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a98923507e
If set, all geometries will be reprojected from their original
coordinate reference system to the destination CRS while
iterating over features.
If a CRS has been set as the destination CRS, then the filterRect
parameter should be specified in the same CRS as this destination
CRS.
Additionally, a callback function can be specified on the request
to be called if a transform exception is encountered while
iterating over features.
This is designed to make it easier for scripts and plugins to
correctly reproject layers in an efficient and robust way, instead
of having to implement lots of repeated code themselves and
potentially missing some of the important considerations which
come with reprojecting geometries & bounding boxes.
Now, if a script wants the features from a layer in a specific
CRS, they can call:
crs = QgsCoordinateReferenceSystem('epsg:4326')
request = QgsFeatureRequest().setDestinationCrs(crs)
for f in layer.getFeatures(reqeuest):
print('geometry in 4326 is {}.format(f.geometry().exportToWkt()))
263 lines
6.7 KiB
Plaintext
263 lines
6.7 KiB
Plaintext
/************************************************************************
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* This file has been generated automatically from *
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* *
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* src/core/qgsfeatureiterator.h *
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* *
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* Do not edit manually ! Edit header and run scripts/sipify.pl again *
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************************************************************************/
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class QgsAbstractFeatureIterator
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{
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%Docstring
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Internal feature iterator to be implemented within data providers
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%End
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%TypeHeaderCode
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#include "qgsfeatureiterator.h"
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%End
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public:
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enum CompileStatus
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{
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NoCompilation,
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PartiallyCompiled,
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Compiled,
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};
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QgsAbstractFeatureIterator( const QgsFeatureRequest &request );
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%Docstring
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base class constructor - stores the iteration parameters
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%End
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virtual ~QgsAbstractFeatureIterator();
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%Docstring
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destructor makes sure that the iterator is closed properly
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%End
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virtual bool nextFeature( QgsFeature &f );
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%Docstring
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fetch next feature, return true on success
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:rtype: bool
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%End
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virtual bool rewind() = 0;
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%Docstring
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reset the iterator to the starting position
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:rtype: bool
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%End
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virtual bool close() = 0;
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%Docstring
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end of iterating: free the resources / lock
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:rtype: bool
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%End
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CompileStatus compileStatus() const;
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%Docstring
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Returns the status of expression compilation for filter expression requests.
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.. versionadded:: 2.16
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:rtype: CompileStatus
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%End
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protected:
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virtual bool fetchFeature( QgsFeature &f ) = 0;
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%Docstring
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If you write a feature iterator for your provider, this is the method you
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need to implement!!
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\param f The feature to write to
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:return: true if a feature was written to f
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:rtype: bool
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%End
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virtual bool nextFeatureFilterExpression( QgsFeature &f );
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%Docstring
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By default, the iterator will fetch all features and check if the feature
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matches the expression.
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If you have a more sophisticated metodology (SQL request for the features...)
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and you check for the expression in your fetchFeature method, you can just
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redirect this call to fetchFeature so the default check will be omitted.
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\param f The feature to write to
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:return: true if a feature was written to f
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:rtype: bool
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%End
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virtual bool nextFeatureFilterFids( QgsFeature &f );
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%Docstring
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By default, the iterator will fetch all features and check if the id
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is in the request.
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If you have a more sophisticated metodology (SQL request for the features...)
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and you are sure, that any feature you return from fetchFeature will match
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if the request was FilterFids you can just redirect this call to fetchFeature
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so the default check will be omitted.
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\param f The feature to write to
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:return: true if a feature was written to f
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:rtype: bool
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%End
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void transformFeatureGeometry( QgsFeature &feature, const QgsCoordinateTransform &transform ) const;
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%Docstring
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Transforms ``feature``'s geometry according to the specified coordinate ``transform``.
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If ``feature`` has no geometry or ``transform`` is invalid then calling this method
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has no effect and will be shortcut.
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Iterators should call this method before returning features to ensure that any
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QgsFeatureRequest.destinationCrs() set on the request is respected.
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.. versionadded:: 3.0
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%End
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QgsRectangle transformedFilterRect( const QgsCoordinateTransform &transform ) const;
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%Docstring
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Returns a rectangle representing the original request's QgsFeatureRequest.filterRect().
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If ``transform`` is a valid coordinate transform, the return rectangle will represent
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the requested filterRect() transformed to the source's coordinate reference system.
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Iterators should call this method and use the returned rectangle for filtering
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features to ensure that any QgsFeatureRequest.destinationCrs() set on the request is respected.
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.. versionadded:: 3.0
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:rtype: QgsRectangle
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%End
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void ref();
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%Docstring
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Add reference
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%End
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void deref();
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%Docstring
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Remove reference, delete if refs == 0
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%End
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virtual bool prepareSimplification( const QgsSimplifyMethod &simplifyMethod );
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%Docstring
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Setup the simplification of geometries to fetch using the specified simplify method
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:rtype: bool
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%End
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};
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template<T>
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class QgsAbstractFeatureIteratorFromSource : QgsAbstractFeatureIterator
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{
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%Docstring
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Helper template that cares of two things: 1. automatic deletion of source if owned by iterator, 2. notification of open/closed iterator.
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.. note::
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not available in Python bindings (although present in SIP file)
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%End
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%TypeHeaderCode
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#include "qgsfeatureiterator.h"
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%End
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public:
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QgsAbstractFeatureIteratorFromSource( T *source, bool ownSource, const QgsFeatureRequest &request );
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~QgsAbstractFeatureIteratorFromSource();
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protected:
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void iteratorClosed();
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%Docstring
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to be called by from subclass in close()
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%End
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};
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class QgsFeatureIterator
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{
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%Docstring
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Wrapper for iterator of features from vector data provider or vector layer
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%End
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%TypeHeaderCode
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#include "qgsfeatureiterator.h"
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%End
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public:
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QgsFeatureIterator *__iter__();
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%Docstring
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:rtype: QgsFeatureIterator
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%End
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%MethodCode
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sipRes = sipCpp;
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%End
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SIP_PYOBJECT __next__();
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%MethodCode
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QgsFeature *f = new QgsFeature;
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if ( sipCpp->nextFeature( *f ) )
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sipRes = sipConvertFromType( f, sipType_QgsFeature, Py_None );
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else
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{
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delete f;
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PyErr_SetString( PyExc_StopIteration, "" );
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}
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%End
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QgsFeatureIterator();
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%Docstring
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construct invalid iterator
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%End
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QgsFeatureIterator( const QgsFeatureIterator &fi );
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%Docstring
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copy constructor copies the iterator, increases ref.count
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%End
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~QgsFeatureIterator();
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%Docstring
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destructor deletes the iterator if it has no more references
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%End
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bool nextFeature( QgsFeature &f );
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%Docstring
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:rtype: bool
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%End
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bool rewind();
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%Docstring
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:rtype: bool
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%End
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bool close();
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%Docstring
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:rtype: bool
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%End
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bool isClosed() const;
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%Docstring
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find out whether the iterator is still valid or closed already
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:rtype: bool
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%End
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QgsAbstractFeatureIterator::CompileStatus compileStatus() const;
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%Docstring
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Returns the status of expression compilation for filter expression requests.
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.. versionadded:: 2.16
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:rtype: QgsAbstractFeatureIterator.CompileStatus
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%End
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protected:
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};
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/************************************************************************
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* This file has been generated automatically from *
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* *
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* src/core/qgsfeatureiterator.h *
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* *
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* Do not edit manually ! Edit header and run scripts/sipify.pl again *
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************************************************************************/
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