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>
 *     Vincent Barichard <Vincent.Barichard@univ-angers.fr>
 *
 *  Copyright:
 *     Guido Tack, 2004
 *     Christian Schulte, 2004
 *     Vincent Barichard, 2012
 *
 *  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 {

  class BoolExpr::Node {
  public:
    unsigned int use;
    int same;
    NodeType t;
    Node *l, *r;
    BoolVar x;
    LinIntRel rl;
#ifdef GECODE_HAS_FLOAT_VARS

    LinFloatRel rfl;
#endif
#ifdef GECODE_HAS_SET_VARS

    SetRel rs;
#endif

    Misc* m;

    Node(void);
    ~Node(void);
    GECODE_MINIMODEL_EXPORT
    bool decrement(void);
    static void* operator new(size_t size);
    static void  operator delete(void* p, size_t size);
  };


  /*
   * Operations for nodes
   *
   */
  BoolExpr::Node::Node(void)
    : use(1), l(nullptr), r(nullptr), m(nullptr) {}

  BoolExpr::Node::~Node(void) {
    delete m;
  }

  void*
  BoolExpr::Node::operator new(size_t size) {
    return heap.ralloc(size);
  }
  void
  BoolExpr::Node::operator delete(void* p, size_t) {
    heap.rfree(p);
  }

  bool
  BoolExpr::Node::decrement(void) {
    if (--use == 0) {
      if ((l != nullptr) && l->decrement())
        delete l;
      if ((r != nullptr) && r->decrement())
        delete r;
      return true;
    }
    return false;
  }

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

  BoolExpr::BoolExpr(const BoolExpr& e) : n(e.n) {
    n->use++;
  }

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

  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++;
  }

  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    = nullptr;
    }
  }

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

#ifdef GECODE_HAS_FLOAT_VARS
  BoolExpr::BoolExpr(const LinFloatRel& rfl)
    : n(new Node) {
    n->same  = 1;
    n->t     = NT_RLINFLOAT;
    n->l     = nullptr;
    n->r     = nullptr;
    n->rfl   = rfl;
  }
#endif

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

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

  BoolExpr::BoolExpr(BoolExpr::Misc* m)
    : n(new Node) {
    n->same = 1;
    n->t    = NT_MISC;
    n->l    = nullptr;
    n->r    = nullptr;
    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::Misc::~Misc(void) {}

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

  namespace {
    class NNF {
    public:
      typedef BoolExpr::NodeType NodeType;
      typedef BoolExpr::Node Node;
      NodeType t;
      int p;
      int n;
      union {
        struct {
          NNF* l;
          NNF* r;
        } b;
        struct {
          bool neg;
          Node* x;
        } a;
      } u;
      static NNF* nnf(Region& r, Node* n, bool neg);
      GECODE_MINIMODEL_EXPORT
      void post(Home home, NodeType t,
                BoolVarArgs& bp, BoolVarArgs& bn,
                int& ip, int& in,
                const IntPropLevels& ipls) const;
      GECODE_MINIMODEL_EXPORT
      BoolVar expr(Home home, const IntPropLevels& ipls) const;
      GECODE_MINIMODEL_EXPORT
      void rel(Home home, const IntPropLevels& ipls) const;
      static void* operator new(size_t s, Region& r);
      static void operator delete(void*);
      static void operator delete(void*, Region&);
    };

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

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

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

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

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

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

    NNF*
    NNF::nnf(Region& r, Node* n, bool neg) {
      switch (n->t) {
      case BoolExpr::NT_VAR:
      case BoolExpr::NT_RLIN:
      case BoolExpr::NT_MISC:
  #ifdef GECODE_HAS_FLOAT_VARS
      case BoolExpr::NT_RLINFLOAT:
  #endif
  #ifdef GECODE_HAS_SET_VARS
      case BoolExpr::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 BoolExpr::NT_NOT:
        return nnf(r,n->l,!neg);
      case BoolExpr::NT_AND: case BoolExpr::NT_OR:
        {
          NodeType t = ((n->t == BoolExpr::NT_AND) == neg) ?
            BoolExpr::NT_OR : BoolExpr::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 == BoolExpr::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 == BoolExpr::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 BoolExpr::NT_EQV:
        {
          NNF* x = new (r) NNF;
          x->t = BoolExpr::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 nullptr;
    }
  }

  BoolVar
  BoolExpr::expr(Home home, const IntPropLevels& ipls) const {
    Region r;
    return NNF::nnf(r,n,false)->expr(home,ipls);
  }

  void
  BoolExpr::rel(Home home, const IntPropLevels& ipls) const {
    Region r;
    return NNF::nnf(r,n,false)->rel(home,ipls);
  }


  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, const IntPropLevels& ipls) {
    PostInfo pi(home);
    if (!home.failed())
      return e.expr(home,ipls);
    BoolVar x(home,0,1);
    return x;
  }

  void
  rel(Home home, const BoolExpr& e, const IntPropLevels& ipls) {
    GECODE_POST;
    e.rel(home,ipls);
  }

  /*
   * Boolean element constraints
   *
   */

  class BElementExpr : public BoolExpr::Misc {
  protected:
    BoolExpr* a;
    int n;
    LinIntExpr idx;
  public:
    BElementExpr(const BoolVarArgs& b, const LinIntExpr& idx);
    virtual ~BElementExpr(void);
    virtual void post(Home home, BoolVar b, bool neg,
                      const IntPropLevels& ipls);
  };

  BElementExpr::BElementExpr(const BoolVarArgs& b, const LinIntExpr& idx)
    : a(static_cast<BoolExpr*>(heap.ralloc(sizeof(BoolExpr)*b.size()))), n(b.size()), idx(idx) {
    for (int i=b.size(); i--;)
      new (&a[i]) BoolExpr(b[i]);
  }

  BElementExpr::~BElementExpr(void) {
    heap.free<BoolExpr>(a,n);
  }

  void
  BElementExpr::post(Home home, BoolVar b, bool neg,
                     const IntPropLevels& ipls) {
    IntVar z = idx.post(home, ipls);
    if (z.assigned() && (z.val() >= 0) && (z.val() < n)) {
      BoolExpr be = neg ? (a[z.val()] == !b) : (a[z.val()] == b);
      be.rel(home,ipls);
    } else {
      BoolVarArgs x(n);
      for (int i=n; i--;)
        x[i] = a[i].expr(home,ipls);
      BoolVar res = neg ? (!b).expr(home,ipls) : b;
      element(home, x, z, res, ipls.element());
    }
  }

  BoolExpr
  element(const BoolVarArgs& b, const LinIntExpr& idx) {
    return BoolExpr(new BElementExpr(b,idx));
  }

}

// STATISTICS: minimodel-any