This patch primarily adds all missing operator types' visitor methods of AlgebraVisitor and implements concrete methods in BaseAlgebraVisitor. Currently, BaseAlgebraVisitor may cause incorrect PlanningException because BaseAlgebraVisitor does not handle all operator types. This patch eliminates this potential bug.
In addition, this patch contains two refactors in order to eliminate duplicate names:
- Rename tajo.algebra.DataType to DataTypeExpr
- Rename tajo.algebra.Target to TargetExpr