Feature request: pop_if()

[garro95]

Please add a new method pop_if() that removes and returns the "top" element from the queue as a Some((item, priority)), but only if the "top" element matches the given predicate. Otherwise, a None should be returned.

The rationale is that currently we need to write a code like this:

while queue.peek().is_some_and(|(item, priority)| some_condition(...)) {
    (item, priority) = queue.pop().unwrap();
    /* ... */
}

But the unwrap() is kind of ugly, because it shouldn't actually be needed. That is because, at this point, we already know for sure there is a next element. But, even more important, the peek() to investigate the "top" element plus the additional pop() to actually remove it, requires two lookups – where this operation should be possible with just a single one!

Hence, this should be simplified to:

while let Some((item, priority)) = queue.pop_if(|(item, priority)| some_condition(...)) {
    /* ... */
}

Or is there a better way already ???

Originally posted by @lordmulder in #55