Add referencedFunctions() to expressions

python/core/auto_generated/expression/qgsexpression.sip.in

@@ -176,6 +176,13 @@ If the list contains a NULL QString, there is a variable name used
 which is determined at runtime.
 
 .. versionadded:: 3.0
+%End
+
+    QSet<QString> referencedFunctions() const;
+%Docstring
+Return a list of all functions which are used in this expression.
+
+.. versionadded:: 3.2
 %End
 
     QSet<int> referencedAttributeIndexes( const QgsFields &fields ) const;

python/core/auto_generated/expression/qgsexpressionnode.sip.in

@@ -196,6 +196,11 @@ to evaluate child nodes.
     virtual QSet<QString> referencedVariables() const = 0;
 %Docstring
 Return a set of all variables which are used in this expression.
+%End
+
+    virtual QSet<QString> referencedFunctions() const = 0;
+%Docstring
+Return a set of all functions which are used in this expression.
 %End
 
     virtual bool needsGeometry() const = 0;

python/core/auto_generated/expression/qgsexpressionnodeimpl.sip.in

@@ -55,6 +55,8 @@ Returns the node the operator will operate upon.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;
@@ -154,6 +156,9 @@ Returns the node to the right of the operator.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;
@@ -224,6 +229,8 @@ Returns the list of nodes to search for matching values within.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;
@@ -275,6 +282,8 @@ Returns a list of arguments specified for the function.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;
@@ -323,6 +332,8 @@ The value of the literal.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;
@@ -367,6 +378,8 @@ The name of the column.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
 
@@ -466,6 +479,8 @@ The ELSE expression used for the condition.
 
     virtual QSet<QString> referencedVariables() const;
 
+    virtual QSet<QString> referencedFunctions() const;
+
     virtual bool needsGeometry() const;
 
     virtual QgsExpressionNode *clone() const /Factory/;

src/core/expression/qgsexpression.cpp

@@ -276,6 +276,14 @@ QSet<QString> QgsExpression::referencedVariables() const
   return d->mRootNode->referencedVariables();
 }
 
+QSet<QString> QgsExpression::referencedFunctions() const
+{
+  if ( !d->mRootNode )
+    return QSet<QString>();
+
+  return d->mRootNode->referencedFunctions();
+}
+
 QSet<int> QgsExpression::referencedAttributeIndexes( const QgsFields &fields ) const
 {
   if ( !d->mRootNode )

src/core/expression/qgsexpression.h

@@ -258,6 +258,13 @@ class CORE_EXPORT QgsExpression
      */
     QSet<QString> referencedVariables() const;
 
+    /**
+     * Return a list of all functions which are used in this expression.
+     *
+     * \since QGIS 3.2
+     */
+    QSet<QString> referencedFunctions() const;
+
     /**
      * Return a list of field name indexes obtained from the provided fields.
      *

src/core/expression/qgsexpressionnode.cpp

@@ -57,3 +57,4 @@ void QgsExpressionNode::cloneTo( QgsExpressionNode *target ) const
   target->parserFirstColumn = parserFirstColumn;
   target->parserFirstLine = parserFirstLine;
 }
+

src/core/expression/qgsexpressionnode.h

@@ -222,6 +222,11 @@ class CORE_EXPORT QgsExpressionNode SIP_ABSTRACT
      */
     virtual QSet<QString> referencedVariables() const = 0;
 
+    /**
+     * Return a set of all functions which are used in this expression.
+     */
+    virtual QSet<QString> referencedFunctions() const = 0;
+
     /**
      * Abstract virtual method which returns if the geometry is required to evaluate
      * this expression.

src/core/expression/qgsexpressionnodeimpl.cpp

@@ -137,6 +137,11 @@ QSet<QString> QgsExpressionNodeUnaryOperator::referencedVariables() const
   return mOperand->referencedVariables();
 }
 
+QSet<QString> QgsExpressionNodeUnaryOperator::referencedFunctions() const
+{
+  return mOperand->referencedFunctions();
+}
+
 bool QgsExpressionNodeUnaryOperator::needsGeometry() const
 {
   return mOperand->needsGeometry();
@@ -720,6 +725,11 @@ QSet<QString> QgsExpressionNodeBinaryOperator::referencedVariables() const
   return mOpLeft->referencedVariables() + mOpRight->referencedVariables();
 }
 
+QSet<QString> QgsExpressionNodeBinaryOperator::referencedFunctions() const
+{
+  return mOpLeft->referencedFunctions() + mOpRight->referencedFunctions();
+}
+
 bool QgsExpressionNodeBinaryOperator::needsGeometry() const
 {
   return mOpLeft->needsGeometry() || mOpRight->needsGeometry();
@@ -978,6 +988,23 @@ QSet<QString> QgsExpressionNodeFunction::referencedVariables() const
   }
 }
 
+QSet<QString> QgsExpressionNodeFunction::referencedFunctions() const
+{
+  QgsExpressionFunction *fd = QgsExpression::QgsExpression::Functions()[mFnIndex];
+  QSet<QString> functions = QSet<QString>();
+  functions.insert( fd->name() );
+
+  if ( !mArgs )
+    return functions;
+
+  const QList< QgsExpressionNode * > nodeList = mArgs->list();
+  for ( QgsExpressionNode *n : nodeList )
+  {
+    functions.unite( n->referencedFunctions() );
+  }
+  return functions;
+}
+
 bool QgsExpressionNodeFunction::needsGeometry() const
 {
   bool needs = QgsExpression::QgsExpression::Functions()[mFnIndex]->usesGeometry( this );
@@ -1128,6 +1155,11 @@ QSet<QString> QgsExpressionNodeLiteral::referencedVariables() const
   return QSet<QString>();
 }
 
+QSet<QString> QgsExpressionNodeLiteral::referencedFunctions() const
+{
+  return QSet<QString>();
+}
+
 bool QgsExpressionNodeLiteral::needsGeometry() const
 {
   return false;
@@ -1215,6 +1247,11 @@ QSet<QString> QgsExpressionNodeColumnRef::referencedVariables() const
   return QSet<QString>();
 }
 
+QSet<QString> QgsExpressionNodeColumnRef::referencedFunctions() const
+{
+  return QSet<QString>();
+}
+
 bool QgsExpressionNodeColumnRef::needsGeometry() const
 {
   return false;
@@ -1338,6 +1375,20 @@ QSet<QString> QgsExpressionNodeCondition::referencedVariables() const
   return lst;
 }
 
+QSet<QString> QgsExpressionNodeCondition::referencedFunctions() const
+{
+  QSet<QString> lst;
+  for ( WhenThen *cond : mConditions )
+  {
+    lst += cond->mWhenExp->referencedFunctions() + cond->mThenExp->referencedFunctions();
+  }
+
+  if ( mElseExp )
+    lst += mElseExp->referencedFunctions();
+
+  return lst;
+}
+
 bool QgsExpressionNodeCondition::needsGeometry() const
 {
   for ( WhenThen *cond : mConditions )
@@ -1393,6 +1444,16 @@ QSet<QString> QgsExpressionNodeInOperator::referencedVariables() const
   return lst;
 }
 
+QSet<QString> QgsExpressionNodeInOperator::referencedFunctions() const
+{
+  QSet<QString> lst( mNode->referencedFunctions() );
+  const QList< QgsExpressionNode * > nodeList = mList->list();
+  for ( const QgsExpressionNode *n : nodeList )
+    lst.unite( n->referencedFunctions() );
+  return lst;
+
+}
+
 QgsExpressionNodeCondition::WhenThen::WhenThen( QgsExpressionNode *whenExp, QgsExpressionNode *thenExp )
   : mWhenExp( whenExp )
   , mThenExp( thenExp )
@@ -1414,3 +1475,4 @@ QString QgsExpressionNodeBinaryOperator::text() const
 {
   return BINARY_OPERATOR_TEXT[mOp];
 }
+

src/core/expression/qgsexpressionnodeimpl.h

@@ -64,6 +64,7 @@ class CORE_EXPORT QgsExpressionNodeUnaryOperator : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
 
@@ -162,6 +163,8 @@ class CORE_EXPORT QgsExpressionNodeBinaryOperator : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
+
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
     bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
@@ -241,6 +244,7 @@ class CORE_EXPORT QgsExpressionNodeInOperator : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
     bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
@@ -284,6 +288,7 @@ class CORE_EXPORT QgsExpressionNodeFunction : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
     bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
@@ -321,6 +326,7 @@ class CORE_EXPORT QgsExpressionNodeLiteral : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
     bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;
@@ -356,6 +362,7 @@ class CORE_EXPORT QgsExpressionNodeColumnRef : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
 
     QgsExpressionNode *clone() const override SIP_FACTORY;
@@ -456,6 +463,7 @@ class CORE_EXPORT QgsExpressionNodeCondition : public QgsExpressionNode
 
     QSet<QString> referencedColumns() const override;
     QSet<QString> referencedVariables() const override;
+    QSet<QString> referencedFunctions() const override;
     bool needsGeometry() const override;
     QgsExpressionNode *clone() const override SIP_FACTORY;
     bool isStatic( QgsExpression *parent, const QgsExpressionContext *context ) const override;

tests/src/core/testqgsexpression.cpp

@@ -1861,6 +1861,24 @@ class TestQgsExpression: public QObject
       QCOMPARE( refVar, expectedVars );
     }
 
+
+    void referenced_functions()
+    {
+      QSet<QString> expectedFunctions;
+      expectedFunctions << QStringLiteral( "current_value" )
+                        << QStringLiteral( "var" )
+                        << QStringLiteral( "intersects" )
+                        << QStringLiteral( "$geometry" )
+                        << QStringLiteral( "buffer" );
+
+      QgsExpression exp( QStringLiteral( "current_value( 'FIELD_NAME' ) = \"A_VALUE\" AND intersects(buffer($geometry, 10), @current_geometry)" ) );
+      QCOMPARE( exp.hasParserError(), false );
+      QSet<QString> refVar = exp.referencedFunctions();
+
+      QCOMPARE( refVar, expectedFunctions );
+    }
+
+
     void referenced_columns_all_attributes()
     {
       QgsExpression exp( QStringLiteral( "attribute($currentfeature,'test')" ) );