/***************************************************************************
                              qgsfeaturefilterprovider.h
                              --------------------------
  begin                : 22-05-2015
  copyright            : (C) 2008 by Stéphane Brunner
  email                : stephane dot brunner at camptocamp dot com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   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.                                   *
 *                                                                         *
 ***************************************************************************/

#ifndef QGSFEATUREFILTERPROVIDER_H
#define QGSFEATUREFILTERPROVIDER_H

#include <QtGlobal>
#include "qgis_sip.h"

#include "qgis_core.h"

class QString;
class QgsVectorLayer;
class QgsFeatureRequest;


/**
 * \ingroup core
 * \class QgsFeatureFilterProvider
 * Abstract interface for use by classes that filter the features of a layer.
 * A QgsFeatureFilterProvider provides a method for modifying a QgsFeatureRequest in place to apply
 * additional filters to the request.
 * \since QGIS 2.14
 */

class CORE_EXPORT QgsFeatureFilterProvider
{
  public:

#ifndef SIP_RUN

    //! Constructor
    QgsFeatureFilterProvider() = default;

    virtual ~QgsFeatureFilterProvider() = default;

#endif

    /**
     * Add additional filters to the feature request to further restrict the features returned by the request.
     * Derived classes must implement this method.
     * \param layer the layer to filter
     * \param featureRequest the feature request to update
     */
    virtual void filterFeatures( const QgsVectorLayer *layer, QgsFeatureRequest &featureRequest ) const = 0;

    /**
     * Create a clone of the feature filter provider
     * \returns a new clone
     */
    virtual QgsFeatureFilterProvider *clone() const = 0 SIP_FACTORY;
};

#endif
