bit_array.h

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#ifndef _PFC_BIT_ARRAY_H_
#define _PFC_BIT_ARRAY_H_

class NOVTABLE bit_array {
public:
        virtual bool get(t_size n) const = 0;
        virtual t_size find(bool val,t_size start,t_ssize count) const//can be overridden for improved speed; returns first occurance of val between start and start+count (excluding start+count), or start+count if not found; count may be negative if we're searching back
        {
                t_ssize d, todo, ptr = start;
                if (count==0) return start;
                else if (count<0) {d = -1; todo = -count;}
                else {d = 1; todo = count;}
                while(todo>0 && get(ptr)!=val) {ptr+=d;todo--;}
                return ptr;
        }
        inline bool operator[](t_size n) const {return get(n);}

        t_size calc_count(bool val,t_size start,t_size count,t_size count_max = ~0) const//counts number of vals for start<=n<start+count
        {
                t_size found = 0;
                t_size max = start+count;
                t_size ptr;
                for(ptr=find(val,start,count);found<count_max && ptr<max;ptr=find(val,ptr+1,max-ptr-1)) found++;
                return found;
        }

        inline t_size find_first(bool val,t_size start,t_size max) const {return find(val,start,max-start);}
        inline t_size find_next(bool val,t_size previous,t_size max) const {return find(val,previous+1,max-(previous+1));}
        //for(n = mask.find_first(true,0,m); n < m; n = mask.find_next(true,n,m) )
protected:
        bit_array() {}
        ~bit_array() {}
};

class NOVTABLE bit_array_var : public bit_array {
public:
        virtual void set(t_size n,bool val)=0;
protected:
        bit_array_var() {}
        ~bit_array_var() {}
};


class bit_array_wrapper_permutation : public bit_array {
public:
        bit_array_wrapper_permutation(const t_size * p_permutation, t_size p_size) : m_permutation(p_permutation), m_size(p_size) {}
        bool get(t_size n) const {
                if (n < m_size) {
                        return m_permutation[n] != n;
                } else {
                        return false;
                }
        }
private:
        const t_size * const m_permutation;
        const t_size m_size;
};

#endif

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