carbon/build/static/store/SubscribeValue.js

import {Subscribable} from "./Subscribable.js"

class SubscribeValue extends Subscribable {
	constructor() {
		super()
		this.hasData = false
		this.data = null
	}

	exists() {
		return this.hasData
	}

	value() {
		if (this.hasData) return this.data
		else return null
	}

	set(data) {
		const exists = this.exists()
		this.data = data
		this.hasData = true
		if (exists) {
			this.broadcast("editSelf", this.data)
		} else {
			this.broadcast("addSelf", this.data)
		}
		return this
	}

	edit(f) {
		if (this.exists()) {
			f(this.data)
			this.set(this.data)
		} else {
			throw new Error("Tried to edit a SubscribeValue that had no value")
		}
	}

	delete() {
		this.hasData = false
		this.broadcast("removeSelf")
		return this
	}
}

export {SubscribeValue}