feat(v-on): support v-on object syntax with no arguments

Note this does not support modifiers and is meant to be used for handling
events proxying in higher-order-components.

Author: yyx990803

flow/compiler.js

@@ -133,6 +133,7 @@ declare type ASTElement = {
   once?: true;
   onceProcessed?: boolean;
   wrapData?: (code: string) => string;
+  wrapListeners?: (code: string) => string;
 
   // 2.4 ssr optimization
   ssrOptimizability?: number;

flow/component.js

@@ -121,6 +121,8 @@ declare interface Component {
   _t: (name: string, fallback: ?Array<VNode>, props: ?Object) => ?Array<VNode>;
   // apply v-bind object
   _b: (data: any, tag: string, value: any, asProp: boolean, isSync?: boolean) => VNodeData;
+  // apply v-on object
+  _g: (data: any, value: any) => VNodeData;
   // check custom keyCode
   _k: (eventKeyCode: number, key: string, builtInAlias: number | Array<number> | void) => boolean;
   // resolve scoped slots

flow/vnode.js

@@ -27,6 +27,7 @@ declare type VNodeWithData = {
   context: Component;
   key: string | number | void;
   parent?: VNodeWithData;
+  componentOptions?: VNodeComponentOptions;
   componentInstance?: Component;
   isRootInsert: boolean;
 };

src/compiler/codegen/index.js

@@ -1,9 +1,9 @@
 /* @flow */
 
 import { genHandlers } from './events'
-import { baseWarn, pluckModuleFunction } from '../helpers'
 import baseDirectives from '../directives/index'
 import { camelize, no, extend } from 'shared/util'
+import { baseWarn, pluckModuleFunction } from '../helpers'
 
 type TransformFunction = (el: ASTElement, code: string) => string;
 type DataGenFunction = (el: ASTElement) => string;
@@ -268,6 +268,10 @@ export function genData (el: ASTElement, state: CodegenState): string {
   if (el.wrapData) {
     data = el.wrapData(data)
   }
+  // v-on data wrap
+  if (el.wrapListeners) {
+    data = el.wrapListeners(data)
+  }
   return data
 }
 

src/compiler/directives/index.js

@@ -1,9 +1,11 @@
 /* @flow */
 
+import on from './on'
 import bind from './bind'
 import { noop } from 'shared/util'
 
 export default {
+  on,
   bind,
   cloak: noop
 }

src/compiler/directives/on.js

@@ -0,0 +1,10 @@
+/* @flow */
+
+import { warn } from 'core/util/index'
+
+export default function on (el: ASTElement, dir: ASTDirective) {
+  if (process.env.NODE_ENV !== 'production' && dir.modifiers) {
+    warn(`v-on without argument does not support modifiers.`)
+  }
+  el.wrapListeners = (code: string) => `_g(${code},${dir.value})`
+}

src/core/instance/render-helpers/bind-object-listeners.js

@@ -0,0 +1,22 @@
+/* @flow */
+
+import { warn, extend, isPlainObject } from 'core/util/index'
+
+export function bindObjectListeners (data: any, value: any): VNodeData {
+  if (value) {
+    if (!isPlainObject(value)) {
+      process.env.NODE_ENV !== 'production' && warn(
+        'v-on without argument expects an Object value',
+        this
+      )
+    } else {
+      const on = data.on = data.on ? extend({}, data.on) : {}
+      for (const key in value) {
+        const existing = on[key]
+        const ours = value[key]
+        on[key] = existing ? [ours].concat(existing) : ours
+      }
+    }
+  }
+  return data
+}

src/core/instance/render.js

@@ -24,6 +24,7 @@ import { resolveFilter } from './render-helpers/resolve-filter'
 import { checkKeyCodes } from './render-helpers/check-keycodes'
 import { bindObjectProps } from './render-helpers/bind-object-props'
 import { renderStatic, markOnce } from './render-helpers/render-static'
+import { bindObjectListeners } from './render-helpers/bind-object-listeners'
 import { resolveSlots, resolveScopedSlots } from './render-helpers/resolve-slots'
 
 export function initRender (vm: Component) {
@@ -121,4 +122,5 @@ export function renderMixin (Vue: Class<Component>) {
   Vue.prototype._v = createTextVNode
   Vue.prototype._e = createEmptyVNode
   Vue.prototype._u = resolveScopedSlots
+  Vue.prototype._g = bindObjectListeners
 }

src/core/vdom/create-component.js

@@ -161,11 +161,8 @@ export function createComponent (
     return createFunctionalComponent(Ctor, propsData, data, context, children)
   }
 
-  // extract listeners, since these needs to be treated as
-  // child component listeners instead of DOM listeners
+  // keep listeners
   const listeners = data.on
-  // replace with listeners with .native modifier
-  data.on = data.nativeOn
 
   if (isTrue(Ctor.options.abstract)) {
     // abstract components do not keep anything

src/platforms/web/runtime/modules/events.js

@@ -66,11 +66,14 @@ function remove (
 }
 
 function updateDOMListeners (oldVnode: VNodeWithData, vnode: VNodeWithData) {
-  if (isUndef(oldVnode.data.on) && isUndef(vnode.data.on)) {
+  const isComponentRoot = isDef(vnode.componentOptions)
+  let oldOn = isComponentRoot ? oldVnode.data.nativeOn : oldVnode.data.on
+  let on = isComponentRoot ? vnode.data.nativeOn : vnode.data.on
+  if (isUndef(oldOn) && isUndef(on)) {
     return
   }
-  const on = vnode.data.on || {}
-  const oldOn = oldVnode.data.on || {}
+  on = on || {}
+  oldOn = oldOn || {}
   target = vnode.elm
   normalizeEvents(on)
   updateListeners(on, oldOn, add, remove, vnode.context)