range.hpp

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/*********************************************************************/
// dar - disk archive - a backup/restoration program
// Copyright (C) 2002-2024 Denis Corbin
//
// 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
//
// to contact the author, see the AUTHOR file
/*********************************************************************/
 
 
 
#ifndef RANGE_HPP
#define RANGE_HPP
 
#include <string>
#include <set>
#include <list>
 
#include "../my_config.h"
#include "infinint.hpp"
 
namespace libdar
{
 
    class range
    {
    public:
    range() { clear(); };
    range(const infinint & low, const infinint & high) { parts.push_back(segment(low, high)); };
    range(const range & ref) = default;
    range(range && ref) noexcept = default;
    range & operator = (const range & ref) = default;
    range & operator = (range && ref) noexcept = default;
    ~range() = default;
 
    void operator += (const range & ref);
    range operator + (const range & ref) const { range ret = *this; ret += ref; return ret; };
    std::string display() const;
 
 
    void reset_read() const { read_cursor = parts.begin(); };
 
 
    bool read_next_segment(infinint & low, infinint & high) const;
 
    void clear() { parts.clear(); };
 
    private:
    class segment
    {
    public:
        segment(const infinint & x_low, const infinint & x_high) { low = x_low; high = x_high; };
 
        const infinint & get_low() const { return low; };
        const infinint & get_high() const { return high; };
 
        bool overlaps_with(const segment & ref) const { return !(ref < *this) && !(ref > *this); };
        void merge_with(const segment & ref); // only possible with a segment that overlaps with the current object
 
        // if two segment make < or > true they cannot be replaced by a single segment
        bool operator < (const segment & ref) const { return high + 1 < ref.low; };
        bool operator > (const segment & ref) const { return ref < *this; };
        bool operator == (const segment & ref) const { return ref.high == high && ref.low == low; };
        bool operator != (const segment & ref) const { return ! (*this == ref); };
 
        // if two segment make <= or >= true they can be replaced by a single (larger) segment
        bool operator <= (const segment & ref) const { return ref.low < low && low <= ref.high + 1 && ref.high < high; };
        bool operator >= (const segment &ref) const { return ref <= *this; };
        bool contains(const segment & ref) const { return low <= ref.low && ref.high <= high; };
 
        std::string display() const;
 
    private:
        infinint low, high;
    };
 
    std::list<segment> parts;
    mutable std::list<segment>::const_iterator read_cursor;
 
    };
 
 
} // end of namespace
 
#endif