non/Loggable.H

/*******************************************************************************/
/* Copyright (C) 2008 Jonathan Moore Liles                                     */
/*                                                                             */
/* 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; see the file COPYING.  If not,write to the Free Software */
/* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
/*******************************************************************************/

/* Master class for journaling. */

#pragma once

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <vector>
#include <map>
#include <string>
#include <queue>
using namespace std;


class Loggable;
typedef Loggable *(create_func)(char **);

class Logger;
class Loggable
{

    static FILE *_fp;
    static int _log_id;
    static int _level;
    static int _undo_index;

    static vector <Loggable *> _loggables;

    static map <string, create_func*> _class_map;

    static queue <char *> _transaction;

private:
    int _id;

    char **_old_state;
    char **_new_state;

    int _nest;

    void log_print(  char **o, char **n );
    static void log ( const char *fmt, ... );

    static void flush ( void );
    static
    void indent ( void )
        {
            int n = Loggable::_level;

            while ( n-- )
                log( "\t" );
        }


public:

    static bool open ( const char *filename );
    static void undo ( void );
    static int undo_index ( void ) { return _undo_index; }
    static bool snapshot( const char *file );

    static
    void
    block_start ( void )
        {
            ++Loggable::_level;
        }

    static
    void
    block_end ( void )
        {
            assert( --Loggable::_level >= 0 );

            if ( Loggable::_level == 0 )
                flush();
        }

    static
    Loggable *
    find ( int id )
        {
            if ( id > _log_id )
                return NULL;

            return _loggables[ id - 1 ];
        }

    Loggable ( )
        {
            _id = ++_log_id;
            _old_state = NULL;
            _nest = 0;

            _loggables.push_back( this );
        }

    /** must be called after construction in create() methods */
    void
    update_id ( int id )
        {
            assert( _id == _log_id );

            _loggables[ _id - 1 ]  = NULL;

            --_log_id;

            _id = id;

            assert( ! _loggables[ _id - 1 ] );

            _loggables[ _id - 1 ] = this;
        }

    virtual ~Loggable (  )
        {
            _loggables[ _id - 1 ] = NULL;
        }

    static
    void
    register_create ( const char *name, create_func *func )
        {
            printf( "registering %s to %p\n", name, func );

            _class_map[ string( name ) ] = func;
        }

    /* log messages for journal */
    virtual const char *class_name ( void ) = 0;
    virtual char ** get ( void ) = 0;

    /* this method must parse an array of name/value pair strings and make the appropriate changes too
       the object state */
    virtual void set ( char **sa ) = 0;
//    void log ( const char *module, const char *action, const char *fmt, ... );

protected:

    void log_start ( void );
    void log_end ( void );
    void log_create ( void );
    void log_destroy ( void );

public:

    int id ( void ) { return _id; }


    friend class Logger;
};


class Logger
{

    Loggable *_this;
    Logger ( ) {}

public:

    Logger ( Loggable *l ) : _this( l )
        {
            _this->log_start();

        }

    ~Logger ( )
        {
            _this->log_end();
        }

    void hold ( void )
        {
            printf( "hold\n" );
            _this->_nest++;
        }

    void release ( void )
        {
            printf( "release\n" );
            _this->_nest--;
            assert( _this->_nest );
        }
};


/* #ifndef _LOGGABLE_C */
/* #define log( act, fmt, args... ) log( __CLASS__, act, fmt, ## args ) */
/* #endif */

/* #define LOG_START Logger _logger( this ) */
/* #define LOG_END          _logger.print( this ) */