@angular/cli/src/utilities/memoize.js

CLI tool for Angular

"use strict";
/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.memoize = memoize;
/**
 * A decorator that memoizes methods and getters.
 *
 * **Note**: Be cautious where and how to use this decorator as the size of the cache will grow unbounded.
 *
 * @see https://en.wikipedia.org/wiki/Memoization
 */
function memoize(target, context) {
    if (context.kind !== 'method' && context.kind !== 'getter') {
        throw new Error('Memoize decorator can only be used on methods or get accessors.');
    }
    const cache = new Map();
    return function (...args) {
        for (const arg of args) {
            if (!isJSONSerializable(arg)) {
                throw new Error(`Argument ${isNonPrimitive(arg) ? arg.toString() : arg} is JSON serializable.`);
            }
        }
        const key = JSON.stringify(args);
        if (cache.has(key)) {
            return cache.get(key);
        }
        const result = target.apply(this, args);
        cache.set(key, result);
        return result;
    };
}
/** Method to check if value is a non primitive. */
function isNonPrimitive(value) {
    return ((value !== null && typeof value === 'object') ||
        typeof value === 'function' ||
        typeof value === 'symbol');
}
/** Method to check if the values are JSON serializable */
function isJSONSerializable(value) {
    if (!isNonPrimitive(value)) {
        // Can be seralized since it's a primitive.
        return true;
    }
    let nestedValues;
    if (Array.isArray(value)) {
        // It's an array, check each item.
        nestedValues = value;
    }
    else if (Object.prototype.toString.call(value) === '[object Object]') {
        // It's a plain object, check each value.
        nestedValues = Object.values(value);
    }
    if (!nestedValues || nestedValues.some((v) => !isJSONSerializable(v))) {
        return false;
    }
    return true;
}