copy new types of event propagators
This commit is contained in:
“chrisshank”
parent
aef4235fc5
commit
1f98215a3c
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@ -0,0 +1,293 @@
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import type { PropagatorFunction, PropagatorParser } from './types.ts';
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interface PropagatorOptions {
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source?: Element | null;
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target?: Element | null;
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sourceEvent?: string | null;
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targetEvent?: string | null;
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sourceHandler?: PropagatorFunction | string | null;
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targetHandler?: PropagatorFunction | string | null;
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onParseSuccess?: ((body: string) => void) | null;
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onParseError?: ((error: Error) => void) | null;
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parser?: PropagatorParser | null;
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}
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/**
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* A propagator takes a source and target element and listens for events on both.
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* When an event is detected on one, it will execute a handler and update the other element.
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*/
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export class BiPropagator {
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#source: Element | null = null;
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#target: Element | null = null;
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#sourceEventName: string | null = null;
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#targetEventName: string | null = null;
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#sourceHandler: PropagatorFunction | null = null;
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#targetHandler: PropagatorFunction | null = null;
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#parser: PropagatorParser | null = null;
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#onParse: ((body: string) => void) | null = null;
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#onError: ((error: Error) => void) | null = null;
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#isPropagationLocked = false;
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/**
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* Creates a new BiPropagator instance.
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* @param {PropagatorOptions} options - Configuration options for the propagator
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*/
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constructor(options: PropagatorOptions = {}) {
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const {
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source = null,
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target = null,
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sourceEvent = null,
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targetEvent = null,
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sourceHandler = null,
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targetHandler = null,
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onParseSuccess: onParse = null,
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onParseError: onError = null,
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parser = null,
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} = options;
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this.#onParse = onParse;
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this.#onError = onError;
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this.#parser = parser;
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this.source = source;
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this.target = target;
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if (sourceEvent) this.sourceEvent = sourceEvent;
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if (targetEvent) this.targetEvent = targetEvent;
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if (sourceHandler) this.sourceHandler = sourceHandler;
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if (targetHandler) this.targetHandler = targetHandler;
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}
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/**
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* The source element that emits events.
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* Setting a new source will automatically update event listeners.
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*/
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get source(): Element | null {
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return this.#source;
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}
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set source(element: Element | null) {
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// Remove listener from old source
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if (this.#source && this.#sourceEventName) {
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this.#source.removeEventListener(this.#sourceEventName, this.#handleSourceEvent);
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}
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this.#source = element;
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// Add listener to new source
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if (this.#source && this.#sourceEventName) {
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this.#source.addEventListener(this.#sourceEventName, this.#handleSourceEvent);
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}
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}
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/**
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* The target element that receives propagated changes.
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* Setting a new target will automatically update event listeners.
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*/
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get target(): Element | null {
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return this.#target;
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}
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set target(element: Element | null) {
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// Remove listener from old target
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if (this.#target && this.#targetEventName) {
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this.#target.removeEventListener(this.#targetEventName, this.#handleTargetEvent);
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}
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this.#target = element;
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// Add listener to new target
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if (this.#target && this.#targetEventName) {
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this.#target.addEventListener(this.#targetEventName, this.#handleTargetEvent);
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}
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}
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/**
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* The name of the event to listen for on both the source and target elements.
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*/
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get sourceEvent(): string | null {
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return this.#sourceEventName;
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}
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set sourceEvent(name: string | null) {
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if (this.#source && this.#sourceEventName) {
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this.#source.removeEventListener(this.#sourceEventName, this.#handleSourceEvent);
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}
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this.#sourceEventName = name;
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if (this.#source && this.#sourceEventName) {
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this.#source.addEventListener(this.#sourceEventName, this.#handleSourceEvent);
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}
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}
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get targetEvent(): string | null {
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return this.#targetEventName;
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}
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set targetEvent(name: string | null) {
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if (this.#target && this.#targetEventName) {
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this.#target.removeEventListener(this.#targetEventName, this.#handleTargetEvent);
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}
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this.#targetEventName = name;
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if (this.#target && this.#targetEventName) {
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this.#target.addEventListener(this.#targetEventName, this.#handleTargetEvent);
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}
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}
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/**
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* The handler function that processes the event and updates the other element.
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* Can be set using either a function or a string expression.
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*/
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get sourceHandler(): PropagatorFunction | null {
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return this.#sourceHandler;
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}
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set sourceHandler(value: PropagatorFunction | string | null) {
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if (typeof value === 'string') {
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try {
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this.#sourceHandler = this.#parser ? this.#parser(value) : this.#defaultParser(value);
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} catch (error) {
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this.#sourceHandler = null;
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}
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} else {
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this.#sourceHandler = value;
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}
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}
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get targetHandler(): PropagatorFunction | null {
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return this.#targetHandler;
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}
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set targetHandler(value: PropagatorFunction | string | null) {
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if (typeof value === 'string') {
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try {
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this.#targetHandler = this.#parser ? this.#parser(value) : this.#defaultParser(value);
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} catch (error) {
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this.#targetHandler = null;
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}
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} else {
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this.#targetHandler = value;
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}
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}
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/**
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* Manually triggers the propagation from the source with an optional event.
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* If no event is provided and an event name is set, creates a new event.
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* @param {Event} [event] - Optional event to propagate
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*/
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propagate(event?: Event): void {
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if (!event && this.#sourceEventName) {
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event = new Event(this.#sourceEventName);
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}
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if (!event) return;
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this.#handleSourceEvent(event);
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}
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/**
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* Cleans up the propagator by removing event listeners and clearing references.
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* Should be called when the propagator is no longer needed.
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*/
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dispose(): void {
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if (this.#source && this.#sourceEventName) {
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this.#source.removeEventListener(this.#sourceEventName, this.#handleSourceEvent);
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}
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if (this.#target && this.#targetEventName) {
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this.#target.removeEventListener(this.#targetEventName, this.#handleTargetEvent);
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}
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this.#source = null;
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this.#target = null;
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this.#sourceHandler = null;
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this.#targetHandler = null;
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}
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#handleSourceEvent = async (event: Event) => {
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if (this.#isPropagationLocked) return;
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if (!this.#source || !this.#target || !this.#sourceHandler) return;
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this.#isPropagationLocked = true;
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try {
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this.#sourceHandler(this.#source, this.#target, event);
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await Promise.resolve();
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} finally {
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this.#isPropagationLocked = false;
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}
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};
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#handleTargetEvent = async (event: Event) => {
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if (this.#isPropagationLocked) return;
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if (!this.#source || !this.#target || !this.#targetHandler) return;
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this.#isPropagationLocked = true;
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try {
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this.#targetHandler(this.#target, this.#source, event);
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await Promise.resolve();
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} finally {
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this.#isPropagationLocked = false;
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}
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};
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// This approach turns object syntax into imperative code.
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// We could alternatively use a parser (i.e. Babel) to statically analyse the code
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// and check on keystrokes if the code is valid.
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// We should try a few different things to figure out how this class could work best.
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#defaultParser = (body: string): PropagatorFunction | null => {
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const processedExp = body.trim();
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const codeLines: string[] = [];
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// Split the expression into lines, handling different line endings
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const lines = processedExp.split(/\r?\n/);
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for (const line of lines) {
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let line_trimmed = line.trim();
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if (!line_trimmed) continue;
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// Remove trailing comma if it exists (only if it's at the very end of the line)
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if (line_trimmed.endsWith(',')) {
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line_trimmed = line_trimmed.slice(0, -1).trim();
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}
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// Find the first colon index, which separates the key and value.
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// Colons can still be used in ternary operators or other expressions,
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const colonIndex = line_trimmed.indexOf(':');
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if (colonIndex === -1) {
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continue;
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}
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const key = line_trimmed.slice(0, colonIndex).trim();
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const value = line_trimmed.slice(colonIndex + 1).trim();
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if (key === '()') {
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// Anonymous function: directly evaluate the value
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codeLines.push(`${value};`);
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} else if (key.endsWith('()')) {
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// If the key is a method, execute it if the condition is true
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const methodName = key.slice(0, -2);
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codeLines.push(`
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if (typeof to.${methodName} !== 'function') throw new Error(\`Method '${methodName}' does not exist on target element.\`);
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else if (${value}) to.${methodName}();`);
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} else {
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// For property assignments, assign the value directly
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codeLines.push(`
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if (!('${key}' in to)) throw new Error(\`Property '${key}' does not exist on target element.\`);
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to.${key} = ${value};`);
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}
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}
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const functionBody = codeLines.join('\n');
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try {
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const handler = new Function('from', 'to', 'event', functionBody) as PropagatorFunction;
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this.#onParse?.(functionBody);
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return handler;
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} catch (error) {
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this.#onError?.(error as Error);
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return null;
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}
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};
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}
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@ -1 +1,2 @@
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export * from './propagator.ts';
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export * from './bipropagator.ts';
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@ -1,29 +1,4 @@
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/**
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* A function that processes the event and updates the target.
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* @param {EventTarget} source - The source that emitted the event
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* @param {EventTarget} target - The target that receives propagated changes
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* @param {Event} event - The event that triggered the propagation
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* @returns {any} - The result of the propagation
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*/
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export type PropagatorFunction = (source: EventTarget, target: EventTarget, event: Event) => any;
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/**
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* A parser function that converts a string expression into a PropagatorFunction.
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* @param {string} body - The string expression to parse
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* @param {Propagator} [propagator] - The Propagator instance (optional)
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* @returns {PropagatorFunction | null} - The parsed PropagatorFunction or null if parsing fails
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*/
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export type PropagatorParser = (body: string, propagator?: Propagator) => PropagatorFunction | null;
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export type PropagatorOptions = {
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source?: EventTarget | null;
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target?: EventTarget | null;
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event?: string | null;
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handler?: PropagatorFunction | string;
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parser?: PropagatorParser;
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onParseSuccess?: (body: string) => void;
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onParseError?: (error: Error) => void;
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};
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import { PropagatorFunction, PropagatorOptions, PropagatorParser } from './types';
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/**
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* A propagator takes in a source and target and listens for events on the source.
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@ -0,0 +1,256 @@
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import type { PropagatorFunction, PropagatorOptions, PropagatorParser } from './types.ts';
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/**
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* A propagator takes a source and target element and listens for events on both.
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* When an event is detected on one, it will execute a handler and update the other element.
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*/
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export class SymmetricPropagator {
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#source: EventTarget | null = null;
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#target: EventTarget | null = null;
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#eventName: string | null = null;
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#handler: PropagatorFunction | null = null;
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#parser: PropagatorParser | null = null;
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#onParse: ((body: string) => void) | null = null;
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#onError: ((error: Error) => void) | null = null;
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#isPropagationLocked = false;
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/**
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* Creates a new BiPropagator instance.
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* @param {PropagatorOptions} options - Configuration options for the propagator
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*/
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constructor(options: PropagatorOptions = {}) {
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const {
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source = null,
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target = null,
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event = null,
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handler = null,
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onParseSuccess: onParse = null,
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onParseError: onError = null,
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parser = null,
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} = options;
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this.#onParse = onParse;
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this.#onError = onError;
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this.#parser = parser;
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this.source = source;
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this.target = target;
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if (event) this.event = event;
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if (handler) this.handler = handler;
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}
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/**
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* The source element that emits events.
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* Setting a new source will automatically update event listeners.
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*/
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get source() {
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return this.#source;
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}
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set source(element) {
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// Remove listener from old source
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if (this.#source && this.#eventName) {
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this.#source.removeEventListener(this.#eventName, this.#handleSourceEvent);
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}
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this.#source = element;
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// Add listener to new source
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if (this.#source && this.#eventName) {
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this.#source.addEventListener(this.#eventName, this.#handleSourceEvent);
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}
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}
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/**
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* The target element that receives propagated changes.
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* Setting a new target will automatically update event listeners.
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*/
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get target() {
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return this.#target;
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}
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set target(element) {
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// Remove listener from old target
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if (this.#target && this.#eventName) {
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this.#target.removeEventListener(this.#eventName, this.#handleTargetEvent);
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}
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this.#target = element;
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// Add listener to new target
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if (this.#target && this.#eventName) {
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this.#target.addEventListener(this.#eventName, this.#handleTargetEvent);
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}
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}
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/**
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* The name of the event to listen for on both the source and target elements.
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*/
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get event(): string | null {
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return this.#eventName;
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}
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set event(name: string | null) {
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// Remove old listeners
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if (this.#source && this.#eventName) {
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this.#source.removeEventListener(this.#eventName, this.#handleSourceEvent);
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}
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if (this.#target && this.#eventName) {
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this.#target.removeEventListener(this.#eventName, this.#handleTargetEvent);
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}
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this.#eventName = name;
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// Add new listeners
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if (this.#source && this.#eventName) {
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this.#source.addEventListener(this.#eventName, this.#handleSourceEvent);
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}
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if (this.#target && this.#eventName) {
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this.#target.addEventListener(this.#eventName, this.#handleTargetEvent);
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}
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}
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/**
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* The handler function that processes the event and updates the other element.
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* Can be set using either a function or a string expression.
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*/
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get handler(): PropagatorFunction | null {
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return this.#handler;
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}
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set handler(value: PropagatorFunction | string | null) {
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if (typeof value === 'string') {
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try {
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this.#handler = this.#parser ? this.#parser(value) : this.#defaultParser(value);
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} catch (error) {
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this.#handler = null;
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}
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} else {
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this.#handler = value;
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}
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}
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/**
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* Manually triggers the propagation from the source with an optional event.
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* If no event is provided and an event name is set, creates a new event.
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* @param {Event} [event] - Optional event to propagate
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*/
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propagate(event?: Event): void {
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if (!event && this.#eventName) {
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event = new Event(this.#eventName);
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}
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if (!event) return;
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this.#handleSourceEvent(event);
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}
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/**
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* Cleans up the propagator by removing event listeners and clearing references.
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* Should be called when the propagator is no longer needed.
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*/
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dispose(): void {
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if (this.#source && this.#eventName) {
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this.#source.removeEventListener(this.#eventName, this.#handleSourceEvent);
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}
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if (this.#target && this.#eventName) {
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this.#target.removeEventListener(this.#eventName, this.#handleTargetEvent);
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}
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this.#source = null;
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this.#target = null;
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this.#handler = null;
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}
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#handleSourceEvent = async (event: Event) => {
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if (this.#isPropagationLocked) return;
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if (!this.#source || !this.#target || !this.#handler) return;
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this.#isPropagationLocked = true;
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|
||||
try {
|
||||
// Update the target element
|
||||
this.#handler(this.#source, this.#target, event);
|
||||
|
||||
// Wait for microtasks to complete
|
||||
await Promise.resolve();
|
||||
} finally {
|
||||
this.#isPropagationLocked = false;
|
||||
}
|
||||
};
|
||||
|
||||
#handleTargetEvent = async (event: Event) => {
|
||||
if (this.#isPropagationLocked) return;
|
||||
if (!this.#source || !this.#target || !this.#handler) return;
|
||||
|
||||
this.#isPropagationLocked = true;
|
||||
|
||||
try {
|
||||
// Update the source element
|
||||
this.#handler(this.#target, this.#source, event);
|
||||
|
||||
// Wait for microtasks to complete
|
||||
await Promise.resolve();
|
||||
} finally {
|
||||
this.#isPropagationLocked = false;
|
||||
}
|
||||
};
|
||||
|
||||
// This approach turns object syntax into imperative code.
|
||||
// We could alternatively use a parser (i.e. Babel) to statically analyse the code
|
||||
// and check on keystrokes if the code is valid.
|
||||
// We should try a few different things to figure out how this class could work best.
|
||||
#defaultParser = (body: string): PropagatorFunction | null => {
|
||||
const processedExp = body.trim();
|
||||
|
||||
const codeLines: string[] = [];
|
||||
|
||||
// Split the expression into lines, handling different line endings
|
||||
const lines = processedExp.split(/\r?\n/);
|
||||
|
||||
for (const line of lines) {
|
||||
let line_trimmed = line.trim();
|
||||
if (!line_trimmed) continue;
|
||||
|
||||
// Remove trailing comma if it exists (only if it's at the very end of the line)
|
||||
if (line_trimmed.endsWith(',')) {
|
||||
line_trimmed = line_trimmed.slice(0, -1).trim();
|
||||
}
|
||||
|
||||
// Find the first colon index, which separates the key and value.
|
||||
// Colons can still be used in ternary operators or other expressions,
|
||||
const colonIndex = line_trimmed.indexOf(':');
|
||||
if (colonIndex === -1) {
|
||||
continue;
|
||||
}
|
||||
|
||||
const key = line_trimmed.slice(0, colonIndex).trim();
|
||||
const value = line_trimmed.slice(colonIndex + 1).trim();
|
||||
|
||||
if (key === '()') {
|
||||
// Anonymous function: directly evaluate the value
|
||||
codeLines.push(`${value};`);
|
||||
} else if (key.endsWith('()')) {
|
||||
// If the key is a method, execute it if the condition is true
|
||||
const methodName = key.slice(0, -2);
|
||||
codeLines.push(`
|
||||
if (typeof to.${methodName} !== 'function') throw new Error(\`Method '${methodName}' does not exist on target element.\`);
|
||||
else if (${value}) to.${methodName}();`);
|
||||
} else {
|
||||
// For property assignments, assign the value directly
|
||||
codeLines.push(`
|
||||
if (!('${key}' in to)) throw new Error(\`Property '${key}' does not exist on target element.\`);
|
||||
to.${key} = ${value};`);
|
||||
}
|
||||
}
|
||||
|
||||
const functionBody = codeLines.join('\n');
|
||||
|
||||
try {
|
||||
const handler = new Function('from', 'to', 'event', functionBody) as PropagatorFunction;
|
||||
this.#onParse?.(functionBody);
|
||||
return handler;
|
||||
} catch (error) {
|
||||
this.#onError?.(error as Error);
|
||||
return null;
|
||||
}
|
||||
};
|
||||
}
|
||||
|
|
@ -0,0 +1,28 @@
|
|||
import { Propagator } from './propagator';
|
||||
|
||||
/**
|
||||
* A function that processes the event and updates the target.
|
||||
* @param {EventTarget} source - The source that emitted the event
|
||||
* @param {EventTarget} target - The target that receives propagated changes
|
||||
* @param {Event} event - The event that triggered the propagation
|
||||
* @returns {any} - The result of the propagation
|
||||
*/
|
||||
export type PropagatorFunction = (source: EventTarget, target: EventTarget, event: Event) => any;
|
||||
|
||||
/**
|
||||
* A parser function that converts a string expression into a PropagatorFunction.
|
||||
* @param {string} body - The string expression to parse
|
||||
* @param {Propagator} [propagator] - The Propagator instance (optional)
|
||||
* @returns {PropagatorFunction | null} - The parsed PropagatorFunction or null if parsing fails
|
||||
*/
|
||||
export type PropagatorParser = (body: string, propagator?: Propagator) => PropagatorFunction | null;
|
||||
|
||||
export type PropagatorOptions = {
|
||||
source?: EventTarget | null;
|
||||
target?: EventTarget | null;
|
||||
event?: string | null;
|
||||
handler?: PropagatorFunction | string;
|
||||
parser?: PropagatorParser;
|
||||
onParseSuccess?: (body: string) => void;
|
||||
onParseError?: (error: Error) => void;
|
||||
};
|
||||
Loading…
Reference in New Issue