feat(getCurrentInstance): Aligning with vue3 (#520)

* feat(getCurrentInstance): Aligning with vue3
BREAKING CHANGE: The internal vm can be accessed with `getCurrentInstance().proxy`

```js
const vm = getCurrentInstance()

// becomes

const vm = getCurrentInstance().proxy
```

* chore: improve

* changes

* update tests

* chore: add tests

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

src/apis/computed.ts

@@ -26,7 +26,7 @@ export function computed<T>(options: Option<T>): WritableComputedRef<T>
 export function computed<T>(
   options: Option<T>['get'] | Option<T>
 ): ComputedRef<T> | WritableComputedRef<T> {
-  const vm = getCurrentInstance()
+  const vm = getCurrentInstance()?.proxy
   let get: Option<T>['get'], set: Option<T>['set'] | undefined
   if (typeof options === 'function') {
     get = options

src/apis/createElement.ts

@@ -8,7 +8,7 @@ type CreateElement = Vue['$createElement']
 let fallbackCreateElement: CreateElement
 
 export const createElement = (function createElement(...args: any) {
-  const instance = getCurrentInstance()
+  const instance = getCurrentInstance()?.proxy
   if (!instance) {
     warn('`createElement()` has been called outside of render function.')
     if (!fallbackCreateElement) {

src/apis/inject.ts

@@ -52,7 +52,7 @@ export function inject(
     return defaultValue
   }
 
-  const vm = getCurrentInstance()
+  const vm = getCurrentInstance()?.proxy
   if (!vm) {
     warn(`inject() can only be used inside setup() or functional components.`)
     return

src/apis/lifecycle.ts

@@ -30,12 +30,12 @@ function injectHookOption(
 
 function wrapHookCall(vm: ComponentInstance, fn: Function) {
   return (...args: any) => {
-    let preVm = getCurrentInstance()
+    let preVm = getCurrentInstance()?.proxy
     setCurrentInstance(vm)
     try {
       return fn(...args)
     } finally {
-      setCurrentInstance(preVm)
+      setCurrentInstance(preVm!)
     }
   }
 }

src/apis/warn.ts

@@ -8,5 +8,5 @@ import { warn as vueWarn } from '../utils'
  * @param message warning message to be displayed
  */
 export function warn(message: string) {
-  vueWarn(message, getCurrentInstance())
+  vueWarn(message, getCurrentInstance()?.proxy)
 }

src/apis/watch.ts

@@ -101,7 +101,7 @@ function getWatchEffectOption(options?: Partial<WatchOptions>): WatchOptions {
 }
 
 function getWatcherVM() {
-  let vm = getCurrentInstance()
+  let vm = getCurrentInstance()?.proxy
   if (!vm) {
     if (!fallbackVM) {
       fallbackVM = defineComponentInstance(getVueConstructor())

src/runtimeContext.ts

@@ -1,6 +1,6 @@
-import type { VueConstructor } from 'vue'
-import { ComponentInstance } from './component'
-import { assert, hasOwn, warn } from './utils'
+import type { VueConstructor, VNode } from 'vue'
+import { ComponentInstance, Data } from './component'
+import { assert, hasOwn, warn, proxy, UnionToIntersection } from './utils'
 
 let vueDependency: VueConstructor | undefined = undefined
 
@@ -71,10 +71,168 @@ export function setVueConstructor(Vue: VueConstructor) {
   })
 }
 
-export function getCurrentInstance(): ComponentInstance | null {
+export function setCurrentInstance(vm: ComponentInstance | null) {
+  // currentInstance?.$scopedSlots
+  currentInstance = vm
+}
+
+export type Slot = (...args: any[]) => VNode[]
+
+export type InternalSlots = {
+  [name: string]: Slot | undefined
+}
+
+export type ObjectEmitsOptions = Record<
+  string,
+  ((...args: any[]) => any) | null
+>
+export type EmitsOptions = ObjectEmitsOptions | string[]
+
+export type EmitFn<
+  Options = ObjectEmitsOptions,
+  Event extends keyof Options = keyof Options
+> = Options extends Array<infer V>
+  ? (event: V, ...args: any[]) => void
+  : {} extends Options // if the emit is empty object (usually the default value for emit) should be converted to function
+  ? (event: string, ...args: any[]) => void
+  : UnionToIntersection<
+      {
+        [key in Event]: Options[key] extends (...args: infer Args) => any
+          ? (event: key, ...args: Args) => void
+          : (event: key, ...args: any[]) => void
+      }[Event]
+    >
+
+/**
+ * We expose a subset of properties on the internal instance as they are
+ * useful for advanced external libraries and tools.
+ */
+export declare interface ComponentInternalInstance {
+  uid: number
+  // type: ConcreteComponent
+  parent: ComponentInternalInstance | null
+  root: ComponentInternalInstance
+
+  //appContext: AppContext
+
+  /**
+   * Vnode representing this component in its parent's vdom tree
+   */
+  vnode: VNode
+  /**
+   * Root vnode of this component's own vdom tree
+   */
+  // subTree: VNode // does not exist in Vue 2
+
+  /**
+   * The reactive effect for rendering and patching the component. Callable.
+   */
+  update: Function
+
+  data: Data
+  props: Data
+  attrs: Data
+  refs: Data
+  emit: EmitFn
+
+  slots: InternalSlots
+  emitted: Record<string, boolean> | null
+
+  proxy: ComponentInstance
+
+  isMounted: boolean
+  isUnmounted: boolean
+  isDeactivated: boolean
+}
+
+export function getCurrentVu2Instance() {
   return currentInstance
 }
 
-export function setCurrentInstance(vm: ComponentInstance | null) {
-  currentInstance = vm
+export function getCurrentInstance() {
+  if (currentInstance) {
+    return toVue3ComponentInstance(currentInstance)
+  }
+  return null
+}
+
+const instanceMapCache = new WeakMap<
+  ComponentInstance,
+  ComponentInternalInstance
+>()
+
+function toVue3ComponentInstance(
+  vue2Instance: ComponentInstance
+): ComponentInternalInstance {
+  if (instanceMapCache.has(vue2Instance)) {
+    return instanceMapCache.get(vue2Instance)!
+  }
+
+  const instance: ComponentInternalInstance = ({
+    proxy: vue2Instance,
+    update: vue2Instance.$forceUpdate,
+    uid: vue2Instance._uid,
+
+    parent: null,
+    root: null as any,
+  } as unknown) as ComponentInternalInstance
+
+  // map vm.$props =
+  const instanceProps = [
+    'data',
+    'props',
+    'attrs',
+    'refs',
+    'emit',
+    'vnode',
+    'slots',
+  ] as const
+
+  instanceProps.forEach((prop) => {
+    proxy(instance, prop, {
+      get() {
+        return (vue2Instance as any)[`$${prop}`]
+      },
+    })
+  })
+
+  proxy(instance, 'isMounted', {
+    get() {
+      // @ts-expect-error private api
+      return vue2Instance._isMounted
+    },
+  })
+
+  proxy(instance, 'isUnmounted', {
+    get() {
+      // @ts-expect-error private api
+      return vue2Instance._isDestroyed
+    },
+  })
+
+  proxy(instance, 'isDeactivated', {
+    get() {
+      // @ts-expect-error private api
+      return vue2Instance._inactive
+    },
+  })
+
+  proxy(instance, 'emitted', {
+    get() {
+      // @ts-expect-error private api
+      return vue2Instance._events
+    },
+  })
+
+  instanceMapCache.set(vue2Instance, instance)
+
+  if (vue2Instance.$parent) {
+    instance.parent = toVue3ComponentInstance(vue2Instance.$parent)
+  }
+
+  if (vue2Instance.$root) {
+    instance.root = toVue3ComponentInstance(vue2Instance.$root)
+  }
+
+  return instance
 }

src/utils/helper.ts

@@ -3,7 +3,7 @@ import { ComponentInstance } from '../component'
 import { getCurrentInstance, getVueConstructor } from '../runtimeContext'
 import { warn } from './utils'
 
-export function currentVMInFn(hook: string): ComponentInstance | null {
+export function currentVMInFn(hook: string): ComponentInstance | undefined {
   const vm = getCurrentInstance()
   if (__DEV__ && !vm) {
     warn(
@@ -12,7 +12,7 @@ export function currentVMInFn(hook: string): ComponentInstance | null {
         `Lifecycle injection APIs can only be used during execution of setup().`
     )
   }
-  return vm
+  return vm?.proxy
 }
 
 export function defineComponentInstance<V extends Vue = Vue>(

src/utils/index.ts

@@ -1,2 +1,3 @@
 export * from './utils'
 export * from './helper'
+export * from './typeutils'

src/utils/instance.ts

@@ -1,6 +1,6 @@
 import { ComponentInstance } from '../component'
 import vmStateManager from './vmStateManager'
-import { setCurrentInstance, getCurrentInstance } from '../runtimeContext'
+import { setCurrentInstance, getCurrentVu2Instance } from '../runtimeContext'
 import { Ref, isRef } from '../apis'
 import { hasOwn, proxy, warn } from './utils'
 import { createSlotProxy, resolveSlots } from './helper'
@@ -112,7 +112,7 @@ export function activateCurrentInstance(
   fn: (vm_: ComponentInstance) => any,
   onError?: (err: Error) => void
 ) {
-  let preVm = getCurrentInstance()
+  let preVm = getCurrentVu2Instance()
   setCurrentInstance(vm)
   try {
     return fn(vm)

src/utils/typeutils.ts

@@ -0,0 +1,5 @@
+export type UnionToIntersection<U> = (
+  U extends any ? (k: U) => void : never
+) extends (k: infer I) => void
+  ? I
+  : never

test/setup.spec.js

@@ -12,7 +12,7 @@ const {
   nextTick,
   isReactive,
   defineComponent,
-  onMounted
+  onMounted,
 } = require('../src')
 const { sleep } = require('./helpers/utils')
 
@@ -998,8 +998,7 @@ describe('setup', () => {
   //   await nextTick()
   //   expect(vm.$el.textContent).toBe('1')
   // })
-
-
+
   // #448
   it('should not cause infinite loop', async () => {
     const A = defineComponent({