declare namespace QuickLRU {
	interface Options<KeyType, ValueType> {
		/**
		The maximum number of milliseconds an item should remain in the cache.

		@default Infinity

		By default, `maxAge` will be `Infinity`, which means that items will never expire.
		Lazy expiration upon the next write or read call.

		Individual expiration of an item can be specified by the `set(key, value, maxAge)` method.
		*/
		readonly maxAge?: number;

		/**
		The target maximum number of items before evicting the least recently used items.

		The dual-cache algorithm may physically retain up to twice `maxSize` entries for performance reasons, even though the reported cache size does not exceed `maxSize`.
		*/
		readonly maxSize: number;

		/**
		Called right before an item is evicted from the cache due to capacity pressure or TTL expiration.

		Useful for side effects or for items like object URLs that need explicit cleanup (`revokeObjectURL`).

		This callback is not called for manual removals via `delete()` or `clear()`.
		*/
		onEviction?: (key: KeyType, value: ValueType) => void;
	}
}

declare class QuickLRU<KeyType, ValueType>
	implements Iterable<[KeyType, ValueType]> {
	/**
	The stored item count.
	*/
	readonly size: number;

	/**
	Simple ["Least Recently Used" (LRU) cache](https://en.m.wikipedia.org/wiki/Cache_replacement_policies#Least_Recently_Used_.28LRU.29).

	The instance is [`iterable`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Iteration_protocols) so you can use it directly in a [`for…of`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for...of) loop.

	@example
	```
	import QuickLRU = require('@alloc/quick-lru');

	const lru = new QuickLRU({maxSize: 1000});

	lru.set('🦄', '🌈');

	lru.has('🦄');
	//=> true

	lru.get('🦄');
	//=> '🌈'
	```
	*/
	constructor(options: QuickLRU.Options<KeyType, ValueType>);

	[Symbol.iterator](): IterableIterator<[KeyType, ValueType]>;

	/**
	Set an item. Returns the instance.

	Individual expiration of an item can be specified with the `maxAge` option. If not specified, the global `maxAge` value will be used in case it is specified in the constructor, otherwise the item will never expire.

	@returns The list instance.
	*/
	set(key: KeyType, value: ValueType, options?: {maxAge?: number}): this;

	/**
	Get an item.

	@returns The stored item or `undefined`.
	*/
	get(key: KeyType): ValueType | undefined;

	/**
	Check if an item exists.
	*/
	has(key: KeyType): boolean;

	/**
	Get an item without marking it as recently used.

	@returns The stored item or `undefined`.
	*/
	peek(key: KeyType): ValueType | undefined;

	/**
	Get the remaining time to live (in milliseconds) for the given item, or `undefined` when the item is not in the cache.

	- Does not mark the item as recently used.
	- Does not trigger lazy expiration or remove the entry when it is expired.
	- Returns `Infinity` if the item has no expiration.
	- May return a negative number if the item is already expired but not yet lazily removed.

	@returns Remaining time to live in milliseconds when set, `Infinity` when there is no expiration, or `undefined` when the item does not exist.
	*/
	expiresIn(key: KeyType): number | undefined;

	/**
	Delete an item.

	@returns `true` if the item is removed or `false` if the item doesn't exist.
	*/
	delete(key: KeyType): boolean;

	/**
	Delete all items.
	*/
	clear(): void;

	/**
	Update the `maxSize` in-place, discarding items as necessary. Insertion order is mostly preserved, though this is not a strong guarantee.

	Useful for on-the-fly tuning of cache sizes in live systems.
	*/
	resize(maxSize: number): void;

	/**
	Iterable for all the keys.
	*/
	keys(): IterableIterator<KeyType>;

	/**
	Iterable for all the values.
	*/
	values(): IterableIterator<ValueType>;

	/**
	Iterable for all entries, starting with the oldest (ascending in recency).
	*/
	entriesAscending(): IterableIterator<[KeyType, ValueType]>;

	/**
	Iterable for all entries, starting with the newest (descending in recency).
	*/
	entriesDescending(): IterableIterator<[KeyType, ValueType]>;
}

export = QuickLRU;