Reduce Observable to single class
This commit is contained in:
parent
dde2aa683e
commit
ea108bdbfb
1 changed files with 159 additions and 255 deletions
412
observable.js
412
observable.js
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@ -3,15 +3,10 @@ const abortRegistry = new FinalizationRegistry(controller => controller.abort())
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/** @param {String} string */
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const camelToKebab = string => string.replace(/([a-z])([A-Z])/g, (_, a, b) => `${a}-${b}`).toLowerCase()
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/** @param {String} string */
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const kebabToCamel = string => string.replace(/([a-z])-([a-z])/g, (_, a, b) => a+b.toUpperCase())
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const identity = object=>object
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const target = Symbol("Proxy Target")
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/* Custom Event Classes */
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/**
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* @typedef {Object} Change
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* @property {string} property
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@ -20,6 +15,8 @@ const target = Symbol("Proxy Target")
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* @property {boolean} mutation - The change happened inside the value without a new assignment
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*/
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/* Custom Event Classes */
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/** Event fired for every change before the internal state has been updated that can be canceled. */
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export class ChangeEvent extends Event {
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/** @param {Change} change */
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@ -30,369 +27,276 @@ export class ChangeEvent extends Event {
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}
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/** Event fired for one or more changed values after the internal state has been updated. */
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export class ChangedEvent extends Event {
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/** @type {any} */
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#final
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/** @type {any} */
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#values
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export class ChangesEvent extends Event {
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/** @param {Change[]} changes */
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constructor(...changes) {
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super('changed')
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super('changes')
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this.changes = changes
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}
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get values() {
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if (!this.#values) {
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const values = new Map()
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for (const {property, from, to} of this.changes) {
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let list = values.get(property)
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if (!list) {
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list = [from]
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values.set(property, list)
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}
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list.push(to)
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}
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this.#values = values
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}
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return this.#values
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}
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/** @return {Map<String,Change[]>} */
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get changesByProperty() {
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const properties = new Map()
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get final() {
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if (!this.#final) {
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this.#final = new Map()
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for (const [property, list] of this.values) {
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if (list[0] !== list[list.length-1]) {
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this.#final.set(property, list[list.length-1])
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}
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for (const {property, ...change} of this.changes) {
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if (!properties.has(property)) {
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properties.set(property, [])
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}
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properties.get(property).push(change)
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}
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return this.#final
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Object.defineProperty(this, "changesByProperty", {value: properties})
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return properties
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}
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}
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/**
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* @typedef {Object} Options
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* @field {boolean} children
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* @field {(a: any, b: any) => boolean} same
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*/
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export class Observable extends EventTarget {
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#synchronous
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/** @type Change[]> */
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#queue
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#queue = []
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#abortController = new AbortController
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#ref = new WeakRef(this)
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get ref() { return this.#ref }
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constructor({synchronous=false}={}) {
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super()
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Object.defineProperty(this, "observable", {value: true, configurable: false, writable: false})
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if (this.constructor === Observable) {
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throw new TypeError("Cannot instantiate abstract class")
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}
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this.#synchronous = !!synchronous
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abortRegistry.register(this, this.#abortController)
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this.proxy = new Proxy(this.constructor.prototype.proxy, {
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get: (target, prop) => target.call(this, prop)
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})
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}
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/** @param {Change[]} changes */
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emit(...changes) {
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this.dispatchEvent(new ChangedEvent(...changes))
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}
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/**
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* @param {string} prop
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*/
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proxy(prop, {get=undefined, set=undefined, ...options}={}) {
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const proxy = new ProxiedObservableValue(this, prop, options)
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if (get) proxy.get = get
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if (set) proxy.set = set
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return proxy
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}
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/**
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* @param {string} prop
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* @param {function(any):void} callback
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*/
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subscribe(prop, callback) {
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const controller = new AbortController()
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// @ts-ignore
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this.addEventListener("change", ({final}) => {
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if (final.has(prop)) return callback(final.get(prop))
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}, {signal: controller.signal})
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callback(this[prop])
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return () => controller.abort()
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}
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/** Queues up a change event
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* @param {string} property - Name of the changed property
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* @param {any} from
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* @param {any} to
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* @param {boolean} mutation - whether a change was an assignment or a mutation (nested change)
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*/
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enqueue(property, from, to, mutation=false) {
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const change = {property, from, to, mutation}
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if (!this.dispatchEvent(new ChangeEvent(change))) return false
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if (!this.synchronous) {
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if (!this.#queue) {
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this.#queue = []
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queueMicrotask(() => {
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this.emit(...this.#queue)
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this.#queue = undefined
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})
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}
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this.#queue.push(change)
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} else {
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this.emit(change)
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}
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return true
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}
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get signal() { return this.#abortController.signal }
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get synchronous() { return this.#synchronous }
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get changesQueued() { return Boolean(this.#queue) }
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}
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export class ObservableObject extends Observable {
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/**
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* @param {Object} target
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* @param {Object} options
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* @param {Options} options
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*/
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constructor(target={}, {shallow=true, ...options}={}) {
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super(options)
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constructor(target={}, {children=false, same}={}) {
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super()
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Object.defineProperty(this, "observable", {value: true, configurable: false, writable: false})
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abortRegistry.register(this, this.#abortController)
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Object.defineProperty(this, "target", target)
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this.values = new Proxy(target, {
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/**
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* @param {Object} target
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* @param {String} prop
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* @param {String} property
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* @param {any} value
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*/
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set: (target, prop, value) => {
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const old = target[prop]
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if (old === value) {
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return true
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} else {
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if (this.enqueue(prop, old, value)) {
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if (!shallow) {
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if (old instanceof Observable) this.disown(prop, old)
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if (value instanceof Observable) this.adopt(prop, value)
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set: (target, property, value) => {
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const old = target[property]
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if (same ? !same(old, value) : (old !== value)) {
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if (this.enqueue({property, from: old, to: value, mutation: false})) {
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if (children) {
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if (old instanceof Observable) this.disown(property, old)
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if (value instanceof Observable) this.adopt(property, value)
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}
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target[prop] = value
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return true
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} else {
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return false
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target[property] = value
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}
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}
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return true
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},
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/**
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* @param {Object} target
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* @param {String} prop
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* @param {String} property
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*/
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get: (target, prop) => target[prop],
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get: (target, property) => target[property],
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})
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}
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/**
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* @param {string} prop
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* @param {Object} options
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#microTaskQueued = false
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/** Queues up a change event
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* @param {Change} change
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*/
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proxy(prop, {get=undefined, set=undefined, ...options}={}) {
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const proxy = new ProxiedObservableValue(this, prop, {values: this.values, ...options})
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if (get) proxy.get = get
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if (set) proxy.set = set
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return proxy
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enqueue(change) {
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if (!this.dispatchEvent(new ChangeEvent(change))) return false
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if (!this.#microTaskQueued) {
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this.#microTaskQueued = true
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queueMicrotask(() => {
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this.#microTaskQueued = false
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this.emitQueue()
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})
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}
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this.#queue.push(change)
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return true
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}
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/** @type Map<Observable, Map<String, Function>> */
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/** @param {Change[]} changes */
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emit(changes) {
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this.dispatchEvent(new ChangesEvent(...changes))
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if (this.#signals.size || this.#promises.size) {
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for (const change of changes) {
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const {property} = change
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if (this.#signals.has(property)) {
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throw("Fallback signals aren't implemented yet!")
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}
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if (this.#promises.has(property)) {
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const {callback} = this.#promises.get(property)
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this.#promises.delete(property)
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callback(change)
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}
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}
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}
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}
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/** Synchronously emits an event with all queued changes. Does nothing when there are no events. */
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emitQueue() {
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const queue = this.#queue
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if (queue.length) {
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this.emit(queue)
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}
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queue.length = 0
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}
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get collectedSignal() { return this.#abortController.signal }
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/** @type {Number} */
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get changesQueued() { return this.#queue.length }
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/** @type Map<Observable, Map<String, EventListener>> */
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#nested = new Map()
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/** Adopts an observable to be notified of its changes
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* @param {string} prop
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* @param {string} property
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* @param {Observable} observable
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*/
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adopt(prop, observable) {
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adopt(property, observable) {
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let handlers = this.#nested.get(observable)
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if (!handlers) {
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// Actual adoption
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handlers = new Map()
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this.#nested.set(observable, handlers)
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}
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const ref = this.ref
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const handler = () => ref.deref()?.emit(prop, observable, observable, {observable: true})
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handlers.set(prop, handler)
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observable.addEventListener("changed", handler, {signal: this.signal})
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const ref = this.ref
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const handler = () => ref.deref()?.enqueue({property, from: observable, to: observable, mutation: true})
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handlers.set(property, handler)
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observable.addEventListener("changed", handler, {signal: this.collectedSignal})
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}
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/** Undoes the adoption of a nested observable, cancelling the associated event hook
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* @param {string} prop
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* @param {string} property
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* @param {Observable} observable
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*/
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disown(prop, observable) {
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disown(property, observable) {
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const handlers = this.#nested.get(observable)
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const handler = handlers.get(prop)
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const handler = handlers.get(property)
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observable.removeEventListener("changed", handler)
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handlers.delete(prop)
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handlers.delete(property)
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if (handlers.size == 0) {
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this.#nested.delete(observable)
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}
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}
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}
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export class ObservableValue extends Observable {
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#value
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/** @type {Map<String,{promise: Promise, callback: (value: any)=>void}>} */
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#promises = new Map()
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// Can't be weak refs because promises are often given callbacks and then forgotten
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/**
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* @param {any} value
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* @param {Object} options
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*/
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constructor(value, options) {
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super(options)
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this.#value = value
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/** @param {String} property */
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when(property) {
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const cached = this.#promises.get(property)
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if (cached) return cached[0]
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let callback = undefined
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const promise = new Promise(accept => { callback = accept })
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this.#promises.set(property, {promise, callback})
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return promise
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}
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get value() { return this.#value }
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set value(value) {
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if (this.enqueue("value", this.#value, value)) {
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this.#value = value
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}
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}
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/** @type {Map<String,FallbackSignal>} */
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#signals = new Map()
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/**
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* @param {(value: any) => any} func
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*/
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transform(func) {
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return new Composition(func, {}, this)
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}
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/** @param {String} property */
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signal(property) {
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const cached = this.#signals.get(property)
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if (cached) return cached
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proxy(methods) {
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const signal = new FallbackSignal(this, property)
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this.#signals.set(property, signal)
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return signal
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}
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}
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class ProxiedObservableValue extends ObservableValue {
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#values
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#prop
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class FallbackSignal {
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/**
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* @param {Observable} backend
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* @param {string} prop
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* @param {Observable} _observable
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* @param {String} _property
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*/
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constructor(backend, prop, {values=backend, ...options}={}) {
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super(options)
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this.#values = values
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this.#prop = prop
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const ref = this.ref
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backend.addEventListener("change", event => {
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const {property, from, to, ...rest} = event.change
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if (property == this.#prop) {
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ref.deref()?.enqueue({
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property,
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from: this.get(from),
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to: this.get(to),
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...rest
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})
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}
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}, { signal: this.signal })
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constructor(_observable, _property) {
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throw("Fallback signals aren't implemented yet!")
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}
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get = identity
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set = identity
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get value() { return this.get(this.#values[this.#prop]) }
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set value(value) { this.#values[this.#prop] = this.set(value) }
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}
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/** @type {WeakMap<Element, Observable>} */
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const componentInstanceStates = new WeakMap()
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const attributeObserver = new MutationObserver(mutations => {
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for (const {type, target, attributeName: name} of mutations) {
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if (type == "attributes" && target instanceof HTMLElement) {
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const next = target.getAttribute(name)
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const camelName = kebabToCamel(name)
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if (String(target.state.values[camelName]) !== next)
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target.state.values[camelName] = next
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const state = componentInstanceStates.get(target)
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if (String(state.values[camelName]) !== next)
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state.values[camelName] = next
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}
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}
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})
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/**
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* @param {String} name
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* @param {(this: HTMLElement, state: Observable) => Node} generator
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* @param {Object<String,Function>} methods
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*/
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export const component = (name, generator, methods) => {
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if (typeof name === "function") {
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methods = generator
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generator = name
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name = camelToKebab(generator.name)
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}
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const jsName = kebabToCamel(name)
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component[jsName] = class extends HTMLElement{
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/** @type {ObservableObject} */
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/** @type {Observable} */
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state
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constructor() {
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super()
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const target = Object.fromEntries([...this.attributes].map(attribute => [kebabToCamel(attribute.name), attribute.value]))
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this.state = new ObservableObject(target)
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this.state = new Observable(target)
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this.state.addEventListener("changed", event => {
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if (event instanceof ChangedEvent)
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if (event instanceof ChangesEvent)
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for (const {property, to: value} of event.changes) {
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const kebabName = camelToKebab(property)
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if (this.getAttribute(kebabName) !== String(value))
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this.setAttribute(kebabName, value)
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}
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})
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attributeObserver.observe(this, {attributes: true})
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const content = generator.call(this, this.state)
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if (content) this.replaceChildren(content)
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}
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}
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const element = component[jsName]
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if (methods) {
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Object.defineProperties(element.prototype, Object.getOwnPropertyDescriptors(methods))
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}
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customElements.define(name, element)
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return element;
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}
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class Composition extends ObservableValue {
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#func
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#states
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/**
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* @param {(...values: any[]) => any} func
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* @param {Object} options
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* @param {Observable[]} states
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*/
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constructor(func, options, ...obesrvables) {
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super(options)
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this.#func = func
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this.#states = obesrvables
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const abortController = new AbortController()
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abortRegistry.register(this, abortController)
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||||
const ref = new WeakRef(this)
|
||||
|
||||
obesrvables.forEach(state => {
|
||||
state.addEventListener("changed", () => {
|
||||
ref.deref()?.update()
|
||||
}, {signal: abortController.signal})
|
||||
})
|
||||
|
||||
this.update()
|
||||
}
|
||||
|
||||
update() {
|
||||
const value = this.#func(...this.#states.map(state => state.value))
|
||||
this.value = value
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* @param {Function} func
|
||||
*/
|
||||
export const compose = func =>
|
||||
/**
|
||||
* @param {Observable[]} observables
|
||||
*/
|
||||
(...observables) =>
|
||||
new Composition(func, {}, ...observables)
|
||||
|
|
|
|||
Loading…
Reference in a new issue