class QgsCacheIndexFeatureId : QgsAbstractCacheIndex
{
%TypeHeaderCode
#include <qgscacheindexfeatureid.h>
%End
  public:
    QgsCacheIndexFeatureId( QgsVectorLayerCache* );

    /**
     * Is called, whenever a feature is removed from the cache. You should update your indexes, so
     * they become invalid in case this feature was required to successfuly answer a request.
     */
    virtual void flushFeature( const QgsFeatureId fid );

    /**
     * Sometimes, the whole cache changes its state and its easier to just withdraw everything.
     * In this case, this method is issued. Be sure to clear all cache information in here.
     */
    virtual void flush();

    /**
     * @brief
     * Implement this method to update the the indices, in case you need information contained by the request
     * to properly index. (E.g. spatial index)
     * Does nothing by default
     *
     * @param featureRequest  The feature request that was answered
     * @param fids            The feature ids that have been returned
     */
    virtual void requestCompleted( QgsFeatureRequest featureRequest, QgsFeatureIds fids );

    /**
     * Is called, when a feature request is issued on a cached layer.
     * If this cache index is able to completely answer the feature request, it will return true
     * and write the list of feature ids of cached features to cachedFeatures. If it is not able
     * it will return false and the cachedFeatures state is undefined.
     *
     * @param featureIterator  A reference to a {@link QgsFeatureIterator}. A valid featureIterator will
     *                         be assigned in case this index is able to answer the request and the return
     *                         value is true.
     * @param featureRequest   The feature request, for which this index is queried.
     *
     * @return   True, if this index holds the information to answer the request.
     *
     */
    virtual bool getCacheIterator( QgsFeatureIterator& featureIterator, const QgsFeatureRequest& featureRequest );
};