From b4c909c260f8028acad97f4bbd207ef02e9cfc03 Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Tue, 3 Sep 2019 23:04:11 -0400
Subject: [PATCH] feat: $nextTick, $forceUpdate, $watch

---
 packages/runtime-core/src/apiOptions.ts     | 21 ++++++++++++++++-----
 packages/runtime-core/src/componentProxy.ts | 18 ++++++++++++++++++
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/packages/runtime-core/src/apiOptions.ts b/packages/runtime-core/src/apiOptions.ts
index 2ab2af29f..6c87daccb 100644
--- a/packages/runtime-core/src/apiOptions.ts
+++ b/packages/runtime-core/src/apiOptions.ts
@@ -13,7 +13,7 @@ import {
   EMPTY_OBJ
 } from '@vue/shared'
 import { computed, ComputedOptions } from './apiReactivity'
-import { watch } from './apiWatch'
+import { watch, WatchOptions } from './apiWatch'
 import { provide, inject } from './apiInject'
 import {
   onBeforeMount,
@@ -133,10 +133,8 @@ export function processOptions(instance: ComponentInstance) {
       } else if (isFunction(raw)) {
         watch(getter, raw.bind(ctx))
       } else if (isObject(raw)) {
-        watch(getter, raw.handler.bind(ctx), {
-          deep: !!raw.deep,
-          lazy: !raw.immediate
-        })
+        // TODO 2.x compat
+        watch(getter, raw.handler.bind(ctx), raw)
       } else if (__DEV__) {
         // TODO warn invalid watch options
       }
@@ -201,3 +199,16 @@ export function processOptions(instance: ComponentInstance) {
     onUnmounted(destroyed.bind(ctx))
   }
 }
+
+export function legacyWatch(
+  this: ComponentInstance,
+  source: string | Function,
+  cb: Function,
+  options?: WatchOptions
+): () => void {
+  const ctx = this.renderProxy as any
+  const getter = isString(source) ? () => ctx[source] : source.bind(ctx)
+  const stop = watch(getter, cb.bind(ctx), options)
+  onBeforeMount(stop, this)
+  return stop
+}
diff --git a/packages/runtime-core/src/componentProxy.ts b/packages/runtime-core/src/componentProxy.ts
index c67244e90..16d1a0e1c 100644
--- a/packages/runtime-core/src/componentProxy.ts
+++ b/packages/runtime-core/src/componentProxy.ts
@@ -1,4 +1,6 @@
 import { ComponentInstance } from './component'
+import { nextTick } from './scheduler'
+import { legacyWatch } from './apiOptions'
 
 export const RenderProxyHandlers = {
   get(target: ComponentInstance, key: string) {
@@ -26,7 +28,23 @@ export const RenderProxyHandlers = {
           return target.root
         case '$emit':
           return target.emit
+        case '$el':
+          return target.vnode.el
+        case '$options':
+          // TODO handle merging
+          return target.type
         default:
+          // methods are only exposed when options are supported
+          if (__FEATURE_OPTIONS__) {
+            switch (key) {
+              case '$forceUpdate':
+                return target.update
+              case '$nextTick':
+                return nextTick
+              case '$watch':
+                return legacyWatch.bind(target)
+            }
+          }
           return target.user[key]
       }
     }