Files
codeql-action/node_modules/mem/dist/index.js
2022-02-01 18:56:42 +00:00

115 lines
3.0 KiB
JavaScript

import mimicFn from 'mimic-fn';
import mapAgeCleaner from 'map-age-cleaner';
const cacheStore = new WeakMap();
/**
[Memoize](https://en.wikipedia.org/wiki/Memoization) functions - An optimization used to speed up consecutive function calls by caching the result of calls with identical input.
@param fn - Function to be memoized.
@example
```
import mem from 'mem';
let index = 0;
const counter = () => ++index;
const memoized = mem(counter);
memoized('foo');
//=> 1
// Cached as it's the same argument
memoized('foo');
//=> 1
// Not cached anymore as the arguments changed
memoized('bar');
//=> 2
memoized('bar');
//=> 2
```
*/
export default function mem(fn, { cacheKey, cache = new Map(), maxAge, } = {}) {
if (typeof maxAge === 'number') {
mapAgeCleaner(cache);
}
const memoized = function (...arguments_) {
const key = cacheKey ? cacheKey(arguments_) : arguments_[0];
const cacheItem = cache.get(key);
if (cacheItem) {
return cacheItem.data; // eslint-disable-line @typescript-eslint/no-unsafe-return
}
const result = fn.apply(this, arguments_);
cache.set(key, {
data: result,
maxAge: maxAge ? Date.now() + maxAge : Number.POSITIVE_INFINITY,
});
return result; // eslint-disable-line @typescript-eslint/no-unsafe-return
};
mimicFn(memoized, fn, {
ignoreNonConfigurable: true,
});
cacheStore.set(memoized, cache);
return memoized;
}
/**
@returns A [decorator](https://github.com/tc39/proposal-decorators) to memoize class methods or static class methods.
@example
```
import {memDecorator} from 'mem';
class Example {
index = 0
@memDecorator()
counter() {
return ++this.index;
}
}
class ExampleWithOptions {
index = 0
@memDecorator({maxAge: 1000})
counter() {
return ++this.index;
}
}
```
*/
export function memDecorator(options = {}) {
const instanceMap = new WeakMap();
return (target, propertyKey, descriptor) => {
const input = target[propertyKey]; // eslint-disable-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access
if (typeof input !== 'function') {
throw new TypeError('The decorated value must be a function');
}
delete descriptor.value;
delete descriptor.writable;
descriptor.get = function () {
if (!instanceMap.has(this)) {
const value = mem(input, options);
instanceMap.set(this, value);
return value;
}
return instanceMap.get(this);
};
};
}
/**
Clear all cached data of a memoized function.
@param fn - Memoized function.
*/
export function memClear(fn) {
const cache = cacheStore.get(fn);
if (!cache) {
throw new TypeError('Can\'t clear a function that was not memoized!');
}
if (typeof cache.clear !== 'function') {
throw new TypeError('The cache Map can\'t be cleared!');
}
cache.clear();
}