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virtual-ranges-inter.icc

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/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2004
 *
 *  Last modified:
 *     $Date: 2006-08-04 16:05:50 +0200 (Fri, 04 Aug 2006) $ by $Author: schulte $
 *     $Revision: 3515 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  See the file "LICENSE" for information on usage and
 *  redistribution of this file, and for a
 *     DISCLAIMER OF ALL WARRANTIES.
 *
 */

#include <algorithm>

namespace Gecode { namespace Iter { namespace Ranges { namespace Virt {

  class Inter : public MinMax, public Iterator {
  private:
    Inter(const Inter&);
  protected:
    Iterator* i;
    Iterator* j;
  public:


    Inter(void);
    Inter(Iterator* i, Iterator* j);
    ~Inter(void);



    virtual int min(void) const;
    virtual int max(void) const;
    virtual unsigned int width(void) const;



    virtual void operator++(void);
    virtual bool operator()(void);
  };


  class NaryInter : public MinMax, public Iterator {
  private:
    NaryInter(const NaryInter&);
  protected:
    Iterator** is;
    int n;
  public:


    NaryInter(void);
    NaryInter(Iterator** i, int n);



    virtual int min(void) const;
    virtual int max(void) const;
    virtual unsigned int width(void) const;



    void operator++(void);
    virtual bool operator()(void);
  };


  /*
   * Binary intersection
   *
   */

  inline void
  Inter::operator++(void) {
    if (!(*i)() || !(*j)()) goto done;
    do {
      while ((*i)() && (i->max() < j->min())) ++(*i);
      if (!(*i)()) goto done;
      while ((*j)() && (j->max() < i->min())) ++(*j);
      if (!(*j)()) goto done;
    } while (i->max() < j->min());
    // Now the intervals overlap: consume the smaller interval
    ma = std::min(i->max(),j->max());
    mi = std::max(i->min(),j->min());
    if (i->max() < j->max()) ++(*i); else ++(*j);
    return;
  done:
    finish();
  }

  forceinline
  Inter::Inter(void) {}

  forceinline
  Inter::Inter(Iterator* i0, Iterator* j0)
    : i(i0), j(j0) {
    operator++();
  }

  forceinline
  Inter::~Inter(void) { delete i; delete j; }

  forceinline bool
  Inter::operator()(void) { return MinMax::operator()(); }

  forceinline int
  Inter::min(void) const { return MinMax::min(); }

  forceinline int
  Inter::max(void) const { return MinMax::max(); }

  forceinline unsigned int
  Inter::width(void) const { return MinMax::width(); }

  /*
   * Nary intersection
   *
   */

  inline void
  NaryInter::operator++(void) {
    // The next interval to be returned must have a hole
    // between it and the previously returned range.
    mi = ma+2;
    ma = is[0]->max();
    // Intersect with all other intervals
  restart:
    for (int i = n; i--;) {
      // Skip intervals that are too small
      while ((*(is[i]))() && (is[i]->max() < mi))
        ++(*(is[i]));
      if (!(*(is[i]))())
        goto done;

      if (is[i]->min() > ma) {
        mi=is[i]->min();
        ma=is[i]->max();
        goto restart;
      }
      // Now the intervals overlap
      if (mi < is[i]->min())
        mi = is[i]->min();
      if (ma > is[i]->max()) {
        ma = is[i]->max();
      }
    }
    return;
  done:
    finish();
  }

  forceinline
  NaryInter::NaryInter(void) {}

  inline
  NaryInter::NaryInter(Iterator** is0, int n0)
    : is(is0), n(n0) {
    if (!(*(is[0]))()) {
      finish();
    } else {
      ma=is[0]->min()-2;
      operator++();
    }
  }

  forceinline bool
  NaryInter::operator()(void) { return MinMax::operator()(); }

  forceinline int
  NaryInter::min(void) const { return MinMax::min(); }

  forceinline int
  NaryInter::max(void) const { return MinMax::max(); }

  forceinline unsigned int
  NaryInter::width(void) const { return MinMax::width(); }

}}}}

// STATISTICS: iter-any