ColumnFunction: better code (incomplete)

dbms/src/Columns/ColumnFunction.cpp

 #include <Interpreters/ExpressionActions.h>
 #include <Columns/ColumnFunction.h>
 #include <Columns/ColumnsCommon.h>
+#include <Columns/ColumnTuple.h>
 #include <IO/WriteHelpers.h>
 #include <Functions/IFunction.h>
 

dbms/src/Columns/ColumnFunction.h

@@ -4,6 +4,7 @@
 #include <Core/ColumnsWithTypeAndName.h>
 #include <Columns/IColumn.h>
 
+
 class IFunctionBase;
 using FunctionBasePtr = std::shared_ptr<IFunctionBase>;
 
@@ -107,10 +108,24 @@ public:
         throw Exception("Method gather is not supported for " + getName(), ErrorCodes::NOT_IMPLEMENTED);
     }
 
+    void forEachSubcolumn(ColumnCallback callback) override
+    {
+        callback(captured_columns);
+    }
+
+    bool structureEquals(const IColumn & rhs) const override
+    {
+        if (auto rhs_concrete = typeid_cast<const ColumnFunction *>(&rhs))
+            return captured_columns->structureEquals(*rhs_concrete->captured_columns)
+                && function->getName() == rhs_concrete->function->getName();
+        return false;
+    }
+
 private:
     size_t size_;
     FunctionBasePtr function;
-    ColumnsWithTypeAndName captured_columns;
+    WrappedPtr captured_columns; /// ColumnTuple
+    DataTypes captured_types;
 
     void appendArgument(const ColumnWithTypeAndName & column);
 };