vos/metaobjects/property/fileproperty.hh

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/*
    This file is part of the Virtual Object System of
    the Interreality project (http://interreality.org).

    Copyright (C) 2001, 2002, 2003 Peter Amstutz

    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 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

    Peter Amstutz <tetron@interreality.org>
*/
#ifndef _FILEPROPERTY_HH_
#define _FILEPROPERTY_HH_

#include "property.hh"
#include <sys/types.h>
#include <sys/stat.h>

/**  @class FileProperty fileproperty.hh vos/metaobjects/property/fileproperty.hh
 *
 * A subclass of LocalProperty that uses a file as the backing store of the
 * property data.  All changes to this property will be reflected in
 * the file (so be careful with access control!), and any changes to the file
 * will be seen in the property data.
 * Use setFileBackend() to set the filename and datatype.
 */

class PROPERTY_API FileProperty : public virtual LocalProperty
{
public:
    class FileAccessError : public runtime_error {
    public:
        FileAccessError(const string& s) : runtime_error(s) { };
    };

private:
    FILE* filehandle;
    string filename;
    struct stat status;
    bool readonly;
    void checkOpenFile() throw (FileAccessError);

public:
    /** @internal */
    FileProperty(MetaObject* superobject);

    /** @internal */
    FileProperty(MetaObject* superobject, const string& filename, const string& datatype = "?");

    ~FileProperty();

    /** Register extender with factoory. You should also call Property::registerExtenders(). */
    static void registerExtenders();

    /** @internal */
    static MetaObject* new_FileProperty(MetaObject* superobject, const string& type);

    /** Open a file and start using it as the backend store for the property.
      * @throw FileAccessError If there was an error opening the file.
      */
    virtual void setFileBackend(const string& filename, const string& filetype = "?") throw(FileAccessError);

    /** Get filename string */
    virtual string getFileBackend();

    virtual int getRawLength() throw(FileAccessError);
    virtual void readRaw(string& target, int start, int length) throw(FileAccessError);
    virtual void read(string& target, int start, int length) throw(FileAccessError) ;
    virtual void write(int start, const string& newdata) throw(FileAccessError);
    virtual void replace(const string& newdata, const string& newtype = "?") throw(FileAccessError);
};

#endif

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