从嵌套结构中删除谓词（Google番石榴谓词）

Question

I use google guava predicates and I want to filter it to be able to remove some of them.

For example in this code

Predicates.or(
    Predicates.and(p1, p2, Predicates.or(p3, p4)),
    Predicates.and(p3, p2, Predicates.or(p1, p4))
    Predicates.and(p3, p2, Predicates.or(Predicates.and(p1, p2), Predicates.and(p2, p3)))
);

I want to remove p1 so the result should look like this

Predicates.or(
    Predicates.and(p2, Predicates.or(p3, p4)),
    Predicates.and(p3, p2, Predicates.or(p4))
    Predicates.and(p3, p2, Predicates.or(Predicates.and(p2), Predicates.and(p2, p3)))
);

Is it possible? If yes, how?

Why? We reuse some of predicates with exceptions.

Answer 1

Not after the fact - the Predicate returned from Predicates.and() and Predicates.or() is a black-box, and (by design) provides no way to inspect its component parts.

The right solution is to refactor your code so that you compose this predicate with only the component predicates you intend. One option would be to replace p1 with a alwaysTrue() or alwaysFalse() predicate, like so:

Predicate<T> p1OrTrue = p1;
Predicate<T> p1OrFalse = p1;
if (dontUseP1) {
  p1OrTrue = Prediactes.alwaysTrue();
  p1OrFalse = Predicates.alwaysFalse();
}

Predicates.or(
    Predicates.and(p1OrTrue, p2, Predicates.or(p3, p4)),
    Predicates.and(p3, p2, Predicates.or(p1OrFalse, p4))
    Predicates.and(p3, p2, Predicates.or(Predicates.and(p1OrTrue, p2), Predicates.and(p2, p3)))
);

This means if dontUseP1 is false then p1 will be incorporated in the composite predicate as before, but if it's true it will instead be replaced with no-op predicates that cause Predicates.or() ( alwaysFalse() ) and Predicates.and() ( alwaysTrue() ) to rely on the result of the remaining component predicates, making the predicate equivalent to not having p1 at all.