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import { LRFUExpirer, EXPIRED_ENTRY } from './LRFUExpirer.js'
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export { LRFUExpirer } from './LRFUExpirer.js'
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let defaultExpirer
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export class WeakLRUCache extends Map {
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constructor(options) {
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super()
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this.hits = 0
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this.misses = 0
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if (options && options.cacheSize) {
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options.lruSize = options.cacheSize >> 2
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}
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this.expirer = (options ? options.expirer === false ? defaultNoLRUExpirer : options.expirer : null) || defaultExpirer || (defaultExpirer = new LRFUExpirer(options))
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this.deferRegister = Boolean(options && options.deferRegister)
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let registry = this.registry = new FinalizationRegistry(key => {
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let entry = super.get(key)
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if (entry && entry.deref && entry.deref() === undefined)
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super.delete(key)
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})
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}
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onRemove(entry) {
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let target = entry.deref && entry.deref()
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if (target) {
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// remove strong reference, so only a weak reference, wait until it is finalized to remove
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this.registry.register(target, entry.key)
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entry.value = undefined
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} else if (entry.key) {
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let currentEntry = super.get(entry.key)
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if (currentEntry === entry)
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super.delete(entry.key)
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}
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}
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get(key, mode) {
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let entry = super.get(key)
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let value
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if (entry) {
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this.hits++
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value = entry.value
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if (value === EXPIRED_ENTRY) {
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value = entry.deref && entry.deref()
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if (value === undefined)
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super.delete(key)
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else {
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entry.value = value
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if (mode !== 1)
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this.expirer.used(entry)
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return mode === 2 ? value : entry
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}
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}
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else {
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if (mode !== 1)
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this.expirer.used(entry)
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return mode === 2 ? value : entry
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}
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} else
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this.misses++
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}
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getValue(key) {
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return this.get(key, 2)
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}
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setValue(key, value, expirationPriority) {
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let entry
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if (value && typeof value == 'object') {
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entry = new WeakRef(value)
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entry.value = value
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if (this.deferRegister) {
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entry.key = key
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entry.cache = this
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} else
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this.registry.register(value, key)
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} else if (value !== undefined)
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entry = { value, key, cache: this }
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// else entry is undefined
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this.set(key, entry, expirationPriority)
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return entry
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}
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set(key, entry, expirationPriority) {
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let oldEntry = super.get(key)
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if (oldEntry)
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this.expirer.delete(oldEntry)
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return this.insert(key, entry, expirationPriority)
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}
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insert(key, entry, expirationPriority) {
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if (entry) {
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this.expirer.used(entry, expirationPriority)
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}
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return super.set(key, entry)
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}
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delete(key) {
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let oldEntry = this.get(key)
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if (oldEntry) {
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this.expirer.delete(oldEntry)
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}
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return super.delete(key)
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}
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used(entry, expirationPriority) {
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this.expirer.used(entry, expirationPriority)
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}
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clear() {
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for (let [ key, entry ] of this) {
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this.expirer.delete(entry)
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super.delete(key)
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}
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}
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}
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class NoLRUExpirer {
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used(entry) {
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if (entry.cache)
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entry.cache.onRemove(entry)
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else if (entry.deref) // if we have already registered the entry in the finalization registry, just mark it expired from the beginning
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entry.value = EXPIRED_ENTRY
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}
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delete(entry) {
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// nothing to do here, we don't have a separate cache here
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}
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}
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const defaultNoLRUExpirer = new NoLRUExpirer()
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