bool-expr.cpp

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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
 *     Christian Schulte, 2004
 *
 *  Last modified:
 *     $Date: 2012-02-22 06:04:20 +0100 (Wed, 22 Feb 2012) $ by $Author: tack $
 *     $Revision: 12537 $
 *
 *  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,
 *  distribute, sublicense, and/or sell copies of the Software, and to
 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
 *
 *  The above copyright notice and this permission notice shall be
 *  included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */

#include <gecode/minimodel.hh>

namespace Gecode {

  /*
   * Operations for nodes
   *
   */
  bool
  BoolExpr::Node::decrement(void) {
    if (--use == 0) {
      if ((l != NULL) && l->decrement())
        delete l;
      if ((r != NULL) && r->decrement())
        delete r;
      return true;
    }
    return false;
  }


  BoolExpr::BoolExpr(void) : n(new Node) {}

  BoolExpr::BoolExpr(const BoolVar& x) : n(new Node) {
    n->same = 1;
    n->t    = NT_VAR;
    n->l    = NULL;
    n->r    = NULL;
    n->x    = x;
    n->m    = NULL;
  }

  BoolExpr::BoolExpr(const BoolExpr& l, NodeType t, const BoolExpr& r)
    : n(new Node) {
    int ls = ((l.n->t == t) || (l.n->t == NT_VAR)) ? l.n->same : 1;
    int rs = ((r.n->t == t) || (r.n->t == NT_VAR)) ? r.n->same : 1;
    n->same = ls+rs;
    n->t    = t;
    n->l    = l.n;
    n->l->use++;
    n->r    = r.n;
    n->r->use++;
    n->m    = NULL;
  }

  BoolExpr::BoolExpr(const BoolExpr& l, NodeType t) {
    (void) t;
    assert(t == NT_NOT);
    if (l.n->t == NT_NOT) {
      n = l.n->l;
      n->use++;
    } else {
      n = new Node;
      n->same = 1;
      n->t    = NT_NOT;
      n->l    = l.n;
      n->l->use++;
      n->r    = NULL;
      n->m    = NULL;
    }
  }

  BoolExpr::BoolExpr(const LinRel& rl)
    : n(new Node) {
    n->same = 1;
    n->t    = NT_RLIN;
    n->l    = NULL;
    n->r    = NULL;
    n->rl   = rl;
    n->m    = NULL;
  }

#ifdef GECODE_HAS_SET_VARS
  BoolExpr::BoolExpr(const SetRel& rs)
    : n(new Node) {
    n->same = 1;
    n->t    = NT_RSET;
    n->l    = NULL;
    n->r    = NULL;
    n->rs   = rs;
    n->m    = NULL;
  }

  BoolExpr::BoolExpr(const SetCmpRel& rs)
    : n(new Node) {
    n->same = 1;
    n->t    = NT_RSET;
    n->l    = NULL;
    n->r    = NULL;
    n->rs   = rs;
    n->m    = NULL;
  }
#endif

  BoolExpr::BoolExpr(BoolExpr::MiscExpr* m)
    : n(new Node) {
    n->same = 1;
    n->t    = NT_MISC;
    n->l    = NULL;
    n->r    = NULL;
    n->m    = m;
  }

  const BoolExpr&
  BoolExpr::operator =(const BoolExpr& e) {
    if (this != &e) {
      if (n->decrement())
        delete n;
      n = e.n;
      n->use++;
    }
    return *this;
  }

  BoolExpr::MiscExpr::~MiscExpr(void) {}

  BoolExpr::~BoolExpr(void) {
    if (n->decrement())
      delete n;
  }

  /*
   * Operations for negation normalform
   *
   */
  forceinline void
  BoolExpr::NNF::operator delete(void*) {}

  forceinline void
  BoolExpr::NNF::operator delete(void*, Region&) {}

  forceinline void*
  BoolExpr::NNF::operator new(size_t s, Region& r) {
    return r.ralloc(s);
  }

  BoolVar
  BoolExpr::NNF::expr(Home home, IntConLevel icl) const {
    if ((t == NT_VAR) && !u.a.neg)
      return u.a.x->x;
    BoolVar b(home,0,1);
    switch (t) {
    case NT_VAR:
      assert(u.a.neg);
      Gecode::rel(home, u.a.x->x, IRT_NQ, b);
      break;
    case NT_RLIN:
      u.a.x->rl.post(home, b, !u.a.neg, icl);
      break;
#ifdef GECODE_HAS_SET_VARS
    case NT_RSET:
      u.a.x->rs.post(home, b, !u.a.neg);
      break;
#endif
    case NT_MISC:
      u.a.x->m->post(home, b, !u.a.neg, icl);
      break;
    case NT_AND:
      {
        BoolVarArgs bp(p), bn(n);
        int ip=0, in=0;
        post(home, NT_AND, bp, bn, ip, in, icl);
        clause(home, BOT_AND, bp, bn, b);
      }
      break;
    case NT_OR:
      {
        BoolVarArgs bp(p), bn(n);
        int ip=0, in=0;
        post(home, NT_OR, bp, bn, ip, in, icl);
        clause(home, BOT_OR, bp, bn, b);
      }
      break;
    case NT_EQV:
      {
        bool n = false;
        BoolVar l;
        if (u.b.l->t == NT_VAR) {
          l = u.b.l->u.a.x->x;
          if (u.b.l->u.a.neg) n = !n;
        } else {
          l = u.b.l->expr(home,icl);
        }
        BoolVar r;
        if (u.b.r->t == NT_VAR) {
          r = u.b.r->u.a.x->x;
          if (u.b.r->u.a.neg) n = !n;
        } else {
          r = u.b.r->expr(home,icl);
        }
        Gecode::rel(home, l, n ? BOT_XOR : BOT_EQV, r, b, icl);
      }
      break;
    default:
      GECODE_NEVER;
    }
    return b;
  }

  void
  BoolExpr::NNF::post(Home home, NodeType t,
                      BoolVarArgs& bp, BoolVarArgs& bn,
                      int& ip, int& in,
                      IntConLevel icl) const {
    if (this->t != t) {
      switch (this->t) {
      case NT_VAR:
        if (u.a.neg) {
          bn[in++]=u.a.x->x;
        } else {
          bp[ip++]=u.a.x->x;
        }
        break;
      case NT_RLIN:
        {
          BoolVar b(home,0,1);
          u.a.x->rl.post(home, b, !u.a.neg, icl);
          bp[ip++]=b;
        }
        break;
#ifdef GECODE_HAS_SET_VARS
      case NT_RSET:
        {
          BoolVar b(home,0,1);
          u.a.x->rs.post(home, b, !u.a.neg);
          bp[ip++]=b;
        }
        break;
#endif
      case NT_MISC:
        {
          BoolVar b(home,0,1);
          u.a.x->m->post(home, b, !u.a.neg, icl);
          bp[ip++]=b;
        }
        break;      
      default:
        bp[ip++] = expr(home, icl);
        break;
      }
    } else {
      u.b.l->post(home, t, bp, bn, ip, in, icl);
      u.b.r->post(home, t, bp, bn, ip, in, icl);
    }
  }

  void
  BoolExpr::NNF::rel(Home home, IntConLevel icl) const {
    switch (t) {
    case NT_VAR:
      Gecode::rel(home, u.a.x->x, IRT_EQ, u.a.neg ? 0 : 1);
      break;
    case NT_RLIN:
      u.a.x->rl.post(home, !u.a.neg, icl);
      break;
#ifdef GECODE_HAS_SET_VARS
    case NT_RSET:
      u.a.x->rs.post(home, !u.a.neg);
      break;
#endif
    case NT_MISC:
      {
        BoolVar b(home,!u.a.neg,!u.a.neg);
        u.a.x->m->post(home, b, false, icl);
      }
      break;
    case NT_AND:
      u.b.l->rel(home, icl);
      u.b.r->rel(home, icl);
      break;
    case NT_OR:
      {
        BoolVarArgs bp(p), bn(n);
        int ip=0, in=0;
        post(home, NT_OR, bp, bn, ip, in, icl);
        clause(home, BOT_OR, bp, bn, 1);
      }
      break;
    case NT_EQV:
      if (u.b.l->t==NT_VAR && u.b.r->t==NT_RLIN) {
        u.b.r->u.a.x->rl.post(home, u.b.l->u.a.x->x,
                              u.b.l->u.a.neg==u.b.r->u.a.neg, icl);
      } else if (u.b.r->t==NT_VAR && u.b.l->t==NT_RLIN) {
        u.b.l->u.a.x->rl.post(home, u.b.r->u.a.x->x,
                              u.b.l->u.a.neg==u.b.r->u.a.neg, icl);
      } else if (u.b.l->t==NT_RLIN) {
        u.b.l->u.a.x->rl.post(home, u.b.r->expr(home,icl),
                              !u.b.l->u.a.neg,icl);
      } else if (u.b.r->t==NT_RLIN) {
        u.b.r->u.a.x->rl.post(home, u.b.l->expr(home,icl),
                              !u.b.r->u.a.neg,icl);
#ifdef GECODE_HAS_SET_VARS
      } else if (u.b.l->t==NT_VAR && u.b.r->t==NT_RSET) {
        u.b.r->u.a.x->rs.post(home, u.b.l->u.a.x->x,
                              u.b.l->u.a.neg==u.b.r->u.a.neg);
      } else if (u.b.r->t==NT_VAR && u.b.l->t==NT_RSET) {
        u.b.l->u.a.x->rs.post(home, u.b.r->u.a.x->x,
                              u.b.l->u.a.neg==u.b.r->u.a.neg);
      } else if (u.b.l->t==NT_RSET) {
        u.b.l->u.a.x->rs.post(home, u.b.r->expr(home,icl),
                              !u.b.l->u.a.neg);
      } else if (u.b.r->t==NT_RSET) {
        u.b.r->u.a.x->rs.post(home, u.b.l->expr(home,icl),
                              !u.b.r->u.a.neg);
#endif
      } else {
        Gecode::rel(home, expr(home, icl), IRT_EQ, 1);
      }
      break;
    default:
      GECODE_NEVER;
    }
  }

  BoolExpr::NNF*
  BoolExpr::NNF::nnf(Region& r, Node* n, bool neg) {
    switch (n->t) {
    case NT_VAR: case NT_RLIN: case NT_MISC:
#ifdef GECODE_HAS_SET_VARS
    case NT_RSET:
#endif
      {
        NNF* x = new (r) NNF;
        x->t = n->t; x->u.a.neg = neg; x->u.a.x = n;
        if (neg) {
          x->p = 0; x->n = 1;
        } else {
          x->p = 1; x->n = 0;
        }
        return x;
      }
    case NT_NOT:
      return nnf(r,n->l,!neg);
    case NT_AND: case NT_OR:
      {
        NodeType t = ((n->t == NT_AND) == neg) ? NT_OR : NT_AND;
        NNF* x = new (r) NNF;
        x->t = t;
        x->u.b.l = nnf(r,n->l,neg);
        x->u.b.r = nnf(r,n->r,neg);
        int p_l, n_l;
        if ((x->u.b.l->t == t) || (x->u.b.l->t == NT_VAR)) {
          p_l=x->u.b.l->p; n_l=x->u.b.l->n;
        } else {
          p_l=1; n_l=0;
        }
        int p_r, n_r;
        if ((x->u.b.r->t == t) || (x->u.b.r->t == NT_VAR)) {
          p_r=x->u.b.r->p; n_r=x->u.b.r->n;
        } else {
          p_r=1; n_r=0;
        }
        x->p = p_l+p_r;
        x->n = n_l+n_r;
        return x;
      }
    case NT_EQV:
      {
        NNF* x = new (r) NNF;
        x->t = NT_EQV;
        x->u.b.l = nnf(r,n->l,neg);
        x->u.b.r = nnf(r,n->r,false);
        x->p = 2; x->n = 0;
        return x;
      }
    default:
      GECODE_NEVER;
    }
    GECODE_NEVER;
    return NULL;
  }


  BoolExpr
  operator &&(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(l,BoolExpr::NT_AND,r);
  }
  BoolExpr
  operator ||(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(l,BoolExpr::NT_OR,r);
  }
  BoolExpr
  operator ^(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(BoolExpr(l,BoolExpr::NT_EQV,r),BoolExpr::NT_NOT);
  }

  BoolExpr
  operator !(const BoolExpr& e) {
    return BoolExpr(e,BoolExpr::NT_NOT);
  }

  BoolExpr
  operator !=(const BoolExpr& l, const BoolExpr& r) {
    return !BoolExpr(l, BoolExpr::NT_EQV, r);
  }
  BoolExpr
  operator ==(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(l, BoolExpr::NT_EQV, r);
  }
  BoolExpr
  operator >>(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(BoolExpr(l,BoolExpr::NT_NOT),
                    BoolExpr::NT_OR,r);
  }
  BoolExpr
  operator <<(const BoolExpr& l, const BoolExpr& r) {
    return BoolExpr(BoolExpr(r,BoolExpr::NT_NOT),
                    BoolExpr::NT_OR,l);
  }
  /*
   * Posting Boolean expressions and relations
   *
   */
  BoolVar
  expr(Home home, const BoolExpr& e, IntConLevel icl) {
    if (!home.failed())
      return e.expr(home,icl);
    BoolVar x(home,0,1);
    return x;
  }

  void
  rel(Home home, const BoolExpr& e, IntConLevel icl) {
    if (home.failed()) return;
    e.rel(home,icl);
  }

  /*
   * Boolean element constraints
   *
   */
  
  class BElementExpr : public BoolExpr::MiscExpr {
  public:
    BoolExpr* a;
    int n;
    LinExpr idx;
    BElementExpr(int size);
    virtual ~BElementExpr(void);
    virtual void post(Space& home, BoolVar b, bool neg, IntConLevel icl);
  };

  BElementExpr::BElementExpr(int size)
    : a(heap.alloc<BoolExpr>(size)), n(size) {}

  BElementExpr::~BElementExpr(void) {
    heap.free<BoolExpr>(a,n);
  }
  
  void
  BElementExpr::post(Space& home, BoolVar b, bool pos, IntConLevel icl) {
    IntVar z = idx.post(home, icl);
    if (z.assigned() && z.val() >= 0 && z.val() < n) {
      BoolExpr be = pos ? (a[z.val()] == b) : (a[z.val()] == !b);
      be.rel(home,icl);
    } else {
      BoolVarArgs x(n);
      for (int i=n; i--;)
        x[i] = a[i].expr(home,icl);
      BoolVar res = pos ? b : (!b).expr(home,icl);
      element(home, x, z, res, icl);
    }
  }

  BoolExpr
  element(const BoolVarArgs& b, const LinExpr& idx) {
    BElementExpr* be = new BElementExpr(b.size());
    for (int i=b.size(); i--;)
      new (&be->a[i]) BoolExpr(b[i]);
    be->idx = idx;
    return BoolExpr(be);
  }

}

// STATISTICS: minimodel-any