MemoizeObject is a decorator which memoize methods using their value checksum as a cache key instead of reference ID.
A decorator returns memoized method which compares objects and arrays by value.
npm i memoize-object-decorator
import { MemoizeObject } from 'memoize-object-decorator';
interface Person {
name: string;
age: number;
}
class SomeClass {
@MemoizeObject()
factorial(num: number): number {
return (num <= 1) ? 1 : num * this.factorial(--num);
}
@MemoizeObject() // for circular structures @MemoizeObject({circular: true})
getFactorialOfPersonAgeMinusSomething(obj: Person, somethingToSubtract: number): number {
return this.factorial(obj.age) - somethingToSubtract;
}
}
const fact: SomeClass = new SomeClass();
const person: Person = {
name: "John Doe",
age: 10
}
fact.factorial(10); // 3628800
fact.factorial(10); // 3628800, cache hitted 1 time for factorial(10) and returned 3628800
fact.factorial(15); // 1307674368000, cache hitted 1 time for factorial(10) and returned 3628800
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache hitted 1 time for factorial(10) and returned 3628800
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
person.age = 12;
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 479001590, cache hitted 1 time for factorial(12) and returned 479001600
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 479001590, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
fact.getFactorialOfPersonAgeMinusSomething(person, 20) // 479001580, cache hitted 1 time for factorial(12) and returned 479001600
import { Memoize } from 'lodash-decorators';
interface Person {
name: string;
age: number;
}
class SomeClass {
@Memoize()
factorial(num: number): number {
return (num <= 1) ? 1 : num * this.factorial(--num);
}
@Memoize()
getFactorialOfPersonAgeMinusSomething(obj: Person, somethingToSubtract: number): number {
return this.factorial(obj.age) - somethingToSubtract;
}
}
const fact: SomeClass = new SomeClass();
const person: Person = {
name: "John Doe",
age: 10
}
fact.factorial(10); // 3628800
fact.factorial(10); // 3628800, cache hitted 1 time for factorial(10) and returned 3628800
fact.factorial(15); // 1307674368000, cache hitted 1 time for factorial(10) and returned 3628800
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache hitted 1 time for factorial(10) and returned 3628800
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
person.age = 12;
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
fact.getFactorialOfPersonAgeMinusSomething(person, 10) // 3628790, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
fact.getFactorialOfPersonAgeMinusSomething(person, 20) // 3628790, cache for fact.getFactorialOfPersonAgeMinusSomething hitted 1 time
The decorator takes all of the arguments of memoized method and calculates their unique SHA1 hash which is used as a Map key for cache.
In this way we can track objects and arrays by their values instead of the reference.
SHA1 hash calculation process is slow in general, so it is not recommended to use this decorator for methods which takes huge objects or/and arrays as an arguments.