text: /***********************************************************************************[SolverTypes.h]
  MiniSat -- Copyright (c) 2003-2005, Niklas Een, Niklas Sorensson
  
  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.
  **************************************************************************************************/
  
  
  #ifndef SolverTypes_h
  #define SolverTypes_h
  
  #ifndef Global_h
  #include "Global.h"
  #endif
  
  
  //=================================================================================================
  // Variables, literals, clause IDs:
  
  
  // 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 sgn = false) : x((var+var) + (int)sgn) {}
      friend Lit operator ~ (Lit p);
  
      friend bool sign  (Lit p);
      friend int  var   (Lit p);
      friend int  index (Lit p);
      friend Lit  toLit (int i);
      friend Lit  unsign(Lit p);
      friend Lit  id    (Lit p, bool sgn);
  
      friend bool operator == (Lit p, Lit q);
      friend bool operator <  (Lit p, Lit q);
  
      uint hash() const { return (uint)x; }
  };
  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 int  index (Lit p) { return p.x; }                // A "toInt" method that guarantees small, positive integers suitable for array indexing.
  inline Lit  toLit (int i) { Lit p; p.x = i; return p; }  // Inverse of 'index()'.
  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; }
  inline bool operator == (Lit p, Lit q) { return index(p) == index(q); }
  inline bool operator <  (Lit p, Lit q) { return index(p)  < index(q); }  // '<' guarantees that p, ~p are adjacent in the ordering.
  
  const Lit lit_Undef(var_Undef, false);  // }- Useful special constants.
  const Lit lit_Error(var_Undef, true );  // }
  
  inline int toDimacs(Lit p) { return sign(p) ? -var(p) - 1 : var(p) + 1; }
  
  
  //=================================================================================================
  // Clause -- a simple class for representing a clause:
  
  
  typedef int ClauseId;     // (might have to use uint64 one day...)
  const   int ClauseId_NULL = INT_MIN;
  
  //- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  
  class Clause {
      uint    size_learnt;
      Lit     data[1];
  public:
      // NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
      Clause(bool learnt, const vec<Lit>& ps, ClauseId id_ = ClauseId_NULL) {
          size_learnt = (ps.size() << 1) | (int)learnt;
          for (int i = 0; i < ps.size(); i++) data[i] = ps[i];
          if (learnt) activity() = 0;
          if (id_ != ClauseId_NULL) id() = id_; }
  
      // -- use this function instead:
      friend Clause* Clause_new(bool, const vec<Lit>&, ClauseId);
  
      int       size        ()      const { return size_learnt >> 1; }
      bool      learnt      ()      const { return size_learnt & 1; }
      Lit       operator [] (int i) const { return data[i]; }
      Lit&      operator [] (int i)       { return data[i]; }
      float&    activity    ()      const { return *((float*)&data[size()]); }
      ClauseId& id          ()      const { return *((ClauseId*)&data[size() + (int)learnt()]); }
  };
  
  inline Clause* Clause_new(bool learnt, const vec<Lit>& ps, ClauseId id = ClauseId_NULL) {
      assert(sizeof(Lit)      == sizeof(uint));
      assert(sizeof(float)    == sizeof(uint));
      assert(sizeof(ClauseId) == sizeof(uint));
      void*   mem = xmalloc<int8_t>(sizeof(Clause) + sizeof(uint)*(ps.size() + (int)learnt + (int)(id != ClauseId_NULL)));
      return new (mem) Clause(learnt, ps, id); }
  
  
  //=================================================================================================
  // GClause -- Generalize clause:
  
  
  // Either a pointer to a clause or a literal.
  class GClause {
      void*   data;
      GClause(void* d) : data(d) {}
  public:
      friend GClause GClause_new(Lit p);
      friend GClause GClause_new(Clause* c);
  
      bool        isLit    () const { return ((uintp)data & 1) == 1; }
      Lit         lit      () const { return toLit(((intp)data) >> 1); }
      Clause*     clause   () const { return (Clause*)data; }
      bool        operator == (GClause c) const { return data == c.data; }
      bool        operator != (GClause c) const { return data != c.data; }
  };
  inline GClause GClause_new(Lit p)     { return GClause((void*)(((intp)index(p) << 1) + 1)); }
  inline GClause GClause_new(Clause* c) { assert(((uintp)c & 1) == 0); return GClause((void*)c); }
  
  #define GClause_NULL GClause_new((Clause*)NULL)
  
  
  //=================================================================================================
  #endif
  