buffer.h

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#ifndef WIBBLE_SYS_BUFFER_H
#define WIBBLE_SYS_BUFFER_H

/*
 * Variable-size, reference-counted memory buffer
 *
 * Copyright (C) 2003--2006  Enrico Zini <enrico@debian.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 */

#include <stddef.h> // for size_t

namespace wibble {
namespace sys {

class Buffer
{
public:
    class Data
    {
    protected:
        mutable int _ref;
        size_t _size;
        void* _data;

    public:
        Data() throw () : _ref(0), _size(0), _data(0) {}
        Data(size_t size);
        // if own == true, take possession of the memory buffer, else copy it
        Data(void* buf, size_t size, bool own = true);
        Data(const void* buf, size_t size);
        ~Data();

        void ref() const throw () { ++_ref; }

        bool unref() const throw () { return --_ref == 0; }

        void resize(size_t size);

        bool operator==(const Data& d) const throw();

        bool operator<(const Data& d) const throw();

        friend class Buffer;
    };

    Data* item;
    
public:
    Buffer() throw () : item(0) {}

    Buffer(size_t size) : item(0)
    {
        if (size)
        {
            item = new Data(size);
            item->ref();
        }
    }

    Buffer(void* buf, size_t size, bool own = true) : item(0)
    {
        if (size)
        {
            item = new Data(buf, size, own);
            item->ref();
        }
    }

    Buffer(const void* buf, size_t size) : item(0)
    {
        if (size)
        {
            item = new Data(buf, size);
            item->ref();
        }
    }

    Buffer(const Buffer& buf) throw ()
    {
        if (buf.item)
            buf.item->ref();
        item = buf.item;
    }
    ~Buffer()
    {
        if (item && item->unref())
            delete item;
    }
    Buffer& operator=(const Buffer& buf)
    {
        if (buf.item)
            buf.item->ref();  // Do it early to correctly handle the case of x = x;
        if (item && item->unref())
            delete item;
        item = buf.item;
        return *this;
    }

    void* data() throw () { return item ? item->_data : 0; }

    const void* data() const throw () { return item ? item->_data : 0; }

    size_t size() const throw () { return item ? item->_size : 0; }

    void resize(size_t newSize)
    {
        if (size() == newSize)
            return;
        if (!newSize)
        {
            if (item && item->unref())
                delete item;
            item = 0;
        } else if (item) {
            item->resize(newSize);
        } else {
            item = new Data(newSize);
            item->ref();
        }
    }

    bool operator==(const Buffer& buf) const throw ()
    {
        if (item == 0 && buf.item == 0)
            return true;
        if (item == 0 || buf.item == 0)
            return false;
        return *item == *buf.item;
    }

    bool operator!=(const Buffer& buf) const throw ()
    {
        return !operator==(buf);
    }

    bool operator<(const Buffer& buf) const throw ()
    {
        if (item == 0 && buf.item == 0)
            return false;
        if (item == 0)
            return true;
        if (buf.item == 0)
            return false;
        return *item < *buf.item;
    }
};

}
}

// vim:set ts=4 sw=4:
#endif