Some API improvements to QgsMapLayerRef, unit tests

src/core/layertree/qgslayertreelayer.h

@@ -54,7 +54,7 @@ class CORE_EXPORT QgsLayerTreeLayer : public QgsLayerTreeNode
 
     QString layerId() const { return mRef.layerId; }
 
-    QgsMapLayer *layer() const { return mRef.layer.data(); }
+    QgsMapLayer *layer() const { return mRef.get(); }
 
     /**
      * Returns the layer's name.

src/core/qgsmaplayerref.h

@@ -19,10 +19,7 @@
 #include <QPointer>
 
 #include "qgsmaplayer.h"
-#include "qgsvectorlayer.h"
+#include "qgsdataprovider.h"
-#include "qgsvectordataprovider.h"
-#include "raster/qgsrasterlayer.h"
-#include "raster/qgsrasterdataprovider.h"
 
 /** Internal structure to keep weak pointer to QgsMapLayer or layerId
  *  if the layer is not available yet.
@@ -31,7 +28,19 @@
 template<typename TYPE>
 struct _LayerRef
 {
-  _LayerRef( TYPE *l = nullptr ): layer( l ), layerId( l ? l->id() : QString() ) {}
+
+  /**
+   * Constructor for a layer reference from an existing map layer.
+   * The layerId, source, name and provider members will automatically
+   * be populated from this layer.
+   */
+  _LayerRef( TYPE *l = nullptr )
+    : layer( l )
+    , layerId( l ? l->id() : QString() )
+    , source( l ? l->publicSource() : QString() )
+    , name( l ? l->name() : QString() )
+    , provider( l && l->dataProvider() ? l->dataProvider()->name() : QString() )
+  {}
 
   /**
    * Constructor for a weak layer reference, using a combination of layer ID,
@@ -45,7 +54,16 @@ struct _LayerRef
     , provider( provider )
   {}
 
+  /**
+   * Returns a pointer to the layer, or nullptr if the reference has not yet been matched
+   * to a layer.
+   */
+  TYPE *get() const { return layer.data(); }
+
+  //! Weak pointer to map layer
   QPointer<TYPE> layer;
+
+  //! Original layer ID
   QString layerId;
 
   //! Weak reference to layer public source

src/core/qgsvectorlayerjoininfo.h

@@ -27,7 +27,7 @@ class CORE_EXPORT QgsVectorLayerJoinInfo
     //! Sets weak reference to the joined layer
     void setJoinLayer( QgsVectorLayer *layer ) { mJoinLayerRef = QgsVectorLayerRef( layer ); }
     //! Returns joined layer (may be null if the reference was set by layer ID and not resolved yet)
-    QgsVectorLayer *joinLayer() const { return mJoinLayerRef.layer.data(); }
+    QgsVectorLayer *joinLayer() const { return mJoinLayerRef.get(); }
 
     //! Sets ID of the joined layer. It will need to be overwritten by setJoinLayer() to a reference to real layer
     void setJoinLayerId( const QString &layerId ) { mJoinLayerRef = QgsVectorLayerRef( layerId ); }

tests/src/core/testqgsmaplayer.cpp

@@ -25,6 +25,7 @@
 #include <qgsvectorlayer.h>
 #include <qgsapplication.h>
 #include <qgsproviderregistry.h>
+#include "qgsvectorlayerref.h"
 
 class TestSignalReceiver : public QObject
 {
@@ -68,9 +69,11 @@ class TestQgsMapLayer : public QObject
     void isInScaleRange_data();
     void isInScaleRange();
 
+    void layerRef();
+
 
   private:
-    QgsMapLayer *mpLayer = nullptr;
+    QgsVectorLayer *mpLayer = nullptr;
 };
 
 void TestQgsMapLayer::initTestCase()
@@ -152,5 +155,32 @@ void TestQgsMapLayer::isInScaleRange()
 
 }
 
+void TestQgsMapLayer::layerRef()
+{
+  // construct from layer
+  QgsVectorLayerRef ref( mpLayer );
+  QCOMPARE( ref.get(), mpLayer );
+  QCOMPARE( ref.layer.data(), mpLayer );
+  QCOMPARE( ref.layerId, mpLayer->id() );
+  QCOMPARE( ref.name, QStringLiteral( "points" ) );
+  QCOMPARE( ref.source, mpLayer->publicSource() );
+  QCOMPARE( ref.provider, QStringLiteral( "ogr" ) );
+
+  // verify that layer matches layer
+  QVERIFY( ref.layerMatchesSource( mpLayer ) );
+
+  // create a weak reference
+  QgsVectorLayerRef ref2( mpLayer->id(), QStringLiteral( "points" ), mpLayer->publicSource(), QStringLiteral( "ogr" ) );
+  QVERIFY( !ref2.get() );
+  QVERIFY( !ref2.layer.data() );
+  QCOMPARE( ref2.layerId, mpLayer->id() );
+  QCOMPARE( ref2.name, QStringLiteral( "points" ) );
+  QCOMPARE( ref2.source, mpLayer->publicSource() );
+  QCOMPARE( ref2.provider, QStringLiteral( "ogr" ) );
+
+  // verify that weak reference matches layer
+  QVERIFY( ref2.layerMatchesSource( mpLayer ) );
+}
+
 QGSTEST_MAIN( TestQgsMapLayer )
 #include "testqgsmaplayer.moc"