Spliterator.tryAdvance (original) (raw)

Remi Forax forax at univ-mlv.fr
Sun Feb 10 09:25:20 PST 2013

Playing a little bit with how findFirst/forEachUntil can be implemented on top of a Spliterator, I think that tryAdvance should be changed to be able to return a value produced in the middle of the consumer taken by tryAdvance.

I would like to have tryAdvance to be like this:

/** * Sentinel value used by tryAdvance to signal that there is no more element. */ public static final Object END = new Object();

/**
  * If a remaining element exists, performs the given action on it,
  * returning the result of the function, otherwise returns {@code END}.
  *
  * @param action The action to perform.
  * @return {@code END} if no remaining elements existed
  * upon entry to this method, else the return value of the action.
  */
Object tryAdvance(Function<? super T, ?> action);

and forEach is a little bit uglier: Function action = element -> { consumer.accept(element); return null; } do {} while(tryAdvance(action) != END);

with that, there is no need to use a side value to express the fact that we have already found the resulting value because we can return it has the return value of tryAdvance.

cheers, Rémi

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