[WIP] Major refactor and API change for version 2.0

This makes the State class fully compatible with svelte stores

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "skooma",
-	"version": "1.6.1",
+	"version": "1.7.0",
 	"author": "darkwiiplayer",
 	"license": "Unlicense",
 	"main": "skooma.js",

skooma.js

@@ -53,9 +53,8 @@ const getCustom = args => args.reduce(
 const isElement = object => HTMLElement.prototype.isPrototypeOf(object)
 
 const isReactive = object => object
-	&& (typeof object == "object")
-	&& ("addEventListener" in object)
-	&& ("value" in object)
+	&& (object instanceof EventTarget)
+	&& ("subscribe" in object)
 
 const toChild = arg => {
 	if (typeof arg == "string" || typeof arg == "number") {

state.js

@@ -5,82 +5,56 @@ const kebabToCamel = string => string.replace(/([a-z])-([a-z])/g, (_, a, b) => a
 
 export class ChangeEvent extends Event {
 	#final
+	#values
 	constructor(...changes) {
 		super('change')
 		this.changes = changes
 	}
+
+	get values() {
+		if (!this.#values) {
+			const values = new Map()
+			for (const {property, from, to} of this.changes) {
+				let list = values.get(property)
+				if (!list) {
+					list = [from]
+					values.set(property, list)
+				}
+				list.push(to)
+			}
+			this.#values = values
+		}
+		return this.#values
+	}
+
 	get final() {
 		if (!this.#final) {
-			this.#final = new Map(this.changes)
+			this.#final = new Map()
+			for (const [property, list] of this.values) {
+				if (list[0] !== list[list.length-1]) {
+					this.#final.set(property, list[list.length-1])
+				}
+			}
 		}
 		return this.#final
 	}
 }
 
-export class SimpleState extends EventTarget {}
-
-export class MapStorage extends Storage {
-	#map = new Map()
-	key(index) {
-		return [...this.#map.keys()][index]
-	}
-	getItem(keyName) {
-		if (this.#map.has(keyName))
-			return this.#map.get(keyName)
-		else
-			return null
-	}
-	setItem(keyName, keyValue) {
-		this.#map.set(keyName, String(keyValue))
-	}
-	removeItem(keyName) {
-		this.#map.delete(keyName)
-	}
-	clear() {
-		this.#map.clear()
-	}
-}
-
-export class State extends SimpleState {
-	#target
-	#options
+export class SimpleState extends EventTarget {
+	#synchronous
 	#queue
-	#forwardCache
-	#abortController
 	#nested = new Map()
 	#weakRef = new WeakRef(this)
+	#abortController = new AbortController
 
-	static isState(object) { return SimpleState.prototype.isPrototypeOf(object) }
-
-	constructor(target={}, options={}) {
+	constructor({synchronous, methods}={}) {
 		super()
-
-		this.#abortController = new AbortController
+		this.#synchronous = !!synchronous
 		abortRegistry.register(this, this.#abortController)
 
-		this.#options = options
-		this.#target = target
-		this.proxy = new Proxy(target, {
-			set: (_target, prop, value) => {
-				const old = this.get(prop)
-				if (old !== value) {
-					this.emit(prop, value)
-					if (this.#options.deep !== false) {
-						if (State.isState(old)) this.disown(prop, old)
-						if (State.isState(value)) this.adopt(prop, value)
-					}
-					this.set(prop, value)
-				}
-				return true
-			},
-			get: (_target, prop) => this.get(prop),
-		})
-
-		this.addEventListener
-
 		// Try running a "<name>Changed" method for every changed property
 		// Can be disabled to maybe squeeze out some performance
-		if (options.methods ?? true) {
+		if (methods ?? true) {
 			this.addEventListener("change", ({final}) => {
 				final.forEach((value, prop) => {
 					if (`${prop}Changed` in this) this[`${prop}Changed`](value)
@@ -89,9 +63,33 @@ export class State extends SimpleState {
 		}
 	}
 
-	// When you only need one value, you can skip the proxy.
-	set value(value) { this.proxy.value = value }
-	get value() { return this.proxy.value }
+	subscribe(prop, callback) {
+		if (!callback) return this.subscribe("value", prop)
+
+		const controller = new AbortController()
+		this.addEventListener("change", ({final}) => {
+			if (final.has(prop)) return callback(final.get(prop))
+		}, {signal: controller.signal})
+		callback(this.value)
+		return () => controller.abort()
+	}
+
+	emit(property, from, to, options={}) {
+		const change = {property, from, to, ...options}
+		if (!this.synchronous) {
+			if (!this.#queue) {
+				this.#queue = []
+				queueMicrotask(() => {
+					this.dispatchEvent(new ChangeEvent(...this.#queue))
+					this.#queue = undefined
+				})
+			}
+			this.#queue.push(change)
+		} else {
+			this.dispatchEvent(new ChangeEvent([change]))
+		}
+	}
+
 
 	adopt(prop, state) {
 		let handlers = this.#nested.get(state)
@@ -101,11 +99,12 @@ export class State extends SimpleState {
 			this.#nested.set(state, handlers)
 		}
 		const ref = this.#weakRef
-		const handler = () => ref.deref()?.emit(prop, state)
+		const handler = () => ref.deref()?.emit(prop, state, state, {state: true})
 
 		handlers.set(prop, handler)
-		state.addEventListener("change", handler, {signal: this.#abortController.signal})
+		state.addEventListener("change", handler, {signal: this.ignal})
 	}
+
 	disown(prop, state) {
 		const handlers = this.#nested.get(state)
 		const handler = handlers.get(prop)
@@ -116,21 +115,41 @@ export class State extends SimpleState {
 		}
 	}
 
-	// Anounces that a prop has changed
-	emit(prop, value) {
-		if (this.#options.defer ?? true) {
-			if (!this.#queue) {
-				this.#queue = []
-				queueMicrotask(() => {
-					this.dispatchEvent(new ChangeEvent(...this.#queue))
-					this.#queue = undefined
+	get signal() { return this.#abortController.signal }
+	get synchronous() { return this.#synchronous }
+}
+
+export class State extends SimpleState {
+	#target
+	#shallow
+	#forwardCache
+
+	static isState(object) { return SimpleState.prototype.isPrototypeOf(object) }
+
+	constructor(target={}, {shallow, ...options}={}) {
+		super(options)
+
+		this.#shallow = !!shallow
+		this.#target = target
+		this.values = new Proxy(target, {
+			set: (_target, prop, value) => {
+				const old = this.get(prop)
+				if (old !== value) {
+					this.emit(prop, old, value)
+					if (this.#shallow) {
+						if (State.isState(old)) this.disown(prop, old)
+						if (State.isState(value)) this.adopt(prop, value)
+					}
+					this.set(prop, value)
+				}
+				return true
+			},
+			get: (_target, prop) => this.get(prop),
 		})
 	}
-			this.#queue.push([prop, value])
-		} else {
-			this.dispatchEvent(new ChangeEvent([prop, value]))
-		}
-	}
+
+	set value(value) { this.values.value = value }
+	get value() { return this.values.value }
 
 	forward(property="value", fallback) {
 		if (!this.#forwardCache) this.#forwardCache = new Map()
@@ -146,11 +165,17 @@ export class State extends SimpleState {
 		}
 	}
 
-	set(prop, value) {
+	set(...args) {
+		if (args.length === 1) return this.set("value", ...args)
+
+		const [prop, value] = args
 		this.#target[prop] = value
 	}
 
-	get(prop) {
+	get(...args) {
+		if (args.length === 0) return this.get("value")
+
+		const prop = args[0]
 		return this.#target[prop]
 	}
 }
@@ -175,8 +200,8 @@ export class ForwardState extends SimpleState {
 			const state = ref.deref()
 			if (state) {
 				const relevantChanges = event.changes
-					.filter(([name]) => name === property)
-					.map(([_, value]) => ["value", value])
+					.filter(({property: name}) => name === property)
+					.map(({from, to}) => ({property: "value", from, to}))
 				if (relevantChanges.length > 0)
 					state.dispatchEvent(new ChangeEvent(...relevantChanges))
 			} else {
@@ -185,8 +210,8 @@ export class ForwardState extends SimpleState {
 		}, {signal: abortController.signal})
 	}
 
-	get value() { return this.#backend.proxy[this.#property] ?? this.#fallback }
-	set value(value) { this.#backend.proxy[this.#property] = value }
+	get value() { return this.#backend.values[this.#property] ?? this.#fallback }
+	set value(value) { this.#backend.values[this.#property] = value }
 }
 
 class StorageChangeEvent extends Event {
@@ -201,16 +226,13 @@ class StorageChangeEvent extends Event {
 
 export class StoredState extends State {
 	#storage
-	#valueKey
 
 	constructor(init, options={}) {
 		super({}, options)
 		this.#storage = options.storage ?? localStorage ?? new MapStorage()
-		this.#valueKey = options.key ?? 'value'
 
 		// Initialise storage from defaults
-		for (let [prop, value] of Object.entries(init)) {
-			if (prop === 'value') prop = this.#valueKey
+		for (const [prop, value] of Object.entries(init)) {
 			if (this.#storage[prop] === undefined)
 				this.set(prop, value)
 		}
@@ -226,9 +248,7 @@ export class StoredState extends State {
 		// Listen for changes from other windows
 		const handler = event => {
 			if (event.targetState !== this && event.storageArea == this.#storage) {
-				let prop = event.key
-				if (prop === this.#valueKey) prop = 'value'
-				this.emit(prop, JSON.parse(event.newValue))
+				this.emit(event.key, JSON.parse(event.newValue))
 			}
 		}
 		addEventListener("storage", handler)
@@ -236,14 +256,12 @@ export class StoredState extends State {
 	}
 
 	set(prop, value) {
-		if (prop == "value") prop = this.#valueKey
 		const json = JSON.stringify(value)
 		dispatchEvent(new StorageChangeEvent(this.#storage, prop, json, this))
 		this.#storage[prop] = json
 	}
 
 	get(prop) {
-		if (prop == "value") prop = this.#valueKey
 		const value = this.#storage[prop]
 		return value && JSON.parse(value)
 	}
@@ -254,8 +272,8 @@ const attributeObserver = new MutationObserver(mutations => {
 		if (type == "attributes") {
 			const next = target.getAttribute(name)
 			const camelName = kebabToCamel(name)
-			if (String(target.state.proxy[camelName]) !== next)
-				target.state.proxy[camelName] = next
+			if (String(target.state.values[camelName]) !== next)
+				target.state.values[camelName] = next
 		}
 	}
 })
@@ -267,8 +285,8 @@ export const component = (generator, name) => {
 			super()
 			this.state = new State(Object.fromEntries([...this.attributes].map(attribute => [kebabToCamel(attribute.name), attribute.value])))
 			this.state.addEventListener("change", event => {
-				for (const [name, value] of event.changes) {
-					const kebabName = camelToKebab(name)
+				for (const {property, to: value} of event.changes) {
+					const kebabName = camelToKebab(property)
 					if (this.getAttribute(kebabName) !== String(value))
 						this.setAttribute(kebabName, value)
 				}
@@ -284,14 +302,12 @@ export const component = (generator, name) => {
 class ComposedState extends SimpleState {
 	#func
 	#states
-	#options
 
 	constructor(func, options, ...states) {
-		super()
+		super(options)
 
 		this.#func = func
 		this.#states = states
-		this.#options = options
 
 		const abortController = new AbortController()
 		abortRegistry.register(this, abortController)
@@ -309,7 +325,7 @@ class ComposedState extends SimpleState {
 
 	#microtaskQueued
 	scheduleUpdate() {
-		if (this.#options.defer) {
+		if (this.defer) {
 			if (!this.#microtaskQueued) {
 				queueMicrotask(() => {
 					this.#microtaskQueued = false
@@ -323,8 +339,10 @@ class ComposedState extends SimpleState {
 	}
 
 	update() {
-		this.value = this.#func(...this.#states.map(state => state.value))
-		this.dispatchEvent(new ChangeEvent([["value", this.value]]))
+		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]))
 	}
 }
 
@@ -346,7 +364,6 @@ const mutationObserver = new MutationObserver(mutations => {
 
 export class DOMState extends SimpleState {
 	#target
-	#defer
 	#getValue
 	#equal
 
@@ -354,8 +371,7 @@ export class DOMState extends SimpleState {
 	#changedValue = false
 
 	constructor(target, options) {
-		super()
-		this.#defer = options.defer ?? false
+		super(options)
 		this.#target = target
 		this.#getValue = options.get ?? (target => target.value)
 		this.#equal = options.equal ?? ((a, b) => a===b)
@@ -383,7 +399,7 @@ export class DOMState extends SimpleState {
 
 		this.#old = current
 
-		if (this.#defer) {
+		if (this.defer) {
 			if (!this.#changedValue) {
 				queueMicrotask(() => {
 					this.#changedValue = false
@@ -397,4 +413,26 @@ export class DOMState extends SimpleState {
 	}
 }
 
+export class MapStorage extends Storage {
+	#map = new Map()
+	key(index) {
+		return [...this.#map.keys()][index]
+	}
+	getItem(keyName) {
+		if (this.#map.has(keyName))
+			return this.#map.get(keyName)
+		else
+			return null
+	}
+	setItem(keyName, keyValue) {
+		this.#map.set(keyName, String(keyValue))
+	}
+	removeItem(keyName) {
+		this.#map.delete(keyName)
+	}
+	clear() {
+		this.#map.clear()
+	}
+}
+
 export default State