Add method to processing registry to create a new instance of an algo…

…rithm directly
qgis · Jul 9, 2017 · cd6e7d7 · cd6e7d7
1 parent ad31087
commit cd6e7d7
Show file tree

Hide file tree

Showing 4 changed files with 41 additions and 0 deletions.
diff --git a/python/core/processing/qgsprocessingregistry.sip b/python/core/processing/qgsprocessingregistry.sip
@@ -85,6 +85,16 @@ class QgsProcessingRegistry : QObject
  Finds an algorithm by its ID. If no matching algorithm is found, a None
  is returned.
 .. seealso:: algorithms()
+.. seealso:: createAlgorithmById()
+ :rtype: QgsProcessingAlgorithm
+%End
+
+    QgsProcessingAlgorithm *createAlgorithmById( const QString &id ) const /Factory/;
+%Docstring
+ Creates a new instance of an algorithm by its ID. If no matching algorithm is found, a None
+ is returned. Callers take responsibility for deleting the returned object.`
+.. seealso:: algorithms()
+.. seealso:: algorithmById()
  :rtype: QgsProcessingAlgorithm
 %End
 

diff --git a/src/core/processing/qgsprocessingregistry.cpp b/src/core/processing/qgsprocessingregistry.cpp
@@ -98,3 +98,14 @@ const QgsProcessingAlgorithm *QgsProcessingRegistry::algorithmById( const QStrin
   return nullptr;
 }
 
+QgsProcessingAlgorithm *QgsProcessingRegistry::createAlgorithmById( const QString &id ) const
+{
+  const QgsProcessingAlgorithm *alg = algorithmById( id );
+  if ( !alg )
+    return nullptr;
+
+  std::unique_ptr< QgsProcessingAlgorithm > creation( alg->create() );
+  creation->setProvider( alg->provider() );
+  return creation.release();
+}
+
diff --git a/src/core/processing/qgsprocessingregistry.h b/src/core/processing/qgsprocessingregistry.h
@@ -96,9 +96,18 @@ class CORE_EXPORT QgsProcessingRegistry : public QObject
      * Finds an algorithm by its ID. If no matching algorithm is found, a nullptr
      * is returned.
      * \see algorithms()
+     * \see createAlgorithmById()
      */
     const QgsProcessingAlgorithm *algorithmById( const QString &id ) const;
 
+    /**
+     * Creates a new instance of an algorithm by its ID. If no matching algorithm is found, a nullptr
+     * is returned. Callers take responsibility for deleting the returned object.`
+     * \see algorithms()
+     * \see algorithmById()
+     */
+    QgsProcessingAlgorithm *createAlgorithmById( const QString &id ) const SIP_FACTORY;
+
   signals:
 
     //! Emitted when a provider has been added to the registry.

diff --git a/tests/src/core/testqgsprocessing.cpp b/tests/src/core/testqgsprocessing.cpp
@@ -827,6 +827,17 @@ void TestQgsProcessing::algorithm()
   QVERIFY( !r.algorithmById( "p1:alg3" ) );
   QVERIFY( !r.algorithmById( "px:alg1" ) );
 
+  // createAlgorithmById
+  QVERIFY( !r.createAlgorithmById( "p1:alg3" ) );
+  std::unique_ptr< QgsProcessingAlgorithm > creation( r.createAlgorithmById( "p1:alg1" ) );
+  QVERIFY( creation.get() );
+  QCOMPARE( creation->provider()->id(), QStringLiteral( "p1" ) );
+  QCOMPARE( creation->id(), QStringLiteral( "p1:alg1" ) );
+  creation.reset( r.createAlgorithmById( "p1:alg2" ) );
+  QVERIFY( creation.get() );
+  QCOMPARE( creation->provider()->id(), QStringLiteral( "p1" ) );
+  QCOMPARE( creation->id(), QStringLiteral( "p1:alg2" ) );
+
   //test that loading a provider triggers an algorithm refresh
   DummyProvider *p2 = new DummyProvider( "p2" );
   QVERIFY( p2->algorithms().isEmpty() );