Support for setSubsetString() in memory provider

qgis · Sep 13, 2014 · 02a9bc8 · 02a9bc8
1 parent b44ef92
commit 02a9bc8
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Showing 4 changed files with 47 additions and 0 deletions.
diff --git a/src/providers/memory/qgsmemoryfeatureiterator.cpp b/src/providers/memory/qgsmemoryfeatureiterator.cpp
@@ -25,7 +25,13 @@
 QgsMemoryFeatureIterator::QgsMemoryFeatureIterator( QgsMemoryFeatureSource* source, bool ownSource, const QgsFeatureRequest& request )
     : QgsAbstractFeatureIteratorFromSource( source, ownSource, request )
     , mSelectRectGeom( 0 )
+    , mSubsetExpression( 0 )
 {
+  if ( !mSource->mSubsetString.isEmpty() )
+  {
+    mSubsetExpression = new QgsExpression( mSource->mSubsetString );
+    mSubsetExpression->prepare( mSource->mFields );
+  }
 
   if ( mRequest.filterType() == QgsFeatureRequest::FilterRect && mRequest.flags() & QgsFeatureRequest::ExactIntersect )
   {
@@ -58,6 +64,8 @@ QgsMemoryFeatureIterator::QgsMemoryFeatureIterator( QgsMemoryFeatureSource* sour
 QgsMemoryFeatureIterator::~QgsMemoryFeatureIterator()
 {
   close();
+
+  delete mSubsetExpression;
 }
 
 
@@ -91,6 +99,9 @@ bool QgsMemoryFeatureIterator::nextFeatureUsingList( QgsFeature& feature )
     else
       hasFeature = true;
 
+    if ( mSubsetExpression && !mSubsetExpression->evaluate( mSource->mFeatures[*mFeatureIdListIterator] ).toBool() )
+        hasFeature = false;
+
     if ( hasFeature )
       break;
 
@@ -141,6 +152,9 @@ bool QgsMemoryFeatureIterator::nextFeatureTraverseAll( QgsFeature& feature )
       }
     }
 
+    if ( mSubsetExpression && !mSubsetExpression->evaluate( *mSelectIterator ).toBool() )
+        hasFeature = false;
+
     if ( hasFeature )
       break;
 
@@ -194,6 +208,7 @@ QgsMemoryFeatureSource::QgsMemoryFeatureSource( const QgsMemoryProvider* p )
     : mFields( p->mFields )
     , mFeatures( p->mFeatures )
     , mSpatialIndex( p->mSpatialIndex ? new QgsSpatialIndex( *p->mSpatialIndex ) : 0 )  // just shallow copy
+    , mSubsetString( p->mSubsetString )
 {
 }
 

diff --git a/src/providers/memory/qgsmemoryfeatureiterator.h b/src/providers/memory/qgsmemoryfeatureiterator.h
@@ -36,6 +36,7 @@ class QgsMemoryFeatureSource : public QgsAbstractFeatureSource
     QgsFields mFields;
     QgsFeatureMap mFeatures;
     QgsSpatialIndex* mSpatialIndex;
+    QString mSubsetString;
 
     friend class QgsMemoryFeatureIterator;
 };
@@ -67,6 +68,7 @@ class QgsMemoryFeatureIterator : public QgsAbstractFeatureIteratorFromSource<Qgs
     bool mUsingFeatureIdList;
     QList<QgsFeatureId> mFeatureIdList;
     QList<QgsFeatureId>::const_iterator mFeatureIdListIterator;
+    QgsExpression* mSubsetExpression;
 
 };
 

diff --git a/src/providers/memory/qgsmemoryprovider.cpp b/src/providers/memory/qgsmemoryprovider.cpp
@@ -420,6 +420,26 @@ bool QgsMemoryProvider::changeGeometryValues( QgsGeometryMap & geometry_map )
   return true;
 }
 
+QString QgsMemoryProvider::subsetString()
+{
+  return mSubsetString;
+}
+
+bool QgsMemoryProvider::setSubsetString( QString theSQL, bool updateFeatureCount )
+{
+  Q_UNUSED( updateFeatureCount );
+
+  if ( !theSQL.isEmpty() )
+  {
+    QgsExpression tempExpression( theSQL );
+    if ( tempExpression.hasParserError() )
+      return false;
+  }
+
+  mSubsetString = theSQL;
+  return true;
+}
+
 bool QgsMemoryProvider::createSpatialIndex()
 {
   if ( !mSpatialIndex )

diff --git a/src/providers/memory/qgsmemoryprovider.h b/src/providers/memory/qgsmemoryprovider.h
@@ -111,6 +111,14 @@ class QgsMemoryProvider : public QgsVectorDataProvider
      */
     virtual bool changeGeometryValues( QgsGeometryMap & geometry_map );
 
+    /** Accessor for sql where clause used to limit dataset */
+    QString subsetString();
+
+    /** mutator for sql where clause used to limit dataset size */
+    bool setSubsetString( QString theSQL, bool updateFeatureCount = true );
+
+    virtual bool supportsSubsetString() { return true; }
+
     /**
      * Creates a spatial index
      * @return true in case of success
@@ -170,5 +178,7 @@ class QgsMemoryProvider : public QgsVectorDataProvider
     // indexing
     QgsSpatialIndex* mSpatialIndex;
 
+    QString mSubsetString;
+
     friend class QgsMemoryFeatureSource;
 };