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49de489c09
This is potentially interesting for race conditions, but whenever it is specified, iterators will need to be carefully checked for validity and error handling needs to be taken care of.
318 lines
11 KiB
C++
318 lines
11 KiB
C++
/***************************************************************************
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qgsvectorlayerfeatureiterator.h
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---------------------
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begin : Dezember 2012
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copyright : (C) 2012 by Martin Dobias
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email : wonder dot sk at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#ifndef QGSVECTORLAYERFEATUREITERATOR_H
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#define QGSVECTORLAYERFEATUREITERATOR_H
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#include "qgis_core.h"
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#include "qgis_sip.h"
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#include "qgsfeatureiterator.h"
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#include "qgsfields.h"
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#include "qgscoordinatereferencesystem.h"
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#include "qgsfeaturesource.h"
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#include <QSet>
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#include <memory>
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typedef QMap<QgsFeatureId, QgsFeature> QgsFeatureMap SIP_SKIP;
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class QgsExpressionFieldBuffer;
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class QgsVectorLayer;
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class QgsVectorLayerEditBuffer;
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class QgsVectorLayerJoinBuffer;
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class QgsVectorLayerJoinInfo;
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class QgsExpressionContext;
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class QgsVectorLayerFeatureIterator;
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#ifdef SIP_RUN
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% ModuleHeaderCode
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#include "qgsfeatureiterator.h"
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% End
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#endif
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/**
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* \ingroup core
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* Partial snapshot of vector layer's state (only the members necessary for access to features)
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*/
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class CORE_EXPORT QgsVectorLayerFeatureSource : public QgsAbstractFeatureSource
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{
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public:
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/**
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* Constructor for QgsVectorLayerFeatureSource.
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* \param layer source layer
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*/
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explicit QgsVectorLayerFeatureSource( const QgsVectorLayer *layer );
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~QgsVectorLayerFeatureSource();
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virtual QgsFeatureIterator getFeatures( const QgsFeatureRequest &request = QgsFeatureRequest() ) override;
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friend class QgsVectorLayerFeatureIterator SIP_SKIP;
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/**
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* Returns the fields that will be available for features that are retrieved from
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* this source.
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*
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* \since QGIS 3.0
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*/
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QgsFields fields() const;
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/**
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* Returns the coordinate reference system for features retrieved from this source.
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* \since QGIS 3.0
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*/
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QgsCoordinateReferenceSystem crs() const;
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protected:
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QgsAbstractFeatureSource *mProviderFeatureSource = nullptr;
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QgsVectorLayerJoinBuffer *mJoinBuffer = nullptr;
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QgsExpressionFieldBuffer *mExpressionFieldBuffer = nullptr;
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QgsFields mFields;
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QgsExpressionContextScope mLayerScope;
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bool mHasEditBuffer;
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// A deep-copy is only performed, if the original maps change
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// see here https://github.com/qgis/Quantum-GIS/pull/673
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// for explanation
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QgsFeatureMap mAddedFeatures;
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QgsGeometryMap mChangedGeometries;
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QgsFeatureIds mDeletedFeatureIds;
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QList<QgsField> mAddedAttributes;
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QgsChangedAttributesMap mChangedAttributeValues;
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QgsAttributeList mDeletedAttributeIds;
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QgsCoordinateReferenceSystem mCrs;
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};
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/**
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* \ingroup core
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*/
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class CORE_EXPORT QgsVectorLayerFeatureIterator : public QgsAbstractFeatureIteratorFromSource<QgsVectorLayerFeatureSource>
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{
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public:
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QgsVectorLayerFeatureIterator( QgsVectorLayerFeatureSource *source, bool ownSource, const QgsFeatureRequest &request );
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~QgsVectorLayerFeatureIterator();
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//! reset the iterator to the starting position
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virtual bool rewind() override;
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//! end of iterating: free the resources / lock
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virtual bool close() override;
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virtual void setInterruptionChecker( QgsInterruptionChecker *interruptionChecker ) override SIP_SKIP;
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/**
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* Join information prepared for fast attribute id mapping in QgsVectorLayerJoinBuffer::updateFeatureAttributes().
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* Created in the select() method of QgsVectorLayerJoinBuffer for the joins that contain fetched attributes
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*/
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struct CORE_EXPORT FetchJoinInfo
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{
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const QgsVectorLayerJoinInfo *joinInfo;//!< Canonical source of information about the join
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QgsAttributeList attributes; //!< Attributes to fetch
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int indexOffset; //!< At what position the joined fields start
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QgsVectorLayer *joinLayer; //!< Resolved pointer to the joined layer
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int targetField; //!< Index of field (of this layer) that drives the join
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int joinField; //!< Index of field (of the joined layer) must have equal value
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void addJoinedAttributesCached( QgsFeature &f, const QVariant &joinValue ) const;
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void addJoinedAttributesDirect( QgsFeature &f, const QVariant &joinValue ) const;
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};
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virtual bool isValid() const override;
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protected:
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//! fetch next feature, return true on success
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virtual bool fetchFeature( QgsFeature &feature ) override;
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/**
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* Overrides default method as we only need to filter features in the edit buffer
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* while for others filtering is left to the provider implementation.
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*/
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virtual bool nextFeatureFilterExpression( QgsFeature &f ) override { return fetchFeature( f ); }
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//! Setup the simplification of geometries to fetch using the specified simplify method
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virtual bool prepareSimplification( const QgsSimplifyMethod &simplifyMethod ) override;
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//! \note not available in Python bindings
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void rewindEditBuffer() SIP_SKIP;
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//! \note not available in Python bindings
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void prepareJoin( int fieldIdx ) SIP_SKIP;
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//! \note not available in Python bindings
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void prepareExpression( int fieldIdx ) SIP_SKIP;
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//! \note not available in Python bindings
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void prepareFields() SIP_SKIP;
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//! \note not available in Python bindings
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void prepareField( int fieldIdx ) SIP_SKIP;
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//! \note not available in Python bindings
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bool fetchNextAddedFeature( QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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bool fetchNextChangedGeomFeature( QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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bool fetchNextChangedAttributeFeature( QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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void useAddedFeature( const QgsFeature &src, QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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void useChangedAttributeFeature( QgsFeatureId fid, const QgsGeometry &geom, QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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bool nextFeatureFid( QgsFeature &f ) SIP_SKIP;
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//! \note not available in Python bindings
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void addJoinedAttributes( QgsFeature &f ) SIP_SKIP;
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/**
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* Adds attributes that don't source from the provider but are added inside QGIS
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* Includes
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* - Joined fields
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* - Expression fields
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*
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* \param f The feature will be modified
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* \note not available in Python bindings
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*/
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void addVirtualAttributes( QgsFeature &f ) SIP_SKIP;
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/**
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* Adds an expression based attribute to a feature
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* \param f feature
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* \param attrIndex attribute index
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* \since QGIS 2.14
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* \note not available in Python bindings
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*/
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void addExpressionAttribute( QgsFeature &f, int attrIndex ) SIP_SKIP;
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/**
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* Update feature with uncommitted attribute updates.
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* \note not available in Python bindings
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*/
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void updateChangedAttributes( QgsFeature &f ) SIP_SKIP;
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/**
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* Update feature with uncommitted geometry updates.
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* \note not available in Python bindings
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*/
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void updateFeatureGeometry( QgsFeature &f ) SIP_SKIP;
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QgsFeatureRequest mProviderRequest;
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QgsFeatureIterator mProviderIterator;
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QgsFeatureRequest mChangedFeaturesRequest;
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QgsFeatureIterator mChangedFeaturesIterator;
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QgsRectangle mFilterRect;
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QgsCoordinateTransform mTransform;
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// only related to editing
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QSet<QgsFeatureId> mFetchConsidered;
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QgsGeometryMap::ConstIterator mFetchChangedGeomIt;
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QgsFeatureMap::ConstIterator mFetchAddedFeaturesIt;
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bool mFetchedFid; // when iterating by FID: indicator whether it has been fetched yet or not
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/**
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* Information about joins used in the current select() statement.
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Allows faster mapping of attribute ids compared to mVectorJoins */
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QMap<const QgsVectorLayerJoinInfo *, QgsVectorLayerFeatureIterator::FetchJoinInfo> mFetchJoinInfo;
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QMap<int, QgsExpression *> mExpressionFieldInfo;
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bool mHasVirtualAttributes;
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private:
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#ifdef SIP_RUN
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QgsVectorLayerFeatureIterator( const QgsVectorLayerFeatureIterator &rhs );
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#endif
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std::unique_ptr<QgsExpressionContext> mExpressionContext;
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QgsInterruptionChecker *mInterruptionChecker = nullptr;
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QList< int > mPreparedFields;
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QList< int > mFieldsToPrepare;
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//! Join list sorted by dependency
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QList< FetchJoinInfo > mOrderedJoinInfoList;
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/**
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* Will always return true. We assume that ordering has been done on provider level already.
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*
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*/
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bool prepareOrderBy( const QList<QgsFeatureRequest::OrderByClause> &orderBys ) override;
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//! returns whether the iterator supports simplify geometries on provider side
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virtual bool providerCanSimplify( QgsSimplifyMethod::MethodType methodType ) const override;
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void createOrderedJoinList();
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/**
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* Performs any post-processing (such as transformation) and feature based validity checking, e.g. checking for geometry validity.
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*/
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bool postProcessFeature( QgsFeature &feature );
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/**
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* Checks a feature's geometry for validity, if requested in feature request.
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*/
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bool checkGeometryValidity( const QgsFeature &feature );
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};
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/**
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* \class QgsVectorLayerSelectedFeatureSource
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* \ingroup core
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* QgsFeatureSource subclass for the selected features from a QgsVectorLayer.
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* \since QGIS 3.0
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*/
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class CORE_EXPORT QgsVectorLayerSelectedFeatureSource : public QgsFeatureSource
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{
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public:
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/**
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* Constructor for QgsVectorLayerSelectedFeatureSource, for selected features from the specified \a layer.
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* The currently selected feature IDs are stored, so change to the layer selection after constructing
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* the QgsVectorLayerSelectedFeatureSource will not be reflected.
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*/
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QgsVectorLayerSelectedFeatureSource( QgsVectorLayer *layer );
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QgsFeatureIterator getFeatures( const QgsFeatureRequest &request = QgsFeatureRequest() ) const override;
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QgsCoordinateReferenceSystem sourceCrs() const override;
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QgsFields fields() const override;
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QgsWkbTypes::Type wkbType() const override;
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long featureCount() const override;
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QString sourceName() const override;
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private:
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// ideally this wouldn't be mutable, but QgsVectorLayerFeatureSource has non-const getFeatures()
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mutable QgsVectorLayerFeatureSource mSource;
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QgsFeatureIds mSelectedFeatureIds;
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QgsWkbTypes::Type mWkbType = QgsWkbTypes::Unknown;
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QString mName;
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};
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#endif // QGSVECTORLAYERFEATUREITERATOR_H
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