This patch involves boolean ring to simplify logical operations. We can treat `&` as ring multiplication and `^` as ring addition.

So we need to canonicalize all other operations to `*` `+`. Like:

a & b -> a * b a ^ b -> a + b ~a -> a + 1 a | b -> a * b + a + b c ? a : b -> c * a + (c + 1) * b

In the code, we use a mask set to represent an expression. Every value that is not comes from logical operations could be a bit in the mask.

The mask itself is a multiplication chain. The mask set is an addiction chain.

We can calculate two expressions based on boolean algebras.

For now, the initial patch only enabled on and/or/xor, Later we can enhance the code step by step.

Reference: https://en.wikipedia.org/wiki/Boolean_ring

It's weird that LogicalOpNode has a reference back to LogicCombiner. Is this just for printing? Would it be better to pass it to the print method?