qgsvectorlayerfeatureiterator.h

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/***************************************************************************
    qgsvectorlayerfeatureiterator.h
    ---------------------
    begin                : Dezember 2012
    copyright            : (C) 2012 by Martin Dobias
    email                : wonder dot sk at gmail 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 QGSVECTORLAYERFEATUREITERATOR_H
#define QGSVECTORLAYERFEATUREITERATOR_H

#include "qgsfeatureiterator.h"

#include <QSet>

typedef QMap<QgsFeatureId, QgsFeature> QgsFeatureMap;

class QgsExpressionFieldBuffer;
class QgsVectorLayer;
class QgsVectorLayerEditBuffer;
class QgsVectorLayerJoinBuffer;
struct QgsVectorJoinInfo;
class QgsExpressionContext;

class QgsVectorLayerFeatureIterator;

class QgsVectorLayerFeatureSource : public QgsAbstractFeatureSource
{
  public:
    explicit QgsVectorLayerFeatureSource( QgsVectorLayer* layer );
    ~QgsVectorLayerFeatureSource();

    virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest& request ) override;

    friend class QgsVectorLayerFeatureIterator;

  protected:

    QgsAbstractFeatureSource* mProviderFeatureSource;

    QgsVectorLayerJoinBuffer* mJoinBuffer;

    QgsExpressionFieldBuffer* mExpressionFieldBuffer;

    QgsFields mFields;

    bool mHasEditBuffer;

    bool mCanBeSimplified;

    // A deep-copy is only performed, if the original maps change
    // see here https://github.com/qgis/Quantum-GIS/pull/673
    // for explanation
    QgsFeatureMap mAddedFeatures;
    QgsGeometryMap mChangedGeometries;
    QgsFeatureIds mDeletedFeatureIds;
    QList<QgsField> mAddedAttributes;
    QgsChangedAttributesMap mChangedAttributeValues;
    QgsAttributeList mDeletedAttributeIds;
};


class CORE_EXPORT QgsVectorLayerFeatureIterator : public QgsAbstractFeatureIteratorFromSource<QgsVectorLayerFeatureSource>
{
  public:
    QgsVectorLayerFeatureIterator( QgsVectorLayerFeatureSource* source, bool ownSource, const QgsFeatureRequest& request );

    ~QgsVectorLayerFeatureIterator();

    virtual bool rewind() override;

    virtual bool close() override;

  protected:
    virtual bool fetchFeature( QgsFeature& feature ) override;

    inline virtual bool nextFeatureFilterExpression( QgsFeature &f ) override { return fetchFeature( f ); }

    virtual bool prepareSimplification( const QgsSimplifyMethod& simplifyMethod ) override;


    QgsFeatureRequest mProviderRequest;
    QgsFeatureIterator mProviderIterator;
    QgsFeatureRequest mChangedFeaturesRequest;
    QgsFeatureIterator mChangedFeaturesIterator;


    // only related to editing
    QSet<QgsFeatureId> mFetchConsidered;
    QgsGeometryMap::ConstIterator mFetchChangedGeomIt;
    QgsFeatureMap::ConstIterator mFetchAddedFeaturesIt;

    bool mFetchedFid; // when iterating by FID: indicator whether it has been fetched yet or not

    void rewindEditBuffer();
    void prepareJoins();
    void prepareExpressions();
    bool fetchNextAddedFeature( QgsFeature& f );
    bool fetchNextChangedGeomFeature( QgsFeature& f );
    bool fetchNextChangedAttributeFeature( QgsFeature& f );
    void useAddedFeature( const QgsFeature& src, QgsFeature& f );
    void useChangedAttributeFeature( QgsFeatureId fid, const QgsGeometry& geom, QgsFeature& f );
    bool nextFeatureFid( QgsFeature& f );
    void addJoinedAttributes( QgsFeature &f );
    void addVirtualAttributes( QgsFeature &f );

    void updateChangedAttributes( QgsFeature& f );

    void updateFeatureGeometry( QgsFeature& f );

    struct FetchJoinInfo
    {
      const QgsVectorJoinInfo* joinInfo;
      QgsAttributeList attributes;      
      int indexOffset;                  
      QgsVectorLayer* joinLayer;        
      int targetField;                  
      int joinField;                    

      void addJoinedAttributesCached( QgsFeature& f, const QVariant& joinValue ) const;
      void addJoinedAttributesDirect( QgsFeature& f, const QVariant& joinValue ) const;
    };

    QMap<const QgsVectorJoinInfo*, FetchJoinInfo> mFetchJoinInfo;

    QMap<int, QgsExpression*> mExpressionFieldInfo;

    bool mHasVirtualAttributes;

  private:
    QgsAbstractGeometrySimplifier* mEditGeometrySimplifier;

    QScopedPointer<QgsExpressionContext> mExpressionContext;

    virtual bool providerCanSimplify( QgsSimplifyMethod::MethodType methodType ) const override;
};

#endif // QGSVECTORLAYERFEATUREITERATOR_H