@fasteroid/maps

A few variations of the vanilla Map<K, V> that might make your life easier.

Classes

AutoMap<K, V>

Populates empty keys when getting them, based on a function that receives the key in question.

💡⠀This package also provides "auto" variants for most of the classes below!

CollisionMap<K, V>

You tell it how to hash keys into primitives.  Has two interesting use-cases:

• Indexing by unordered pairs—if you want [1, 2] and [2, 1] to point at the same thing
• Indexing by objects that feel primitive but aren't—eg. regexes

⚠️⠀DON'T use JSON.stringify for your hash function.  Hash functions need to be fast.

SemiWeakMap<K, V>

Like a native WeakMap, but you can store primitives on it.

WeakPairing<K, V>

Like a SemiWeakMap, but the values are also weakly held.  Useful as a weak bidirectional lookup table.
Values referenced by a pair can be garbage-collected as long as at least one of them is garbage-collectable.

Ordering<T>

Stores the concept of an enumerable "order" for any set of values.
Has one method, apply(values: T[]), which sorts the values into an unspecified but consistent ordering within the scope of the ordering's lifetime.

⚠️⠀Objects are sorted by reference, not contents.  Don't assume the same order between program executions.

TagMap<K, V>

Indexes items by unordered collections of keys rather than traditional single keys.

License

MIT License