view data/fileio/DataFileReader.h @ 1376:d9511f9e04d7 dev/refactor-piper-related

Introduce some POD structs for describing an external server application and the desired libraries to load from it, and disambiguating between empty list request and invalid list request. This allows for overriding PiperVampPluginFactory behaviour for using a PluginScan to populate the list request.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 Chris Cannam.
    
    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.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef _DATA_FILE_READER_H_
#define _DATA_FILE_READER_H_

#include <QString>
#include <QObject>

class Model;

class DataFileReader : public QObject
{
public:
    /**
     * Return true if the file appears to be of the correct type.
     *
     * The DataFileReader will be constructed by passing a file path
     * to its constructor.  If the file can at that time be determined
     * to be not of a type that this reader can read, it should return
     * false in response to any subsequent call to isOK().
     *
     * If the file is apparently of the correct type, isOK() should
     * return true; if it turns out that the file cannot after all be
     * read (because it's corrupted or the detection misfired), then
     * the read() function may return NULL.
     */
    virtual bool isOK() const = 0;

    virtual QString getError() const { return ""; }

    /**
     * Read the file and return the corresponding data model.  This
     * function is not expected to be thread-safe or reentrant.  This
     * function may be interactive (i.e. it's permitted to pop up
     * dialogs and windows and ask the user to specify any details
     * that can't be automatically extracted from the file).
     *
     * Return NULL if the file cannot be parsed at all (although it's
     * preferable to return a partial model and warn the user).
     *
     * Caller owns the returned model and must delete it after use.
     */
    virtual Model *load() const = 0;
};

#endif