/***********************************************************************************[SolverTypes.h]
MiniSat -- Copyright (c) 2003-2005, Niklas Een, Niklas Sorensson

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NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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**************************************************************************************************/


#ifndef SolverTypes_h
#define SolverTypes_h

#include "Global.h"

namespace MINISAT {

//=================================================================================================
// 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)


struct Lit {
    int     x;

    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.
inline  int  toInt       (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 'toInt()'

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; }

inline  bool operator == (Lit p, Lit q)    { return toInt(p) == toInt(q); }
inline  bool operator != (Lit p, Lit q)    { return toInt(p) != toInt(q); }
inline  bool operator <  (Lit p, Lit q)    { return toInt(p)  < toInt(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 );  // }


//=================================================================================================
// Clause -- a simple class for representing a clause:

class Clause {
    uint    size_etc;
    union { float act; uint abst; } apa;
    Lit     data[1];
public:
    // 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) | (uint)learnt;
        for (int i = 0; i < ps.size(); i++) data[i] = ps[i];
        if (learnt) apa.act = 0; else apa.abst = 0; }

    // -- use this function instead:
    template<class V>
    friend Clause* Clause_new(const V& ps, bool learnt = false) {
        assert(sizeof(Lit)      == sizeof(uint));
        assert(sizeof(float)    == sizeof(uint));

        size_t aux_size = 0;
        if (ps.size() > 0)
          aux_size = sizeof(uint)*(ps.size() - 1);

        void*   mem = xmalloc<char>(sizeof(Clause) + aux_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; }
    uint      mark        ()      const { return (size_etc >> 1) & 3; }
    void      mark        (uint m)      { size_etc = (size_etc & ~6) | ((m & 3) << 1); }
    Lit       operator [] (int i) const { return data[i]; }
    Lit&      operator [] (int i)       { return data[i]; }

    float&    activity    ()       { return apa.act; }

    uint      abstraction () const { return apa.abst; }

    void calcAbstraction() {
        uint abstraction = 0;
        for (int i = 0; i < size(); i++)
            abstraction |= 1 << (var(data[i]) & 31);
        apa.abst = abstraction;  }
};


//=================================================================================================
// TrailPos -- Stores an index into the trail as well as an approximation of a level. This data
// is recorded for each assigment. (Replaces the old level information)


class TrailPos {
    int tp;
 public:
    explicit TrailPos(int index, int level) : tp( (index << 5) + (level & 31) ) { }

    friend int abstractLevel(const TrailPos& p) { return 1 << (p.tp & 31); }
    friend int position     (const TrailPos& p) { return p.tp >> 5; }

    bool operator ==  (TrailPos other) const { return tp == other.tp; }
    bool operator <   (TrailPos other) const { return tp <  other.tp; }
};

}
#endif