SolverTypes.h

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

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**************************************************************************************************/


#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 sign = false) : x((var+var) + (int)sign) { }
    friend Lit operator ~ (Lit p) { Lit q; q.x = p.x ^ 1; return q; }

    friend bool sign  (Lit p) { return p.x & 1; }
    friend int  var   (Lit p) { return p.x >> 1; }
    friend int  index (Lit p) { return p.x; }                // A "toInt" method that guarantees small, positive integers suitable for array indexing.
    friend Lit  toLit (int i) { Lit p; p.x = i; return p; }  // Inverse of 'index()'.
    friend Lit  unsign(Lit p) { Lit q; q.x = p.x & ~1; return q; }
    friend Lit  id    (Lit p, bool sgn) { Lit q; q.x = p.x ^ (int)sgn; return q; }

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

Lit toLit(int i);

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:


typedef int ClauseId;     // (might have to use uint64 one day...)
const   int ClauseId_NULL = INT_MIN;

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

class Clause {
    uint    size_learnt;
    Lit     data[0];
public:
    // NOTE: This constructor cannot be used directly (doesn't allocate enough memory).
    Clause(bool learnt, const vec<Lit>& ps) {
        size_learnt = (ps.size() << 1) | (int)learnt;
        for (int i = 0; i < ps.size(); i++) data[i] = ps[i];
        if (learnt) activity() = 0; }

    // -- use this function instead:
    friend Clause* Clause_new(bool learnt, const vec<Lit>& ps) {
        assert(sizeof(Lit)      == sizeof(uint));
        assert(sizeof(float)    == sizeof(uint));
        void*   mem = xmalloc<char>(sizeof(Clause) + sizeof(uint)*(ps.size() + (int)learnt));
        return new (mem) Clause(learnt, ps); }

    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()]); }
};

Clause* Clause_new(bool learnt, const vec<Lit>& ps);

//=================================================================================================
// 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)     { return GClause((void*)((index(p) << 1) + 1)); }
    friend GClause GClause_new(Clause* c) { assert(((uintp)c & 1) == 0); return GClause((void*)c); }

    bool        isLit    () const { return ((uintp)data & 1) == 1; }
    bool        isNull   () const { return data == NULL; }
    Lit         lit      () const { return toLit(((long)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; }
};
#define GClause_NULL GClause_new((Clause*)NULL)

GClause GClause_new(Lit p);
GClause GClause_new(Clause* c);
//=================================================================================================
#endif