int-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, 2011
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
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 *  a copy of this software and associated documentation files (the
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#include <gecode/int/rel.hh>
#include <gecode/int/distinct.hh>

namespace Gecode { namespace Int { namespace NValues {

  template<class VY>
  forceinline
  EqInt<VY>::EqInt(Home home, ValSet& vs, ViewArray<IntView>& x, VY y)
    : IntBase<VY>(home,vs,x,y) {
    home.notice(*this, AP_WEAKLY);
  }

  template<class VY>
  inline ExecStatus
  EqInt<VY>::post(Home home, ViewArray<IntView>& x, VY y) {
    if (x.size() == 0) {
      GECODE_ME_CHECK(y.eq(home,0));
      return ES_OK;
    }

    x.unique();

    if (x.size() == 1) {
      GECODE_ME_CHECK(y.eq(home,1));
      return ES_OK;
    }

    GECODE_ME_CHECK(y.gq(home,1));
    GECODE_ME_CHECK(y.lq(home,x.size()));

    if (y.max() == 1) {
      assert(y.assigned());
      return Rel::NaryEqDom<IntView>::post(home,x);
    }

    if (y.min() == x.size()) {
      assert(y.assigned());
      return Distinct::Dom<IntView>::post(home,x);
    }

    // Eliminate assigned views and store them into the value set
    ValSet vs;
    int n = x.size();
    for (int i=n; i--; )
      if (x[i].assigned()) {
        vs.add(home, x[i].val());
        x[i] = x[--n];
      }

    GECODE_ME_CHECK(y.gq(home,vs.size()));
    GECODE_ME_CHECK(y.lq(home,n + vs.size()));

    if (n == 0) {
      assert(y.val() == vs.size());
      return ES_OK;
    }
    x.size(n);
    (void) new (home) EqInt<VY>(home, vs, x, y);
    return ES_OK;
  }

  template<class VY>
  forceinline
  EqInt<VY>::EqInt(Space& home, EqInt<VY>& p)
    : IntBase<VY>(home, p) {}

  template<class VY>
  Propagator*
  EqInt<VY>::copy(Space& home) {
    return new (home) EqInt<VY>(home, *this);
  }

  template<class VY>
  forceinline size_t
  EqInt<VY>::dispose(Space& home) {
    home.ignore(*this, AP_WEAKLY);
    (void) IntBase<VY>::dispose(home);
    return sizeof(*this);
  }

  template<class VY>
  ExecStatus
  EqInt<VY>::propagate(Space& home, const ModEventDelta& med) {
    // Add assigned views to value set
    if (IntView::me(med) == ME_INT_VAL)
      add(home);

    GECODE_ME_CHECK(y.gq(home, vs.size()));
    GECODE_ME_CHECK(y.lq(home, x.size() + vs.size()));

    if (x.size() == 0)
      return home.ES_SUBSUMED(*this);

    // All values must be in the value set
    if (y.max() == vs.size())
      return all_in_valset(home);

    // Compute positions of disjoint views and eliminate subsumed views
    Region r;
    int* dis; int n_dis;
    disjoint(home,r,dis,n_dis);

    // The number might have changed due to elimination of subsumed views
    GECODE_ME_CHECK(y.lq(home, x.size() + vs.size()));

    if (x.size() == 0) {
      assert(y.val() == vs.size());
      return home.ES_SUBSUMED(*this);
    }

    GECODE_ES_CHECK(prune_upper(home,g));

    // No lower bound pruning possible
    if (n_dis == 0)
      return ES_NOFIX;

    // Only if the propagator is at fixpoint here, continue with
    // propagating the lower bound
    if (IntView::me(Propagator::modeventdelta()) != ME_INT_NONE)
      return ES_NOFIX;

    // Do lower bound-based pruning
    GECODE_ES_CHECK(prune_lower(home,dis,n_dis));

    return ES_NOFIX;
  }

}}}

// STATISTICS: int-prop