1 unstable release
0.1.0 | Jul 15, 2023 |
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#1957 in Data structures
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forgetful observer
This crate allows you to track items seen during execution of an algorithm using RAII.
An observation of a particular item is represented by an Obervation<T>
. When this object falls
out of scope, the item is forgotten.
This might be useful when implementing a recursive algorithm on a graph that must detect cycles.
Here's an example:
let observer = Observer::new();
{
let observation = observer.notice("foo").expect("never seen before");
// While 'observation' is in scope, subsequent calls to notice return None.
assert!(observer.notice("foo").is_none());
}
// Now that 'observation' is out of scope, this will return Some(Observation).
assert!(observer.notice("foo").is_some());
The Observer
can track any item that is Eq + Hash
. For example:
observer.notice(&42);
Internally, Observer
stores references to the items
it notices in a HashSet
.
Upon the Observation
's destruction, the item reference is removed from the set.