RView>
  Support::Symbol
  ElementUnionConst<SView,RView>::ati(void) {
    return Reflection::mangle<SView,RView>("Gecode::Set::Element::UnionConst");
  }

  template <class SView, class RView>
  Reflection::ActorSpec
  ElementUnionConst<SView,RView>::spec(const Space* home,
                                      Reflection::VarMap& m) const {
    Reflection::ActorSpec s(ati());
    Reflection::ArrayArg* a = Reflection::Arg::newArray(iv.size());
    for (int i=0; i<iv.size(); i++) {
      int count = 0;
      for (IntSetRanges isr(iv[i]); isr(); ++isr)
        count++;
      Reflection::IntArrayArg* aa = Reflection::Arg::newIntArray(count*2);
      count = 0;
      for (IntSetRanges isr(iv[i]); isr(); ++isr) {
        (*aa)[count++] = isr.min();
        (*aa)[count++] = isr.max();
      }
      (*a)[i] = aa;
    }

    return s << x0.spec(home, m)
             << a
             << x1.spec(home, m);
  }

  template <class SView, class RView>
  void
  ElementUnionConst<SView,RView>::post(Space* home,
                                      Reflection::VarMap& vars,
                                      const Reflection::ActorSpec& spec) {
    spec.checkArity(3);
    SView x0(home, vars, spec[0]);
    Reflection::ArrayArg* sets = spec[1]->toArray();
    SharedArray<IntSet> iv(sets->size());
    for (int i=sets->size(); i--; ) {
      Reflection::IntArrayArgRanges r((*sets)[i]->toIntArray());
      new (&iv[i]) IntSet(r);
    }
    RView x1(home, vars, spec[2]);
    (void) new (home) ElementUnionConst(home, x0, iv, x1);
  }

  template <class SView, class RView>
  size_t
  ElementUnionConst<SView,RView>::dispose(Space* home) {
    unforce(home);
    if (!home->failed()) {
      x0.cancel(home,this, PC_SET_ANY);
      x1.cancel(home,this, PC_SET_ANY);
    }
    iv.~SharedArray();
    (void) Propagator::dispose(home);
    return sizeof(*this);
  }

  template <class SView, class RView>
  ExecStatus
  ElementUnionConst<SView,RView>::
  post(Space* home, SView x0, SharedArray<IntSet>& xs,
       RView x1) {
    int n = xs.size();

    // s2 \subseteq {1,...,n}
    Iter::Ranges::Singleton s(0, n-1);
    GECODE_ME_CHECK(x1.intersectI(home,s));
    (void) new (home)
      ElementUnionConst<SView,RView>(home,x0,xs,x1);
    return ES_OK;
  }

  template <class SView, class RView>
  Actor*
  ElementUnionConst<SView,RView>::copy(Space* home, bool share) {
    return new (home) ElementUnionConst<SView,RView>(home,share,*this);
  }

  template <class SView, class RView>
  ExecStatus
  ElementUnionConst<SView,RView>::propagate(Space* home, ModEventDelta) {
    int n = iv.size();

    GECODE_AUTOARRAY(bool, stillSelected, n);

    bool loopVar;
    do {
      loopVar = false;
      for (int i=n; i--;)
        stillSelected[i] = false;

      // Cache the upper bound iterator, as we have to
      // modify the upper bound while iterating
      LubRanges<RView> x1ub(x1);
      Iter::Ranges::Cache<LubRanges<RView> > x1ubc(x1ub);
      Iter::Ranges::ToValues<Iter::Ranges::Cache<LubRanges<RView> > >
        vx1ub(x1ubc);

      GlbRanges<RView> x1lb(x1);
      Iter::Ranges::Cache<GlbRanges<RView> > x1lbc(x1lb);
      Iter::Ranges::ToValues<Iter::Ranges::Cache<GlbRanges<RView> > >
        vx1(x1lbc);

      // In the first iteration, compute in before[i] the union
      // of all the upper bounds of the x_i. At the same time,
      // exclude inconsistent x_i from x1.

      GLBndSet sofarBefore(home);
      LUBndSet selectedInter(home, IntSet (Limits::min,
                                   Limits::max));
      GECODE_AUTOARRAY(GLBndSet, before, n);

      int i = 0;
      
      unsigned int maxCard = 0;
      unsigned int minCard = Limits::card;
      
      while ( vx1ub() ) {

        i = vx1ub.val();
        IntSetRanges candCardR(iv[i]);
        unsigned int candidateCard = Iter::Ranges::size(candCardR);

        IntSetRanges candlb(iv[i]);
        LubRanges<SView> x0ub(x0);
        Iter::Ranges::Diff<IntSetRanges,
          LubRanges<SView> > diff(candlb, x0ub);

        bool selectSingleInconsistent = false;
        if (x1.cardMax() <= 1) {
          GlbRanges<SView> x0lb(x0);
          IntSetRanges candub(iv[i]);
          Iter::Ranges::Diff<GlbRanges<SView>,
                             IntSetRanges > diff2(x0lb, candub);
          selectSingleInconsistent = diff2() || candidateCard < x0.cardMin();
        }

        // exclude inconsistent x_i
        // an x_i is inconsistent if
        //  * at most one x_i can be selected and there are
        //    elements in x_0 that can't be in x_i
        //    (selectSingleInconsistent)
        //  * its min cardinality is greater than maxCard of x0
        //  * inter is not empty (there are elements in x_i
        //    that can't be in x_0)
        if (selectSingleInconsistent ||
            candidateCard > x0.cardMax() ||
            diff()) {
          ModEvent me = (x1.exclude(home,i));
          loopVar |= me_modified(me);
          GECODE_ME_CHECK(me);
        } else {
          stillSelected[i] = true;
          // if x_i is consistent, check whether we know
          // that its index is in x1
          if (vx1() && vx1.val()==i) {
            // x0 >= candidate, candidate <= x0
            // GlbRanges<SView> candlb(candidate);
            IntSetRanges candlb(iv[i]);
            ModEvent me = x0.includeI(home,candlb);
            loopVar |= me_modified(me);
            GECODE_ME_CHECK(me);
            ++vx1;
          }
          new (&before[i]) GLBndSet(home);
          before[i].update(home,sofarBefore);
          IntSetRanges cub(iv[i]);
          sofarBefore.includeI(home,cub);
          IntSetRanges clb(iv[i]);
          selectedInter.intersectI(home,clb);
          maxCard = std::max(maxCard, candidateCard);
          minCard = std::min(minCard, candidateCard);
        }

        ++vx1ub;
      }

      if (x1.cardMax()==0) {
        // Selector is empty, hence the result must be empty
        {
          GECODE_ME_CHECK(x0.cardMax(home,0));
        }
        for (int i=n; i--;)
          if (stillSelected[i])
            before[i].dispose(home);
        selectedInter.dispose(home);
        sofarBefore.dispose(home);
        return ES_SUBSUMED(this,home);
      }

      if (x1.cardMin() > 0) {
        // Selector is not empty, hence the intersection of the
        // possibly selected lower bounds is contained in x0
        BndSetRanges si(selectedInter);
        ModEvent me = x0.includeI(home, si);
        loopVar |= me_modified(me);
        GECODE_ME_CHECK(me);
        me = x0.cardMin(home, minCard);
        loopVar |= me_modified(me);
        GECODE_ME_CHECK(me);
      }
      selectedInter.dispose(home);

      if (x1.cardMax() <= 1) {
        ModEvent me = x0.cardMax(home, maxCard);
        loopVar |= me_modified(me);
        GECODE_ME_CHECK(me);
      }

      {
        // x0 <= sofarBefore
        BndSetRanges sfB(sofarBefore);
        ModEvent me = x0.intersectI(home,sfB);
        loopVar |= me_modified(me);
        GECODE_ME_CHECK(me);
      }

      sofarBefore.dispose(home);

      GLBndSet sofarAfter(home);

      // In the second iteration, this time backwards, compute
      // sofarAfter as the union of all lub(x_j) with j>i
      for (int i=n; i--;) {
        if (!stillSelected[i])
          continue;                
        BndSetRanges b(before[i]);
        BndSetRanges s(sofarAfter);
        GlbRanges<SView> x0lb(x0);
        Iter::Ranges::Union<BndSetRanges, BndSetRanges> inter(b,s);
        Iter::Ranges::Diff<GlbRanges<SView>,
          Iter::Ranges::Union<BndSetRanges,BndSetRanges> > diff(x0lb, inter);
        if (diff()) {
          ModEvent me = (x1.include(home,i));
          loopVar |= me_modified(me);
          GECODE_ME_CHECK(me);

          // candidate != extra
          IntSetRanges ivi(iv[i]);
          if (!Iter::Ranges::subset(diff, ivi))
            GECODE_ME_CHECK(ME_SET_FAILED);
        }

        IntSetRanges iviub(iv[i]);
        sofarAfter.includeI(home,iviub);
        before[i].dispose(home);
      }
      sofarAfter.dispose(home);

    } while (loopVar);

    if (x0.assigned() || x1.assigned()) {
      return ES_SUBSUMED(this,home);
    }

    return ES_FIX;
  }

}}}

// STATISTICS: set-prop