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index.ts
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index.ts
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export interface Resolver {
(...args: any[]): any;
}
export interface MapLike<K = unknown, V = unknown> {
set(key: K, v: V): MapLike<K, V>;
get(key: K): V;
has(key: K): boolean;
}
export interface Config {
resolver?: Resolver;
cache?: MapLike;
}
function memoize(func: Function, resolver: Resolver, cache: MapLike) {
const memoized = function() {
const args = arguments;
const key = resolver.apply(this, args);
const cache = memoized.cache;
if (cache.has(key)) {
return cache.get(key);
}
const result = func.apply(this, args);
memoized.cache = cache.set(key, result) ?? cache;
return result;
};
memoized.cache = cache;
return memoized;
}
const defaultResolver: Resolver = (...args: any[]) => args[0];
export default (config: Config = {}) => (
_: any,
__: string,
descriptor: PropertyDescriptor
): PropertyDescriptor => {
if (typeof descriptor.value !== 'function') {
throw new Error('Memoization can be applied only to methods');
}
const resolver = config.resolver ?? defaultResolver;
const cache = config.cache ?? new Map();
descriptor.value = memoize(descriptor.value, resolver, cache);
return descriptor;
};