decorator.ts

/**
 * @fileoverview `Memoize` — class-method decorator that wraps the
 * decorated method via `memoize`. Preserves `this`-context by
 * installing the wrapper on the property descriptor. Defaults the
 * cache `name` option to the property key for nicer debug output.
 */

import { memoize } from './memoize'

import type { MemoizeOptions } from './types'

/**
 * Create a memoized version of a method.
 * Preserves 'this' context for class methods.
 *
 * @param target - Object containing the method
 * @param propertyKey - Method name
 * @param descriptor - Property descriptor
 * @returns Modified descriptor with memoized method
 *
 * @example
 * import { Memoize } from '@socketsecurity/lib/memo/decorator'
 *
 * class Calculator {
 *   @Memoize()
 *   fibonacci(n: number): number {
 *     if (n <= 1) return n
 *     return this.fibonacci(n - 1) + this.fibonacci(n - 2)
 *   }
 * }
 */
export function Memoize(options: MemoizeOptions<unknown[]> = {}) {
  return (
    _target: unknown,
    propertyKey: string,
    descriptor: PropertyDescriptor,
  ): PropertyDescriptor => {
    const originalMethod = descriptor.value as (...args: unknown[]) => unknown

    descriptor.value = memoize(originalMethod, {
      ...options,
      name: options.name || propertyKey,
    })

    return descriptor
  }
}