avoid required call to leaveCategory by adding a RAII private class

qgis · Feb 28, 2018 · 8582517 · 8582517
1 parent 8989292
commit 8582517
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Showing 6 changed files with 46 additions and 32 deletions.
diff --git a/python/core/qgsreadwritecontext.sip.in b/python/core/qgsreadwritecontext.sip.in
@@ -9,6 +9,7 @@
 
 
 
+
 class QgsReadWriteContext
 {
 %Docstring
@@ -63,26 +64,13 @@ Returns path resolver for conversion between relative and absolute paths
 Sets up path resolver for conversion between relative and absolute paths
 %End
 
-    void pushMessage( const QString &message, Qgis::MessageLevel level );
+    void pushMessage( const QString &message, Qgis::MessageLevel level = Qgis::Warning );
 %Docstring
 Append a message to the context
 
 .. versionadded:: 3.2
 %End
 
-    void enterCategory( const QString &category, const QString &details = QString() );
-%Docstring
-Push a category to the stack
-
-.. versionadded:: 3.2
-%End
-
-    void leaveCategory();
-%Docstring
-Pop the last category
-
-.. versionadded:: 3.2
-%End
 
     QList<QgsReadWriteContext::ReadWriteMessage> takeMessages();
 %Docstring
@@ -91,8 +79,10 @@ Return the stored messages and remove them
 .. versionadded:: 3.2
 %End
 
+
 };
 
+
 /************************************************************************
  * This file has been generated automatically from                      *
  *                                                                      *

diff --git a/src/core/qgseditformconfig.cpp b/src/core/qgseditformconfig.cpp
@@ -260,7 +260,8 @@ void QgsEditFormConfig::setSuppress( QgsEditFormConfig::FeatureFormSuppress s )
 
 void QgsEditFormConfig::readXml( const QDomNode &node, QgsReadWriteContext &context )
 {
-  context.enterCategory( QObject::tr( "Edit form config" ) );
+  MAYBE_UNUSED QgsReadWriteContextCategoryPopper p = context.enterCategory( QObject::tr( "Edit form config" ) );
+
   d.detach();
 
   QDomNode editFormNode = node.namedItem( QStringLiteral( "editform" ) );
@@ -388,8 +389,6 @@ void QgsEditFormConfig::readXml( const QDomNode &node, QgsReadWriteContext &cont
       onRelationsLoaded();
     }
   }
-
-  context.leaveCategory();
 }
 
 void QgsEditFormConfig::writeXml( QDomNode &node, const QgsReadWriteContext &context ) const

diff --git a/src/core/qgsmaplayer.cpp b/src/core/qgsmaplayer.cpp
@@ -430,7 +430,7 @@ bool QgsMapLayer::readLayerXml( const QDomElement &layerElement,  QgsReadWriteCo
   // the subclass can also read custom properties
   readCustomProperties( layerElement );
 
-  context.enterCategory( tr( "Layer" ), mne.text() );
+  MAYBE_UNUSED QgsReadWriteContextCategoryPopper p = context.enterCategory( tr( "Layer" ), mne.text() );
 
   // now let the children grab what they need from the Dom node.
   layerError = !readXml( layerElement, context );
@@ -557,8 +557,6 @@ bool QgsMapLayer::readLayerXml( const QDomElement &layerElement,  QgsReadWriteCo
   QDomElement metadataElem = layerElement.firstChildElement( QStringLiteral( "resourceMetadata" ) );
   mMetadata.readMetadataXml( metadataElem );
 
-  context.leaveCategory();
-
   return true;
 } // bool QgsMapLayer::readLayerXML
 

diff --git a/src/core/qgsreadwritecontext.cpp b/src/core/qgsreadwritecontext.cpp
@@ -35,12 +35,13 @@ void QgsReadWriteContext::pushMessage( const QString &message, Qgis::MessageLeve
   mMessages.append( ReadWriteMessage( message, level, mCategories ) );
 }
 
-void QgsReadWriteContext::enterCategory( const QString &category, const QString &details )
+QgsReadWriteContextCategoryPopper QgsReadWriteContext::enterCategory( const QString &category, const QString &details )
 {
   QString message = category;
   if ( !details.isEmpty() )
     message.append( QString( " :: %1" ).arg( details ) );
   mCategories.push_back( message );
+  return QgsReadWriteContextCategoryPopper( this );
 }
 
 void QgsReadWriteContext::leaveCategory()

diff --git a/src/core/qgsreadwritecontext.h b/src/core/qgsreadwritecontext.h
@@ -21,6 +21,8 @@
 #include "qgspathresolver.h"
 #include "qgis.h"
 
+class QgsReadWriteContextCategoryPopper;
+
 /**
  * \class QgsReadWriteContext
  * \ingroup core
@@ -76,30 +78,56 @@ class CORE_EXPORT QgsReadWriteContext
      * Append a message to the context
      * \since QGIS 3.2
      */
-    void pushMessage( const QString &message, Qgis::MessageLevel level );
+    void pushMessage( const QString &message, Qgis::MessageLevel level = Qgis::Warning );
 
-    /**
-     * Push a category to the stack
-     * \since QGIS 3.2
-     */
-    void enterCategory( const QString &category, const QString &details = QString() );
+#ifndef SIP_RUN
 
     /**
-     * Pop the last category
+     * Push a category to the stack
+     * \note The return value should always be used so category can be automatically left.
+     * \note Not available in the Python bindings.
      * \since QGIS 3.2
      */
-    void leaveCategory();
+    NODISCARD QgsReadWriteContextCategoryPopper enterCategory( const QString &category, const QString &details = QString() );
+#endif
 
     /**
      * Return the stored messages and remove them
      * \since QGIS 3.2
      */
     QList<QgsReadWriteContext::ReadWriteMessage> takeMessages();
 
+
   private:
+    //! Pop the last category
+    void leaveCategory();
+
     QgsPathResolver mPathResolver;
     QList<ReadWriteMessage> mMessages;
     QStringList mCategories = QStringList();
+
+    friend class QgsReadWriteContextCategoryPopper;
+};
+
+#ifndef SIP_RUN
+///@cond PRIVATE
+class QgsReadWriteContextCategoryPopper
+{
+  public:
+
+    QgsReadWriteContextCategoryPopper( QgsReadWriteContext *context )
+      : mContext( context )
+    {}
+
+    ~QgsReadWriteContextCategoryPopper()
+    {
+      if ( mContext )
+        mContext->leaveCategory();
+    }
+
+    QgsReadWriteContext *mContext;
 };
+///@endcond PRIVATE
+#endif
 
 #endif // QGSREADWRITECONTEXT_H
diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -1688,7 +1688,7 @@ void QgsVectorLayer::resolveReferences( QgsProject *project )
 
 bool QgsVectorLayer::readSymbology( const QDomNode &layerNode, QString &errorMessage, QgsReadWriteContext &context )
 {
-  context.enterCategory( tr( "Symbology" ) );
+  MAYBE_UNUSED QgsReadWriteContextCategoryPopper p = context.enterCategory( tr( "Symbology" ) );
 
   if ( !mExpressionFieldBuffer )
     mExpressionFieldBuffer = new QgsExpressionFieldBuffer();
@@ -1875,8 +1875,6 @@ bool QgsVectorLayer::readSymbology( const QDomNode &layerNode, QString &errorMes
 
   updateFields();
 
-  context.leaveCategory();
-
   return true;
 }