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39 lines
976 B
JavaScript
39 lines
976 B
JavaScript
/**
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* @template V
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* @param {number} [maxSize]
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*/
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export function createMapCache(maxSize = 100) {
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/** @type {Map<string, V>} */
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const map = new Map();
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/** @param {string} key @param {V} value */
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const set = (key, value) => {
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if (map.size >= maxSize && !map.has(key)) {
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const first = map.keys().next().value;
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if (first !== undefined) map.delete(first);
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}
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map.set(key, value);
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};
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return {
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/** @param {string} key @returns {V | undefined} */
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get: (key) => map.get(key),
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/** @param {string} key @returns {boolean} */
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has: (key) => map.has(key),
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set,
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/** @param {string} key @param {() => Promise<V>} fetcher @returns {Promise<V>} */
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async fetch(key, fetcher) {
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const hit = map.get(key);
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if (hit !== undefined) return hit;
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const value = await fetcher();
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set(key, value);
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return value;
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},
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};
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}
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/**
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* @template V
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* @typedef {ReturnType<typeof createMapCache<V>>} MapCache
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*/
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