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       1                 :            : /***************************************************************************
       2                 :            :     qgscacheindex.h
       3                 :            :      --------------------------------------
       4                 :            :     Date                 : 13.2.2013
       5                 :            :     Copyright            : (C) 2013 Matthias Kuhn
       6                 :            :     Email                : matthias at opengis dot ch
       7                 :            :  ***************************************************************************
       8                 :            :  *                                                                         *
       9                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      10                 :            :  *   it under the terms of the GNU General Public License as published by  *
      11                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      12                 :            :  *   (at your option) any later version.                                   *
      13                 :            :  *                                                                         *
      14                 :            :  ***************************************************************************/
      15                 :            : 
      16                 :            : #ifndef QGSCACHEINDEX_H
      17                 :            : #define QGSCACHEINDEX_H
      18                 :            : 
      19                 :            : #include "qgis_core.h"
      20                 :            : #include "qgsfeatureid.h"
      21                 :            : 
      22                 :            : class QgsFeatureRequest;
      23                 :            : class QgsFeatureIterator;
      24                 :            : 
      25                 :            : /**
      26                 :            :  * \ingroup core
      27                 :            :  * \brief
      28                 :            :  * \brief Abstract base class for cache indices
      29                 :            :  */
      30                 :            : 
      31                 :            : class CORE_EXPORT QgsAbstractCacheIndex
      32                 :            : {
      33                 :            :   public:
      34                 :            : 
      35                 :            :     /**
      36                 :            :      * Constructor for QgsAbstractCacheIndex.
      37                 :            :      */
      38                 :          0 :     QgsAbstractCacheIndex() = default;
      39                 :          0 :     virtual ~QgsAbstractCacheIndex() = default;
      40                 :            : 
      41                 :            :     /**
      42                 :            :      * Is called whenever a feature is removed from the cache. You should update your indexes so
      43                 :            :      * they become invalid in case this feature was required to successfully answer a request.
      44                 :            :      */
      45                 :            :     virtual void flushFeature( QgsFeatureId fid ) = 0;
      46                 :            : 
      47                 :            :     /**
      48                 :            :      * Sometimes, the whole cache changes its state and its easier to just withdraw everything.
      49                 :            :      * In this case, this method is issued. Be sure to clear all cache information in here.
      50                 :            :      */
      51                 :            :     virtual void flush() = 0;
      52                 :            : 
      53                 :            :     /**
      54                 :            :      * \brief
      55                 :            :      * Implement this method to update the the indices, in case you need information contained by the request
      56                 :            :      * to properly index. (E.g. spatial index)
      57                 :            :      * Does nothing by default
      58                 :            :      *
      59                 :            :      * \param featureRequest  The feature request that was answered
      60                 :            :      * \param fids            The feature ids that have been returned
      61                 :            :      */
      62                 :            :     virtual void requestCompleted( const QgsFeatureRequest &featureRequest, const QgsFeatureIds &fids );
      63                 :            : 
      64                 :            :     /**
      65                 :            :      * Is called when a feature request is issued on a cached layer.
      66                 :            :      *
      67                 :            :      * If this cache index is able to completely answer the feature request, it will return TRUE
      68                 :            :      * and set the iterator to a valid iterator over the cached features. If it is not able
      69                 :            :      * it will return FALSE.
      70                 :            :      *
      71                 :            :      * \param featureIterator  A reference to a QgsFeatureIterator. A valid featureIterator will
      72                 :            :      *                         be assigned in case this index is able to answer the request and the return
      73                 :            :      *                         value is TRUE.
      74                 :            :      * \param featureRequest   The feature request, for which this index is queried.
      75                 :            :      *
      76                 :            :      * \returns   TRUE, if this index holds the information to answer the request.
      77                 :            :      *
      78                 :            :      */
      79                 :            :     virtual bool getCacheIterator( QgsFeatureIterator &featureIterator, const QgsFeatureRequest &featureRequest ) = 0;
      80                 :            : };
      81                 :            : 
      82                 :            : #endif // QGSCACHEINDEX_H