refactor: simplify functional renderStatic

Author: yyx990803

src/core/instance/render-helpers/render-static.js

@@ -10,13 +10,10 @@ export function renderStatic (
   isInFor?: boolean
 ): VNode | Array<VNode> {
   // static trees can be rendered once and cached on the contructor options
-  // so every instance shares the same trees
-  let options = this.constructor.options
-  if (this.$options.staticRenderFns !== options.staticRenderFns) {
-    options = this.$options
-  }
-  const trees = options._staticTrees || (options._staticTrees = [])
-  let tree = trees[index]
+  // so every instance shares the same cached trees
+  const renderFns = this.$options.staticRenderFns
+  const cached = renderFns.cached || (renderFns.cached = [])
+  let tree = cached[index]
   // if has already-rendered static tree and not inside v-for,
   // we can reuse the same tree by doing a shallow clone.
   if (tree && !isInFor) {
@@ -25,8 +22,7 @@ export function renderStatic (
       : cloneVNode(tree)
   }
   // otherwise, render a fresh tree.
-  tree = trees[index] =
-    options.staticRenderFns[index].call(this._renderProxy, null, this)
+  tree = cached[index] = renderFns[index].call(this._renderProxy, null, this)
   markStatic(tree, `__static__${index}`, false)
   return tree
 }

src/core/instance/render.js

@@ -17,9 +17,10 @@ import { isUpdatingChildComponent } from './lifecycle'
 
 export function initRender (vm: Component) {
   vm._vnode = null // the root of the child tree
-  const parentVnode = vm.$vnode = vm.$options._parentVnode // the placeholder node in parent tree
+  const options = vm.$options
+  const parentVnode = vm.$vnode = options._parentVnode // the placeholder node in parent tree
   const renderContext = parentVnode && parentVnode.context
-  vm.$slots = resolveSlots(vm.$options._renderChildren, renderContext)
+  vm.$slots = resolveSlots(options._renderChildren, renderContext)
   vm.$scopedSlots = emptyObject
   // bind the createElement fn to this instance
   // so that we get proper render context inside it.
@@ -39,12 +40,12 @@ export function initRender (vm: Component) {
     defineReactive(vm, '$attrs', parentData && parentData.attrs || emptyObject, () => {
       !isUpdatingChildComponent && warn(`$attrs is readonly.`, vm)
     }, true)
-    defineReactive(vm, '$listeners', vm.$options._parentListeners || emptyObject, () => {
+    defineReactive(vm, '$listeners', options._parentListeners || emptyObject, () => {
       !isUpdatingChildComponent && warn(`$listeners is readonly.`, vm)
     }, true)
   } else {
     defineReactive(vm, '$attrs', parentData && parentData.attrs || emptyObject, null, true)
-    defineReactive(vm, '$listeners', vm.$options._parentListeners || emptyObject, null, true)
+    defineReactive(vm, '$listeners', options._parentListeners || emptyObject, null, true)
   }
 }
 

src/core/vdom/create-functional-component.js

@@ -38,9 +38,7 @@ function FunctionalRenderContext (
 
   // support for compiled functional template
   if (isCompiled) {
-    // exposing constructor and $options for renderStatic() because it needs
-    // to cache the rendered trees on shared options
-    this.constructor = Ctor
+    // exposing $options for renderStatic()
     this.$options = options
     // pre-resolve slots for renderSlot()
     this.$slots = this.slots()