lru-cache.ts•1.63 kB
// Export is needed because TypeScript complains about an error otherwise:
// Error: …/tailwind-merge/src/config-utils.ts(8,17): semantic error TS4058: Return type of exported function has or is using name 'LruCache' from external module "…/tailwind-merge/src/lru-cache" but cannot be named.
export interface LruCache<Key, Value> {
get(key: Key): Value | undefined
set(key: Key, value: Value): void
}
// LRU cache inspired from hashlru (https://github.com/dominictarr/hashlru/blob/v1.0.4/index.js) but object replaced with Map to improve performance
export const createLruCache = <Key, Value>(maxCacheSize: number): LruCache<Key, Value> => {
if (maxCacheSize < 1) {
return {
get: () => undefined,
set: () => {},
}
}
let cacheSize = 0
let cache = new Map<Key, Value>()
let previousCache = new Map<Key, Value>()
const update = (key: Key, value: Value) => {
cache.set(key, value)
cacheSize++
if (cacheSize > maxCacheSize) {
cacheSize = 0
previousCache = cache
cache = new Map()
}
}
return {
get(key) {
let value = cache.get(key)
if (value !== undefined) {
return value
}
if ((value = previousCache.get(key)) !== undefined) {
update(key, value)
return value
}
},
set(key, value) {
if (cache.has(key)) {
cache.set(key, value)
} else {
update(key, value)
}
},
}
}