kopia lustrzana https://github.com/Tldraw/Tldraw
21 wiersze
686 B
TypeScript
21 wiersze
686 B
TypeScript
/** A micro cache used when storing records in memory (using a WeakMap). */
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export class Cache<T extends object, K> {
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/** The map of items to their cached values. */
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items = new WeakMap<T, K>()
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/**
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* Get the cached value for a given record. If the record is not present in the map, the callback
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* will be used to create the value (with the result being stored in the cache for next time).
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*
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* @param item - The item to get.
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* @param cb - The callback to use to create the value when a cached value is not found.
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*/
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get<P extends T>(item: P, cb: (item: P) => K) {
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if (!this.items.has(item)) {
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this.items.set(item, cb(item))
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}
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return this.items.get(item)!
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}
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}
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