solvertypes.h

多核环境下运行了可满足性分析的工具软件

/***********************************************************************************[SolverTypes.h]
MiniSat -- Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
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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
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**************************************************************************************************/


#ifndef SolverTypes_h
#define SolverTypes_h

#include <cassert>
#include <stdint.h>


namespace minisat {

  //=================================================================================================
  // Variables, literals, lifted booleans, clauses:
  
  
  // NOTE! Variables are just integers. No abstraction here. They should be chosen from 0..N,
  // so that they can be used as array indices.
  
  typedef int Var;

#define var_Undef (-1)
    
  class Lit {
    int     x;
  public:
    Lit() : x(2*var_Undef)                                              { }   // (lit_Undef)
    explicit Lit(Var var, bool sign = false) : x((var+var) + (int)sign) { }
    
    // Don't use these for constructing/deconstructing literals. Use the normal constructors instead.
    friend int  toInt       (Lit p);  // Guarantees small, positive integers suitable for array indexing.
    friend Lit  toLit       (int i);  // Inverse of 'toInt()'
    friend Lit  operator   ~(Lit p);
    friend bool sign        (Lit p);
    friend int  var         (Lit p);
    friend Lit  unsign      (Lit p);
    friend Lit  id          (Lit p, bool sgn);

    bool operator == (Lit p) const { return x == p.x; }
    bool operator != (Lit p) const { return x != p.x; }
    bool operator <  (Lit p) const { return x < p.x;  } // '<' guarantees that p, ~p are adjacent in the ordering.
  };

  inline  int  toInt       (Lit p)           { return p.x; }
  inline  Lit  toLit       (int i)           { Lit p; p.x = i; return p; }
  inline  Lit  operator   ~(Lit p)           { Lit q; q.x = p.x ^ 1; return q; }
  inline  bool sign        (Lit p)           { return p.x & 1; }
  inline  int  var         (Lit p)           { return p.x >> 1; }
  inline  Lit  unsign      (Lit p)           { Lit q; q.x = p.x & ~1; return q; }
  inline  Lit  id          (Lit p, bool sgn) { Lit q; q.x = p.x ^ (int)sgn; return q; }
  
  const Lit lit_Undef(var_Undef, false);  // }- Useful special constants.
  const Lit lit_Error(var_Undef, true );  // }
  
  //=================================================================================================
  // Lifted booleans:

  class lbool {
    char     value;
    explicit lbool(int v) : value(v) { }

  public:
    lbool()       : value(0) { }
    lbool(bool x) : value((int)x*2-1) { }
    int toInt(void) const { return value; }

    bool  operator == (lbool b) const { return value == b.value; }
    bool  operator != (lbool b) const { return value != b.value; }
    lbool operator ^ (bool b) const { return b ? lbool(-value) : lbool(value); }

    friend int   toInt  (lbool l);
    friend lbool toLbool(int   v);
  };

  inline int   toInt  (lbool l) { return l.toInt(); }
  inline lbool toLbool(int   v) { return lbool(v);  }

  const lbool l_True  = toLbool( 1);
  const lbool l_False = toLbool(-1);
  const lbool l_Undef = toLbool( 0);
  
  //=================================================================================================
  // Clause -- a simple class for representing a clause:

  class Clause {
    uint32_t size_etc;
    union { float act; uint32_t abst; } extra;
    Lit     data[0];
    
  public:
    void calcAbstraction() {
      uint32_t abstraction = 0;
      for (int i = 0; i < size(); i++)
	abstraction |= 1 << (var(data[i]) & 31);
      extra.abst = abstraction;  }
    
    // NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
    template<class V>
      Clause(const V& ps, bool learnt) {
      size_etc = (ps.size() << 3) | (uint32_t)learnt;
      for (int i = 0; i < ps.size(); i++) data[i] = ps[i];
      if (learnt) extra.act = 0; else calcAbstraction(); }
    
    // -- use this function instead:
    template<class V>
      friend Clause* Clause_new(const V& ps, bool learnt = false) {
      assert(sizeof(Lit)      == sizeof(uint32_t));
      assert(sizeof(float)    == sizeof(uint32_t));
      void* mem = malloc(sizeof(Clause) + sizeof(uint32_t)*(ps.size()));
      return new (mem) Clause(ps, learnt); }

    int          size        ()      const   { return size_etc >> 3; }
    void         shrink      (int i)         { assert(i <= size()); size_etc = (((size_etc >> 3) - i) << 3) | (size_etc & 7); }
    void         pop         ()              { shrink(1); }
    bool         learnt      ()      const   { return size_etc & 1; }
    uint32_t     mark        ()      const   { return (size_etc >> 1) & 3; }
    void         mark        (uint32_t m)    { size_etc = (size_etc & ~6) | ((m & 3) << 1); }
    const Lit&   last        ()      const   { return data[size()-1]; }
    
    // NOTE: somewhat unsafe to change the clause in-place! Must manually call 'calcAbstraction' afterwards for
    //       subsumption operations to behave correctly.
    Lit&         operator [] (int i)         { return data[i]; }
    Lit          operator [] (int i) const   { return data[i]; }
    operator const Lit* (void) const         { return data; }
    
    float&       activity    ()              { return extra.act; }
    uint32_t     abstraction () const { return extra.abst; }
    
    Lit          subsumes    (const Clause& other) const;
    void         strengthen  (Lit p);
  };


  /*_________________________________________________________________________________________________
    |
    |  subsumes : (other : const Clause&)  ->  Lit
    |  
    |  Description:
    |       Checks if clause subsumes 'other', and at the same time, if it can be used to simplify 'other'
    |       by subsumption resolution.
    |  
    |    Result:
    |       lit_Error  - No subsumption or simplification
    |       lit_Undef  - Clause subsumes 'other'
    |       p          - The literal p can be deleted from 'other'
    |________________________________________________________________________________________________@*/
  inline Lit Clause::subsumes(const Clause& other) const
    {
      if (other.size() < size() || (extra.abst & ~other.extra.abst) != 0)  
        return lit_Error;
      
      Lit        ret = lit_Undef;
      const Lit* c  = (const Lit*)(*this);
      const Lit* d  = (const Lit*)other;
      
      for (int i = 0; i < size(); i++) {
	// search for c[i] or ~c[i]
        for (int j = 0; j < other.size(); j++)
	  if (c[i] == d[j])
	    goto ok;
	  else if (ret == lit_Undef && c[i] == ~d[j]){  
	    ret = c[i];
	    goto ok;
	  }
	
        // did not find it
        return lit_Error;
      ok:;
      }
      
      return ret;
    }
  

  inline void Clause::strengthen(Lit p)
    {
      remove(*this, p);
      calcAbstraction();
    }
  
} // end namespace minisat

#endif