preact

frontend/node_modules/three/examples/jsm/renderers/common/ChainMap.js

@@ -0,0 +1,59 @@
+export default class ChainMap {
+
+	constructor() {
+
+		this.weakMap = new WeakMap();
+
+	}
+
+	get( keys ) {
+
+		let map = this.weakMap;
+
+		for ( let i = 0; i < keys.length; i ++ ) {
+
+			map = map.get( keys[ i ] );
+
+			if ( map === undefined ) return undefined;
+
+		}
+
+		return map.get( keys[ keys.length - 1 ] );
+
+	}
+
+	set( keys, value ) {
+
+		let map = this.weakMap;
+
+		for ( let i = 0; i < keys.length; i ++ ) {
+
+			const key = keys[ i ];
+
+			if ( map.has( key ) === false ) map.set( key, new WeakMap() );
+
+			map = map.get( key );
+
+		}
+
+		return map.set( keys[ keys.length - 1 ], value );
+
+	}
+
+	delete( keys ) {
+
+		let map = this.weakMap;
+
+		for ( let i = 0; i < keys.length; i ++ ) {
+
+			map = map.get( keys[ i ] );
+
+			if ( map === undefined ) return false;
+
+		}
+
+		return map.delete( keys[ keys.length - 1 ] );
+
+	}
+
+}