Allow access to parent algorithm for processing parameters

python/core/processing/qgsprocessingparameters.sip

@@ -353,6 +353,13 @@ class QgsProcessingParameterDefinition
  :rtype: list of str
 %End
 
+    QgsProcessingAlgorithm *algorithm() const;
+%Docstring
+ Returns a pointer to the algorithm which owns this parameter. May be None
+ for non-owned parameters.
+ :rtype: QgsProcessingAlgorithm
+%End
+
   protected:
 
 
@@ -360,6 +367,8 @@ class QgsProcessingParameterDefinition
 
 
 
+
+
 };
 
 QFlags<QgsProcessingParameterDefinition::Flag> operator|(QgsProcessingParameterDefinition::Flag f1, QFlags<QgsProcessingParameterDefinition::Flag> f2);

src/core/processing/qgsprocessingalgorithm.cpp

@@ -242,6 +242,7 @@ bool QgsProcessingAlgorithm::addParameter( QgsProcessingParameterDefinition *def
   }
 
   mParameters << definition;
+  definition->mAlgorithm = this;
 
   if ( createOutput )
     return createAutoOutputForParameter( definition );

src/core/processing/qgsprocessingparameters.cpp

@@ -1237,6 +1237,11 @@ bool QgsProcessingParameterDefinition::fromVariantMap( const QVariantMap &map )
   return true;
 }
 
+QgsProcessingAlgorithm *QgsProcessingParameterDefinition::algorithm() const
+{
+  return mAlgorithm;
+}
+
 QgsProcessingParameterBoolean::QgsProcessingParameterBoolean( const QString &name, const QString &description, const QVariant &defaultValue, bool optional )
   : QgsProcessingParameterDefinition( name, description, defaultValue, optional )
 {}

src/core/processing/qgsprocessingparameters.h

@@ -391,6 +391,12 @@ class CORE_EXPORT QgsProcessingParameterDefinition
      */
     virtual QStringList dependsOnOtherParameters() const { return QStringList(); }
 
+    /**
+     * Returns a pointer to the algorithm which owns this parameter. May be nullptr
+     * for non-owned parameters.
+     */
+    QgsProcessingAlgorithm *algorithm() const;
+
   protected:
 
     //! Parameter name
@@ -408,6 +414,12 @@ class CORE_EXPORT QgsProcessingParameterDefinition
     //! Freeform metadata for parameter. Mostly used by widget wrappers to customise their appearance and behavior.
     QVariantMap mMetadata;
 
+    //! Pointer to algorithm which owns this parameter
+    QgsProcessingAlgorithm *mAlgorithm = nullptr;
+
+    // To allow access to mAlgorithm. We don't want a public setter for this!
+    friend class QgsProcessingAlgorithm;
+
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS( QgsProcessingParameterDefinition::Flags )

tests/src/analysis/testqgsprocessing.cpp

@@ -75,6 +75,7 @@ class DummyAlgorithm : public QgsProcessingAlgorithm
       QVERIFY( addParameter( new QgsProcessingParameterBoolean( "p1" ) ) );
       QCOMPARE( parameterDefinitions().count(), 1 );
       QCOMPARE( parameterDefinitions().at( 0 )->name(), QString( "p1" ) );
+      QCOMPARE( parameterDefinitions().at( 0 )->algorithm(), this );
 
       QVERIFY( !addParameter( nullptr ) );
       QCOMPARE( parameterDefinitions().count(), 1 );