feat(vanilla): add testing infrastructure and tests (NK-wjnczv)

1 files changed, 1323 insertions, 0 deletions

diff --git a/vanilla/node_modules/lru-cache/dist/esm/index.d.ts b/vanilla/node_modules/lru-cache/dist/esm/index.d.ts
new file mode 100644
index 0000000..67f177b
--- /dev/null
+++ b/vanilla/node_modules/lru-cache/dist/esm/index.d.ts
@@ -0,0 +1,1323 @@
+/**
+ * @module LRUCache
+ */
+export type Perf = {
+    now: () => number;
+};
+declare const TYPE: unique symbol;
+export type PosInt = number & {
+    [TYPE]: 'Positive Integer';
+};
+export type Index = number & {
+    [TYPE]: 'LRUCache Index';
+};
+export type UintArray = Uint8Array | Uint16Array | Uint32Array;
+export type NumberArray = UintArray | number[];
+declare class ZeroArray extends Array<number> {
+    constructor(size: number);
+}
+export type { ZeroArray };
+export type { Stack };
+export type StackLike = Stack | Index[];
+declare class Stack {
+    #private;
+    heap: NumberArray;
+    length: number;
+    static create(max: number): StackLike;
+    constructor(max: number, HeapCls: {
+        new (n: number): NumberArray;
+    });
+    push(n: Index): void;
+    pop(): Index;
+}
+/**
+ * Promise representing an in-progress {@link LRUCache#fetch} call
+ */
+export type BackgroundFetch<V> = Promise<V | undefined> & {
+    __returned: BackgroundFetch<V> | undefined;
+    __abortController: AbortController;
+    __staleWhileFetching: V | undefined;
+};
+export type DisposeTask<K, V> = [
+    value: V,
+    key: K,
+    reason: LRUCache.DisposeReason
+];
+export declare namespace LRUCache {
+    /**
+     * An integer greater than 0, reflecting the calculated size of items
+     */
+    type Size = number;
+    /**
+     * Integer greater than 0, representing some number of milliseconds, or the
+     * time at which a TTL started counting from.
+     */
+    type Milliseconds = number;
+    /**
+     * An integer greater than 0, reflecting a number of items
+     */
+    type Count = number;
+    /**
+     * The reason why an item was removed from the cache, passed
+     * to the {@link Disposer} methods.
+     *
+     * - `evict`: The item was evicted because it is the least recently used,
+     *   and the cache is full.
+     * - `set`: A new value was set, overwriting the old value being disposed.
+     * - `delete`: The item was explicitly deleted, either by calling
+     *   {@link LRUCache#delete}, {@link LRUCache#clear}, or
+     *   {@link LRUCache#set} with an undefined value.
+     * - `expire`: The item was removed due to exceeding its TTL.
+     * - `fetch`: A {@link OptionsBase#fetchMethod} operation returned
+     *   `undefined` or was aborted, causing the item to be deleted.
+     */
+    type DisposeReason = 'evict' | 'set' | 'delete' | 'expire' | 'fetch';
+    /**
+     * A method called upon item removal, passed as the
+     * {@link OptionsBase.dispose} and/or
+     * {@link OptionsBase.disposeAfter} options.
+     */
+    type Disposer<K, V> = (value: V, key: K, reason: DisposeReason) => void;
+    /**
+     * The reason why an item was added to the cache, passed
+     * to the {@link Inserter} methods.
+     *
+     * - `add`: the item was not found in the cache, and was added
+     * - `update`: the item was in the cache, with the same value provided
+     * - `replace`: the item was in the cache, and replaced
+     */
+    type InsertReason = 'add' | 'update' | 'replace';
+    /**
+     * A method called upon item insertion, passed as the
+     * {@link OptionsBase.insert}
+     */
+    type Inserter<K, V> = (value: V, key: K, reason: InsertReason) => void;
+    /**
+     * A function that returns the effective calculated size
+     * of an entry in the cache.
+     */
+    type SizeCalculator<K, V> = (value: V, key: K) => Size;
+    /**
+     * Options provided to the
+     * {@link OptionsBase.fetchMethod} function.
+     */
+    interface FetcherOptions<K, V, FC = unknown> {
+        signal: AbortSignal;
+        options: FetcherFetchOptions<K, V, FC>;
+        /**
+         * Object provided in the {@link FetchOptions.context} option to
+         * {@link LRUCache#fetch}
+         */
+        context: FC;
+    }
+    /**
+     * Occasionally, it may be useful to track the internal behavior of the
+     * cache, particularly for logging, debugging, or for behavior within the
+     * `fetchMethod`. To do this, you can pass a `status` object to the
+     * {@link LRUCache#fetch}, {@link LRUCache#get}, {@link LRUCache#set},
+     * {@link LRUCache#memo}, and {@link LRUCache#has} methods.
+     *
+     * The `status` option should be a plain JavaScript object. The following
+     * fields will be set on it appropriately, depending on the situation.
+     */
+    interface Status<V> {
+        /**
+         * The status of a set() operation.
+         *
+         * - add: the item was not found in the cache, and was added
+         * - update: the item was in the cache, with the same value provided
+         * - replace: the item was in the cache, and replaced
+         * - miss: the item was not added to the cache for some reason
+         */
+        set?: 'add' | 'update' | 'replace' | 'miss';
+        /**
+         * the ttl stored for the item, or undefined if ttls are not used.
+         */
+        ttl?: Milliseconds;
+        /**
+         * the start time for the item, or undefined if ttls are not used.
+         */
+        start?: Milliseconds;
+        /**
+         * The timestamp used for TTL calculation
+         */
+        now?: Milliseconds;
+        /**
+         * the remaining ttl for the item, or undefined if ttls are not used.
+         */
+        remainingTTL?: Milliseconds;
+        /**
+         * The calculated size for the item, if sizes are used.
+         */
+        entrySize?: Size;
+        /**
+         * The total calculated size of the cache, if sizes are used.
+         */
+        totalCalculatedSize?: Size;
+        /**
+         * A flag indicating that the item was not stored, due to exceeding the
+         * {@link OptionsBase.maxEntrySize}
+         */
+        maxEntrySizeExceeded?: true;
+        /**
+         * The old value, specified in the case of `set:'update'` or
+         * `set:'replace'`
+         */
+        oldValue?: V;
+        /**
+         * The results of a {@link LRUCache#has} operation
+         *
+         * - hit: the item was found in the cache
+         * - stale: the item was found in the cache, but is stale
+         * - miss: the item was not found in the cache
+         */
+        has?: 'hit' | 'stale' | 'miss';
+        /**
+         * The status of a {@link LRUCache#fetch} operation.
+         * Note that this can change as the underlying fetch() moves through
+         * various states.
+         *
+         * - inflight: there is another fetch() for this key which is in process
+         * - get: there is no {@link OptionsBase.fetchMethod}, so
+         *   {@link LRUCache#get} was called.
+         * - miss: the item is not in cache, and will be fetched.
+         * - hit: the item is in the cache, and was resolved immediately.
+         * - stale: the item is in the cache, but stale.
+         * - refresh: the item is in the cache, and not stale, but
+         *   {@link FetchOptions.forceRefresh} was specified.
+         */
+        fetch?: 'get' | 'inflight' | 'miss' | 'hit' | 'stale' | 'refresh';
+        /**
+         * The {@link OptionsBase.fetchMethod} was called
+         */
+        fetchDispatched?: true;
+        /**
+         * The cached value was updated after a successful call to
+         * {@link OptionsBase.fetchMethod}
+         */
+        fetchUpdated?: true;
+        /**
+         * The reason for a fetch() rejection.  Either the error raised by the
+         * {@link OptionsBase.fetchMethod}, or the reason for an
+         * AbortSignal.
+         */
+        fetchError?: Error;
+        /**
+         * The fetch received an abort signal
+         */
+        fetchAborted?: true;
+        /**
+         * The abort signal received was ignored, and the fetch was allowed to
+         * continue.
+         */
+        fetchAbortIgnored?: true;
+        /**
+         * The fetchMethod promise resolved successfully
+         */
+        fetchResolved?: true;
+        /**
+         * The fetchMethod promise was rejected
+         */
+        fetchRejected?: true;
+        /**
+         * The status of a {@link LRUCache#get} operation.
+         *
+         * - fetching: The item is currently being fetched.  If a previous value
+         *   is present and allowed, that will be returned.
+         * - stale: The item is in the cache, and is stale.
+         * - hit: the item is in the cache
+         * - miss: the item is not in the cache
+         */
+        get?: 'stale' | 'hit' | 'miss';
+        /**
+         * A fetch or get operation returned a stale value.
+         */
+        returnedStale?: true;
+    }
+    /**
+     * options which override the options set in the LRUCache constructor
+     * when calling {@link LRUCache#fetch}.
+     *
+     * This is the union of {@link GetOptions} and {@link SetOptions}, plus
+     * {@link OptionsBase.noDeleteOnFetchRejection},
+     * {@link OptionsBase.allowStaleOnFetchRejection},
+     * {@link FetchOptions.forceRefresh}, and
+     * {@link FetcherOptions.context}
+     *
+     * Any of these may be modified in the {@link OptionsBase.fetchMethod}
+     * function, but the {@link GetOptions} fields will of course have no
+     * effect, as the {@link LRUCache#get} call already happened by the time
+     * the fetchMethod is called.
+     */
+    interface FetcherFetchOptions<K, V, FC = unknown> extends Pick<OptionsBase<K, V, FC>, 'allowStale' | 'updateAgeOnGet' | 'noDeleteOnStaleGet' | 'sizeCalculation' | 'ttl' | 'noDisposeOnSet' | 'noUpdateTTL' | 'noDeleteOnFetchRejection' | 'allowStaleOnFetchRejection' | 'ignoreFetchAbort' | 'allowStaleOnFetchAbort'> {
+        status?: Status<V>;
+        size?: Size;
+    }
+    /**
+     * Options that may be passed to the {@link LRUCache#fetch} method.
+     */
+    interface FetchOptions<K, V, FC> extends FetcherFetchOptions<K, V, FC> {
+        /**
+         * Set to true to force a re-load of the existing data, even if it
+         * is not yet stale.
+         */
+        forceRefresh?: boolean;
+        /**
+         * Context provided to the {@link OptionsBase.fetchMethod} as
+         * the {@link FetcherOptions.context} param.
+         *
+         * If the FC type is specified as unknown (the default),
+         * undefined or void, then this is optional.  Otherwise, it will
+         * be required.
+         */
+        context?: FC;
+        signal?: AbortSignal;
+        status?: Status<V>;
+    }
+    /**
+     * Options provided to {@link LRUCache#fetch} when the FC type is something
+     * other than `unknown`, `undefined`, or `void`
+     */
+    interface FetchOptionsWithContext<K, V, FC> extends FetchOptions<K, V, FC> {
+        context: FC;
+    }
+    /**
+     * Options provided to {@link LRUCache#fetch} when the FC type is
+     * `undefined` or `void`
+     */
+    interface FetchOptionsNoContext<K, V> extends FetchOptions<K, V, undefined> {
+        context?: undefined;
+    }
+    interface MemoOptions<K, V, FC = unknown> extends Pick<OptionsBase<K, V, FC>, 'allowStale' | 'updateAgeOnGet' | 'noDeleteOnStaleGet' | 'sizeCalculation' | 'ttl' | 'noDisposeOnSet' | 'noUpdateTTL' | 'noDeleteOnFetchRejection' | 'allowStaleOnFetchRejection' | 'ignoreFetchAbort' | 'allowStaleOnFetchAbort'> {
+        /**
+         * Set to true to force a re-load of the existing data, even if it
+         * is not yet stale.
+         */
+        forceRefresh?: boolean;
+        /**
+         * Context provided to the {@link OptionsBase.memoMethod} as
+         * the {@link MemoizerOptions.context} param.
+         *
+         * If the FC type is specified as unknown (the default),
+         * undefined or void, then this is optional.  Otherwise, it will
+         * be required.
+         */
+        context?: FC;
+        status?: Status<V>;
+    }
+    /**
+     * Options provided to {@link LRUCache#memo} when the FC type is something
+     * other than `unknown`, `undefined`, or `void`
+     */
+    interface MemoOptionsWithContext<K, V, FC> extends MemoOptions<K, V, FC> {
+        context: FC;
+    }
+    /**
+     * Options provided to {@link LRUCache#memo} when the FC type is
+     * `undefined` or `void`
+     */
+    interface MemoOptionsNoContext<K, V> extends MemoOptions<K, V, undefined> {
+        context?: undefined;
+    }
+    /**
+     * Options provided to the
+     * {@link OptionsBase.memoMethod} function.
+     */
+    interface MemoizerOptions<K, V, FC = unknown> {
+        options: MemoizerMemoOptions<K, V, FC>;
+        /**
+         * Object provided in the {@link MemoOptions.context} option to
+         * {@link LRUCache#memo}
+         */
+        context: FC;
+    }
+    /**
+     * options which override the options set in the LRUCache constructor
+     * when calling {@link LRUCache#memo}.
+     *
+     * This is the union of {@link GetOptions} and {@link SetOptions}, plus
+     * {@link MemoOptions.forceRefresh}, and
+     * {@link MemoOptions.context}
+     *
+     * Any of these may be modified in the {@link OptionsBase.memoMethod}
+     * function, but the {@link GetOptions} fields will of course have no
+     * effect, as the {@link LRUCache#get} call already happened by the time
+     * the memoMethod is called.
+     */
+    interface MemoizerMemoOptions<K, V, FC = unknown> extends Pick<OptionsBase<K, V, FC>, 'allowStale' | 'updateAgeOnGet' | 'noDeleteOnStaleGet' | 'sizeCalculation' | 'ttl' | 'noDisposeOnSet' | 'noUpdateTTL'> {
+        status?: Status<V>;
+        size?: Size;
+        start?: Milliseconds;
+    }
+    /**
+     * Options that may be passed to the {@link LRUCache#has} method.
+     */
+    interface HasOptions<K, V, FC> extends Pick<OptionsBase<K, V, FC>, 'updateAgeOnHas'> {
+        status?: Status<V>;
+    }
+    /**
+     * Options that may be passed to the {@link LRUCache#get} method.
+     */
+    interface GetOptions<K, V, FC> extends Pick<OptionsBase<K, V, FC>, 'allowStale' | 'updateAgeOnGet' | 'noDeleteOnStaleGet'> {
+        status?: Status<V>;
+    }
+    /**
+     * Options that may be passed to the {@link LRUCache#peek} method.
+     */
+    interface PeekOptions<K, V, FC> extends Pick<OptionsBase<K, V, FC>, 'allowStale'> {
+    }
+    /**
+     * Options that may be passed to the {@link LRUCache#set} method.
+     */
+    interface SetOptions<K, V, FC> extends Pick<OptionsBase<K, V, FC>, 'sizeCalculation' | 'ttl' | 'noDisposeOnSet' | 'noUpdateTTL'> {
+        /**
+         * If size tracking is enabled, then setting an explicit size
+         * in the {@link LRUCache#set} call will prevent calling the
+         * {@link OptionsBase.sizeCalculation} function.
+         */
+        size?: Size;
+        /**
+         * If TTL tracking is enabled, then setting an explicit start
+         * time in the {@link LRUCache#set} call will override the
+         * default time from `performance.now()` or `Date.now()`.
+         *
+         * Note that it must be a valid value for whichever time-tracking
+         * method is in use.
+         */
+        start?: Milliseconds;
+        status?: Status<V>;
+    }
+    /**
+     * The type signature for the {@link OptionsBase.fetchMethod} option.
+     */
+    type Fetcher<K, V, FC = unknown> = (key: K, staleValue: V | undefined, options: FetcherOptions<K, V, FC>) => Promise<V | undefined | void> | V | undefined | void;
+    /**
+     * the type signature for the {@link OptionsBase.memoMethod} option.
+     */
+    type Memoizer<K, V, FC = unknown> = (key: K, staleValue: V | undefined, options: MemoizerOptions<K, V, FC>) => V;
+    /**
+     * Options which may be passed to the {@link LRUCache} constructor.
+     *
+     * Most of these may be overridden in the various options that use
+     * them.
+     *
+     * Despite all being technically optional, the constructor requires that
+     * a cache is at minimum limited by one or more of {@link OptionsBase.max},
+     * {@link OptionsBase.ttl}, or {@link OptionsBase.maxSize}.
+     *
+     * If {@link OptionsBase.ttl} is used alone, then it is strongly advised
+     * (and in fact required by the type definitions here) that the cache
+     * also set {@link OptionsBase.ttlAutopurge}, to prevent potentially
+     * unbounded storage.
+     *
+     * All options are also available on the {@link LRUCache} instance, making
+     * it safe to pass an LRUCache instance as the options argumemnt to
+     * make another empty cache of the same type.
+     *
+     * Some options are marked as read-only, because changing them after
+     * instantiation is not safe. Changing any of the other options will of
+     * course only have an effect on subsequent method calls.
+     */
+    interface OptionsBase<K, V, FC> {
+        /**
+         * The maximum number of items to store in the cache before evicting
+         * old entries. This is read-only on the {@link LRUCache} instance,
+         * and may not be overridden.
+         *
+         * If set, then storage space will be pre-allocated at construction
+         * time, and the cache will perform significantly faster.
+         *
+         * Note that significantly fewer items may be stored, if
+         * {@link OptionsBase.maxSize} and/or {@link OptionsBase.ttl} are also
+         * set.
+         *
+         * **It is strongly recommended to set a `max` to prevent unbounded growth
+         * of the cache.**
+         */
+        max?: Count;
+        /**
+         * Max time in milliseconds for items to live in cache before they are
+         * considered stale.  Note that stale items are NOT preemptively removed by
+         * default, and MAY live in the cache, contributing to its LRU max, long
+         * after they have expired, unless {@link OptionsBase.ttlAutopurge} is
+         * set.
+         *
+         * If set to `0` (the default value), then that means "do not track
+         * TTL", not "expire immediately".
+         *
+         * Also, as this cache is optimized for LRU/MRU operations, some of
+         * the staleness/TTL checks will reduce performance, as they will incur
+         * overhead by deleting items.
+         *
+         * This is not primarily a TTL cache, and does not make strong TTL
+         * guarantees. There is no pre-emptive pruning of expired items, but you
+         * _may_ set a TTL on the cache, and it will treat expired items as missing
+         * when they are fetched, and delete them.
+         *
+         * Optional, but must be a non-negative integer in ms if specified.
+         *
+         * This may be overridden by passing an options object to `cache.set()`.
+         *
+         * At least one of `max`, `maxSize`, or `TTL` is required. This must be a
+         * positive integer if set.
+         *
+         * Even if ttl tracking is enabled, **it is strongly recommended to set a
+         * `max` to prevent unbounded growth of the cache.**
+         *
+         * If ttl tracking is enabled, and `max` and `maxSize` are not set,
+         * and `ttlAutopurge` is not set, then a warning will be emitted
+         * cautioning about the potential for unbounded memory consumption.
+         * (The TypeScript definitions will also discourage this.)
+         */
+        ttl?: Milliseconds;
+        /**
+         * Minimum amount of time in ms in which to check for staleness.
+         * Defaults to 1, which means that the current time is checked
+         * at most once per millisecond.
+         *
+         * Set to 0 to check the current time every time staleness is tested.
+         * (This reduces performance, and is theoretically unnecessary.)
+         *
+         * Setting this to a higher value will improve performance somewhat
+         * while using ttl tracking, albeit at the expense of keeping stale
+         * items around a bit longer than their TTLs would indicate.
+         *
+         * @default 1
+         */
+        ttlResolution?: Milliseconds;
+        /**
+         * Preemptively remove stale items from the cache.
+         *
+         * Note that this may *significantly* degrade performance, especially if
+         * the cache is storing a large number of items. It is almost always best
+         * to just leave the stale items in the cache, and let them fall out as new
+         * items are added.
+         *
+         * Note that this means that {@link OptionsBase.allowStale} is a bit
+         * pointless, as stale items will be deleted almost as soon as they
+         * expire.
+         *
+         * Use with caution!
+         */
+        ttlAutopurge?: boolean;
+        /**
+         * When using time-expiring entries with `ttl`, setting this to `true` will
+         * make each item's age reset to 0 whenever it is retrieved from cache with
+         * {@link LRUCache#get}, causing it to not expire. (It can still fall out
+         * of cache based on recency of use, of course.)
+         *
+         * Has no effect if {@link OptionsBase.ttl} is not set.
+         *
+         * This may be overridden by passing an options object to `cache.get()`.
+         */
+        updateAgeOnGet?: boolean;
+        /**
+         * When using time-expiring entries with `ttl`, setting this to `true` will
+         * make each item's age reset to 0 whenever its presence in the cache is
+         * checked with {@link LRUCache#has}, causing it to not expire. (It can
+         * still fall out of cache based on recency of use, of course.)
+         *
+         * Has no effect if {@link OptionsBase.ttl} is not set.
+         */
+        updateAgeOnHas?: boolean;
+        /**
+         * Allow {@link LRUCache#get} and {@link LRUCache#fetch} calls to return
+         * stale data, if available.
+         *
+         * By default, if you set `ttl`, stale items will only be deleted from the
+         * cache when you `get(key)`. That is, it's not preemptively pruning items,
+         * unless {@link OptionsBase.ttlAutopurge} is set.
+         *
+         * If you set `allowStale:true`, it'll return the stale value *as well as*
+         * deleting it. If you don't set this, then it'll return `undefined` when
+         * you try to get a stale entry.
+         *
+         * Note that when a stale entry is fetched, _even if it is returned due to
+         * `allowStale` being set_, it is removed from the cache immediately. You
+         * can suppress this behavior by setting
+         * {@link OptionsBase.noDeleteOnStaleGet}, either in the constructor, or in
+         * the options provided to {@link LRUCache#get}.
+         *
+         * This may be overridden by passing an options object to `cache.get()`.
+         * The `cache.has()` method will always return `false` for stale items.
+         *
+         * Only relevant if a ttl is set.
+         */
+        allowStale?: boolean;
+        /**
+         * Function that is called on items when they are dropped from the
+         * cache, as `dispose(value, key, reason)`.
+         *
+         * This can be handy if you want to close file descriptors or do
+         * other cleanup tasks when items are no longer stored in the cache.
+         *
+         * **NOTE**: It is called _before_ the item has been fully removed
+         * from the cache, so if you want to put it right back in, you need
+         * to wait until the next tick. If you try to add it back in during
+         * the `dispose()` function call, it will break things in subtle and
+         * weird ways.
+         *
+         * Unlike several other options, this may _not_ be overridden by
+         * passing an option to `set()`, for performance reasons.
+         *
+         * The `reason` will be one of the following strings, corresponding
+         * to the reason for the item's deletion:
+         *
+         * - `evict` Item was evicted to make space for a new addition
+         * - `set` Item was overwritten by a new value
+         * - `expire` Item expired its TTL
+         * - `fetch` Item was deleted due to a failed or aborted fetch, or a
+         *   fetchMethod returning `undefined.
+         * - `delete` Item was removed by explicit `cache.delete(key)`,
+         *   `cache.clear()`, or `cache.set(key, undefined)`.
+         */
+        dispose?: Disposer<K, V>;
+        /**
+         * Function that is called when new items are inserted into the cache,
+         * as `onInsert(value, key, reason)`.
+         *
+         * This can be useful if you need to perform actions when an item is
+         * added, such as logging or tracking insertions.
+         *
+         * Unlike some other options, this may _not_ be overridden by passing
+         * an option to `set()`, for performance and consistency reasons.
+         */
+        onInsert?: Inserter<K, V>;
+        /**
+         * The same as {@link OptionsBase.dispose}, but called *after* the entry
+         * is completely removed and the cache is once again in a clean state.
+         *
+         * It is safe to add an item right back into the cache at this point.
+         * However, note that it is *very* easy to inadvertently create infinite
+         * recursion this way.
+         */
+        disposeAfter?: Disposer<K, V>;
+        /**
+         * Set to true to suppress calling the
+         * {@link OptionsBase.dispose} function if the entry key is
+         * still accessible within the cache.
+         *
+         * This may be overridden by passing an options object to
+         * {@link LRUCache#set}.
+         *
+         * Only relevant if `dispose` or `disposeAfter` are set.
+         */
+        noDisposeOnSet?: boolean;
+        /**
+         * Boolean flag to tell the cache to not update the TTL when setting a new
+         * value for an existing key (ie, when updating a value rather than
+         * inserting a new value).  Note that the TTL value is _always_ set (if
+         * provided) when adding a new entry into the cache.
+         *
+         * Has no effect if a {@link OptionsBase.ttl} is not set.
+         *
+         * May be passed as an option to {@link LRUCache#set}.
+         */
+        noUpdateTTL?: boolean;
+        /**
+         * Set to a positive integer to track the sizes of items added to the
+         * cache, and automatically evict items in order to stay below this size.
+         * Note that this may result in fewer than `max` items being stored.
+         *
+         * Attempting to add an item to the cache whose calculated size is greater
+         * that this amount will be a no-op. The item will not be cached, and no
+         * other items will be evicted.
+         *
+         * Optional, must be a positive integer if provided.
+         *
+         * Sets `maxEntrySize` to the same value, unless a different value is
+         * provided for `maxEntrySize`.
+         *
+         * At least one of `max`, `maxSize`, or `TTL` is required. This must be a
+         * positive integer if set.
+         *
+         * Even if size tracking is enabled, **it is strongly recommended to set a
+         * `max` to prevent unbounded growth of the cache.**
+         *
+         * Note also that size tracking can negatively impact performance,
+         * though for most cases, only minimally.
+         */
+        maxSize?: Size;
+        /**
+         * The maximum allowed size for any single item in the cache.
+         *
+         * If a larger item is passed to {@link LRUCache#set} or returned by a
+         * {@link OptionsBase.fetchMethod} or {@link OptionsBase.memoMethod}, then
+         * it will not be stored in the cache.
+         *
+         * Attempting to add an item whose calculated size is greater than
+         * this amount will not cache the item or evict any old items, but
+         * WILL delete an existing value if one is already present.
+         *
+         * Optional, must be a positive integer if provided. Defaults to
+         * the value of `maxSize` if provided.
+         */
+        maxEntrySize?: Size;
+        /**
+         * A function that returns a number indicating the item's size.
+         *
+         * Requires {@link OptionsBase.maxSize} to be set.
+         *
+         * If not provided, and {@link OptionsBase.maxSize} or
+         * {@link OptionsBase.maxEntrySize} are set, then all
+         * {@link LRUCache#set} calls **must** provide an explicit
+         * {@link SetOptions.size} or sizeCalculation param.
+         */
+        sizeCalculation?: SizeCalculator<K, V>;
+        /**
+         * Method that provides the implementation for {@link LRUCache#fetch}
+         *
+         * ```ts
+         * fetchMethod(key, staleValue, { signal, options, context })
+         * ```
+         *
+         * If `fetchMethod` is not provided, then `cache.fetch(key)` is equivalent
+         * to `Promise.resolve(cache.get(key))`.
+         *
+         * If at any time, `signal.aborted` is set to `true`, or if the
+         * `signal.onabort` method is called, or if it emits an `'abort'` event
+         * which you can listen to with `addEventListener`, then that means that
+         * the fetch should be abandoned. This may be passed along to async
+         * functions aware of AbortController/AbortSignal behavior.
+         *
+         * The `fetchMethod` should **only** return `undefined` or a Promise
+         * resolving to `undefined` if the AbortController signaled an `abort`
+         * event. In all other cases, it should return or resolve to a value
+         * suitable for adding to the cache.
+         *
+         * The `options` object is a union of the options that may be provided to
+         * `set()` and `get()`. If they are modified, then that will result in
+         * modifying the settings to `cache.set()` when the value is resolved, and
+         * in the case of
+         * {@link OptionsBase.noDeleteOnFetchRejection} and
+         * {@link OptionsBase.allowStaleOnFetchRejection}, the handling of
+         * `fetchMethod` failures.
+         *
+         * For example, a DNS cache may update the TTL based on the value returned
+         * from a remote DNS server by changing `options.ttl` in the `fetchMethod`.
+         */
+        fetchMethod?: Fetcher<K, V, FC>;
+        /**
+         * Method that provides the implementation for {@link LRUCache#memo}
+         */
+        memoMethod?: Memoizer<K, V, FC>;
+        /**
+         * Set to true to suppress the deletion of stale data when a
+         * {@link OptionsBase.fetchMethod} returns a rejected promise.
+         */
+        noDeleteOnFetchRejection?: boolean;
+        /**
+         * Do not delete stale items when they are retrieved with
+         * {@link LRUCache#get}.
+         *
+         * Note that the `get` return value will still be `undefined`
+         * unless {@link OptionsBase.allowStale} is true.
+         *
+         * When using time-expiring entries with `ttl`, by default stale
+         * items will be removed from the cache when the key is accessed
+         * with `cache.get()`.
+         *
+         * Setting this option will cause stale items to remain in the cache, until
+         * they are explicitly deleted with `cache.delete(key)`, or retrieved with
+         * `noDeleteOnStaleGet` set to `false`.
+         *
+         * This may be overridden by passing an options object to `cache.get()`.
+         *
+         * Only relevant if a ttl is used.
+         */
+        noDeleteOnStaleGet?: boolean;
+        /**
+         * Set to true to allow returning stale data when a
+         * {@link OptionsBase.fetchMethod} throws an error or returns a rejected
+         * promise.
+         *
+         * This differs from using {@link OptionsBase.allowStale} in that stale
+         * data will ONLY be returned in the case that the {@link LRUCache#fetch}
+         * fails, not any other times.
+         *
+         * If a `fetchMethod` fails, and there is no stale value available, the
+         * `fetch()` will resolve to `undefined`. Ie, all `fetchMethod` errors are
+         * suppressed.
+         *
+         * Implies `noDeleteOnFetchRejection`.
+         *
+         * This may be set in calls to `fetch()`, or defaulted on the constructor,
+         * or overridden by modifying the options object in the `fetchMethod`.
+         */
+        allowStaleOnFetchRejection?: boolean;
+        /**
+         * Set to true to return a stale value from the cache when the
+         * `AbortSignal` passed to the {@link OptionsBase.fetchMethod} dispatches
+         * an `'abort'` event, whether user-triggered, or due to internal cache
+         * behavior.
+         *
+         * Unless {@link OptionsBase.ignoreFetchAbort} is also set, the underlying
+         * {@link OptionsBase.fetchMethod} will still be considered canceled, and
+         * any value it returns will be ignored and not cached.
+         *
+         * Caveat: since fetches are aborted when a new value is explicitly
+         * set in the cache, this can lead to fetch returning a stale value,
+         * since that was the fallback value _at the moment the `fetch()` was
+         * initiated_, even though the new updated value is now present in
+         * the cache.
+         *
+         * For example:
+         *
+         * ```ts
+         * const cache = new LRUCache<string, any>({
+         *   ttl: 100,
+         *   fetchMethod: async (url, oldValue, { signal }) =>  {
+         *     const res = await fetch(url, { signal })
+         *     return await res.json()
+         *   }
+         * })
+         * cache.set('https://example.com/', { some: 'data' })
+         * // 100ms go by...
+         * const result = cache.fetch('https://example.com/')
+         * cache.set('https://example.com/', { other: 'thing' })
+         * console.log(await result) // { some: 'data' }
+         * console.log(cache.get('https://example.com/')) // { other: 'thing' }
+         * ```
+         */
+        allowStaleOnFetchAbort?: boolean;
+        /**
+         * Set to true to ignore the `abort` event emitted by the `AbortSignal`
+         * object passed to {@link OptionsBase.fetchMethod}, and still cache the
+         * resulting resolution value, as long as it is not `undefined`.
+         *
+         * When used on its own, this means aborted {@link LRUCache#fetch} calls
+         * are not immediately resolved or rejected when they are aborted, and
+         * instead take the full time to await.
+         *
+         * When used with {@link OptionsBase.allowStaleOnFetchAbort}, aborted
+         * {@link LRUCache#fetch} calls will resolve immediately to their stale
+         * cached value or `undefined`, and will continue to process and eventually
+         * update the cache when they resolve, as long as the resulting value is
+         * not `undefined`, thus supporting a "return stale on timeout while
+         * refreshing" mechanism by passing `AbortSignal.timeout(n)` as the signal.
+         *
+         * For example:
+         *
+         * ```ts
+         * const c = new LRUCache({
+         *   ttl: 100,
+         *   ignoreFetchAbort: true,
+         *   allowStaleOnFetchAbort: true,
+         *   fetchMethod: async (key, oldValue, { signal }) => {
+         *     // note: do NOT pass the signal to fetch()!
+         *     // let's say this fetch can take a long time.
+         *     const res = await fetch(`https://slow-backend-server/${key}`)
+         *     return await res.json()
+         *   },
+         * })
+         *
+         * // this will return the stale value after 100ms, while still
+         * // updating in the background for next time.
+         * const val = await c.fetch('key', { signal: AbortSignal.timeout(100) })
+         * ```
+         *
+         * **Note**: regardless of this setting, an `abort` event _is still
+         * emitted on the `AbortSignal` object_, so may result in invalid results
+         * when passed to other underlying APIs that use AbortSignals.
+         *
+         * This may be overridden in the {@link OptionsBase.fetchMethod} or the
+         * call to {@link LRUCache#fetch}.
+         */
+        ignoreFetchAbort?: boolean;
+        /**
+         * In some cases, you may want to swap out the performance/Date object
+         * used for TTL tracking. This should almost certainly NOT be done in
+         * production environments!
+         *
+         * This value defaults to `global.performance` if it has a `now()` method,
+         * or the `global.Date` object otherwise.
+         */
+        perf?: Perf;
+    }
+    interface OptionsMaxLimit<K, V, FC> extends OptionsBase<K, V, FC> {
+        max: Count;
+    }
+    interface OptionsTTLLimit<K, V, FC> extends OptionsBase<K, V, FC> {
+        ttl: Milliseconds;
+        ttlAutopurge: boolean;
+    }
+    interface OptionsSizeLimit<K, V, FC> extends OptionsBase<K, V, FC> {
+        maxSize: Size;
+    }
+    /**
+     * The valid safe options for the {@link LRUCache} constructor
+     */
+    type Options<K, V, FC> = OptionsMaxLimit<K, V, FC> | OptionsSizeLimit<K, V, FC> | OptionsTTLLimit<K, V, FC>;
+    /**
+     * Entry objects used by {@link LRUCache#load} and {@link LRUCache#dump},
+     * and returned by {@link LRUCache#info}.
+     */
+    interface Entry<V> {
+        value: V;
+        ttl?: Milliseconds;
+        size?: Size;
+        start?: Milliseconds;
+    }
+}
+/**
+ * Default export, the thing you're using this module to get.
+ *
+ * The `K` and `V` types define the key and value types, respectively. The
+ * optional `FC` type defines the type of the `context` object passed to
+ * `cache.fetch()` and `cache.memo()`.
+ *
+ * Keys and values **must not** be `null` or `undefined`.
+ *
+ * All properties from the options object (with the exception of `max`,
+ * `maxSize`, `fetchMethod`, `memoMethod`, `dispose` and `disposeAfter`) are
+ * added as normal public members. (The listed options are read-only getters.)
+ *
+ * Changing any of these will alter the defaults for subsequent method calls.
+ */
+export declare class LRUCache<K extends {}, V extends {}, FC = unknown> {
+    #private;
+    /**
+     * {@link LRUCache.OptionsBase.perf}
+     */
+    get perf(): Perf;
+    /**
+     * {@link LRUCache.OptionsBase.ttl}
+     */
+    ttl: LRUCache.Milliseconds;
+    /**
+     * {@link LRUCache.OptionsBase.ttlResolution}
+     */
+    ttlResolution: LRUCache.Milliseconds;
+    /**
+     * {@link LRUCache.OptionsBase.ttlAutopurge}
+     */
+    ttlAutopurge: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.updateAgeOnGet}
+     */
+    updateAgeOnGet: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.updateAgeOnHas}
+     */
+    updateAgeOnHas: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.allowStale}
+     */
+    allowStale: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.noDisposeOnSet}
+     */
+    noDisposeOnSet: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.noUpdateTTL}
+     */
+    noUpdateTTL: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.maxEntrySize}
+     */
+    maxEntrySize: LRUCache.Size;
+    /**
+     * {@link LRUCache.OptionsBase.sizeCalculation}
+     */
+    sizeCalculation?: LRUCache.SizeCalculator<K, V>;
+    /**
+     * {@link LRUCache.OptionsBase.noDeleteOnFetchRejection}
+     */
+    noDeleteOnFetchRejection: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.noDeleteOnStaleGet}
+     */
+    noDeleteOnStaleGet: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.allowStaleOnFetchAbort}
+     */
+    allowStaleOnFetchAbort: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.allowStaleOnFetchRejection}
+     */
+    allowStaleOnFetchRejection: boolean;
+    /**
+     * {@link LRUCache.OptionsBase.ignoreFetchAbort}
+     */
+    ignoreFetchAbort: boolean;
+    /**
+     * Do not call this method unless you need to inspect the
+     * inner workings of the cache.  If anything returned by this
+     * object is modified in any way, strange breakage may occur.
+     *
+     * These fields are private for a reason!
+     *
+     * @internal
+     */
+    static unsafeExposeInternals<K extends {}, V extends {}, FC extends unknown = unknown>(c: LRUCache<K, V, FC>): {
+        starts: ZeroArray | undefined;
+        ttls: ZeroArray | undefined;
+        autopurgeTimers: (NodeJS.Timeout | undefined)[] | undefined;
+        sizes: ZeroArray | undefined;
+        keyMap: Map<K, number>;
+        keyList: (K | undefined)[];
+        valList: (V | BackgroundFetch<V> | undefined)[];
+        next: NumberArray;
+        prev: NumberArray;
+        readonly head: Index;
+        readonly tail: Index;
+        free: StackLike;
+        isBackgroundFetch: (p: any) => p is BackgroundFetch<V>;
+        backgroundFetch: (k: K, index: number | undefined, options: LRUCache.FetchOptions<K, V, FC>, context: any) => BackgroundFetch<V>;
+        moveToTail: (index: number) => void;
+        indexes: (options?: {
+            allowStale: boolean;
+        }) => Generator<Index, void, unknown>;
+        rindexes: (options?: {
+            allowStale: boolean;
+        }) => Generator<Index, void, unknown>;
+        isStale: (index: number | undefined) => boolean;
+    };
+    /**
+     * {@link LRUCache.OptionsBase.max} (read-only)
+     */
+    get max(): LRUCache.Count;
+    /**
+     * {@link LRUCache.OptionsBase.maxSize} (read-only)
+     */
+    get maxSize(): LRUCache.Count;
+    /**
+     * The total computed size of items in the cache (read-only)
+     */
+    get calculatedSize(): LRUCache.Size;
+    /**
+     * The number of items stored in the cache (read-only)
+     */
+    get size(): LRUCache.Count;
+    /**
+     * {@link LRUCache.OptionsBase.fetchMethod} (read-only)
+     */
+    get fetchMethod(): LRUCache.Fetcher<K, V, FC> | undefined;
+    get memoMethod(): LRUCache.Memoizer<K, V, FC> | undefined;
+    /**
+     * {@link LRUCache.OptionsBase.dispose} (read-only)
+     */
+    get dispose(): LRUCache.Disposer<K, V> | undefined;
+    /**
+     * {@link LRUCache.OptionsBase.onInsert} (read-only)
+     */
+    get onInsert(): LRUCache.Inserter<K, V> | undefined;
+    /**
+     * {@link LRUCache.OptionsBase.disposeAfter} (read-only)
+     */
+    get disposeAfter(): LRUCache.Disposer<K, V> | undefined;
+    constructor(options: LRUCache.Options<K, V, FC> | LRUCache<K, V, FC>);
+    /**
+     * Return the number of ms left in the item's TTL. If item is not in cache,
+     * returns `0`. Returns `Infinity` if item is in cache without a defined TTL.
+     */
+    getRemainingTTL(key: K): number;
+    /**
+     * Return a generator yielding `[key, value]` pairs,
+     * in order from most recently used to least recently used.
+     */
+    entries(): Generator<[K, V], void, unknown>;
+    /**
+     * Inverse order version of {@link LRUCache.entries}
+     *
+     * Return a generator yielding `[key, value]` pairs,
+     * in order from least recently used to most recently used.
+     */
+    rentries(): Generator<(K | V)[], void, unknown>;
+    /**
+     * Return a generator yielding the keys in the cache,
+     * in order from most recently used to least recently used.
+     */
+    keys(): Generator<K, void, unknown>;
+    /**
+     * Inverse order version of {@link LRUCache.keys}
+     *
+     * Return a generator yielding the keys in the cache,
+     * in order from least recently used to most recently used.
+     */
+    rkeys(): Generator<K, void, unknown>;
+    /**
+     * Return a generator yielding the values in the cache,
+     * in order from most recently used to least recently used.
+     */
+    values(): Generator<V, void, unknown>;
+    /**
+     * Inverse order version of {@link LRUCache.values}
+     *
+     * Return a generator yielding the values in the cache,
+     * in order from least recently used to most recently used.
+     */
+    rvalues(): Generator<V | undefined, void, unknown>;
+    /**
+     * Iterating over the cache itself yields the same results as
+     * {@link LRUCache.entries}
+     */
+    [Symbol.iterator](): Generator<[K, V], void, unknown>;
+    /**
+     * A String value that is used in the creation of the default string
+     * description of an object. Called by the built-in method
+     * `Object.prototype.toString`.
+     */
+    [Symbol.toStringTag]: string;
+    /**
+     * Find a value for which the supplied fn method returns a truthy value,
+     * similar to `Array.find()`. fn is called as `fn(value, key, cache)`.
+     */
+    find(fn: (v: V, k: K, self: LRUCache<K, V, FC>) => boolean, getOptions?: LRUCache.GetOptions<K, V, FC>): V | undefined;
+    /**
+     * Call the supplied function on each item in the cache, in order from most
+     * recently used to least recently used.
+     *
+     * `fn` is called as `fn(value, key, cache)`.
+     *
+     * If `thisp` is provided, function will be called in the `this`-context of
+     * the provided object, or the cache if no `thisp` object is provided.
+     *
+     * Does not update age or recenty of use, or iterate over stale values.
+     */
+    forEach(fn: (v: V, k: K, self: LRUCache<K, V, FC>) => any, thisp?: any): void;
+    /**
+     * The same as {@link LRUCache.forEach} but items are iterated over in
+     * reverse order.  (ie, less recently used items are iterated over first.)
+     */
+    rforEach(fn: (v: V, k: K, self: LRUCache<K, V, FC>) => any, thisp?: any): void;
+    /**
+     * Delete any stale entries. Returns true if anything was removed,
+     * false otherwise.
+     */
+    purgeStale(): boolean;
+    /**
+     * Get the extended info about a given entry, to get its value, size, and
+     * TTL info simultaneously. Returns `undefined` if the key is not present.
+     *
+     * Unlike {@link LRUCache#dump}, which is designed to be portable and survive
+     * serialization, the `start` value is always the current timestamp, and the
+     * `ttl` is a calculated remaining time to live (negative if expired).
+     *
+     * Always returns stale values, if their info is found in the cache, so be
+     * sure to check for expirations (ie, a negative {@link LRUCache.Entry#ttl})
+     * if relevant.
+     */
+    info(key: K): LRUCache.Entry<V> | undefined;
+    /**
+     * Return an array of [key, {@link LRUCache.Entry}] tuples which can be
+     * passed to {@link LRUCache#load}.
+     *
+     * The `start` fields are calculated relative to a portable `Date.now()`
+     * timestamp, even if `performance.now()` is available.
+     *
+     * Stale entries are always included in the `dump`, even if
+     * {@link LRUCache.OptionsBase.allowStale} is false.
+     *
+     * Note: this returns an actual array, not a generator, so it can be more
+     * easily passed around.
+     */
+    dump(): [K, LRUCache.Entry<V>][];
+    /**
+     * Reset the cache and load in the items in entries in the order listed.
+     *
+     * The shape of the resulting cache may be different if the same options are
+     * not used in both caches.
+     *
+     * The `start` fields are assumed to be calculated relative to a portable
+     * `Date.now()` timestamp, even if `performance.now()` is available.
+     */
+    load(arr: [K, LRUCache.Entry<V>][]): void;
+    /**
+     * Add a value to the cache.
+     *
+     * Note: if `undefined` is specified as a value, this is an alias for
+     * {@link LRUCache#delete}
+     *
+     * Fields on the {@link LRUCache.SetOptions} options param will override
+     * their corresponding values in the constructor options for the scope
+     * of this single `set()` operation.
+     *
+     * If `start` is provided, then that will set the effective start
+     * time for the TTL calculation. Note that this must be a previous
+     * value of `performance.now()` if supported, or a previous value of
+     * `Date.now()` if not.
+     *
+     * Options object may also include `size`, which will prevent
+     * calling the `sizeCalculation` function and just use the specified
+     * number if it is a positive integer, and `noDisposeOnSet` which
+     * will prevent calling a `dispose` function in the case of
+     * overwrites.
+     *
+     * If the `size` (or return value of `sizeCalculation`) for a given
+     * entry is greater than `maxEntrySize`, then the item will not be
+     * added to the cache.
+     *
+     * Will update the recency of the entry.
+     *
+     * If the value is `undefined`, then this is an alias for
+     * `cache.delete(key)`. `undefined` is never stored in the cache.
+     */
+    set(k: K, v: V | BackgroundFetch<V> | undefined, setOptions?: LRUCache.SetOptions<K, V, FC>): this;
+    /**
+     * Evict the least recently used item, returning its value or
+     * `undefined` if cache is empty.
+     */
+    pop(): V | undefined;
+    /**
+     * Check if a key is in the cache, without updating the recency of use.
+     * Will return false if the item is stale, even though it is technically
+     * in the cache.
+     *
+     * Check if a key is in the cache, without updating the recency of
+     * use. Age is updated if {@link LRUCache.OptionsBase.updateAgeOnHas} is set
+     * to `true` in either the options or the constructor.
+     *
+     * Will return `false` if the item is stale, even though it is technically in
+     * the cache. The difference can be determined (if it matters) by using a
+     * `status` argument, and inspecting the `has` field.
+     *
+     * Will not update item age unless
+     * {@link LRUCache.OptionsBase.updateAgeOnHas} is set.
+     */
+    has(k: K, hasOptions?: LRUCache.HasOptions<K, V, FC>): boolean;
+    /**
+     * Like {@link LRUCache#get} but doesn't update recency or delete stale
+     * items.
+     *
+     * Returns `undefined` if the item is stale, unless
+     * {@link LRUCache.OptionsBase.allowStale} is set.
+     */
+    peek(k: K, peekOptions?: LRUCache.PeekOptions<K, V, FC>): V | undefined;
+    /**
+     * Make an asynchronous cached fetch using the
+     * {@link LRUCache.OptionsBase.fetchMethod} function.
+     *
+     * If the value is in the cache and not stale, then the returned
+     * Promise resolves to the value.
+     *
+     * If not in the cache, or beyond its TTL staleness, then
+     * `fetchMethod(key, staleValue, { options, signal, context })` is
+     * called, and the value returned will be added to the cache once
+     * resolved.
+     *
+     * If called with `allowStale`, and an asynchronous fetch is
+     * currently in progress to reload a stale value, then the former
+     * stale value will be returned.
+     *
+     * If called with `forceRefresh`, then the cached item will be
+     * re-fetched, even if it is not stale. However, if `allowStale` is also
+     * set, then the old value will still be returned. This is useful
+     * in cases where you want to force a reload of a cached value. If
+     * a background fetch is already in progress, then `forceRefresh`
+     * has no effect.
+     *
+     * If multiple fetches for the same key are issued, then they will all be
+     * coalesced into a single call to fetchMethod.
+     *
+     * Note that this means that handling options such as
+     * {@link LRUCache.OptionsBase.allowStaleOnFetchAbort},
+     * {@link LRUCache.FetchOptions.signal},
+     * and {@link LRUCache.OptionsBase.allowStaleOnFetchRejection} will be
+     * determined by the FIRST fetch() call for a given key.
+     *
+     * This is a known (fixable) shortcoming which will be addresed on when
+     * someone complains about it, as the fix would involve added complexity and
+     * may not be worth the costs for this edge case.
+     *
+     * If {@link LRUCache.OptionsBase.fetchMethod} is not specified, then this is
+     * effectively an alias for `Promise.resolve(cache.get(key))`.
+     *
+     * When the fetch method resolves to a value, if the fetch has not
+     * been aborted due to deletion, eviction, or being overwritten,
+     * then it is added to the cache using the options provided.
+     *
+     * If the key is evicted or deleted before the `fetchMethod`
+     * resolves, then the AbortSignal passed to the `fetchMethod` will
+     * receive an `abort` event, and the promise returned by `fetch()`
+     * will reject with the reason for the abort.
+     *
+     * If a `signal` is passed to the `fetch()` call, then aborting the
+     * signal will abort the fetch and cause the `fetch()` promise to
+     * reject with the reason provided.
+     *
+     * **Setting `context`**
+     *
+     * If an `FC` type is set to a type other than `unknown`, `void`, or
+     * `undefined` in the {@link LRUCache} constructor, then all
+     * calls to `cache.fetch()` _must_ provide a `context` option. If
+     * set to `undefined` or `void`, then calls to fetch _must not_
+     * provide a `context` option.
+     *
+     * The `context` param allows you to provide arbitrary data that
+     * might be relevant in the course of fetching the data. It is only
+     * relevant for the course of a single `fetch()` operation, and
+     * discarded afterwards.
+     *
+     * **Note: `fetch()` calls are inflight-unique**
+     *
+     * If you call `fetch()` multiple times with the same key value,
+     * then every call after the first will resolve on the same
+     * promise<sup>1</sup>,
+     * _even if they have different settings that would otherwise change
+     * the behavior of the fetch_, such as `noDeleteOnFetchRejection`
+     * or `ignoreFetchAbort`.
+     *
+     * In most cases, this is not a problem (in fact, only fetching
+     * something once is what you probably want, if you're caching in
+     * the first place). If you are changing the fetch() options
+     * dramatically between runs, there's a good chance that you might
+     * be trying to fit divergent semantics into a single object, and
+     * would be better off with multiple cache instances.
+     *
+     * **1**: Ie, they're not the "same Promise", but they resolve at
+     * the same time, because they're both waiting on the same
+     * underlying fetchMethod response.
+     */
+    fetch(k: K, fetchOptions: unknown extends FC ? LRUCache.FetchOptions<K, V, FC> : FC extends undefined | void ? LRUCache.FetchOptionsNoContext<K, V> : LRUCache.FetchOptionsWithContext<K, V, FC>): Promise<undefined | V>;
+    fetch(k: unknown extends FC ? K : FC extends undefined | void ? K : never, fetchOptions?: unknown extends FC ? LRUCache.FetchOptions<K, V, FC> : FC extends undefined | void ? LRUCache.FetchOptionsNoContext<K, V> : never): Promise<undefined | V>;
+    /**
+     * In some cases, `cache.fetch()` may resolve to `undefined`, either because
+     * a {@link LRUCache.OptionsBase#fetchMethod} was not provided (turning
+     * `cache.fetch(k)` into just an async wrapper around `cache.get(k)`) or
+     * because `ignoreFetchAbort` was specified (either to the constructor or
+     * in the {@link LRUCache.FetchOptions}). Also, the
+     * {@link LRUCache.OptionsBase.fetchMethod} may return `undefined` or `void`, making
+     * the test even more complicated.
+     *
+     * Because inferring the cases where `undefined` might be returned are so
+     * cumbersome, but testing for `undefined` can also be annoying, this method
+     * can be used, which will reject if `this.fetch()` resolves to undefined.
+     */
+    forceFetch(k: K, fetchOptions: unknown extends FC ? LRUCache.FetchOptions<K, V, FC> : FC extends undefined | void ? LRUCache.FetchOptionsNoContext<K, V> : LRUCache.FetchOptionsWithContext<K, V, FC>): Promise<V>;
+    forceFetch(k: unknown extends FC ? K : FC extends undefined | void ? K : never, fetchOptions?: unknown extends FC ? LRUCache.FetchOptions<K, V, FC> : FC extends undefined | void ? LRUCache.FetchOptionsNoContext<K, V> : never): Promise<V>;
+    /**
+     * If the key is found in the cache, then this is equivalent to
+     * {@link LRUCache#get}. If not, in the cache, then calculate the value using
+     * the {@link LRUCache.OptionsBase.memoMethod}, and add it to the cache.
+     *
+     * If an `FC` type is set to a type other than `unknown`, `void`, or
+     * `undefined` in the LRUCache constructor, then all calls to `cache.memo()`
+     * _must_ provide a `context` option. If set to `undefined` or `void`, then
+     * calls to memo _must not_ provide a `context` option.
+     *
+     * The `context` param allows you to provide arbitrary data that might be
+     * relevant in the course of fetching the data. It is only relevant for the
+     * course of a single `memo()` operation, and discarded afterwards.
+     */
+    memo(k: K, memoOptions: unknown extends FC ? LRUCache.MemoOptions<K, V, FC> : FC extends undefined | void ? LRUCache.MemoOptionsNoContext<K, V> : LRUCache.MemoOptionsWithContext<K, V, FC>): V;
+    memo(k: unknown extends FC ? K : FC extends undefined | void ? K : never, memoOptions?: unknown extends FC ? LRUCache.MemoOptions<K, V, FC> : FC extends undefined | void ? LRUCache.MemoOptionsNoContext<K, V> : never): V;
+    /**
+     * Return a value from the cache. Will update the recency of the cache
+     * entry found.
+     *
+     * If the key is not found, get() will return `undefined`.
+     */
+    get(k: K, getOptions?: LRUCache.GetOptions<K, V, FC>): V | undefined;
+    /**
+     * Deletes a key out of the cache.
+     *
+     * Returns true if the key was deleted, false otherwise.
+     */
+    delete(k: K): boolean;
+    /**
+     * Clear the cache entirely, throwing away all values.
+     */
+    clear(): void;
+}
+//# sourceMappingURL=index.d.ts.map
\ No newline at end of file