rewrite

src/runtime/internal/Component.ts

@@ -1,9 +1,9 @@
 import { add_render_callback, flush, flush_render_callbacks, schedule_update, dirty_components } from './scheduler';
-import { current_component, set_current_component, start_callback, stop_callback } from './lifecycle';
+import { add_callback, current_component, set_current_component } from './lifecycle';
 import { blank_object, is_empty, is_function, run, run_all, noop } from './utils';
 import { children, detach, start_hydrating, end_hydrating } from './dom';
 import { transition_in } from './transitions';
-import { Callback, T$$ } from './types';
+import { T$$ } from './types';
 
 export function bind(component, name, callback) {
 	const index = component.$$.props[name];
@@ -181,22 +181,7 @@ if (typeof HTMLElement === 'function') {
 		}
 
 		$on(type: string, callback: EventListener, options?: boolean | AddEventListenerOptions | EventListenerOptions) {
-			if (!is_function(callback)) {
-				return noop;
-			}
-			const callbacks = (this.$$.callbacks[type] || (this.$$.callbacks[type] = []));
-			const c: Callback = {f:callback, o:options};
-			callbacks.push(c);
-			
-			start_callback(this as any, type, c);
-	
-			return () => {
-				const index = callbacks.indexOf(c);
-				if (index !== -1) {
-					callbacks.splice(index, 1);
-					stop_callback(this as any, type, c);
-				}
-			};
+			return add_callback(this, type, callback, options);
 		}
 
 		$set($$props) {
@@ -222,20 +207,7 @@ export class SvelteComponent {
 	}
 
 	$on(type: string, callback: EventListener, options?: boolean | AddEventListenerOptions | EventListenerOptions) {
-		if (!is_function(callback)) {
-			return noop;
-		}
-		const callbacks = (this.$$.callbacks[type] || (this.$$.callbacks[type] = []));
-		const c: Callback = {f:callback, o:options};
-		callbacks.push(c);
-		
-		start_callback(this as any, type, c);
-
-		return () => {
-			const index = callbacks.indexOf(c);
-			if (index !== -1) callbacks.splice(index, 1);
-			stop_callback(this as any, type, c);
-		};
+		return add_callback(this, type, callback, options);
 	}
 
 	$set($$props) {

src/runtime/internal/lifecycle.ts

@@ -1,7 +1,7 @@
 import { SvelteComponent } from './Component';
 import { custom_event, wrap_handler } from './dom';
 import { Bubble, Callback, CallbackFactory } from './types';
-import { noop } from './utils';
+import { is_function, noop } from './utils';
 
 export let current_component;
 
@@ -159,7 +159,15 @@ function start_bubbles(comp : SvelteComponent, bubble: Bubble) {
 	}
 }
 
-export function start_callback(comp : SvelteComponent, type: string, callback: Callback) {
+export function restart_all_callback(comp : SvelteComponent) {
+	for (const type of Object.keys(comp.$$.callbacks)) {
+		for (const callback of comp.$$.callbacks[type]) {
+			start_callback(comp, type, callback);
+		}
+	}
+}
+
+function start_callback(comp : SvelteComponent, type: string, callback: Callback) {
 	for (const bubbles of [ comp.$$.bubbles[type], comp.$$.bubbles['*'] ]) {
 		if (bubbles) {
 			for(const bubble of bubbles) {
@@ -169,7 +177,28 @@ export function start_callback(comp : SvelteComponent, type: string, callback: C
 	}
 }
 
-export function stop_callback(comp : SvelteComponent, type: string, callback: Callback) {
+export function add_callback(comp : SvelteComponent, type: string, f: EventListener, o?: boolean | AddEventListenerOptions | EventListenerOptions) {
+	if (!is_function(f)) {
+		return noop;
+	}
+	
+	const callbacks = (comp.$$.callbacks[type] || (comp.$$.callbacks[type] = []));
+	const callback: Callback = {f, o};
+	
+	if (o && (o as any)?.once === true) {
+		callback.f = function () {
+			const r = f.apply(this, arguments);
+			remove_callback(comp, type, callback);
+			return r;
+		};
+	}
+
+	callbacks.push(callback);
+	start_callback(comp, type, callback);
+	return () => remove_callback(comp, type, callback);
+}
+
+function stop_callback(comp : SvelteComponent, type: string, callback: Callback) {
 	for (const bubbles of [ comp.$$.bubbles[type], comp.$$.bubbles['*'] ]) {
 		if (bubbles) {
 			for (const bubble of bubbles) {
@@ -183,6 +212,17 @@ export function stop_callback(comp : SvelteComponent, type: string, callback: Ca
 	}
 }
 
+function remove_callback(comp : SvelteComponent, type: string, callback: Callback) {
+	const callbacks = comp.$$.callbacks[type];
+	if (callbacks) {
+		const index = callbacks.indexOf(callback);
+		if (index !== -1) {
+			callbacks.splice(index, 1);
+			stop_callback(comp, type, callback);
+		}
+	}
+}
+
 function add_bubble(comp: SvelteComponent, type: string, f: CallbackFactory): Function {
 	const bubble : Bubble = {f, r: new Map()};
 	const bubbles = (comp.$$.bubbles[type] || (comp.$$.bubbles[type] = []));