local

src/events-observer.js

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+import { enviroment as env } from './dom-common.js';
+export const c_ch_o= env.M ? connectionsChangesObserverConstructor() : new Proxy({}, {
+	get(){ return ()=> {}; }
+});
+
+function connectionsChangesObserverConstructor(){
+	const store= new Map();
+	let is_observing= false;
+	const observerListener= stop=> function(mutations){
+		for(const mutation of mutations){
+			if(mutation.type!=="childList") continue;
+			if(observerAdded(mutation.addedNodes, true)){
+				stop();
+				continue;
+			}
+			if(observerRemoved(mutation.removedNodes, true))
+				stop();
+		}
+	};
+	const observer= new env.M(observerListener(stop));
+	return {
+		observe(element){
+			const o= new env.M(observerListener(()=> {}));
+			o.observe(element, { childList: true, subtree: true });
+			return ()=> o.disconnect();
+		},
+		onConnected(element, listener){
+			start();
+			const listeners= getElementStore(element);
+			if(listeners.connected.has(listener)) return;
+			listeners.connected.add(listener);
+			listeners.length_c+= 1;
+		},
+		offConnected(element, listener){
+			if(!store.has(element)) return;
+			const ls= store.get(element);
+			if(!ls.connected.has(listener)) return;
+			ls.connected.delete(listener);
+			ls.length_c-= 1;
+			cleanWhenOff(element, ls);
+		},
+		onDisconnected(element, listener){
+			start();
+			const listeners= getElementStore(element);
+			if(listeners.disconnected.has(listener)) return;
+			listeners.disconnected.add(listener);
+			listeners.length_d+= 1;
+		},
+		offDisconnected(element, listener){
+			if(!store.has(element)) return;
+			const ls= store.get(element);
+			if(!ls.disconnected.has(listener)) return;
+			ls.disconnected.delete(listener);
+			ls.length_d-= 1;
+			cleanWhenOff(element, ls);
+		}
+	};
+	function cleanWhenOff(element, ls){
+		if(ls.length_c || ls.length_d)
+			return;
+		store.delete(element);
+		stop();
+	}
+	function getElementStore(element){
+		if(store.has(element)) return store.get(element);
+		const out= {
+			connected: new WeakSet(),
+			length_c: 0,
+			disconnected: new WeakSet(),
+			length_d: 0
+		};
+		store.set(element, out);
+		return out;
+	}
+	function start(){
+		if(is_observing) return;
+		is_observing= true;
+		observer.observe(env.D.body, { childList: true, subtree: true });
+	}
+	function stop(){
+		if(!is_observing || store.size) return;
+		is_observing= false;
+		observer.disconnect();
+	}
+	//TODO remount support?
+	function requestIdle(){ return new Promise(function(resolve){
+		(requestIdleCallback || requestAnimationFrame)(resolve);
+	}); }
+	async function collectChildren(element){
+		if(store.size > 30)//TODO limit?
+			await requestIdle();
+		const out= [];
+		if(!(element instanceof Node)) return out;
+		for(const el of store.keys()){
+			if(el===element || !(el instanceof Node)) continue;
+			if(element.contains(el))
+				out.push(el);
+		}
+		return out;
+	}
+	function observerAdded(addedNodes, is_root){
+		let out= false;
+		for(const element of addedNodes){
+			if(is_root) collectChildren(element).then(observerAdded);
+			if(!store.has(element)) continue;
+			
+			const ls= store.get(element);
+			if(!ls.length_c) continue;
+			
+			element.dispatchEvent(new Event("dde:connected"));
+			ls.connected= new WeakSet();
+			ls.length_c= 0;
+			if(!ls.length_d) store.delete(element);
+			out= true;
+		}
+		return out;
+	}
+	function observerRemoved(removedNodes, is_root){
+		let out= false;
+		for(const element of removedNodes){
+			if(is_root) collectChildren(element).then(observerRemoved);
+			if(!store.has(element)) continue;
+			
+			const ls= store.get(element);
+			if(!ls.length_d) continue;
+			(queueMicrotask || setTimeout)(dispatchRemove(element));
+			out= true;
+		}
+		return out;
+	}
+	function dispatchRemove(element){
+		return ()=> {
+			if(element.isConnected) return;
+			element.dispatchEvent(new Event("dde:disconnected"));
+			store.delete(element);
+		};
+	}
+}