Port providers to expression contexts

Author: nyalldawson

src/providers/delimitedtext/qgsdelimitedtextfeatureiterator.cpp

@@ -345,7 +345,8 @@ bool QgsDelimitedTextFeatureIterator::nextFeatureInternal( QgsFeature& feature )
 
     if ( mTestSubset )
     {
-      QVariant isOk = mSource->mSubsetExpression->evaluate( &feature );
+      mSource->mExpressionContext.setFeature( feature );
+      QVariant isOk = mSource->mSubsetExpression->evaluate( &mSource->mExpressionContext );
       if ( mSource->mSubsetExpression->hasEvalError() ) continue;
       if ( ! isOk.toBool() ) continue;
     }
@@ -490,6 +491,10 @@ QgsDelimitedTextFeatureSource::QgsDelimitedTextFeatureSource( const QgsDelimited
 {
   mFile = new QgsDelimitedTextFile();
   mFile->setFromUrl( p->mFile->url() );
+
+  mExpressionContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+  mExpressionContext.setFields( mFields );
 }
 
 QgsDelimitedTextFeatureSource::~QgsDelimitedTextFeatureSource()

src/providers/delimitedtext/qgsdelimitedtextfeatureiterator.h

@@ -18,6 +18,7 @@
 #include <QList>
 #include "qgsfeatureiterator.h"
 #include "qgsfeature.h"
+#include "qgsexpressioncontext.h"
 
 #include "qgsdelimitedtextprovider.h"
 
@@ -32,6 +33,7 @@ class QgsDelimitedTextFeatureSource : public QgsAbstractFeatureSource
   protected:
     QgsDelimitedTextProvider::GeomRepresentationType mGeomRep;
     QgsExpression *mSubsetExpression;
+    QgsExpressionContext mExpressionContext;
     QgsRectangle mExtent;
     bool mUseSpatialIndex;
     QgsSpatialIndex *mSpatialIndex;

src/providers/delimitedtext/qgsdelimitedtextprovider.cpp

@@ -1006,7 +1006,8 @@ bool QgsDelimitedTextProvider::setSubsetString( QString subset, bool updateFeatu
     }
     else
     {
-      expression->prepare( fields() );
+      QgsExpressionContext context = QgsExpressionContextUtils::createFeatureBasedContext( QgsFeature(), fields() );
+      expression->prepare( &context );
       if ( expression->hasEvalError() )
       {
         error = expression->evalErrorString();

src/providers/memory/qgsmemoryfeatureiterator.cpp

@@ -30,7 +30,7 @@ QgsMemoryFeatureIterator::QgsMemoryFeatureIterator( QgsMemoryFeatureSource* sour
   if ( !mSource->mSubsetString.isEmpty() )
   {
     mSubsetExpression = new QgsExpression( mSource->mSubsetString );
-    mSubsetExpression->prepare( mSource->mFields );
+    mSubsetExpression->prepare( &mSource->mExpressionContext );
   }
 
   if ( !mRequest.filterRect().isNull() && mRequest.flags() & QgsFeatureRequest::ExactIntersect )
@@ -99,8 +99,12 @@ bool QgsMemoryFeatureIterator::nextFeatureUsingList( QgsFeature& feature )
     else
       hasFeature = true;
 
-    if ( mSubsetExpression && !mSubsetExpression->evaluate( mSource->mFeatures[*mFeatureIdListIterator] ).toBool() )
-      hasFeature = false;
+    if ( mSubsetExpression )
+    {
+      mSource->mExpressionContext.setFeature( mSource->mFeatures[*mFeatureIdListIterator] );
+      if ( !mSubsetExpression->evaluate( &mSource->mExpressionContext ).toBool() )
+        hasFeature = false;
+    }
 
     if ( hasFeature )
       break;
@@ -152,8 +156,12 @@ bool QgsMemoryFeatureIterator::nextFeatureTraverseAll( QgsFeature& feature )
       }
     }
 
-    if ( mSubsetExpression && !mSubsetExpression->evaluate( *mSelectIterator ).toBool() )
-      hasFeature = false;
+    if ( mSubsetExpression )
+    {
+      mSource->mExpressionContext.setFeature( *mSelectIterator );
+      if ( !mSubsetExpression->evaluate( &mSource->mExpressionContext ).toBool() )
+        hasFeature = false;
+    }
 
     if ( hasFeature )
       break;
@@ -210,6 +218,9 @@ QgsMemoryFeatureSource::QgsMemoryFeatureSource( const QgsMemoryProvider* p )
     , mSpatialIndex( p->mSpatialIndex ? new QgsSpatialIndex( *p->mSpatialIndex ) : 0 )  // just shallow copy
     , mSubsetString( p->mSubsetString )
 {
+  mExpressionContext << QgsExpressionContextUtils::globalScope()
+  << QgsExpressionContextUtils::projectScope();
+  mExpressionContext.setFields( mFields );
 }
 
 QgsMemoryFeatureSource::~QgsMemoryFeatureSource()

src/providers/memory/qgsmemoryfeatureiterator.h

@@ -16,6 +16,7 @@
 #define QGSMEMORYFEATUREITERATOR_H
 
 #include "qgsfeatureiterator.h"
+#include "qgsexpressioncontext.h"
 
 class QgsMemoryProvider;
 
@@ -37,6 +38,7 @@ class QgsMemoryFeatureSource : public QgsAbstractFeatureSource
     QgsFeatureMap mFeatures;
     QgsSpatialIndex* mSpatialIndex;
     QString mSubsetString;
+    QgsExpressionContext mExpressionContext;
 
     friend class QgsMemoryFeatureIterator;
 };