qgsexpression: lazy initialization of geometry calculator

Author: jef-n

src/core/qgsexpression.cpp

@@ -1612,10 +1612,8 @@ QgsExpression::QgsExpression( const QString& expr )
     : mExpression( expr )
     , mRowNumber( 0 )
     , mScale( 0 )
-
+    , mCalc( 0 )
 {
-  initGeomCalculator();
-
   mRootNode = ::parseExpression( mExpression, mParserErrorString );
 
   if ( mParserErrorString.isNull() )
@@ -1626,6 +1624,8 @@ QgsExpression::QgsExpression( const QString& expr )
 
 QgsExpression::~QgsExpression()
 {
+  if ( mCalc )
+    delete mCalc;
   delete mRootNode;
 }
 
@@ -1661,16 +1661,23 @@ bool QgsExpression::needsGeometry()
 
 void QgsExpression::initGeomCalculator()
 {
+  if( mCalc )
+    return;
+
   // Use planimetric as default
-  mCalc.setEllipsoidalMode( false );
+  mCalc = new QgsDistanceArea();
+  mCalc->setEllipsoidalMode( false );
 }
 
-void QgsExpression::setGeomCalculator( QgsDistanceArea& calc )
+void QgsExpression::setGeomCalculator( QgsDistanceArea &calc )
 {
+  if( !mCalc )
+    mCalc = new QgsDistanceArea();
+
   // Copy from supplied calculator
-  mCalc.setEllipsoid( calc.ellipsoid() );
-  mCalc.setEllipsoidalMode( calc.ellipsoidalEnabled() );
-  mCalc.setSourceCrs( calc.sourceCrs() );
+  mCalc->setEllipsoid( calc.ellipsoid() );
+  mCalc->setEllipsoidalMode( calc.ellipsoidalEnabled() );
+  mCalc->setSourceCrs( calc.sourceCrs() );
 }
 
 bool QgsExpression::prepare( const QgsFields& fields )

src/core/qgsexpression.h

@@ -157,11 +157,11 @@ class CORE_EXPORT QgsExpression
 
     //! Return calculator used for distance and area calculations
     //! (used by internal functions)
-    QgsDistanceArea* geomCalculator() { return & mCalc; }
+    QgsDistanceArea *geomCalculator() { initGeomCalculator(); return mCalc; }
 
     //! Sets the geometry calculator used in evaluation of expressions,
     // instead of the default.
-    void setGeomCalculator( QgsDistanceArea& calc );
+    void setGeomCalculator( QgsDistanceArea &calc );
 
     /** This function currently replaces each expression between [% and %]
        in the string with the result of its evaluation on the feature
@@ -613,7 +613,7 @@ class CORE_EXPORT QgsExpression
     double mScale;
 
     static QMap<QString, QVariant> gmSpecialColumns;
-    QgsDistanceArea mCalc;
+    QgsDistanceArea *mCalc;
 
     friend class QgsOgcUtils;