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node_modules/next/dist/client/components/segment-cache/cache-map.d.ts

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+import type { VaryPath } from './vary-path';
+/**
+ * A specialized data type for storing multi-key cache entries.
+ *
+ * The basic structure is a map whose keys are tuples, called the keypath.
+ * When querying the cache, keypaths are compared per-element.
+ *
+ * Example:
+ *   set(map, ['https://localhost', 'foo/bar/baz'], 'yay');
+ *   get(map, ['https://localhost', 'foo/bar/baz']) -> 'yay'
+ *
+ * NOTE: Array syntax is used in these examples for illustration purposes, but
+ * in reality the paths are lists.
+ *
+ * The parts of the keypath represent the different inputs that contribute
+ * to the entry value. To illustrate, if you were to use this data type to store
+ * HTTP responses, the keypath would include the URL and everything listed by
+ * the Vary header.
+ *
+ * See vary-path.ts for more details.
+ *
+ * The order of elements in a keypath must be consistent between lookups to
+ * be considered the same, but besides that, the order of the keys is not
+ * semantically meaningful.
+ *
+ * Keypaths may include a special kind of key called Fallback. When an entry is
+ * stored with Fallback as part of its keypath, it means that the entry does not
+ * vary by that key. When querying the cache, if an exact match is not found for
+ * a keypath, the cache will check for a Fallback match instead. Each element of
+ * the keypath may have a Fallback, so retrieval is an O(n ^ 2) operation, but
+ * it's expected that keypaths are relatively short.
+ *
+ * Example:
+ *   set(cacheMap, ['store', 'product', 1], PRODUCT_PAGE_1);
+ *   set(cacheMap, ['store', 'product', Fallback], GENERIC_PRODUCT_PAGE);
+ *
+ *   // Exact match
+ *   get(cacheMap, ['store', 'product', 1]) -> PRODUCT_PAGE_1
+ *
+ *   // Fallback match
+ *   get(cacheMap, ['store', 'product', 2]) -> GENERIC_PRODUCT_PAGE
+ *
+ * Because we have the Fallback mechanism, we can impose a constraint that
+ * regular JS maps do not have: a value cannot be stored at multiple keypaths
+ * simultaneously. These cases should be expressed with Fallback keys instead.
+ *
+ * Additionally, because values only exist at a single keypath at a time, we
+ * can optimize successive lookups by caching the internal map entry on the
+ * value itself, using the `ref` field. This is especially useful because it
+ * lets us skip the O(n ^ 2) lookup that occurs when Fallback entries
+ * are present.
+ *
+
+ * How to decide if stuff belongs in here, or in cache.ts?
+ * -------------------------------------------------------
+ *
+ * Anything to do with retrival, lifetimes, or eviction needs to go in this
+ * module because it affects the fallback algorithm. For example, when
+ * performing a lookup, if an entry is stale, it needs to be treated as
+ * semantically equivalent to if the entry was not present at all.
+ *
+ * If there's logic that's not related to the fallback algorithm, though, we
+ * should prefer to put it in cache.ts.
+ */
+export interface MapValue {
+    ref: UnknownMapEntry | null;
+    size: number;
+    staleAt: number;
+    version: number;
+}
+/**
+ * Represents a node in the cache map and LRU.
+ * MapEntry<V> structurally satisfies this interface for any V extends MapValue.
+ *
+ * The LRU can contain entries of different value types
+ * (e.g., both RouteCacheEntry and SegmentCacheEntry). This interface captures
+ * the common structure needed for cache map and LRU operations without
+ * requiring knowledge of the specific value type.
+ */
+export interface MapEntry<V extends MapValue> {
+    parent: MapEntry<V> | null;
+    key: unknown;
+    map: Map<unknown, MapEntry<V>> | null;
+    value: V | null;
+    prev: MapEntry<V> | null;
+    next: MapEntry<V> | null;
+    size: number;
+}
+/**
+ * A looser type for MapEntry
+ * This allows the LRU to work with entries of different
+ * value types while still providing type safety.
+ *
+ * The `map` field lets Map<unknown, MapEntry<V>> be assignable to this
+ * type since we're only reading from the map, not inserting into it.
+ */
+export type UnknownMapEntry = {
+    parent: UnknownMapEntry | null;
+    key: unknown;
+    map: Pick<Map<unknown, UnknownMapEntry>, 'get' | 'delete' | 'size'> | null;
+    value: MapValue | null;
+    prev: UnknownMapEntry | null;
+    next: UnknownMapEntry | null;
+    size: number;
+};
+export type CacheMap<V extends MapValue> = MapEntry<V>;
+export type FallbackType = {
+    __brand: 'Fallback';
+};
+export declare const Fallback: FallbackType;
+export declare function createCacheMap<V extends MapValue>(): CacheMap<V>;
+export declare function getFromCacheMap<V extends MapValue>(now: number, currentCacheVersion: number, rootEntry: CacheMap<V>, keys: VaryPath, isRevalidation: boolean): V | null;
+export declare function isValueExpired(now: number, currentCacheVersion: number, value: MapValue): boolean;
+export declare function setInCacheMap<V extends MapValue>(cacheMap: CacheMap<V>, keys: VaryPath, value: V, isRevalidation: boolean): void;
+export declare function deleteFromCacheMap(value: MapValue): void;
+export declare function deleteMapEntry(entry: UnknownMapEntry): void;
+export declare function setSizeInCacheMap<V extends MapValue>(value: V, size: number): void;