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/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2002
 *
 *  Last modified:
 *     $Date: 2006-08-25 10:43:21 +0200 (Fri, 25 Aug 2006) $ by $Author: schulte $
 *     $Revision: 3568 $
 *
 *  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 "gecode/int.hh"

#include "gecode/limits.hh"

#include "gecode/int/var/imp-body.icc"

namespace Gecode { namespace Int {

  forceinline bool
  IntVarImp::closer_min(int n) const {
    unsigned int l = n - dom.min();
    unsigned int r = dom.max() - n;
    return l < r;
  }

  int
  IntVarImp::med(void) const {
    // Computes the median
    if (fst() == NULL)
      return (dom.min()+dom.max())/2;
    unsigned int i = size() / 2;
    const RangeList* p = NULL;
    const RangeList* c = fst();
    while (i >= c->width()) {
      i -= c->width();
      const RangeList* n=c->next(p); p=c; c=n;
    }
    return c->min() + static_cast<int>(i);
  }

  bool
  IntVarImp::in_full(int m) const {
    if (closer_min(m)) {
      const RangeList* p = NULL;
      const RangeList* c = fst();
      while (m > c->max()) {
        const RangeList* n=c->next(p); p=c; c=n;
      }
      return (m >= c->min());
    } else {
      const RangeList* n = NULL;
      const RangeList* c = lst();
      while (m < c->min()) {
        const RangeList* p=c->prev(n); n=c; c=p;
      }
      return (m <= c->max());
    }
  }

  /*
   * "Standard" tell operations
   *
   */

  void
  IntVarImp::lq_full(Space* home, int m) {
    assert((m >= dom.min()) && (m <= dom.max()));
    if (range()) { // Is already range...
      dom.max(m);
      if (assigned()) goto notify_val;
    } else if (m < fst()->next(NULL)->min()) { // Becomes range...
      dom.max(std::min(m,fst()->max()));
      fst()->dispose(home,NULL,lst());
      fst(NULL); holes = 0;
      if (assigned()) goto notify_val;
    } else { // Stays non-range...
      RangeList* n = NULL;
      RangeList* c = lst();
      unsigned int h = 0;
      while (m < c->min()) {
        RangeList* p = c->prev(n); c->fix(n);
        h += (c->min() - p->max() - 1);
        n=c; c=p;
      }
      holes -= h;
      int max_c = std::min(m,c->max());
      dom.max(max_c); c->max(max_c);
      if (c != lst()) {
        lst()->dispose(home,n);
        c->next(n,NULL); lst(c);
      }
    }
    notify(home,ME_INT_BND);
    return;
  notify_val:
    notify(home,ME_INT_VAL);
  }

  void
  IntVarImp::gq_full(Space* home, int m) {
    assert((m >= dom.min()) && (m <= dom.max()));
    if (range()) { // Is already range...
      dom.min(m);
      if (assigned()) goto notify_val;
    } else if (m > lst()->prev(NULL)->max()) { // Becomes range...
      dom.min(std::max(m,lst()->min()));
      fst()->dispose(home,NULL,lst());
      fst(NULL); holes = 0;
      if (assigned()) goto notify_val;
    } else { // Stays non-range...
      RangeList* p = NULL;
      RangeList* c = fst();
      unsigned int h = 0;
      while (m > c->max()) {
        RangeList* n = c->next(p); c->fix(n);
        h += (n->min() - c->max() - 1);
        p=c; c=n;
      }
      holes -= h;
      int min_c = std::max(m,c->min());
      dom.min(min_c); c->min(min_c);
      if (c != fst()) {
        fst()->dispose(home,p);
        c->prev(p,NULL); fst(c);
      }
    }
    notify(home,ME_INT_BND);
    return;
  notify_val:
    notify(home,ME_INT_VAL);
  }

  void
  IntVarImp::eq_full(Space* home, int m) {
    if (!range()) {
      RangeList* p = NULL;
      RangeList* c = fst();
      while (m > c->max()) {
        RangeList* n=c->next(p); c->fix(n); p=c; c=n;
      }
      if (m < c->min()) {
        dom.min(Limits::Int::int_max+1);
        return;
      }
      while (c != NULL) {
        RangeList* n=c->next(p); c->fix(n); p=c; c=n;
      }
      assert(p == lst());
      fst()->dispose(home,p);
      fst(NULL); holes = 0;
    }
    dom.min(m); dom.max(m);
    notify(home,ME_INT_VAL);
  }

  ModEvent
  IntVarImp::nq_full(Space* home, int m) {
    assert(!((m < dom.min()) || (m > dom.max())));
    if (range()) {
      if ((m == dom.min()) && (m == dom.max()))
        return ME_INT_FAILED;
      if (m == dom.min()) {
        dom.min(m+1); goto notify_bnd_or_val;
      }
      if (m == dom.max()) {
        dom.max(m-1); goto notify_bnd_or_val;
      }
      RangeList* f = new (home) RangeList(dom.min(),m-1);
      RangeList* l = new (home) RangeList(m+1,dom.max());
      f->prevnext(NULL,l);
      l->prevnext(f,NULL);
      fst(f); lst(l); holes = 1;
    } else if (m < fst()->next(NULL)->min()) { // Concerns the first range...
      int f_max = fst()->max();
      if (m > f_max)
        return ME_INT_NONE;
      int f_min = dom.min();
      if ((m == f_min) && (m == f_max)) {
        RangeList* f_next = fst()->next(NULL);
        dom.min(f_next->min());
        if (f_next == lst()) { // Turns into range
          // Works as at the ends there are only NULL pointers
          fst()->dispose(home,f_next);
          fst(NULL); holes = 0;
          goto notify_bnd_or_val;
        } else { // Remains non-range
          f_next->prev(fst(),NULL);
          fst()->dispose(home); fst(f_next);
          holes -= dom.min() - f_min - 1;
          goto notify_bnd;
        }
      } else if (m == f_min) {
        dom.min(m+1); fst()->min(m+1);
        goto notify_bnd;
      } else if (m == f_max) {
        fst()->max(m-1); holes += 1;
      } else {
        // Create new hole
        RangeList* f = new (home) RangeList(f_min,m-1);
        f->prevnext(NULL,fst());
        fst()->min(m+1); fst()->prev(NULL,f);
        fst(f); holes += 1;
      }
    } else if (m > lst()->prev(NULL)->max()) { // Concerns the last range...
      int l_min = lst()->min();
      if (m < l_min)
        return ME_INT_NONE;
      int l_max = dom.max();
      if ((m == l_min) && (m == l_max)) {
        RangeList* l_prev = lst()->prev(NULL);
        dom.max(l_prev->max());
        if (l_prev == fst()) {
          // Turns into range
          l_prev->dispose(home,lst());
          fst(NULL); holes = 0;
          goto notify_bnd_or_val;
        } else { // Remains non-range
          l_prev->next(lst(),NULL);
          lst()->dispose(home); lst(l_prev);
          holes -= l_max - dom.max() - 1;
          goto notify_bnd;
        }
      } else if (m == l_max) {
        dom.max(m-1); lst()->max(m-1);
        goto notify_bnd;
      } else if (m == l_min) {
        lst()->min(m+1); holes += 1;
      } else { // Create new hole
        RangeList* l = new (home) RangeList(m+1,l_max);
        l->prevnext(lst(),NULL);
        lst()->max(m-1); lst()->next(NULL,l);
        lst(l); holes += 1;
      }
    } else { // Concerns element in the middle of the list of ranges
      RangeList* p;
      RangeList* c;
      RangeList* n;
      if (closer_min(m)) {
        assert(m > fst()->max());
        p = NULL;
        c = fst();
        do {
          n=c->next(p); p=c; c=n;
        } while (m > c->max());
        if (m < c->min())
          return ME_INT_NONE;
        n=c->next(p);
      } else {
        assert(m < lst()->min());
        n = NULL;
        c = lst();
        do {
          p=c->prev(n); n=c; c=p;
        } while (m < c->min());
        if (m > c->max())
          return ME_INT_NONE;
        p=c->prev(n);
      }
      assert((fst() != c) && (lst() != c));
      assert((m >= c->min()) && (m <= c->max()));
      holes += 1;
      int c_min = c->min();
      int c_max = c->max();
      if ((c_min == m) && (c_max == m)) {
        c->dispose(home);
        p->next(c,n); n->prev(c,p);
      } else if (c_min == m) {
        c->min(m+1);
      } else {
        c->max(m-1);
        if (c_max != m) {
          RangeList* l = new (home) RangeList(m+1,c_max);
          l->prevnext(c,n);
          c->next(n,l);
          n->prev(c,l);
        }
      }
    }
    notify(home,ME_INT_DOM);
    return ME_INT_DOM;
  notify_bnd_or_val:
    if (assigned()) {
      notify(home,ME_INT_VAL);
      return ME_INT_VAL;
    }
  notify_bnd:
    notify(home,ME_INT_BND);
    return ME_INT_BND;
  }



  /*
   * Copying variables
   *
   */

  forceinline
  IntVarImp::IntVarImp(Space* home, bool share, IntVarImp& x, bool is_bool)
    : IntVarImpBase(home,share,x), dom(x.dom.min(),x.dom.max()) { 
    if (is_bool) {
      holes = 0; fst(NULL);
    } else {
      holes = x.holes;
      if (holes) {
        int m = 1;
        // Compute length
        {
          RangeList* s_p = x.fst();
          RangeList* s_c = s_p->next(NULL);
          do {
            m++;
            RangeList* s_n = s_c->next(s_p); s_p=s_c; s_c=s_n;
          } while (s_c != NULL);
        }
        RangeList* d_c =
          reinterpret_cast<RangeList*>(home->alloc(m*sizeof(RangeList)));
        fst(d_c); lst(d_c+m-1);
        d_c->min(x.fst()->min());
        d_c->max(x.fst()->max());
        d_c->prevnext(NULL,NULL);
        RangeList* s_p = x.fst();
        RangeList* s_c = s_p->next(NULL);
        do {
          RangeList* d_n = d_c + 1;
          d_c->next(NULL,d_n);
          d_n->prevnext(d_c,NULL);
          d_n->min(s_c->min()); d_n->max(s_c->max());
          d_c = d_n;
          RangeList* s_n=s_c->next(s_p); s_p=s_c; s_c=s_n;
        } while (s_c != NULL);
        d_c->next(NULL,NULL);
      } else {
        fst(NULL);
      }
    }
  }

  IntVarImp*
  IntVarImp::perform_copy(Space* home, bool share) {
    return new (home) IntVarImp(home,share,*this,false);
  }
  IntVarImp*
  IntVarImp::perform_copy_bool(Space* home, bool share) {
    return new (home) IntVarImp(home,share,*this,true);
  }

}}

// STATISTICS: int-var