#ifndef __BITVEC_H__
#define __BITVEC_H__

#include <cstdlib>
#include <cassert>
/************************************************
 * Classes for bit-vector and k-width bit-vector.
 * Warning: doesn't do any bounds checking.
 * Also, don't use the push/pop interface with growTo.
 * Since pop doesn't reset the value, successive growTo
 * calls may leave some ghost elements.
 ************************************************/
template<unsigned int B>
struct BitMask
{
    enum { value = 2*BitMask<B-1>::value + 1 };
};

template<>
struct BitMask<0>
{
    enum { value = 0 };
};

template<class T = unsigned int, unsigned int B = 1>
class ValVec {
public:
    static const unsigned int eltsT = (8*sizeof(T))/B;
    static const unsigned int mask = BitMask<B>::value;

    ValVec(unsigned int i = 0)
        : elts(i),
          sz( 1 + (i/eltsT) ),
          data( (T*) malloc( sizeof(T)*sz ) )
    {
        for( unsigned int ii = 0; ii < sz; ii++ )
        {
            data[ii] = 0;
        }
    }

    ~ValVec(void)
    {
        free(data);
    }
    
    unsigned int operator[](unsigned int el)
    {
        unsigned int shift = B*(el%eltsT);
        return (data[el/eltsT]&(mask<<shift))>>shift;
    }
    
    bool elem(unsigned int el)
    {
        return data[el/eltsT]&(mask<<(B*(el%eltsT)));
    }

    void set(unsigned int el, unsigned int val)
    {
        T Smask = ~(mask<<(B*(el%eltsT)));
        data[el/eltsT] = (data[el/eltsT]&Smask) | val<<(B*(el%eltsT));
    }

    void push(unsigned int val)
    {
        if( elts + 1 >= sz*eltsT )
        {
            unsigned int newsz = 2*sz;
            data = (T*) realloc(data,sizeof(T)*sz);
            for( ; sz < newsz; sz++ )
                data[sz] = 0;
        }

        set(elts,val);
        elts++;
    }

    unsigned int pop(void)
    {
        assert( elts > 0 );
        elts--;
        return (*this)[elts];
    }

    unsigned int size(void)
    {
        return elts;
    }
protected:
    unsigned int elts;
    unsigned int sz;
    T* data; 
};

template<class T = unsigned int>
class BitVec {
public:
    static const unsigned int eltsT = 8*sizeof(T);

    BitVec(unsigned int i = 0)
        : elts(i),
          sz( 1 + (i/eltsT) ),
          data( (T*) malloc( sizeof(T)*sz ) )
    {
        for( unsigned int ii = 0; ii < sz; ii++ )
        {
            data[ii] = 0;
        }
    }

    ~BitVec(void)
    {
        free(data);
    }
    
    bool operator[](unsigned int el)
    {
        return elem(el);
    }


    bool elem(unsigned int el)
    {
        return data[el/eltsT]&(1<<(el%eltsT));
    }

    void insert(unsigned int el)
    {
        data[el/eltsT] |= 1<<(el%eltsT);
    }

    void remove(unsigned int el)
    {
        data[el/eltsT] &= ~(1<<(el%eltsT));
    }

    void push(bool val)
    {
        if( elts + 1 >= sz*eltsT )
        {
            unsigned int newsz = sz*2;
            data = (T*) realloc(data,sizeof(T)*newsz);
            for( ; sz < newsz; sz++ )
            {
                data[sz] = 0;
            }
        }

        if( val )
        {
            insert(elts);
        } else {
            remove(elts);
        }
        elts++;
    }

    void growTo(unsigned int newsz)
    {
        if( newsz > sz*eltsT )
        {
            sz = 1 + newsz/eltsT;
            data = (T*) realloc(data,sizeof(T)*sz);
        }
    }

    bool pop(void)
    {
        assert( elts > 0 );

        elts--;
        return elem(elts);
    }

    unsigned int size(void)
    {
        return elts;
    }

protected:
    unsigned int elts;
    unsigned int sz;
    T* data; 
};

// Trailed variant of the bit-vector.
// template<class T = unsigned int>
class TBitVec : public BitVec<unsigned int> {
public:
    TBitVec(unsigned int i = 0) : BitVec<unsigned int>(i)
    {

    }

    void insert(unsigned int el)
    {
      trailChange(data[el/eltsT], data[el/eltsT] | 1<<(el%eltsT)); 
    }
};

#endif