Convert `datum` to `toType` and then mask using `maskFunc`, returns new datum and its coresponding type.

Create a mask worker for MySQL Events.

Create a `RestoreVisitor` with mode `NameOnly`, which ignores restoring of constant values.

Create a `RestoreVisitor` with mode `NameValue`.

All mask functions.

A visitor for physical plans, which extract sconstants for masking, and builds a `CastGraph` for inferring types.

Replace constants with disjoint numbers as `ReplaceMarker`s.

In replace phase, we replace constants with disjoint numbers as `ReplaceMarker`s in order to infer types of them and construct a `TypeMap`.