92 lines
2.1 KiB
JavaScript
92 lines
2.1 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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*/
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"use strict";
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/** @typedef {import("./ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
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/** @typedef {import("./ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */
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const cache = new WeakMap();
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class ObjectStructure {
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constructor() {
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this.keys = undefined;
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this.children = undefined;
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}
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getKeys(keys) {
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if (this.keys === undefined) this.keys = keys;
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return this.keys;
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}
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key(key) {
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if (this.children === undefined) this.children = new Map();
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const child = this.children.get(key);
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if (child !== undefined) return child;
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const newChild = new ObjectStructure();
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this.children.set(key, newChild);
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return newChild;
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}
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}
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const getCachedKeys = (keys, cacheAssoc) => {
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let root = cache.get(cacheAssoc);
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if (root === undefined) {
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root = new ObjectStructure();
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cache.set(cacheAssoc, root);
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}
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let current = root;
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for (const key of keys) {
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current = current.key(key);
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}
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return current.getKeys(keys);
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};
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class PlainObjectSerializer {
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/**
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* @param {Object} obj plain object
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* @param {ObjectSerializerContext} context context
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*/
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serialize(obj, context) {
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const keys = Object.keys(obj);
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if (keys.length > 128) {
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// Objects with so many keys are unlikely to share structure
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// with other objects
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context.write(keys);
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for (const key of keys) {
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context.write(obj[key]);
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}
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} else if (keys.length > 1) {
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context.write(getCachedKeys(keys, context.write));
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for (const key of keys) {
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context.write(obj[key]);
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}
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} else if (keys.length === 1) {
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const key = keys[0];
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context.write(key);
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context.write(obj[key]);
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} else {
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context.write(null);
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}
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}
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/**
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* @param {ObjectDeserializerContext} context context
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* @returns {Object} plain object
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*/
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deserialize(context) {
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const keys = context.read();
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const obj = {};
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if (Array.isArray(keys)) {
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for (const key of keys) {
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obj[key] = context.read();
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}
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} else if (keys !== null) {
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obj[keys] = context.read();
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}
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return obj;
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}
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}
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module.exports = PlainObjectSerializer;
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