[WIP] Major refactor and API change for version 2.0

domLense.js

@@ -12,6 +12,8 @@ class ChildObserver extends MutationObserver {
 	}
 }
 
+const childObserver = new ChildObserver()
+
 export const lense = (methods, extra) => {
 	if (extra) return lense(extra)(methods)
 
@@ -22,12 +24,12 @@ export const lense = (methods, extra) => {
 			} else if (prop === Symbol.iterator) {
 				return function*() {
 					for (const child of target.children) {
-						yield methods.get.call(child)
+						yield methods.get(child)
 					}
 				}
 			} else if (prop.match?.call(prop, /^[0-9]+$/)) {
 				const child = target.children[prop]
-				if (child) return methods.get.call(child)
+				if (child) return methods.get(child)
 				return child
 			} else {
 				return Array.prototype[prop]
@@ -37,7 +39,7 @@ export const lense = (methods, extra) => {
 			if (prop.match?.call(prop, /^[0-9]+$/)) {
 				const child = target.children[prop]
 				if (child) {
-					methods.set.call(child, value)
+					methods.set(child, value)
 					return true
 				} else {
 					for (let i = target.children.length; i < Number(prop); i++) {
@@ -45,8 +47,8 @@ export const lense = (methods, extra) => {
 					}
 					const element = methods.new(value)
 					target.appendChild(element)
-					if (methods.get.call(element) !== value)
-						methods.set.call(element, value)
+					if (methods.get(element) !== value)
+						methods.set(element, value)
 					return true
 				}
 			} else if (prop == "length") {
@@ -69,8 +71,14 @@ export const lense = (methods, extra) => {
 	}
 
 	return element => {
-		if (!(element instanceof Element)) throw(new Error("Creating domLense on non-element"))
-		return new Proxy(element, traps)
+		const proxy = new Proxy(element, traps)
+
+		if (methods.event) childObserver.observe(element)
+		if (typeof methods.event === "function") element.addEventListener("change", event => {
+			methods.event(proxy, element, event.detail)
+		})
+
+		return proxy
 	}
 }
 

skooma.js

@@ -1,30 +1,37 @@
+/*
+A functional HTML generation library.
+
+Example:
+	html.label(
+		html.span("Delete everything", {class: ["warning", "important"]}),
+		html.button("Click", {onClick: e => document.body.innerHTML=""}),
+	)
+or
+	html.ul([1, 2, 3, 4, 5].map(x => html.li(x)), {class: "numbers"})
+*/
+
 // Keep a referee alive until a referrer is collected
 const weakReferences = new WeakMap()
 const untilDeathDoThemPart = (referrer, reference) => {
-	if (!weakReferences.has(referrer)) weakReferences.set(referrer, new Set())
+	if (!weakReferences.has(referrer)) {
+		weakReferences.set(referrer, new Set())
+	}
 	weakReferences.get(referrer).add(reference)
 }
 
-// Like AbortController, but resets after each abort
-class MultiAbortController {
-	#controller = new AbortController()
-	get signal() { return this.#controller.signal }
-	abort() { this.#controller.abort(); this.#controller = new AbortController() }
-}
-
 export const empty = Symbol("Explicit empty argument for Skooma")
 
-const snakeToCSS = key => key.replace(/^[A-Z]/, a => "-"+a).replace(/[A-Z]/g, a => '-'+a.toLowerCase())
+const keyToPropName = key => key.replace(/^[A-Z]/, a => "-"+a).replace(/[A-Z]/g, a => '-'+a.toLowerCase())
 
 const insertStyles = (rule, styles) => {
 	for (const [key, value] of Object.entries(styles))
 		if (typeof value == "undefined")
-			rule.removeProperty(snakeToCSS(key))
+			rule.removeProperty(keyToPropName(key))
 	else
-		rule.setProperty(snakeToCSS(key), value.toString())
+		rule.setProperty(keyToPropName(key), value.toString())
 }
 
-const processAttribute = (attribute) => {
+const parseAttribute = (attribute) => {
 	if (typeof attribute == "string" || typeof attribute == "number")
 		return attribute
 	else if (attribute && "join" in attribute)
@@ -43,54 +50,55 @@ const getCustom = args => args.reduce(
 	,undefined
 )
 
-export const isReactive = object => object
-	&& typeof object == "object"
-	&& !(object instanceof HTMLElement)
-	&& object.subscribe
+const isElement = object => HTMLElement.prototype.isPrototypeOf(object)
+
+const isReactive = object => object
+	&& (object instanceof EventTarget)
+	&& ("subscribe" in object)
 
 const toChild = arg => {
-	if (typeof arg == "string" || typeof arg == "number")
+	if (typeof arg == "string" || typeof arg == "number") {
 		return document.createTextNode(arg)
-	else if (arg instanceof HTMLElement)
+	} else if (isElement(arg)) {
 		return arg
-	else if (isReactive(arg))
+	} else if (isReactive(arg)) {
 		return reactiveChild(arg)
+	}
 }
 
 const reactiveChild = reactive => {
-	let ref
-	const abort = reactive.subscribe(value => {
-		if (ref && !ref.deref()) return abort()
-		const child = toChild(value) ?? document.createComment("Placeholder for reactive content")
-		untilDeathDoThemPart(child, reactive)
-		if (ref) ref.deref().replaceWith(child)
-		ref = new WeakRef(child)
-	})
+	const ref = new WeakRef(toChild(reactive.value))
+	reactive.addEventListener("change", () => {
+		const value = ref.deref()
+		if (value)
+			value.replaceWith(reactiveChild(reactive))
+	}, {once: true})
+	untilDeathDoThemPart(ref.deref(), reactive)
 	return ref.deref()
 }
 
 const specialAttributes = {
 	value: {
-		get() { return this.value },
-		set(value) {
-			this.setAttribute("value", value)
-			this.value = value
+		get: element => element.value,
+		set: (element, value) => {
+			element.setAttribute("value", value)
+			element.value = value
 		},
-		hook(callback) { this.addEventListener("input", callback) }
+		hook: (element, callback) => { element.addEventListener("input", callback) }
 	},
 	style: {
-		set(value) { insertStyles(this.style, value) }
+		set: (element, value) => { insertStyles(element.style, value) }
 	},
 	dataset: {
-		set(value) {
+		set: (element, value) => {
 			for (const [attribute2, value2] of Object.entries(value)) {
-				this.dataset[attribute2] = processAttribute(value2)
+				element.dataset[attribute2] = parseAttribute(value2)
 			}
 		}
 	},
 	shadowRoot: {
-		set(value) {
-			processArgs((this.shadowRoot || this.attachShadow({mode: "open"})), value)
+		set: (element, value) => {
+			parseArgs((element.shadowRoot || element.attachShadow({mode: "open"})), null, value)
 		}
 	}
 }
@@ -100,57 +108,59 @@ const setAttribute = (element, attribute, value, cleanupSignal) => {
 	if (isReactive(value))
 		setReactiveAttribute(element, attribute, value)
 	else if (typeof value === "function")
-		element.addEventListener(attribute, value, {signal: cleanupSignal})
-	else if (special?.set)
-		special.set.call(element, value)
+		element.addEventListener(attribute.replace(/^on[A-Z]/, x => x.charAt(x.length-1).toLowerCase()), value, {signal: cleanupSignal})
+	else if (special) {
+		special.set(element, value)
+	}
 	else if (value === true)
 		{if (!element.hasAttribute(attribute)) element.setAttribute(attribute, '')}
 	else if (value === false)
 		element.removeAttribute(attribute)
 	else {
-		element.setAttribute(attribute, processAttribute(value))
+		element.setAttribute(attribute, parseAttribute(value))
 	}
 }
 
-// (Two-way) binding between an attribute and a state container
-const setReactiveAttribute = (element, attribute, reactive) => {
+const setReactiveAttribute = (element, attribute, reactive, abortController) => {
 	untilDeathDoThemPart(element, reactive)
-	const multiAbort = new MultiAbortController()
-	let old
-	reactive.subscribe(value => {
-		old = value
-		multiAbort.abort()
-		setAttribute(element, attribute, value, multiAbort.signal)
-	})
+
+	if (abortController) abortController.abort()
+	abortController = new AbortController()
+
+	const ref = new WeakRef(element)
+	setAttribute(element, attribute, reactive.value, abortController.signal)
+
+	reactive.addEventListener("change", () => {
+		const element = ref.deref()
+		if (element)
+			setReactiveAttribute(element, attribute, reactive, abortController)
+	}, {once: true})
+
 	const special = specialAttributes[attribute]
-	if (special?.hook && reactive.set) {
-		special.hook.call(element, () => {
-			const value = special.get.call(element, attribute)
-			if (value != old) reactive.set(value)
+	if (special?.hook) {
+		special.hook(element, () => {
+			const value = special.get(element, attribute)
+			if (value != reactive.value) reactive.value = value
 		})
 	}
 }
 
-const processArgs = (element, ...args) => {
+const parseArgs = (element, before, ...args) => {
 	if (element.content) element = element.content
 	for (const arg of args) if (arg !== empty) {
-		if (arg instanceof Array) {
-			processArgs(element, ...arg)
-		} else {
 		const child = toChild(arg)
 		if (child)
-				element.append(child)
+			element.insertBefore(child, before)
 		else if (arg === undefined || arg == null)
 			console.warn(`An argument of type ${typeof arg} has been ignored`, element)
-			else if (typeof arg == "function" && arg.length == 0)
-				processArgs(element, arg())
 		else if (typeof arg == "function")
 			arg(element)
+		else if ("length" in arg)
+			parseArgs(element, before, ...arg)
 		else
 			for (const key in arg)
 				setAttribute(element, key, arg[key])
 	}
-	}
 }
 
 const node = (name, args, options) => {
@@ -163,7 +173,7 @@ const node = (name, args, options) => {
 		element = document.createElementNS(options.xmlns, name, opts)
 	else
 		element = document.createElement(name, opts)
-	processArgs(element, args)
+	parseArgs(element, null, args)
 	return element
 }
 

state.js

@@ -74,9 +74,6 @@ export class SimpleState extends EventTarget {
 		return () => controller.abort()
 	}
 
-	get() { return this.value }
-	set(value) { this.value = value }
-
 	emit(property, from, to, options={}) {
 		const change = {property, from, to, ...options}
 		if (!this.synchronous) {
@@ -124,6 +121,7 @@ export class SimpleState extends EventTarget {
 export class State extends SimpleState {
 	#target
 	#shallow
+	#forwardCache
 
 	static isState(object) { return SimpleState.prototype.isPrototypeOf(object) }
 
@@ -149,52 +147,58 @@ export class State extends SimpleState {
 		})
 	}
 
-	forward(property="value", methods) {
-		return new ForwardState(this, property, methods)
+	set value(value) { this.values.value = value }
+	get value() { return this.values.value }
+
+	forward(property="value") {
+		if (!this.#forwardCache) this.#forwardCache = new Map()
+		const cached = this.#forwardCache.get(property)?.deref()
+		if (cached) {
+			return cached
+		} else {
+			const forwarded = new ForwardState(this, property)
+			const ref = new WeakRef(forwarded)
+			this.#forwardCache.set(property, ref)
+			forwardFinalizationRegistry.register(forwarded, [this.#forwardCache, property])
+			return forwarded
+		}
 	}
 
-	set(prop, value) {
-		if (arguments.length === 1) return this.set("value", prop)
+	set(...args) {
+		if (args.length === 1) return this.set("value", ...args)
+
+		const [prop, value] = args
 		this.#target[prop] = value
 	}
 
-	get(prop="value") {
+	get(...args) {
+		if (args.length === 0) return this.get("value")
+
+		const prop = args[0]
 		return this.#target[prop]
 	}
-
-	set value(value) { this.set(value) }
-	get value() { return this.get() }
 }
 
+const forwardFinalizationRegistry = new FinalizationRegistry(([cache, name]) => {
+	cache.remove(name)
+})
+
 export class ForwardState extends SimpleState {
 	#backend
 	#property
-	#methods
 
-	constructor(backend, property, methods = {}) {
+	constructor(backend, property) {
 		super()
-		this.#methods = methods
 		this.#backend = backend
 		this.#property = property
-
 		const ref = new WeakRef(this)
 		const abortController = new AbortController()
-		abortRegistry.register(this, abortController)
 		backend.addEventListener("change", event => {
 			const state = ref.deref()
 			if (state) {
-				let relevantChanges = event.changes
+				const relevantChanges = event.changes
 					.filter(({property: name}) => name === property)
-				const get = methods.get
-				if (methods.get) {
-					relevantChanges = relevantChanges.map(
-						({from, to}) => ({property: "value", from: get(from), to: get(to)})
-					)
-				} else {
-					relevantChanges = relevantChanges.map(
-						({from, to}) => ({property: "value", from, to})
-					)
-				}
+					.map(({from, to}) => ({property: "value", from, to}))
 				if (relevantChanges.length > 0)
 					state.dispatchEvent(new ChangeEvent(...relevantChanges))
 			} else {
@@ -203,23 +207,8 @@ export class ForwardState extends SimpleState {
 		}, {signal: abortController.signal})
 	}
 
-	get value() {
-		const methods = this.#methods
-		if (methods.get) {
-			return methods.get(this.#backend.values[this.#property])
-		} else {
-			return this.#backend.values[this.#property]
-		}
-	}
-
-	set value(value) {
-		const methods = this.#methods
-		if (methods.set) {
-			this.#backend.values[this.#property] = methods.set(value)
-		} else {
-			this.#backend.values[this.#property] = value
-		}
-	}
+	get value() { return this.#backend.values[this.#property]}
+	set value(value) { this.#backend.values[this.#property] = value }
 }
 
 class StorageChangeEvent extends Event {
@@ -286,12 +275,8 @@ const attributeObserver = new MutationObserver(mutations => {
 	}
 })
 
-export const component = (name, generator, methods) => {
-	if (typeof name === "function") {
-		methods = generator
-		generator = name
-		name = camelToKebab(generator.name)
-	}
+export const component = (generator, name) => {
+	name = name ?? camelToKebab(generator.name)
 	const Element = class extends HTMLElement{
 		constructor() {
 			super()
@@ -304,12 +289,9 @@ export const component = (name, generator, methods) => {
 				}
 			})
 			attributeObserver.observe(this, {attributes: true})
-			this.replaceChildren(generator.call(this, this.state))
+			this.replaceChildren(generator(this))
 		}
 	}
-	if (methods) {
-		Object.defineProperties(Element.prototype, Object.getOwnPropertyDescriptors(methods))
-	}
 	customElements.define(name, Element)
 	return Element;
 }
@@ -340,9 +322,7 @@ class ComposedState extends SimpleState {
 
 	#microtaskQueued
 	scheduleUpdate() {
-		if (this.synchronous) {
-			this.update()
-		} else {
+		if (this.defer) {
 			if (!this.#microtaskQueued) {
 				queueMicrotask(() => {
 					this.#microtaskQueued = false
@@ -350,6 +330,8 @@ class ComposedState extends SimpleState {
 				})
 			}
 			this.#microtaskQueued = true
+		} else {
+			this.update()
 		}
 	}
 
@@ -357,11 +339,11 @@ class ComposedState extends SimpleState {
 		const value = this.#func(...this.#states.map(state => state.value))
 		const change = {property: "value", from: this.value, to: value}
 		this.value = value
-		this.dispatchEvent(new ChangeEvent(change))
+		this.dispatchEvent(new ChangeEvent([change]))
 	}
 }
 
-export const compose = func => (...states) => new ComposedState(func, {}, ...states)
+export const compose = func => (...states) => new ComposedState(func, {defer: true}, ...states)
 
 const eventName = "mutation"
 
@@ -414,9 +396,7 @@ export class DOMState extends SimpleState {
 
 		this.#old = current
 
-		if (this.synchronous) {
-			this.dispatchEvent(new ChangeEvent(["value", current]))
-		} else {
+		if (this.defer) {
 			if (!this.#changedValue) {
 				queueMicrotask(() => {
 					this.#changedValue = false
@@ -424,6 +404,8 @@ export class DOMState extends SimpleState {
 				})
 				this.#changedValue = current
 			}
+		} else {
+			this.dispatchEvent(new ChangeEvent(["value", current]))
 		}
 	}
 }