fix apply on user-defined aggregate init

The `init` expression of user-define aggregates was never
handed-over to `apply`'s `mapper`.

One visible issue is that the `TupleId` transformer would not update the
tuple of the `init` expression while shuffling tuple identifiers.
That would then result in the `init` expression peeking data in the
wrong tuple during execution of the RAM program.

src/ast/UserDefinedAggregator.cpp

@@ -34,10 +34,9 @@ Node::NodeVec UserDefinedAggregator::getChildren() const {
 }
 
 void UserDefinedAggregator::print(std::ostream& os) const {
-    os << "@" << name;
-    os << " init: " << *initValue;
+    os << "@@" << name << " " << *initValue;
     if (targetExpression) {
-        os << " " << *targetExpression;
+        os << ", " << *targetExpression;
     }
     os << " : { " << join(body) << " }";
 }

src/ram/Aggregate.h

@@ -63,6 +63,7 @@ class Aggregate : public RelationOperation, public AbstractAggregate {
         RelationOperation::apply(map);
         condition = map(std::move(condition));
         expression = map(std::move(expression));
+        function->apply(map);
     }
 
     static bool classof(const Node* n) {

src/ram/Aggregator.h

@@ -45,6 +45,8 @@ class Aggregator {
         return {};
     }
 
+    virtual void apply(const NodeMapper&) {}
+
     /**
      * @brief Create a cloning (i.e. deep copy) of this node
      */

src/ram/IndexAggregate.h

@@ -66,6 +66,7 @@ class IndexAggregate : public IndexOperation, public AbstractAggregate {
         IndexOperation::apply(map);
         condition = map(std::move(condition));
         expression = map(std::move(expression));
+        function->apply(map);
     }
 
     static bool classof(const Node* n) {

src/ram/UserDefinedAggregator.h

@@ -77,6 +77,10 @@ class UserDefinedAggregator : public Aggregator {
         os << name << " INIT " << *initValue << " ";
     }
 
+    void apply(const NodeMapper& map) override {
+        initValue = map(std::move(initValue));
+    }
+
 protected:
     /** Aggregation function */
     const std::string name;
@@ -92,4 +96,4 @@ class UserDefinedAggregator : public Aggregator {
     /** Stateful */
     const bool stateful;
 };
-}  // namespace souffle::ram
+}  // namespace souffle::ram