chert_cursor.h

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/* Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002,2003,2004,2006,2007,2008,2010 Olly Betts
 *
 * 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 St, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

#ifndef OM_HGUARD_CHERT_CURSOR_H
#define OM_HGUARD_CHERT_CURSOR_H

#include "chert_types.h"

#include <string>
using std::string;

#define BLK_UNUSED uint4(-1)

class Cursor {
    private:
        // Prevent copying
        Cursor(const Cursor &);
        Cursor & operator=(const Cursor &);

    public:
        Cursor() : p(0), c(-1), n(BLK_UNUSED), rewrite(false)
        {}

        uint8_t * p;
        int c;
        uint4 n;
        bool rewrite;
};

class ChertTable;

class ChertCursor {
    private:
        ChertCursor(const ChertCursor &);

        ChertCursor & operator=(const ChertCursor &);

        void rebuild();

    protected:
        bool is_positioned;

        bool is_after_end;

    private:
        enum { UNREAD, UNCOMPRESSED, COMPRESSED } tag_status;

    protected:
        const ChertTable * B;

    private:
        Cursor * C;

        unsigned long version;

        int level;

        void get_key(string * key) const;

    public:
        explicit ChertCursor(const ChertTable *B);

        ~ChertCursor();

        string current_key;

        string current_tag;

        bool read_tag(bool keep_compressed = false);

        bool next();

        bool prev();

        bool find_entry(const string &key);

        void find_entry_lt(const string &key) {
            if (find_entry(key)) prev();
        }

        bool find_entry_ge(const string &key);

        void to_end() { is_after_end = true; }

        bool after_end() const { return is_after_end; }

        const ChertTable * get_table() const { return B; }
};

class MutableChertCursor : public ChertCursor {
  public:
    explicit MutableChertCursor(ChertTable *B_) : ChertCursor(B_) { }

    bool del();
};

#endif /* OM_HGUARD_CHERT_CURSOR_H */