Dynamic_Bitset.h

/* Copyright (C) 
 * 2016 - Tsing Gu
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 * 
 */

#pragma once
#include <iostream>
#include <vector>
#include <bitset>
using std::ostream;

class Dynamic_Bitset{
private:
    std::vector<unsigned char> bits;
    const size_t BITS_PER_BYTE;

    /* Set or clear a bit in uchar
     * position should be within BIT_PER_BYTE
     * http://stackoverflow.com/questions/47981/how-do-you-set-clear-and-toggle-a-single-bit-in-c-c
     */

    /**
     * @brief Set bit of a char to 1
     *
     * @param ch Char to operate
     * @param pos Position within the char
     */
    void setUChar(unsigned char& ch, const size_t &pos) { ch |= 1<<pos; }
    /**
     * @brief Set bit of a char to 0
     *
     * @param ch Char to operate
     * @param pos Position within the char
     */
    void clearUChar(unsigned char& ch, const size_t &pos) { ch &= ~(1<<pos);}

    /**
     * @brief Get bit of within a char
     *
     * @param ch Char to query
     * @param pos position of bit in char
     *
     * @return Ture if 1; otherwise, 0.
     */
    bool getUChar(const unsigned char& ch, const size_t &pos)const {return (ch>>pos)&1;}
public:

    /**
     * @brief Init an empty bitset
     */
    Dynamic_Bitset(): BITS_PER_BYTE{8}{}

    /**
     * @brief Init an empty bitset with given length
     *
     * @param sz number of bits 
     */
    Dynamic_Bitset(const size_t &sz):BITS_PER_BYTE{8}{resize(sz);}

    /**
     * @brief Get number of bits
     *
     * @return number of bits
     */
    size_t size() const {return bits.size()*BITS_PER_BYTE;}

    /**
     * @brief Resize bit array length, will set bit array to 0
     *
     * @param sz number of bits
     */
    void resize(const size_t &sz) {bits.resize((sz+BITS_PER_BYTE-1)/ BITS_PER_BYTE, 0);}

    /**
     * @brief Set a bit to 1
     *
     * @param pos 0-based position of bit
     */
    void setBit(const size_t &pos){    //Set the bit to one
        setUChar(bits[pos/BITS_PER_BYTE], pos%BITS_PER_BYTE);
    }

    /**
     * @brief Set a bit to 0
     *
     * @param pos 0-based position of bit
     */
    void clearBit(const size_t &pos){  //Set the bit to zero
        clearUChar(bits[pos/BITS_PER_BYTE], pos%BITS_PER_BYTE);
    }

    /**
     * @brief Get the value of bit
     *
     * @param pos 0-based position of bit
     *
     * @return Ture if the bit is 1; otherwise, false.
     */
    bool getBit(const size_t &pos) const
    {
        return getUChar(bits[pos/BITS_PER_BYTE], pos%BITS_PER_BYTE);
    }
    //Friend operators
    friend std::ostream& operator<<(std::ostream& os, const Dynamic_Bitset& db);
};
std::ostream& operator<<(std::ostream& os, const Dynamic_Bitset& db)
{
    //for (size_t i=db.bits.size()-1; i >=0; i--)
    for (std::vector<unsigned char>::const_reverse_iterator rit = db.bits.rbegin();
            rit != db.bits.rend(); rit++)
        os << (std::bitset<8>)(*rit);
    return os;
}