fix contextual references in events

src/compile/nodes/EventHandler.ts

@@ -12,8 +12,7 @@ const validBuiltins = new Set(['set', 'fire', 'destroy']);
 export default class EventHandler extends Node {
 	name: string;
 	modifiers: Set<string>;
-	dependencies: Set<string>;
-	expression: Node;
+	expression: Expression;
 	callee: any; // TODO
 
 	usesComponent: boolean;
@@ -31,15 +30,13 @@ export default class EventHandler extends Node {
 		this.name = info.name;
 		this.modifiers = new Set(info.modifiers);
 
-		this.dependencies = new Set();
-
 		if (info.expression) {
 			this.expression = new Expression(component, parent, template_scope, info.expression, true);
 			this.snippet = this.expression.snippet;
 
 			let { scope, map } = createScopes(info.expression);
 
-			walk(this.expression, {
+			walk(info.expression, {
 				enter: (node, parent) => {
 					if (map.has(node)) {
 						scope = map.get(node);

src/compile/nodes/shared/Expression.ts

@@ -54,11 +54,12 @@ const precedence: Record<string, (node?: Node) => number> = {
 };
 
 export default class Expression {
-	component: Component;
+	startnent: Component;
 	node: any;
 	snippet: string;
 	references: Set<string>;
 	dependencies: Set<string>;
+	contextual_dependencies: Set<string>;
 
 	usesContext = false;
 	usesEvent = false;
@@ -79,6 +80,7 @@ export default class Expression {
 		this.snippet = `[✂${info.start}-${info.end}✂]`;
 
 		const dependencies = new Set();
+		const contextual_dependencies = new Set();
 
 		const { code, helpers } = component;
 
@@ -119,6 +121,7 @@ export default class Expression {
 					}
 
 					expression.usesContext = true;
+					contextual_dependencies.add(name);
 
 					if (!isSynthetic && !isEventHandler) {
 						// <option> value attribute could be synthetic — avoid double editing
@@ -153,6 +156,7 @@ export default class Expression {
 		});
 
 		this.dependencies = dependencies;
+		this.contextual_dependencies = contextual_dependencies;
 	}
 
 	getPrecedence() {

src/compile/render-dom/wrappers/Element/index.ts

@@ -170,7 +170,7 @@ export default class ElementWrapper extends Wrapper {
 		});
 
 		node.handlers.forEach(handler => {
-			block.addDependencies(handler.dependencies);
+			block.addDependencies(handler.expression.dependencies);
 		});
 
 		if (this.parent) {
@@ -609,7 +609,6 @@ export default class ElementWrapper extends Wrapper {
 			const { isCustomEvent } = handler;
 
 			// get a name for the event handler that is globally unique
-			// if hoisted, locally unique otherwise
 			const handler_name = component.getUniqueName(
 				`${handler.name.replace(/[^a-zA-Z0-9_$]/g, '_')}_handler`
 			);
@@ -634,15 +633,40 @@ export default class ElementWrapper extends Wrapper {
 				if (handler.modifiers.has('preventDefault')) modifiers.push('event.preventDefault();');
 				if (handler.modifiers.has('stopPropagation')) modifiers.push('event.stopPropagation();');
 
-				component.event_handlers.push({
-					name: handler_name,
-					body: deindent`
-						function ${handler_name}(event) {
-							${modifiers}
-							(${handler.snippet})(event);
-						}
-					`
-				});
+				let name;
+
+				if (handler.expression.contextual_dependencies.size > 0) {
+					name = handler_name;
+
+					const deps = Array.from(handler.expression.contextual_dependencies);
+
+					component.event_handlers.push({
+						name: handler_name,
+						body: deindent`
+							function ${handler_name}(event, { ${deps.join(', ')} }) {
+								(${handler.snippet})(event);
+							}
+						`
+					});
+
+					block.builders.init.addBlock(deindent`
+						${name}.$on("${handler.name}", function(event) {
+							ctx.${handler_name}.call(this, event, ctx);
+						});
+					`);
+				} else {
+					name = `ctx.${handler_name}`;
+
+					component.event_handlers.push({
+						name: handler_name,
+						body: deindent`
+							function ${handler_name}(event) {
+								${modifiers}
+								(${handler.snippet})(event);
+							}
+						`
+					});
+				}
 
 				const opts = ['passive', 'once', 'capture'].filter(mod => handler.modifiers.has(mod));
 				if (opts.length) {
@@ -651,19 +675,19 @@ export default class ElementWrapper extends Wrapper {
 						: `{ ${opts.map(opt => `${opt}: true`).join(', ')} }`;
 
 					block.builders.hydrate.addLine(
-						`@addListener(${this.var}, "${handler.name}", ctx.${handler_name}, ${optString});`
+						`@addListener(${this.var}, "${handler.name}", ${name}, ${optString});`
 					);
 
 					block.builders.destroy.addLine(
-						`@removeListener(${this.var}, "${handler.name}", ctx.${handler_name}, ${optString});`
+						`@removeListener(${this.var}, "${handler.name}", ${name}, ${optString});`
 					);
 				} else {
 					block.builders.hydrate.addLine(
-						`@addListener(${this.var}, "${handler.name}", ctx.${handler_name});`
+						`@addListener(${this.var}, "${handler.name}", ${name});`
 					);
 
 					block.builders.destroy.addLine(
-						`@removeListener(${this.var}, "${handler.name}", ctx.${handler_name});`
+						`@removeListener(${this.var}, "${handler.name}", ${name});`
 					);
 				}
 			}

src/compile/render-dom/wrappers/InlineComponent/index.ts

@@ -54,7 +54,7 @@ export default class InlineComponentWrapper extends Wrapper {
 		});
 
 		this.node.handlers.forEach(handler => {
-			block.addDependencies(handler.dependencies);
+			block.addDependencies(handler.expression.dependencies);
 		});
 
 		this.var = (
@@ -428,15 +428,49 @@ export default class InlineComponentWrapper extends Wrapper {
 
 				${beforecreate}
 
-				${this.node.handlers.map(handler => deindent`
-					${name}.$on("${handler.name}", function(event) {
-						(${handler.snippet || `() => { throw new Error('TODO shorthand events'); }`})(event);
-					});
-				`)}
-
 				${this.node.ref && `#component.$$refs.${this.node.ref.name} = ${name};`}
 			`);
 
+			this.node.handlers.forEach(handler => {
+				let { snippet } = handler;
+				if (!snippet) snippet = `() => { throw new Error('TODO shorthand events'); }`;
+
+				// get a name for the event handler that is globally unique
+				const handler_name = component.getUniqueName(
+					`${handler.name.replace(/[^a-zA-Z0-9_$]/g, '_')}_handler`
+				);
+
+				if (handler.expression.contextual_dependencies.size > 0) {
+					const deps = Array.from(handler.expression.contextual_dependencies);
+
+					component.event_handlers.push({
+						name: handler_name,
+						body: deindent`
+							function ${handler_name}(event, { ${deps.join(', ')} }) {
+								(${snippet})(event);
+							}
+						`
+					});
+
+					block.builders.init.addBlock(deindent`
+						${name}.$on("${handler.name}", function(event) {
+							ctx.${handler_name}.call(this, event, ctx);
+						});
+					`);
+				} else {
+					component.event_handlers.push({
+						name: handler_name,
+						body: deindent`
+							function ${handler_name}(event) {
+								(${snippet})(event);
+							}
+						`
+					});
+
+					block.builders.init.addLine(`${name}.$on("${handler.name}", ctx.${handler_name});`);
+				}
+			});
+
 			block.builders.create.addLine(`${name}.$$fragment.c();`);
 
 			if (parentNodes) {

src/compile/render-dom/wrappers/Window.ts

@@ -45,7 +45,7 @@ export default class WindowWrapper extends Wrapper {
 
 			const isCustomEvent = component.events.has(handler.name);
 
-			let usesState = handler.dependencies.size > 0;
+			let usesState = handler.expression.dependencies.size > 0;
 
 			const handler_name = block.getUniqueName(`onwindow${handler.name}`);
 			const handler_body = deindent`