source: frontend/node_modules/webpack/lib/serialization/PlainObjectSerializer.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

/** @typedef {import("./ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("./ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */

/** @typedef {EXPECTED_FUNCTION} CacheAssoc */

/**
 * Defines the shared type used by this module.
 * @template T
 * @typedef {WeakMap<CacheAssoc, ObjectStructure<T>>}
 */
const cache = new WeakMap();

/**
 * Represents ObjectStructure.
 * @template T
 */
class ObjectStructure {
        constructor() {
                /** @type {undefined | keyof T[]} */
                this.keys = undefined;
                /** @type {undefined | Map<keyof T, ObjectStructure<T>>} */
                this.children = undefined;
        }

        /**
         * Returns keys.
         * @param {keyof T[]} keys keys
         * @returns {keyof T[]} keys
         */
        getKeys(keys) {
                if (this.keys === undefined) this.keys = keys;
                return this.keys;
        }

        /**
         * Returns object structure.
         * @param {keyof T} key key
         * @returns {ObjectStructure<T>} object structure
         */
        key(key) {
                if (this.children === undefined) this.children = new Map();
                const child = this.children.get(key);
                if (child !== undefined) return child;
                const newChild = new ObjectStructure();
                this.children.set(key, newChild);
                return newChild;
        }
}

/**
 * Returns keys.
 * @template T
 * @param {(keyof T)[]} keys keys
 * @param {CacheAssoc} cacheAssoc cache assoc fn
 * @returns {(keyof T)[]} keys
 */
const getCachedKeys = (keys, cacheAssoc) => {
        let root = cache.get(cacheAssoc);
        if (root === undefined) {
                root = new ObjectStructure();
                cache.set(cacheAssoc, root);
        }
        let current = root;
        for (const key of keys) {
                current = current.key(key);
        }
        return current.getKeys(keys);
};

class PlainObjectSerializer {
        /**
         * Serializes this instance into the provided serializer context.
         * @template {object} T
         * @param {T} obj plain object
         * @param {ObjectSerializerContext} context context
         */
        serialize(obj, context) {
                const keys = /** @type {(keyof T)[]} */ (Object.keys(obj));
                if (keys.length > 128) {
                        // Objects with so many keys are unlikely to share structure
                        // with other objects
                        context.write(keys);
                        for (const key of keys) {
                                context.write(obj[key]);
                        }
                } else if (keys.length > 1) {
                        context.write(getCachedKeys(keys, context.write));
                        for (const key of keys) {
                                context.write(obj[key]);
                        }
                } else if (keys.length === 1) {
                        const key = keys[0];
                        context.write(key);
                        context.write(obj[key]);
                } else {
                        context.write(null);
                }
        }

        /**
         * Restores this instance from the provided deserializer context.
         * @template {object} T
         * @param {ObjectDeserializerContext} context context
         * @returns {T} plain object
         */
        deserialize(context) {
                const keys = context.read();
                const obj = /** @type {T} */ ({});
                if (Array.isArray(keys)) {
                        for (const key of keys) {
                                obj[/** @type {keyof T} */ (key)] = context.read();
                        }
                } else if (keys !== null) {
                        obj[/** @type {keyof T} */ (keys)] = context.read();
                }
                return obj;
        }
}

module.exports = PlainObjectSerializer;