项目中

前言

这里的 vue 项目是指通过 vue/cli 创建的项目，通过 webpack/vite 运行的项目；根组件配置 render，vue 源码不带编译函数，xx.vue 文件由 webpack 插件 vue-loader 编译成 xx.js 文件，template 被编译为 render 函数，这里只考虑首次加载的情况。

1.Vue 引入

import { createApp } from "vue"

2.根组件

2.1 app

const app = createApp(App)

/packages/runtime-dom/src/index.ts

export const createApp = ((...args) => {
  const app = ensureRenderer().createApp(...args)

  if (__DEV__) {
    injectNativeTagCheck(app)
    injectCompilerOptionsCheck(app)
  }

  const { mount } = app
  app.mount = (containerOrSelector: Element | ShadowRoot | string): any => {
    const container = normalizeContainer(containerOrSelector)
    if (!container) return

    const component = app._component
    if (!isFunction(component) && !component.render && !component.template) {
      // __UNSAFE__
      // Reason: potential execution of JS expressions in in-DOM template.
      // The user must make sure the in-DOM template is trusted. If it's
      // rendered by the server, the template should not contain any user data.
      component.template = container.innerHTML
      // 2.x compat check
      if (__COMPAT__ && __DEV__) {
        for (let i = 0; i < container.attributes.length; i++) {
          const attr = container.attributes[i]
          if (attr.name !== 'v-cloak' && /^(v-|:|@)/.test(attr.name)) {
            compatUtils.warnDeprecation(
              DeprecationTypes.GLOBAL_MOUNT_CONTAINER,
              null
            )
            break
          }
        }
      }
    }

    // clear content before mounting
    container.innerHTML = ''
    const proxy = mount(container, false, container instanceof SVGElement)
    if (container instanceof Element) {
      container.removeAttribute('v-cloak')
      container.setAttribute('data-v-app', '')
    }
    return proxy
  }

  return app
}) as CreateAppFunction<Element>

/packages/runtime-dom/src/index.ts

function ensureRenderer() {
  return (
    renderer ||
    (renderer = createRenderer<Node, Element | ShadowRoot>(rendererOptions))
  )
}

/packages/runtime-core/src/renderer.ts

export function createRenderer<
  HostNode = RendererNode,
  HostElement = RendererElement
>(options: RendererOptions<HostNode, HostElement>) {
  return baseCreateRenderer<HostNode, HostElement>(options)
}

/packages/runtime-core/src/renderer.ts

function baseCreateRenderer(
  options: RendererOptions,
  createHydrationFns?: typeof createHydrationFunctions
): any {
  // compile-time feature flags check
  if (__ESM_BUNDLER__ && !__TEST__) {
    initFeatureFlags()
  }

  const target = getGlobalThis()
  target.__VUE__ = true
  if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
    setDevtoolsHook(target.__VUE_DEVTOOLS_GLOBAL_HOOK__, target)
  }

  const {
    insert: hostInsert,
    remove: hostRemove,
    patchProp: hostPatchProp,
    createElement: hostCreateElement,
    createText: hostCreateText,
    createComment: hostCreateComment,
    setText: hostSetText,
    setElementText: hostSetElementText,
    parentNode: hostParentNode,
    nextSibling: hostNextSibling,
    setScopeId: hostSetScopeId = NOOP,
    cloneNode: hostCloneNode,
    insertStaticContent: hostInsertStaticContent
  } = options

  // Note: functions inside this closure should use `const xxx = () => {}`
  // style in order to prevent being inlined by minifiers.
  const patch: PatchFn = (
    n1,
    n2,
    container,
    anchor = null,
    parentComponent = null,
    parentSuspense = null,
    isSVG = false,
    slotScopeIds = null,
    optimized = __DEV__ && isHmrUpdating ? false : !!n2.dynamicChildren
  ) => {
    if (n1 === n2) {
      return
    }

    // patching & not same type, unmount old tree
    if (n1 && !isSameVNodeType(n1, n2)) {
      anchor = getNextHostNode(n1)
      unmount(n1, parentComponent, parentSuspense, true)
      n1 = null
    }

    if (n2.patchFlag === PatchFlags.BAIL) {
      optimized = false
      n2.dynamicChildren = null
    }

    const { type, ref, shapeFlag } = n2
    switch (type) {
      case Text:
        processText(n1, n2, container, anchor)
        break
      case Comment:
        processCommentNode(n1, n2, container, anchor)
        break
      case Static:
        if (n1 == null) {
          mountStaticNode(n2, container, anchor, isSVG)
        } else if (__DEV__) {
          patchStaticNode(n1, n2, container, isSVG)
        }
        break
      case Fragment:
        processFragment(
          n1,
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        break
      default:
        if (shapeFlag & ShapeFlags.ELEMENT) {
          processElement(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & ShapeFlags.COMPONENT) {
          processComponent(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & ShapeFlags.TELEPORT) {
          ;(type as typeof TeleportImpl).process(
            n1 as TeleportVNode,
            n2 as TeleportVNode,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else if (__FEATURE_SUSPENSE__ && shapeFlag & ShapeFlags.SUSPENSE) {
          ;(type as typeof SuspenseImpl).process(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else if (__DEV__) {
          warn('Invalid VNode type:', type, `(${typeof type})`)
        }
    }

    // set ref
    if (ref != null && parentComponent) {
      setRef(ref, n1 && n1.ref, parentSuspense, n2 || n1, !n2)
    }
  }
  const processText: ProcessTextOrCommentFn = (n1, n2, container, anchor) => {
    if (n1 == null) {
      hostInsert(
        (n2.el = hostCreateText(n2.children as string)),
        container,
        anchor
      )
    } else {
      const el = (n2.el = n1.el!)
      if (n2.children !== n1.children) {
        hostSetText(el, n2.children as string)
      }
    }
  }

  const processCommentNode: ProcessTextOrCommentFn = (
    n1,
    n2,
    container,
    anchor
  ) => {
    if (n1 == null) {
      hostInsert(
        (n2.el = hostCreateComment((n2.children as string) || '')),
        container,
        anchor
      )
    } else {
      // there's no support for dynamic comments
      n2.el = n1.el
    }
  }

  const mountStaticNode = (
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    isSVG: boolean
  ) => {
    // static nodes are only present when used with compiler-dom/runtime-dom
    // which guarantees presence of hostInsertStaticContent.
    ;[n2.el, n2.anchor] = hostInsertStaticContent!(
      n2.children as string,
      container,
      anchor,
      isSVG,
      n2.el,
      n2.anchor
    )
  }

  /**
   * Dev / HMR only
   */
  const patchStaticNode = (
    n1: VNode,
    n2: VNode,
    container: RendererElement,
    isSVG: boolean
  ) => {
    // static nodes are only patched during dev for HMR
    if (n2.children !== n1.children) {
      const anchor = hostNextSibling(n1.anchor!)
      // remove existing
      removeStaticNode(n1)
      // insert new
      ;[n2.el, n2.anchor] = hostInsertStaticContent!(
        n2.children as string,
        container,
        anchor,
        isSVG
      )
    } else {
      n2.el = n1.el
      n2.anchor = n1.anchor
    }
  }

  const moveStaticNode = (
    { el, anchor }: VNode,
    container: RendererElement,
    nextSibling: RendererNode | null
  ) => {
    let next
    while (el && el !== anchor) {
      next = hostNextSibling(el)
      hostInsert(el, container, nextSibling)
      el = next
    }
    hostInsert(anchor!, container, nextSibling)
  }

  const removeStaticNode = ({ el, anchor }: VNode) => {
    let next
    while (el && el !== anchor) {
      next = hostNextSibling(el)
      hostRemove(el)
      el = next
    }
    hostRemove(anchor!)
  }
  const processElement = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    isSVG = isSVG || (n2.type as string) === 'svg'
    if (n1 == null) {
      mountElement(
        n2,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    } else {
      patchElement(
        n1,
        n2,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }
  const mountElement = (
    vnode: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    let el: RendererElement
    let vnodeHook: VNodeHook | undefined | null
    const { type, props, shapeFlag, transition, patchFlag, dirs } = vnode
    if (
      !__DEV__ &&
      vnode.el &&
      hostCloneNode !== undefined &&
      patchFlag === PatchFlags.HOISTED
    ) {
      // If a vnode has non-null el, it means it's being reused.
      // Only static vnodes can be reused, so its mounted DOM nodes should be
      // exactly the same, and we can simply do a clone here.
      // only do this in production since cloned trees cannot be HMR updated.
      el = vnode.el = hostCloneNode(vnode.el)
    } else {
      el = vnode.el = hostCreateElement(
        vnode.type as string,
        isSVG,
        props && props.is,
        props
      )

      // mount children first, since some props may rely on child content
      // being already rendered, e.g. `<select value>`
      if (shapeFlag & ShapeFlags.TEXT_CHILDREN) {
        hostSetElementText(el, vnode.children as string)
      } else if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
        mountChildren(
          vnode.children as VNodeArrayChildren,
          el,
          null,
          parentComponent,
          parentSuspense,
          isSVG && type !== 'foreignObject',
          slotScopeIds,
          optimized
        )
      }

      if (dirs) {
        invokeDirectiveHook(vnode, null, parentComponent, 'created')
      }
      // props
      if (props) {
        for (const key in props) {
          if (key !== 'value' && !isReservedProp(key)) {
            hostPatchProp(
              el,
              key,
              null,
              props[key],
              isSVG,
              vnode.children as VNode[],
              parentComponent,
              parentSuspense,
              unmountChildren
            )
          }
        }
        /**
         * Special case for setting value on DOM elements:
         * - it can be order-sensitive (e.g. should be set *after* min/max, #2325, #4024)
         * - it needs to be forced (#1471)
         * #2353 proposes adding another renderer option to configure this, but
         * the properties affects are so finite it is worth special casing it
         * here to reduce the complexity. (Special casing it also should not
         * affect non-DOM renderers)
         */
        if ('value' in props) {
          hostPatchProp(el, 'value', null, props.value)
        }
        if ((vnodeHook = props.onVnodeBeforeMount)) {
          invokeVNodeHook(vnodeHook, parentComponent, vnode)
        }
      }
      // scopeId
      setScopeId(el, vnode, vnode.scopeId, slotScopeIds, parentComponent)
    }
    if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
      Object.defineProperty(el, '__vnode', {
        value: vnode,
        enumerable: false
      })
      Object.defineProperty(el, '__vueParentComponent', {
        value: parentComponent,
        enumerable: false
      })
    }
    if (dirs) {
      invokeDirectiveHook(vnode, null, parentComponent, 'beforeMount')
    }
    // #1583 For inside suspense + suspense not resolved case, enter hook should call when suspense resolved
    // #1689 For inside suspense + suspense resolved case, just call it
    const needCallTransitionHooks =
      (!parentSuspense || (parentSuspense && !parentSuspense.pendingBranch)) &&
      transition &&
      !transition.persisted
    if (needCallTransitionHooks) {
      transition!.beforeEnter(el)
    }
    hostInsert(el, container, anchor)
    if (
      (vnodeHook = props && props.onVnodeMounted) ||
      needCallTransitionHooks ||
      dirs
    ) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, vnode)
        needCallTransitionHooks && transition!.enter(el)
        dirs && invokeDirectiveHook(vnode, null, parentComponent, 'mounted')
      }, parentSuspense)
    }
  }

  const setScopeId = (
    el: RendererElement,
    vnode: VNode,
    scopeId: string | null,
    slotScopeIds: string[] | null,
    parentComponent: ComponentInternalInstance | null
  ) => {
    if (scopeId) {
      hostSetScopeId(el, scopeId)
    }
    if (slotScopeIds) {
      for (let i = 0; i < slotScopeIds.length; i++) {
        hostSetScopeId(el, slotScopeIds[i])
      }
    }
    if (parentComponent) {
      let subTree = parentComponent.subTree
      if (
        __DEV__ &&
        subTree.patchFlag > 0 &&
        subTree.patchFlag & PatchFlags.DEV_ROOT_FRAGMENT
      ) {
        subTree =
          filterSingleRoot(subTree.children as VNodeArrayChildren) || subTree
      }
      if (vnode === subTree) {
        const parentVNode = parentComponent.vnode
        setScopeId(
          el,
          parentVNode,
          parentVNode.scopeId,
          parentVNode.slotScopeIds,
          parentComponent.parent
        )
      }
    }
  }

  const mountChildren: MountChildrenFn = (
    children,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized,
    start = 0
  ) => {
    for (let i = start; i < children.length; i++) {
      const child = (children[i] = optimized
        ? cloneIfMounted(children[i] as VNode)
        : normalizeVNode(children[i]))
      patch(
        null,
        child,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }
  const patchElement = (
    n1: VNode,
    n2: VNode,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    const el = (n2.el = n1.el!)
    let { patchFlag, dynamicChildren, dirs } = n2
    // #1426 take the old vnode's patch flag into account since user may clone a
    // compiler-generated vnode, which de-opts to FULL_PROPS
    patchFlag |= n1.patchFlag & PatchFlags.FULL_PROPS
    const oldProps = n1.props || EMPTY_OBJ
    const newProps = n2.props || EMPTY_OBJ
    let vnodeHook: VNodeHook | undefined | null

    // disable recurse in beforeUpdate hooks
    parentComponent && toggleRecurse(parentComponent, false)
    if ((vnodeHook = newProps.onVnodeBeforeUpdate)) {
      invokeVNodeHook(vnodeHook, parentComponent, n2, n1)
    }
    if (dirs) {
      invokeDirectiveHook(n2, n1, parentComponent, 'beforeUpdate')
    }
    parentComponent && toggleRecurse(parentComponent, true)

    if (__DEV__ && isHmrUpdating) {
      // HMR updated, force full diff
      patchFlag = 0
      optimized = false
      dynamicChildren = null
    }

    const areChildrenSVG = isSVG && n2.type !== 'foreignObject'
    if (dynamicChildren) {
      patchBlockChildren(
        n1.dynamicChildren!,
        dynamicChildren,
        el,
        parentComponent,
        parentSuspense,
        areChildrenSVG,
        slotScopeIds
      )
      if (__DEV__ && parentComponent && parentComponent.type.__hmrId) {
        traverseStaticChildren(n1, n2)
      }
    } else if (!optimized) {
      // full diff
      patchChildren(
        n1,
        n2,
        el,
        null,
        parentComponent,
        parentSuspense,
        areChildrenSVG,
        slotScopeIds,
        false
      )
    }

    if (patchFlag > 0) {
      // the presence of a patchFlag means this element's render code was
      // generated by the compiler and can take the fast path.
      // in this path old node and new node are guaranteed to have the same shape
      // (i.e. at the exact same position in the source template)
      if (patchFlag & PatchFlags.FULL_PROPS) {
        // element props contain dynamic keys, full diff needed
        patchProps(
          el,
          n2,
          oldProps,
          newProps,
          parentComponent,
          parentSuspense,
          isSVG
        )
      } else {
        // class
        // this flag is matched when the element has dynamic class bindings.
        if (patchFlag & PatchFlags.CLASS) {
          if (oldProps.class !== newProps.class) {
            hostPatchProp(el, 'class', null, newProps.class, isSVG)
          }
        }

        // style
        // this flag is matched when the element has dynamic style bindings
        if (patchFlag & PatchFlags.STYLE) {
          hostPatchProp(el, 'style', oldProps.style, newProps.style, isSVG)
        }

        // props
        // This flag is matched when the element has dynamic prop/attr bindings
        // other than class and style. The keys of dynamic prop/attrs are saved for
        // faster iteration.
        // Note dynamic keys like :[foo]="bar" will cause this optimization to
        // bail out and go through a full diff because we need to unset the old key
        if (patchFlag & PatchFlags.PROPS) {
          // if the flag is present then dynamicProps must be non-null
          const propsToUpdate = n2.dynamicProps!
          for (let i = 0; i < propsToUpdate.length; i++) {
            const key = propsToUpdate[i]
            const prev = oldProps[key]
            const next = newProps[key]
            // #1471 force patch value
            if (next !== prev || key === 'value') {
              hostPatchProp(
                el,
                key,
                prev,
                next,
                isSVG,
                n1.children as VNode[],
                parentComponent,
                parentSuspense,
                unmountChildren
              )
            }
          }
        }
      }

      // text
      // This flag is matched when the element has only dynamic text children.
      if (patchFlag & PatchFlags.TEXT) {
        if (n1.children !== n2.children) {
          hostSetElementText(el, n2.children as string)
        }
      }
    } else if (!optimized && dynamicChildren == null) {
      // unoptimized, full diff
      patchProps(
        el,
        n2,
        oldProps,
        newProps,
        parentComponent,
        parentSuspense,
        isSVG
      )
    }

    if ((vnodeHook = newProps.onVnodeUpdated) || dirs) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, n2, n1)
        dirs && invokeDirectiveHook(n2, n1, parentComponent, 'updated')
      }, parentSuspense)
    }
  }
  // The fast path for blocks.
  const patchBlockChildren: PatchBlockChildrenFn = (
    oldChildren,
    newChildren,
    fallbackContainer,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds
  ) => {
    for (let i = 0; i < newChildren.length; i++) {
      const oldVNode = oldChildren[i]
      const newVNode = newChildren[i]
      // Determine the container (parent element) for the patch.
      const container =
        // oldVNode may be an errored async setup() component inside Suspense
        // which will not have a mounted element
        oldVNode.el &&
        // - In the case of a Fragment, we need to provide the actual parent
        // of the Fragment itself so it can move its children.
        (oldVNode.type === Fragment ||
          // - In the case of different nodes, there is going to be a replacement
          // which also requires the correct parent container
          !isSameVNodeType(oldVNode, newVNode) ||
          // - In the case of a component, it could contain anything.
          oldVNode.shapeFlag & (ShapeFlags.COMPONENT | ShapeFlags.TELEPORT))
          ? hostParentNode(oldVNode.el)!
          : // In other cases, the parent container is not actually used so we
            // just pass the block element here to avoid a DOM parentNode call.
            fallbackContainer
      patch(
        oldVNode,
        newVNode,
        container,
        null,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        true
      )
    }
  }

  const patchProps = (
    el: RendererElement,
    vnode: VNode,
    oldProps: Data,
    newProps: Data,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean
  ) => {
    if (oldProps !== newProps) {
      for (const key in newProps) {
        // empty string is not valid prop
        if (isReservedProp(key)) continue
        const next = newProps[key]
        const prev = oldProps[key]
        // defer patching value
        if (next !== prev && key !== 'value') {
          hostPatchProp(
            el,
            key,
            prev,
            next,
            isSVG,
            vnode.children as VNode[],
            parentComponent,
            parentSuspense,
            unmountChildren
          )
        }
      }
      if (oldProps !== EMPTY_OBJ) {
        for (const key in oldProps) {
          if (!isReservedProp(key) && !(key in newProps)) {
            hostPatchProp(
              el,
              key,
              oldProps[key],
              null,
              isSVG,
              vnode.children as VNode[],
              parentComponent,
              parentSuspense,
              unmountChildren
            )
          }
        }
      }
      if ('value' in newProps) {
        hostPatchProp(el, 'value', oldProps.value, newProps.value)
      }
    }
  }

  const processFragment = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    const fragmentStartAnchor = (n2.el = n1 ? n1.el : hostCreateText(''))!
    const fragmentEndAnchor = (n2.anchor = n1 ? n1.anchor : hostCreateText(''))!

    let { patchFlag, dynamicChildren, slotScopeIds: fragmentSlotScopeIds } = n2

    if (__DEV__ && isHmrUpdating) {
      // HMR updated, force full diff
      patchFlag = 0
      optimized = false
      dynamicChildren = null
    }

    // check if this is a slot fragment with :slotted scope ids
    if (fragmentSlotScopeIds) {
      slotScopeIds = slotScopeIds
        ? slotScopeIds.concat(fragmentSlotScopeIds)
        : fragmentSlotScopeIds
    }

    if (n1 == null) {
      hostInsert(fragmentStartAnchor, container, anchor)
      hostInsert(fragmentEndAnchor, container, anchor)
      // a fragment can only have array children
      // since they are either generated by the compiler, or implicitly created
      // from arrays.
      mountChildren(
        n2.children as VNodeArrayChildren,
        container,
        fragmentEndAnchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    } else {
      if (
        patchFlag > 0 &&
        patchFlag & PatchFlags.STABLE_FRAGMENT &&
        dynamicChildren &&
        // #2715 the previous fragment could've been a BAILed one as a result
        // of renderSlot() with no valid children
        n1.dynamicChildren
      ) {
        // a stable fragment (template root or <template v-for>) doesn't need to
        // patch children order, but it may contain dynamicChildren.
        patchBlockChildren(
          n1.dynamicChildren,
          dynamicChildren,
          container,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds
        )
        if (__DEV__ && parentComponent && parentComponent.type.__hmrId) {
          traverseStaticChildren(n1, n2)
        } else if (
          // #2080 if the stable fragment has a key, it's a <template v-for> that may
          //  get moved around. Make sure all root level vnodes inherit el.
          // #2134 or if it's a component root, it may also get moved around
          // as the component is being moved.
          n2.key != null ||
          (parentComponent && n2 === parentComponent.subTree)
        ) {
          traverseStaticChildren(n1, n2, true /* shallow */)
        }
      } else {
        // keyed / unkeyed, or manual fragments.
        // for keyed & unkeyed, since they are compiler generated from v-for,
        // each child is guaranteed to be a block so the fragment will never
        // have dynamicChildren.
        patchChildren(
          n1,
          n2,
          container,
          fragmentEndAnchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      }
    }
  }

  const processComponent = (
    n1: VNode | null,
    n2: VNode,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    n2.slotScopeIds = slotScopeIds
    if (n1 == null) {
      if (n2.shapeFlag & ShapeFlags.COMPONENT_KEPT_ALIVE) {
        ;(parentComponent!.ctx as KeepAliveContext).activate(
          n2,
          container,
          anchor,
          isSVG,
          optimized
        )
      } else {
        mountComponent(
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          optimized
        )
      }
    } else {
      updateComponent(n1, n2, optimized)
    }
  }

  const mountComponent: MountComponentFn = (
    initialVNode,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    // 2.x compat may pre-create the component instance before actually
    // mounting
    const compatMountInstance =
      __COMPAT__ && initialVNode.isCompatRoot && initialVNode.component
    const instance: ComponentInternalInstance =
      compatMountInstance ||
      (initialVNode.component = createComponentInstance(
        initialVNode,
        parentComponent,
        parentSuspense
      ))

    if (__DEV__ && instance.type.__hmrId) {
      registerHMR(instance)
    }

    if (__DEV__) {
      pushWarningContext(initialVNode)
      startMeasure(instance, `mount`)
    }

    // inject renderer internals for keepAlive
    if (isKeepAlive(initialVNode)) {
      ;(instance.ctx as KeepAliveContext).renderer = internals
    }

    // resolve props and slots for setup context
    if (!(__COMPAT__ && compatMountInstance)) {
      if (__DEV__) {
        startMeasure(instance, `init`)
      }
      setupComponent(instance)
      if (__DEV__) {
        endMeasure(instance, `init`)
      }
    }

    // setup() is async. This component relies on async logic to be resolved
    // before proceeding
    if (__FEATURE_SUSPENSE__ && instance.asyncDep) {
      parentSuspense && parentSuspense.registerDep(instance, setupRenderEffect)

      // Give it a placeholder if this is not hydration
      // TODO handle self-defined fallback
      if (!initialVNode.el) {
        const placeholder = (instance.subTree = createVNode(Comment))
        processCommentNode(null, placeholder, container!, anchor)
      }
      return
    }

    setupRenderEffect(
      instance,
      initialVNode,
      container,
      anchor,
      parentSuspense,
      isSVG,
      optimized
    )

    if (__DEV__) {
      popWarningContext()
      endMeasure(instance, `mount`)
    }
  }

  const updateComponent = (n1: VNode, n2: VNode, optimized: boolean) => {
    const instance = (n2.component = n1.component)!
    if (shouldUpdateComponent(n1, n2, optimized)) {
      if (
        __FEATURE_SUSPENSE__ &&
        instance.asyncDep &&
        !instance.asyncResolved
      ) {
        // async & still pending - just update props and slots
        // since the component's reactive effect for render isn't set-up yet
        if (__DEV__) {
          pushWarningContext(n2)
        }
        updateComponentPreRender(instance, n2, optimized)
        if (__DEV__) {
          popWarningContext()
        }
        return
      } else {
        // normal update
        instance.next = n2
        // in case the child component is also queued, remove it to avoid
        // double updating the same child component in the same flush.
        invalidateJob(instance.update)
        // instance.update is the reactive effect.
        instance.update()
      }
    } else {
      // no update needed. just copy over properties
      n2.component = n1.component
      n2.el = n1.el
      instance.vnode = n2
    }
  }

  const setupRenderEffect: SetupRenderEffectFn = (
    instance,
    initialVNode,
    container,
    anchor,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    const componentUpdateFn = () => {
      if (!instance.isMounted) {
        let vnodeHook: VNodeHook | null | undefined
        const { el, props } = initialVNode
        const { bm, m, parent } = instance
        const isAsyncWrapperVNode = isAsyncWrapper(initialVNode)

        toggleRecurse(instance, false)
        // beforeMount hook
        if (bm) {
          invokeArrayFns(bm)
        }
        // onVnodeBeforeMount
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeBeforeMount)
        ) {
          invokeVNodeHook(vnodeHook, parent, initialVNode)
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          instance.emit('hook:beforeMount')
        }
        toggleRecurse(instance, true)

        if (el && hydrateNode) {
          // vnode has adopted host node - perform hydration instead of mount.
          const hydrateSubTree = () => {
            if (__DEV__) {
              startMeasure(instance, `render`)
            }
            instance.subTree = renderComponentRoot(instance)
            if (__DEV__) {
              endMeasure(instance, `render`)
            }
            if (__DEV__) {
              startMeasure(instance, `hydrate`)
            }
            hydrateNode!(
              el as Node,
              instance.subTree,
              instance,
              parentSuspense,
              null
            )
            if (__DEV__) {
              endMeasure(instance, `hydrate`)
            }
          }

          if (isAsyncWrapperVNode) {
            ;(initialVNode.type as ComponentOptions).__asyncLoader!().then(
              // note: we are moving the render call into an async callback,
              // which means it won't track dependencies - but it's ok because
              // a server-rendered async wrapper is already in resolved state
              // and it will never need to change.
              () => !instance.isUnmounted && hydrateSubTree()
            )
          } else {
            hydrateSubTree()
          }
        } else {
          if (__DEV__) {
            startMeasure(instance, `render`)
          }
          const subTree = (instance.subTree = renderComponentRoot(instance))
          if (__DEV__) {
            endMeasure(instance, `render`)
          }
          if (__DEV__) {
            startMeasure(instance, `patch`)
          }
          patch(
            null,
            subTree,
            container,
            anchor,
            instance,
            parentSuspense,
            isSVG
          )
          if (__DEV__) {
            endMeasure(instance, `patch`)
          }
          initialVNode.el = subTree.el
        }
        // mounted hook
        if (m) {
          queuePostRenderEffect(m, parentSuspense)
        }
        // onVnodeMounted
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeMounted)
        ) {
          const scopedInitialVNode = initialVNode
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook!, parent, scopedInitialVNode),
            parentSuspense
          )
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          queuePostRenderEffect(
            () => instance.emit('hook:mounted'),
            parentSuspense
          )
        }

        // activated hook for keep-alive roots.
        // #1742 activated hook must be accessed after first render
        // since the hook may be injected by a child keep-alive
        if (initialVNode.shapeFlag & ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE) {
          instance.a && queuePostRenderEffect(instance.a, parentSuspense)
          if (
            __COMPAT__ &&
            isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
          ) {
            queuePostRenderEffect(
              () => instance.emit('hook:activated'),
              parentSuspense
            )
          }
        }
        instance.isMounted = true

        if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
          devtoolsComponentAdded(instance)
        }

        // #2458: deference mount-only object parameters to prevent memleaks
        initialVNode = container = anchor = null as any
      } else {
        // updateComponent
        // This is triggered by mutation of component's own state (next: null)
        // OR parent calling processComponent (next: VNode)
        let { next, bu, u, parent, vnode } = instance
        let originNext = next
        let vnodeHook: VNodeHook | null | undefined
        if (__DEV__) {
          pushWarningContext(next || instance.vnode)
        }

        // Disallow component effect recursion during pre-lifecycle hooks.
        toggleRecurse(instance, false)
        if (next) {
          next.el = vnode.el
          updateComponentPreRender(instance, next, optimized)
        } else {
          next = vnode
        }

        // beforeUpdate hook
        if (bu) {
          invokeArrayFns(bu)
        }
        // onVnodeBeforeUpdate
        if ((vnodeHook = next.props && next.props.onVnodeBeforeUpdate)) {
          invokeVNodeHook(vnodeHook, parent, next, vnode)
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          instance.emit('hook:beforeUpdate')
        }
        toggleRecurse(instance, true)

        // render
        if (__DEV__) {
          startMeasure(instance, `render`)
        }
        const nextTree = renderComponentRoot(instance)
        if (__DEV__) {
          endMeasure(instance, `render`)
        }
        const prevTree = instance.subTree
        instance.subTree = nextTree

        if (__DEV__) {
          startMeasure(instance, `patch`)
        }
        patch(
          prevTree,
          nextTree,
          // parent may have changed if it's in a teleport
          hostParentNode(prevTree.el!)!,
          // anchor may have changed if it's in a fragment
          getNextHostNode(prevTree),
          instance,
          parentSuspense,
          isSVG
        )
        if (__DEV__) {
          endMeasure(instance, `patch`)
        }
        next.el = nextTree.el
        if (originNext === null) {
          // self-triggered update. In case of HOC, update parent component
          // vnode el. HOC is indicated by parent instance's subTree pointing
          // to child component's vnode
          updateHOCHostEl(instance, nextTree.el)
        }
        // updated hook
        if (u) {
          queuePostRenderEffect(u, parentSuspense)
        }
        // onVnodeUpdated
        if ((vnodeHook = next.props && next.props.onVnodeUpdated)) {
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook!, parent, next!, vnode),
            parentSuspense
          )
        }
        if (
          __COMPAT__ &&
          isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
        ) {
          queuePostRenderEffect(
            () => instance.emit('hook:updated'),
            parentSuspense
          )
        }

        if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
          devtoolsComponentUpdated(instance)
        }

        if (__DEV__) {
          popWarningContext()
        }
      }
    }

    // create reactive effect for rendering
    const effect = (instance.effect = new ReactiveEffect(
      componentUpdateFn,
      () => queueJob(instance.update),
      instance.scope // track it in component's effect scope
    ))

    const update = (instance.update = effect.run.bind(effect) as SchedulerJob)
    update.id = instance.uid
    // allowRecurse
    // #1801, #2043 component render effects should allow recursive updates
    toggleRecurse(instance, true)

    if (__DEV__) {
      effect.onTrack = instance.rtc
        ? e => invokeArrayFns(instance.rtc!, e)
        : void 0
      effect.onTrigger = instance.rtg
        ? e => invokeArrayFns(instance.rtg!, e)
        : void 0
      // @ts-ignore (for scheduler)
      update.ownerInstance = instance
    }

    update()
  }

  const updateComponentPreRender = (
    instance: ComponentInternalInstance,
    nextVNode: VNode,
    optimized: boolean
  ) => {
    nextVNode.component = instance
    const prevProps = instance.vnode.props
    instance.vnode = nextVNode
    instance.next = null
    updateProps(instance, nextVNode.props, prevProps, optimized)
    updateSlots(instance, nextVNode.children, optimized)

    pauseTracking()
    // props update may have triggered pre-flush watchers.
    // flush them before the render update.
    flushPreFlushCbs(undefined, instance.update)
    resetTracking()
  }

  const patchChildren: PatchChildrenFn = (
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized = false
  ) => {
    const c1 = n1 && n1.children
    const prevShapeFlag = n1 ? n1.shapeFlag : 0
    const c2 = n2.children

    const { patchFlag, shapeFlag } = n2
    // fast path
    if (patchFlag > 0) {
      if (patchFlag & PatchFlags.KEYED_FRAGMENT) {
        // this could be either fully-keyed or mixed (some keyed some not)
        // presence of patchFlag means children are guaranteed to be arrays
        patchKeyedChildren(
          c1 as VNode[],
          c2 as VNodeArrayChildren,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        return
      } else if (patchFlag & PatchFlags.UNKEYED_FRAGMENT) {
        // unkeyed
        patchUnkeyedChildren(
          c1 as VNode[],
          c2 as VNodeArrayChildren,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        return
      }
    }

    // children has 3 possibilities: text, array or no children.
    if (shapeFlag & ShapeFlags.TEXT_CHILDREN) {
      // text children fast path
      if (prevShapeFlag & ShapeFlags.ARRAY_CHILDREN) {
        unmountChildren(c1 as VNode[], parentComponent, parentSuspense)
      }
      if (c2 !== c1) {
        hostSetElementText(container, c2 as string)
      }
    } else {
      if (prevShapeFlag & ShapeFlags.ARRAY_CHILDREN) {
        // prev children was array
        if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
          // two arrays, cannot assume anything, do full diff
          patchKeyedChildren(
            c1 as VNode[],
            c2 as VNodeArrayChildren,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else {
          // no new children, just unmount old
          unmountChildren(c1 as VNode[], parentComponent, parentSuspense, true)
        }
      } else {
        // prev children was text OR null
        // new children is array OR null
        if (prevShapeFlag & ShapeFlags.TEXT_CHILDREN) {
          hostSetElementText(container, '')
        }
        // mount new if array
        if (shapeFlag & ShapeFlags.ARRAY_CHILDREN) {
          mountChildren(
            c2 as VNodeArrayChildren,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        }
      }
    }
  }

  const patchUnkeyedChildren = (
    c1: VNode[],
    c2: VNodeArrayChildren,
    container: RendererElement,
    anchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    c1 = c1 || EMPTY_ARR
    c2 = c2 || EMPTY_ARR
    const oldLength = c1.length
    const newLength = c2.length
    const commonLength = Math.min(oldLength, newLength)
    let i
    for (i = 0; i < commonLength; i++) {
      const nextChild = (c2[i] = optimized
        ? cloneIfMounted(c2[i] as VNode)
        : normalizeVNode(c2[i]))
      patch(
        c1[i],
        nextChild,
        container,
        null,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
    if (oldLength > newLength) {
      // remove old
      unmountChildren(
        c1,
        parentComponent,
        parentSuspense,
        true,
        false,
        commonLength
      )
    } else {
      // mount new
      mountChildren(
        c2,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized,
        commonLength
      )
    }
  }

  // can be all-keyed or mixed
  const patchKeyedChildren = (
    c1: VNode[],
    c2: VNodeArrayChildren,
    container: RendererElement,
    parentAnchor: RendererNode | null,
    parentComponent: ComponentInternalInstance | null,
    parentSuspense: SuspenseBoundary | null,
    isSVG: boolean,
    slotScopeIds: string[] | null,
    optimized: boolean
  ) => {
    let i = 0
    const l2 = c2.length
    let e1 = c1.length - 1 // prev ending index
    let e2 = l2 - 1 // next ending index

    // 1. sync from start
    // (a b) c
    // (a b) d e
    while (i <= e1 && i <= e2) {
      const n1 = c1[i]
      const n2 = (c2[i] = optimized
        ? cloneIfMounted(c2[i] as VNode)
        : normalizeVNode(c2[i]))
      if (isSameVNodeType(n1, n2)) {
        patch(
          n1,
          n2,
          container,
          null,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      } else {
        break
      }
      i++
    }

    // 2. sync from end
    // a (b c)
    // d e (b c)
    while (i <= e1 && i <= e2) {
      const n1 = c1[e1]
      const n2 = (c2[e2] = optimized
        ? cloneIfMounted(c2[e2] as VNode)
        : normalizeVNode(c2[e2]))
      if (isSameVNodeType(n1, n2)) {
        patch(
          n1,
          n2,
          container,
          null,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      } else {
        break
      }
      e1--
      e2--
    }

    // 3. common sequence + mount
    // (a b)
    // (a b) c
    // i = 2, e1 = 1, e2 = 2
    // (a b)
    // c (a b)
    // i = 0, e1 = -1, e2 = 0
    if (i > e1) {
      if (i <= e2) {
        const nextPos = e2 + 1
        const anchor = nextPos < l2 ? (c2[nextPos] as VNode).el : parentAnchor
        while (i <= e2) {
          patch(
            null,
            (c2[i] = optimized
              ? cloneIfMounted(c2[i] as VNode)
              : normalizeVNode(c2[i])),
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
          i++
        }
      }
    }

    // 4. common sequence + unmount
    // (a b) c
    // (a b)
    // i = 2, e1 = 2, e2 = 1
    // a (b c)
    // (b c)
    // i = 0, e1 = 0, e2 = -1
    else if (i > e2) {
      while (i <= e1) {
        unmount(c1[i], parentComponent, parentSuspense, true)
        i++
      }
    }

    // 5. unknown sequence
    // [i ... e1 + 1]: a b [c d e] f g
    // [i ... e2 + 1]: a b [e d c h] f g
    // i = 2, e1 = 4, e2 = 5
    else {
      const s1 = i // prev starting index
      const s2 = i // next starting index

      // 5.1 build key:index map for newChildren
      const keyToNewIndexMap: Map<string | number | symbol, number> = new Map()
      for (i = s2; i <= e2; i++) {
        const nextChild = (c2[i] = optimized
          ? cloneIfMounted(c2[i] as VNode)
          : normalizeVNode(c2[i]))
        if (nextChild.key != null) {
          if (__DEV__ && keyToNewIndexMap.has(nextChild.key)) {
            warn(
              `Duplicate keys found during update:`,
              JSON.stringify(nextChild.key),
              `Make sure keys are unique.`
            )
          }
          keyToNewIndexMap.set(nextChild.key, i)
        }
      }

      // 5.2 loop through old children left to be patched and try to patch
      // matching nodes & remove nodes that are no longer present
      let j
      let patched = 0
      const toBePatched = e2 - s2 + 1
      let moved = false
      // used to track whether any node has moved
      let maxNewIndexSoFar = 0
      // works as Map<newIndex, oldIndex>
      // Note that oldIndex is offset by +1
      // and oldIndex = 0 is a special value indicating the new node has
      // no corresponding old node.
      // used for determining longest stable subsequence
      const newIndexToOldIndexMap = new Array(toBePatched)
      for (i = 0; i < toBePatched; i++) newIndexToOldIndexMap[i] = 0

      for (i = s1; i <= e1; i++) {
        const prevChild = c1[i]
        if (patched >= toBePatched) {
          // all new children have been patched so this can only be a removal
          unmount(prevChild, parentComponent, parentSuspense, true)
          continue
        }
        let newIndex
        if (prevChild.key != null) {
          newIndex = keyToNewIndexMap.get(prevChild.key)
        } else {
          // key-less node, try to locate a key-less node of the same type
          for (j = s2; j <= e2; j++) {
            if (
              newIndexToOldIndexMap[j - s2] === 0 &&
              isSameVNodeType(prevChild, c2[j] as VNode)
            ) {
              newIndex = j
              break
            }
          }
        }
        if (newIndex === undefined) {
          unmount(prevChild, parentComponent, parentSuspense, true)
        } else {
          newIndexToOldIndexMap[newIndex - s2] = i + 1
          if (newIndex >= maxNewIndexSoFar) {
            maxNewIndexSoFar = newIndex
          } else {
            moved = true
          }
          patch(
            prevChild,
            c2[newIndex] as VNode,
            container,
            null,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
          patched++
        }
      }

      // 5.3 move and mount
      // generate longest stable subsequence only when nodes have moved
      const increasingNewIndexSequence = moved
        ? getSequence(newIndexToOldIndexMap)
        : EMPTY_ARR
      j = increasingNewIndexSequence.length - 1
      // looping backwards so that we can use last patched node as anchor
      for (i = toBePatched - 1; i >= 0; i--) {
        const nextIndex = s2 + i
        const nextChild = c2[nextIndex] as VNode
        const anchor =
          nextIndex + 1 < l2 ? (c2[nextIndex + 1] as VNode).el : parentAnchor
        if (newIndexToOldIndexMap[i] === 0) {
          // mount new
          patch(
            null,
            nextChild,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (moved) {
          // move if:
          // There is no stable subsequence (e.g. a reverse)
          // OR current node is not among the stable sequence
          if (j < 0 || i !== increasingNewIndexSequence[j]) {
            move(nextChild, container, anchor, MoveType.REORDER)
          } else {
            j--
          }
        }
      }
    }
  }
  const move: MoveFn = (
    vnode,
    container,
    anchor,
    moveType,
    parentSuspense = null
  ) => {
    const { el, type, transition, children, shapeFlag } = vnode
    if (shapeFlag & ShapeFlags.COMPONENT) {
      move(vnode.component!.subTree, container, anchor, moveType)
      return
    }

    if (__FEATURE_SUSPENSE__ && shapeFlag & ShapeFlags.SUSPENSE) {
      vnode.suspense!.move(container, anchor, moveType)
      return
    }

    if (shapeFlag & ShapeFlags.TELEPORT) {
      ;(type as typeof TeleportImpl).move(vnode, container, anchor, internals)
      return
    }

    if (type === Fragment) {
      hostInsert(el!, container, anchor)
      for (let i = 0; i < (children as VNode[]).length; i++) {
        move((children as VNode[])[i], container, anchor, moveType)
      }
      hostInsert(vnode.anchor!, container, anchor)
      return
    }

    if (type === Static) {
      moveStaticNode(vnode, container, anchor)
      return
    }

    // single nodes
    const needTransition =
      moveType !== MoveType.REORDER &&
      shapeFlag & ShapeFlags.ELEMENT &&
      transition
    if (needTransition) {
      if (moveType === MoveType.ENTER) {
        transition!.beforeEnter(el!)
        hostInsert(el!, container, anchor)
        queuePostRenderEffect(() => transition!.enter(el!), parentSuspense)
      } else {
        const { leave, delayLeave, afterLeave } = transition!
        const remove = () => hostInsert(el!, container, anchor)
        const performLeave = () => {
          leave(el!, () => {
            remove()
            afterLeave && afterLeave()
          })
        }
        if (delayLeave) {
          delayLeave(el!, remove, performLeave)
        } else {
          performLeave()
        }
      }
    } else {
      hostInsert(el!, container, anchor)
    }
  }

  const unmount: UnmountFn = (
    vnode,
    parentComponent,
    parentSuspense,
    doRemove = false,
    optimized = false
  ) => {
    const {
      type,
      props,
      ref,
      children,
      dynamicChildren,
      shapeFlag,
      patchFlag,
      dirs
    } = vnode
    // unset ref
    if (ref != null) {
      setRef(ref, null, parentSuspense, vnode, true)
    }

    if (shapeFlag & ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE) {
      ;(parentComponent!.ctx as KeepAliveContext).deactivate(vnode)
      return
    }

    const shouldInvokeDirs = shapeFlag & ShapeFlags.ELEMENT && dirs
    const shouldInvokeVnodeHook = !isAsyncWrapper(vnode)

    let vnodeHook: VNodeHook | undefined | null
    if (
      shouldInvokeVnodeHook &&
      (vnodeHook = props && props.onVnodeBeforeUnmount)
    ) {
      invokeVNodeHook(vnodeHook, parentComponent, vnode)
    }

    if (shapeFlag & ShapeFlags.COMPONENT) {
      unmountComponent(vnode.component!, parentSuspense, doRemove)
    } else {
      if (__FEATURE_SUSPENSE__ && shapeFlag & ShapeFlags.SUSPENSE) {
        vnode.suspense!.unmount(parentSuspense, doRemove)
        return
      }

      if (shouldInvokeDirs) {
        invokeDirectiveHook(vnode, null, parentComponent, 'beforeUnmount')
      }

      if (shapeFlag & ShapeFlags.TELEPORT) {
        ;(vnode.type as typeof TeleportImpl).remove(
          vnode,
          parentComponent,
          parentSuspense,
          optimized,
          internals,
          doRemove
        )
      } else if (
        dynamicChildren &&
        // #1153: fast path should not be taken for non-stable (v-for) fragments
        (type !== Fragment ||
          (patchFlag > 0 && patchFlag & PatchFlags.STABLE_FRAGMENT))
      ) {
        // fast path for block nodes: only need to unmount dynamic children.
        unmountChildren(
          dynamicChildren,
          parentComponent,
          parentSuspense,
          false,
          true
        )
      } else if (
        (type === Fragment &&
          patchFlag &
            (PatchFlags.KEYED_FRAGMENT | PatchFlags.UNKEYED_FRAGMENT)) ||
        (!optimized && shapeFlag & ShapeFlags.ARRAY_CHILDREN)
      ) {
        unmountChildren(children as VNode[], parentComponent, parentSuspense)
      }

      if (doRemove) {
        remove(vnode)
      }
    }

    if (
      (shouldInvokeVnodeHook &&
        (vnodeHook = props && props.onVnodeUnmounted)) ||
      shouldInvokeDirs
    ) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, vnode)
        shouldInvokeDirs &&
          invokeDirectiveHook(vnode, null, parentComponent, 'unmounted')
      }, parentSuspense)
    }
  }

  const remove: RemoveFn = vnode => {
    const { type, el, anchor, transition } = vnode
    if (type === Fragment) {
      removeFragment(el!, anchor!)
      return
    }

    if (type === Static) {
      removeStaticNode(vnode)
      return
    }

    const performRemove = () => {
      hostRemove(el!)
      if (transition && !transition.persisted && transition.afterLeave) {
        transition.afterLeave()
      }
    }

    if (
      vnode.shapeFlag & ShapeFlags.ELEMENT &&
      transition &&
      !transition.persisted
    ) {
      const { leave, delayLeave } = transition
      const performLeave = () => leave(el!, performRemove)
      if (delayLeave) {
        delayLeave(vnode.el!, performRemove, performLeave)
      } else {
        performLeave()
      }
    } else {
      performRemove()
    }
  }

  const removeFragment = (cur: RendererNode, end: RendererNode) => {
    // For fragments, directly remove all contained DOM nodes.
    // (fragment child nodes cannot have transition)
    let next
    while (cur !== end) {
      next = hostNextSibling(cur)!
      hostRemove(cur)
      cur = next
    }
    hostRemove(end)
  }

  const unmountComponent = (
    instance: ComponentInternalInstance,
    parentSuspense: SuspenseBoundary | null,
    doRemove?: boolean
  ) => {
    if (__DEV__ && instance.type.__hmrId) {
      unregisterHMR(instance)
    }

    const { bum, scope, update, subTree, um } = instance

    // beforeUnmount hook
    if (bum) {
      invokeArrayFns(bum)
    }

    if (
      __COMPAT__ &&
      isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
    ) {
      instance.emit('hook:beforeDestroy')
    }

    // stop effects in component scope
    scope.stop()

    // update may be null if a component is unmounted before its async
    // setup has resolved.
    if (update) {
      // so that scheduler will no longer invoke it
      update.active = false
      unmount(subTree, instance, parentSuspense, doRemove)
    }
    // unmounted hook
    if (um) {
      queuePostRenderEffect(um, parentSuspense)
    }
    if (
      __COMPAT__ &&
      isCompatEnabled(DeprecationTypes.INSTANCE_EVENT_HOOKS, instance)
    ) {
      queuePostRenderEffect(
        () => instance.emit('hook:destroyed'),
        parentSuspense
      )
    }
    queuePostRenderEffect(() => {
      instance.isUnmounted = true
    }, parentSuspense)

    // A component with async dep inside a pending suspense is unmounted before
    // its async dep resolves. This should remove the dep from the suspense, and
    // cause the suspense to resolve immediately if that was the last dep.
    if (
      __FEATURE_SUSPENSE__ &&
      parentSuspense &&
      parentSuspense.pendingBranch &&
      !parentSuspense.isUnmounted &&
      instance.asyncDep &&
      !instance.asyncResolved &&
      instance.suspenseId === parentSuspense.pendingId
    ) {
      parentSuspense.deps--
      if (parentSuspense.deps === 0) {
        parentSuspense.resolve()
      }
    }

    if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
      devtoolsComponentRemoved(instance)
    }
  }

  const unmountChildren: UnmountChildrenFn = (
    children,
    parentComponent,
    parentSuspense,
    doRemove = false,
    optimized = false,
    start = 0
  ) => {
    for (let i = start; i < children.length; i++) {
      unmount(children[i], parentComponent, parentSuspense, doRemove, optimized)
    }
  }

  const getNextHostNode: NextFn = vnode => {
    if (vnode.shapeFlag & ShapeFlags.COMPONENT) {
      return getNextHostNode(vnode.component!.subTree)
    }
    if (__FEATURE_SUSPENSE__ && vnode.shapeFlag & ShapeFlags.SUSPENSE) {
      return vnode.suspense!.next()
    }
    return hostNextSibling((vnode.anchor || vnode.el)!)
  }

  const render: RootRenderFunction = (vnode, container, isSVG) => {
    if (vnode == null) {
      if (container._vnode) {
        unmount(container._vnode, null, null, true)
      }
    } else {
      patch(container._vnode || null, vnode, container, null, null, null, isSVG)
    }
    flushPostFlushCbs()
    container._vnode = vnode
  }

  const internals: RendererInternals = {
    p: patch,
    um: unmount,
    m: move,
    r: remove,
    mt: mountComponent,
    mc: mountChildren,
    pc: patchChildren,
    pbc: patchBlockChildren,
    n: getNextHostNode,
    o: options
  }

  let hydrate: ReturnType<typeof createHydrationFunctions>[0] | undefined
  let hydrateNode: ReturnType<typeof createHydrationFunctions>[1] | undefined
  if (createHydrationFns) {
    ;[hydrate, hydrateNode] = createHydrationFns(
      internals as RendererInternals<Node, Element>
    )
  }

  return {
    render,
    hydrate,
    createApp: createAppAPI(render, hydrate)
  }
}

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此处得到createApp

/packages/runtime-core/src/apiCreateApp.ts

export function createAppAPI<HostElement>(
  render: RootRenderFunction,
  hydrate?: RootHydrateFunction
): CreateAppFunction<HostElement> {
  return function createApp(rootComponent, rootProps = null) {
    if (rootProps != null && !isObject(rootProps)) {
      __DEV__ && warn(`root props passed to app.mount() must be an object.`)
      rootProps = null
    }

    const context = createAppContext()
    const installedPlugins = new Set()

    let isMounted = false
    const app: App = (context.app = {
      _uid: uid++,
      _component: rootComponent as ConcreteComponent,
      _props: rootProps,
      _container: null,
      _context: context,
      _instance: null,

      version,

      get config() {
        return context.config
      },

      set config(v) {
        if (__DEV__) {
          warn(
            `app.config cannot be replaced. Modify individual options instead.`
          )
        }
      },

      use(plugin: Plugin, ...options: any[]) {
        if (installedPlugins.has(plugin)) {
          __DEV__ && warn(`Plugin has already been applied to target app.`)
        } else if (plugin && isFunction(plugin.install)) {
          installedPlugins.add(plugin)
          plugin.install(app, ...options)
        } else if (isFunction(plugin)) {
          installedPlugins.add(plugin)
          plugin(app, ...options)
        } else if (__DEV__) {
          warn(
            `A plugin must either be a function or an object with an "install" ` +
              `function.`
          )
        }
        return app
      },

      mixin(mixin: ComponentOptions) {
        if (__FEATURE_OPTIONS_API__) {
          if (!context.mixins.includes(mixin)) {
            context.mixins.push(mixin)
          } else if (__DEV__) {
            warn(
              'Mixin has already been applied to target app' +
                (mixin.name ? `: ${mixin.name}` : '')
            )
          }
        } else if (__DEV__) {
          warn('Mixins are only available in builds supporting Options API')
        }
        return app
      },

      component(name: string, component?: Component): any {
        if (__DEV__) {
          validateComponentName(name, context.config)
        }
        if (!component) {
          return context.components[name]
        }
        if (__DEV__ && context.components[name]) {
          warn(`Component "${name}" has already been registered in target app.`)
        }
        context.components[name] = component
        return app
      },

      directive(name: string, directive?: Directive) {
        if (__DEV__) {
          validateDirectiveName(name)
        }

        if (!directive) {
          return context.directives[name] as any
        }
        if (__DEV__ && context.directives[name]) {
          warn(`Directive "${name}" has already been registered in target app.`)
        }
        context.directives[name] = directive
        return app
      },

      mount(
        rootContainer: HostElement,
        isHydrate?: boolean,
        isSVG?: boolean
      ): any {
        if (!isMounted) {
          const vnode = createVNode(
            rootComponent as ConcreteComponent,
            rootProps
          )
          // store app context on the root VNode.
          // this will be set on the root instance on initial mount.
          vnode.appContext = context

          // HMR root reload
          if (__DEV__) {
            context.reload = () => {
              render(cloneVNode(vnode), rootContainer, isSVG)
            }
          }

          if (isHydrate && hydrate) {
            hydrate(vnode as VNode<Node, Element>, rootContainer as any)
          } else {
            render(vnode, rootContainer, isSVG)
          }
          isMounted = true
          app._container = rootContainer
          // for devtools and telemetry
          ;(rootContainer as any).__vue_app__ = app

          if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
            app._instance = vnode.component
            devtoolsInitApp(app, version)
          }

          return getExposeProxy(vnode.component!) || vnode.component!.proxy
        } else if (__DEV__) {
          warn(
            `App has already been mounted.\n` +
              `If you want to remount the same app, move your app creation logic ` +
              `into a factory function and create fresh app instances for each ` +
              `mount - e.g. \`const createMyApp = () => createApp(App)\``
          )
        }
      },

      unmount() {
        if (isMounted) {
          render(null, app._container)
          if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
            app._instance = null
            devtoolsUnmountApp(app)
          }
          delete app._container.__vue_app__
        } else if (__DEV__) {
          warn(`Cannot unmount an app that is not mounted.`)
        }
      },

      provide(key, value) {
        if (__DEV__ && (key as string | symbol) in context.provides) {
          warn(
            `App already provides property with key "${String(key)}". ` +
              `It will be overwritten with the new value.`
          )
        }
        // TypeScript doesn't allow symbols as index type
        // https://github.com/Microsoft/TypeScript/issues/24587
        context.provides[key as string] = value

        return app
      }
    })
    if (__COMPAT__) {
      installAppCompatProperties(app, context, render)
    }

    return app
  }
}

app 就是

/packages/runtime-core/src/apiCreateApp.ts

const app: App = (context.app = {
  _uid: uid++,
  _component: rootComponent as ConcreteComponent,
  _props: rootProps,
  _container: null,
  _context: context,
  _instance: null,

  version,

  get config() {
    return context.config
  },

  set config(v) {
    if (__DEV__) {
      warn(
        `app.config cannot be replaced. Modify individual options instead.`
      )
    }
  },

  use(plugin: Plugin, ...options: any[]) {
    if (installedPlugins.has(plugin)) {
      __DEV__ && warn(`Plugin has already been applied to target app.`)
    } else if (plugin && isFunction(plugin.install)) {
      installedPlugins.add(plugin)
      plugin.install(app, ...options)
    } else if (isFunction(plugin)) {
      installedPlugins.add(plugin)
      plugin(app, ...options)
    } else if (__DEV__) {
      warn(
        `A plugin must either be a function or an object with an "install" ` +
          `function.`
      )
    }
    return app
  },

  mixin(mixin: ComponentOptions) {
    if (__FEATURE_OPTIONS_API__) {
      if (!context.mixins.includes(mixin)) {
        context.mixins.push(mixin)
      } else if (__DEV__) {
        warn(
          'Mixin has already been applied to target app' +
            (mixin.name ? `: ${mixin.name}` : '')
        )
      }
    } else if (__DEV__) {
      warn('Mixins are only available in builds supporting Options API')
    }
    return app
  },

  component(name: string, component?: Component): any {
    if (__DEV__) {
      validateComponentName(name, context.config)
    }
    if (!component) {
      return context.components[name]
    }
    if (__DEV__ && context.components[name]) {
      warn(`Component "${name}" has already been registered in target app.`)
    }
    context.components[name] = component
    return app
  },

  directive(name: string, directive?: Directive) {
    if (__DEV__) {
      validateDirectiveName(name)
    }

    if (!directive) {
      return context.directives[name] as any
    }
    if (__DEV__ && context.directives[name]) {
      warn(`Directive "${name}" has already been registered in target app.`)
    }
    context.directives[name] = directive
    return app
  },

  mount(
    rootContainer: HostElement,
    isHydrate?: boolean,
    isSVG?: boolean
  ): any {
    if (!isMounted) {
      const vnode = createVNode(
        rootComponent as ConcreteComponent,
        rootProps
      )
      // store app context on the root VNode.
      // this will be set on the root instance on initial mount.
      vnode.appContext = context

      // HMR root reload
      if (__DEV__) {
        context.reload = () => {
          render(cloneVNode(vnode), rootContainer, isSVG)
        }
      }

      if (isHydrate && hydrate) {
        hydrate(vnode as VNode<Node, Element>, rootContainer as any)
      } else {
        render(vnode, rootContainer, isSVG)
      }
      isMounted = true
      app._container = rootContainer
      // for devtools and telemetry
      ;(rootContainer as any).__vue_app__ = app

      if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
        app._instance = vnode.component
        devtoolsInitApp(app, version)
      }

      return getExposeProxy(vnode.component!) || vnode.component!.proxy
    } else if (__DEV__) {
      warn(
        `App has already been mounted.\n` +
          `If you want to remount the same app, move your app creation logic ` +
          `into a factory function and create fresh app instances for each ` +
          `mount - e.g. \`const createMyApp = () => createApp(App)\``
      )
    }
  },

  unmount() {
    if (isMounted) {
      render(null, app._container)
      if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
        app._instance = null
        devtoolsUnmountApp(app)
      }
      delete app._container.__vue_app__
    } else if (__DEV__) {
      warn(`Cannot unmount an app that is not mounted.`)
    }
  },

  provide(key, value) {
    if (__DEV__ && (key as string | symbol) in context.provides) {
      warn(
        `App already provides property with key "${String(key)}". ` +
          `It will be overwritten with the new value.`
      )
    }
    // TypeScript doesn't allow symbols as index type
    // https://github.com/Microsoft/TypeScript/issues/24587
    context.provides[key as string] = value

    return app
  }
})

2.2 use

2.3 mount

app.mount("#app")

3.App.vue

1.开发使用 vue3.x

App.vue

vue

<template>
  <img alt="Vue logo" src="./assets/logo.png" />
  <HelloWorld msg="Welcome to Your Vue.js App" />
</template>

<script>
import HelloWorld from "./components/HelloWorld.vue"

export default {
  name: "App",
  components: {
    HelloWorld,
  },
}
</script>

main.js

import { createApp } from "vue"
import App from "./App.vue"

createApp(App).mount("#app")

2.vue3.x 源码内部

createApp(App) <-- createRenderer <-- baseCreateRenderer

const createApp = (...args) => {
  const app = ensureRenderer().createApp(...args)
  {
    injectNativeTagCheck(app)
    injectCompilerOptionsCheck(app)
  }
  const { mount } = app
  app.mount = (containerOrSelector) => {
    const container = normalizeContainer(containerOrSelector)
    if (!container) return
    const component = app._component
    if (!isFunction(component) && !component.render && !component.template) {
      // __UNSAFE__
      // Reason: potential execution of JS expressions in in-DOM template.
      // The user must make sure the in-DOM template is trusted. If it's
      // rendered by the server, the template should not contain any user data.
      component.template = container.innerHTML
    }
    // clear content before mounting
    container.innerHTML = ""
    const proxy = mount(container, false, container instanceof SVGElement)
    if (container instanceof Element) {
      container.removeAttribute("v-cloak")
      container.setAttribute("data-v-app", "")
    }
    return proxy
  }
  return app
}

function ensureRenderer() {
  return renderer || (renderer = createRenderer(rendererOptions))
}

2.1 createRenderer

function createRenderer(options) {
  return baseCreateRenderer(options)
}

2.2 baseCreateRenderer

baseCreateRenderer 的核心就是闭包，返回渲染函数和创建 app 的函数

function baseCreateRenderer(options, createHydrationFns) {
  const target = getGlobalThis()
  target.__VUE__ = true
  {
    setDevtoolsHook(target.__VUE_DEVTOOLS_GLOBAL_HOOK__, target)
  }
  const {
    insert: hostInsert,
    remove: hostRemove,
    patchProp: hostPatchProp,
    createElement: hostCreateElement,
    createText: hostCreateText,
    createComment: hostCreateComment,
    setText: hostSetText,
    setElementText: hostSetElementText,
    parentNode: hostParentNode,
    nextSibling: hostNextSibling,
    setScopeId: hostSetScopeId = NOOP,
    insertStaticContent: hostInsertStaticContent,
  } = options
  // Note: functions inside this closure should use `const xxx = () => {}`
  // style in order to prevent being inlined by minifiers.
  const patch = (
    n1,
    n2,
    container,
    anchor = null,
    parentComponent = null,
    parentSuspense = null,
    isSVG = false,
    slotScopeIds = null,
    optimized = isHmrUpdating ? false : !!n2.dynamicChildren
  ) => {
    if (n1 === n2) {
      return
    }
    // patching & not same type, unmount old tree
    if (n1 && !isSameVNodeType(n1, n2)) {
      anchor = getNextHostNode(n1)
      unmount(n1, parentComponent, parentSuspense, true)
      n1 = null
    }
    if (n2.patchFlag === -2 /* PatchFlags.BAIL */) {
      optimized = false
      n2.dynamicChildren = null
    }
    const { type, ref, shapeFlag } = n2
    switch (type) {
      case Text:
        processText(n1, n2, container, anchor)
        break
      case Comment:
        processCommentNode(n1, n2, container, anchor)
        break
      case Static:
        if (n1 == null) {
          mountStaticNode(n2, container, anchor, isSVG)
        } else {
          patchStaticNode(n1, n2, container, isSVG)
        }
        break
      case Fragment:
        processFragment(
          n1,
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        break
      default:
        if (shapeFlag & 1 /* ShapeFlags.ELEMENT */) {
          processElement(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & 6 /* ShapeFlags.COMPONENT */) {
          processComponent(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (shapeFlag & 64 /* ShapeFlags.TELEPORT */) {
          type.process(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else if (shapeFlag & 128 /* ShapeFlags.SUSPENSE */) {
          type.process(
            n1,
            n2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized,
            internals
          )
        } else {
          warn$1("Invalid VNode type:", type, `(${typeof type})`)
        }
    }
    // set ref
    if (ref != null && parentComponent) {
      setRef(ref, n1 && n1.ref, parentSuspense, n2 || n1, !n2)
    }
  }
  const processText = (n1, n2, container, anchor) => {
    if (n1 == null) {
      hostInsert((n2.el = hostCreateText(n2.children)), container, anchor)
    } else {
      const el = (n2.el = n1.el)
      if (n2.children !== n1.children) {
        hostSetText(el, n2.children)
      }
    }
  }
  const processCommentNode = (n1, n2, container, anchor) => {
    if (n1 == null) {
      hostInsert(
        (n2.el = hostCreateComment(n2.children || "")),
        container,
        anchor
      )
    } else {
      // there's no support for dynamic comments
      n2.el = n1.el
    }
  }
  const mountStaticNode = (n2, container, anchor, isSVG) => {
    ;[n2.el, n2.anchor] = hostInsertStaticContent(
      n2.children,
      container,
      anchor,
      isSVG,
      n2.el,
      n2.anchor
    )
  }
  /**
   * Dev / HMR only
   */
  const patchStaticNode = (n1, n2, container, isSVG) => {
    // static nodes are only patched during dev for HMR
    if (n2.children !== n1.children) {
      const anchor = hostNextSibling(n1.anchor)
      // remove existing
      removeStaticNode(n1)
      ;[n2.el, n2.anchor] = hostInsertStaticContent(
        n2.children,
        container,
        anchor,
        isSVG
      )
    } else {
      n2.el = n1.el
      n2.anchor = n1.anchor
    }
  }
  const moveStaticNode = ({ el, anchor }, container, nextSibling) => {
    let next
    while (el && el !== anchor) {
      next = hostNextSibling(el)
      hostInsert(el, container, nextSibling)
      el = next
    }
    hostInsert(anchor, container, nextSibling)
  }
  const removeStaticNode = ({ el, anchor }) => {
    let next
    while (el && el !== anchor) {
      next = hostNextSibling(el)
      hostRemove(el)
      el = next
    }
    hostRemove(anchor)
  }
  const processElement = (
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    isSVG = isSVG || n2.type === "svg"
    if (n1 == null) {
      mountElement(
        n2,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    } else {
      patchElement(
        n1,
        n2,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }
  const mountElement = (
    vnode,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    let el
    let vnodeHook
    const { type, props, shapeFlag, transition, dirs } = vnode
    el = vnode.el = hostCreateElement(
      vnode.type,
      isSVG,
      props && props.is,
      props
    )
    // mount children first, since some props may rely on child content
    // being already rendered, e.g. `<select value>`
    if (shapeFlag & 8 /* ShapeFlags.TEXT_CHILDREN */) {
      hostSetElementText(el, vnode.children)
    } else if (shapeFlag & 16 /* ShapeFlags.ARRAY_CHILDREN */) {
      mountChildren(
        vnode.children,
        el,
        null,
        parentComponent,
        parentSuspense,
        isSVG && type !== "foreignObject",
        slotScopeIds,
        optimized
      )
    }
    if (dirs) {
      invokeDirectiveHook(vnode, null, parentComponent, "created")
    }
    // props
    if (props) {
      for (const key in props) {
        if (key !== "value" && !isReservedProp(key)) {
          hostPatchProp(
            el,
            key,
            null,
            props[key],
            isSVG,
            vnode.children,
            parentComponent,
            parentSuspense,
            unmountChildren
          )
        }
      }
      /**
       * Special case for setting value on DOM elements:
       * - it can be order-sensitive (e.g. should be set *after* min/max, #2325, #4024)
       * - it needs to be forced (#1471)
       * #2353 proposes adding another renderer option to configure this, but
       * the properties affects are so finite it is worth special casing it
       * here to reduce the complexity. (Special casing it also should not
       * affect non-DOM renderers)
       */
      if ("value" in props) {
        hostPatchProp(el, "value", null, props.value)
      }
      if ((vnodeHook = props.onVnodeBeforeMount)) {
        invokeVNodeHook(vnodeHook, parentComponent, vnode)
      }
    }
    // scopeId
    setScopeId(el, vnode, vnode.scopeId, slotScopeIds, parentComponent)
    {
      Object.defineProperty(el, "__vnode", {
        value: vnode,
        enumerable: false,
      })
      Object.defineProperty(el, "__vueParentComponent", {
        value: parentComponent,
        enumerable: false,
      })
    }
    if (dirs) {
      invokeDirectiveHook(vnode, null, parentComponent, "beforeMount")
    }
    // #1583 For inside suspense + suspense not resolved case, enter hook should call when suspense resolved
    // #1689 For inside suspense + suspense resolved case, just call it
    const needCallTransitionHooks =
      (!parentSuspense || (parentSuspense && !parentSuspense.pendingBranch)) &&
      transition &&
      !transition.persisted
    if (needCallTransitionHooks) {
      transition.beforeEnter(el)
    }
    hostInsert(el, container, anchor)
    if (
      (vnodeHook = props && props.onVnodeMounted) ||
      needCallTransitionHooks ||
      dirs
    ) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, vnode)
        needCallTransitionHooks && transition.enter(el)
        dirs && invokeDirectiveHook(vnode, null, parentComponent, "mounted")
      }, parentSuspense)
    }
  }
  const setScopeId = (el, vnode, scopeId, slotScopeIds, parentComponent) => {
    if (scopeId) {
      hostSetScopeId(el, scopeId)
    }
    if (slotScopeIds) {
      for (let i = 0; i < slotScopeIds.length; i++) {
        hostSetScopeId(el, slotScopeIds[i])
      }
    }
    if (parentComponent) {
      let subTree = parentComponent.subTree
      if (
        subTree.patchFlag > 0 &&
        subTree.patchFlag & 2048 /* PatchFlags.DEV_ROOT_FRAGMENT */
      ) {
        subTree = filterSingleRoot(subTree.children) || subTree
      }
      if (vnode === subTree) {
        const parentVNode = parentComponent.vnode
        setScopeId(
          el,
          parentVNode,
          parentVNode.scopeId,
          parentVNode.slotScopeIds,
          parentComponent.parent
        )
      }
    }
  }
  const mountChildren = (
    children,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized,
    start = 0
  ) => {
    for (let i = start; i < children.length; i++) {
      const child = (children[i] = optimized
        ? cloneIfMounted(children[i])
        : normalizeVNode(children[i]))
      patch(
        null,
        child,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
  }
  const patchElement = (
    n1,
    n2,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    const el = (n2.el = n1.el)
    let { patchFlag, dynamicChildren, dirs } = n2
    // #1426 take the old vnode's patch flag into account since user may clone a
    // compiler-generated vnode, which de-opts to FULL_PROPS
    patchFlag |= n1.patchFlag & 16 /* PatchFlags.FULL_PROPS */
    const oldProps = n1.props || EMPTY_OBJ
    const newProps = n2.props || EMPTY_OBJ
    let vnodeHook
    // disable recurse in beforeUpdate hooks
    parentComponent && toggleRecurse(parentComponent, false)
    if ((vnodeHook = newProps.onVnodeBeforeUpdate)) {
      invokeVNodeHook(vnodeHook, parentComponent, n2, n1)
    }
    if (dirs) {
      invokeDirectiveHook(n2, n1, parentComponent, "beforeUpdate")
    }
    parentComponent && toggleRecurse(parentComponent, true)
    if (isHmrUpdating) {
      // HMR updated, force full diff
      patchFlag = 0
      optimized = false
      dynamicChildren = null
    }
    const areChildrenSVG = isSVG && n2.type !== "foreignObject"
    if (dynamicChildren) {
      patchBlockChildren(
        n1.dynamicChildren,
        dynamicChildren,
        el,
        parentComponent,
        parentSuspense,
        areChildrenSVG,
        slotScopeIds
      )
      if (parentComponent && parentComponent.type.__hmrId) {
        traverseStaticChildren(n1, n2)
      }
    } else if (!optimized) {
      // full diff
      patchChildren(
        n1,
        n2,
        el,
        null,
        parentComponent,
        parentSuspense,
        areChildrenSVG,
        slotScopeIds,
        false
      )
    }
    if (patchFlag > 0) {
      // the presence of a patchFlag means this element's render code was
      // generated by the compiler and can take the fast path.
      // in this path old node and new node are guaranteed to have the same shape
      // (i.e. at the exact same position in the source template)
      if (patchFlag & 16 /* PatchFlags.FULL_PROPS */) {
        // element props contain dynamic keys, full diff needed
        patchProps(
          el,
          n2,
          oldProps,
          newProps,
          parentComponent,
          parentSuspense,
          isSVG
        )
      } else {
        // class
        // this flag is matched when the element has dynamic class bindings.
        if (patchFlag & 2 /* PatchFlags.CLASS */) {
          if (oldProps.class !== newProps.class) {
            hostPatchProp(el, "class", null, newProps.class, isSVG)
          }
        }
        // style
        // this flag is matched when the element has dynamic style bindings
        if (patchFlag & 4 /* PatchFlags.STYLE */) {
          hostPatchProp(el, "style", oldProps.style, newProps.style, isSVG)
        }
        // props
        // This flag is matched when the element has dynamic prop/attr bindings
        // other than class and style. The keys of dynamic prop/attrs are saved for
        // faster iteration.
        // Note dynamic keys like :[foo]="bar" will cause this optimization to
        // bail out and go through a full diff because we need to unset the old key
        if (patchFlag & 8 /* PatchFlags.PROPS */) {
          // if the flag is present then dynamicProps must be non-null
          const propsToUpdate = n2.dynamicProps
          for (let i = 0; i < propsToUpdate.length; i++) {
            const key = propsToUpdate[i]
            const prev = oldProps[key]
            const next = newProps[key]
            // #1471 force patch value
            if (next !== prev || key === "value") {
              hostPatchProp(
                el,
                key,
                prev,
                next,
                isSVG,
                n1.children,
                parentComponent,
                parentSuspense,
                unmountChildren
              )
            }
          }
        }
      }
      // text
      // This flag is matched when the element has only dynamic text children.
      if (patchFlag & 1 /* PatchFlags.TEXT */) {
        if (n1.children !== n2.children) {
          hostSetElementText(el, n2.children)
        }
      }
    } else if (!optimized && dynamicChildren == null) {
      // unoptimized, full diff
      patchProps(
        el,
        n2,
        oldProps,
        newProps,
        parentComponent,
        parentSuspense,
        isSVG
      )
    }
    if ((vnodeHook = newProps.onVnodeUpdated) || dirs) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, n2, n1)
        dirs && invokeDirectiveHook(n2, n1, parentComponent, "updated")
      }, parentSuspense)
    }
  }
  // The fast path for blocks.
  const patchBlockChildren = (
    oldChildren,
    newChildren,
    fallbackContainer,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds
  ) => {
    for (let i = 0; i < newChildren.length; i++) {
      const oldVNode = oldChildren[i]
      const newVNode = newChildren[i]
      // Determine the container (parent element) for the patch.
      const container =
        // oldVNode may be an errored async setup() component inside Suspense
        // which will not have a mounted element
        oldVNode.el &&
        // - In the case of a Fragment, we need to provide the actual parent
        // of the Fragment itself so it can move its children.
        (oldVNode.type === Fragment ||
          // - In the case of different nodes, there is going to be a replacement
          // which also requires the correct parent container
          !isSameVNodeType(oldVNode, newVNode) ||
          // - In the case of a component, it could contain anything.
          oldVNode.shapeFlag &
            (6 /* ShapeFlags.COMPONENT */ | 64)) /* ShapeFlags.TELEPORT */
          ? hostParentNode(oldVNode.el)
          : // In other cases, the parent container is not actually used so we
            // just pass the block element here to avoid a DOM parentNode call.
            fallbackContainer
      patch(
        oldVNode,
        newVNode,
        container,
        null,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        true
      )
    }
  }
  const patchProps = (
    el,
    vnode,
    oldProps,
    newProps,
    parentComponent,
    parentSuspense,
    isSVG
  ) => {
    if (oldProps !== newProps) {
      if (oldProps !== EMPTY_OBJ) {
        for (const key in oldProps) {
          if (!isReservedProp(key) && !(key in newProps)) {
            hostPatchProp(
              el,
              key,
              oldProps[key],
              null,
              isSVG,
              vnode.children,
              parentComponent,
              parentSuspense,
              unmountChildren
            )
          }
        }
      }
      for (const key in newProps) {
        // empty string is not valid prop
        if (isReservedProp(key)) continue
        const next = newProps[key]
        const prev = oldProps[key]
        // defer patching value
        if (next !== prev && key !== "value") {
          hostPatchProp(
            el,
            key,
            prev,
            next,
            isSVG,
            vnode.children,
            parentComponent,
            parentSuspense,
            unmountChildren
          )
        }
      }
      if ("value" in newProps) {
        hostPatchProp(el, "value", oldProps.value, newProps.value)
      }
    }
  }
  const processFragment = (
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    const fragmentStartAnchor = (n2.el = n1 ? n1.el : hostCreateText(""))
    const fragmentEndAnchor = (n2.anchor = n1 ? n1.anchor : hostCreateText(""))
    let { patchFlag, dynamicChildren, slotScopeIds: fragmentSlotScopeIds } = n2
    if (
      // #5523 dev root fragment may inherit directives
      isHmrUpdating ||
      patchFlag & 2048 /* PatchFlags.DEV_ROOT_FRAGMENT */
    ) {
      // HMR updated / Dev root fragment (w/ comments), force full diff
      patchFlag = 0
      optimized = false
      dynamicChildren = null
    }
    // check if this is a slot fragment with :slotted scope ids
    if (fragmentSlotScopeIds) {
      slotScopeIds = slotScopeIds
        ? slotScopeIds.concat(fragmentSlotScopeIds)
        : fragmentSlotScopeIds
    }
    if (n1 == null) {
      hostInsert(fragmentStartAnchor, container, anchor)
      hostInsert(fragmentEndAnchor, container, anchor)
      // a fragment can only have array children
      // since they are either generated by the compiler, or implicitly created
      // from arrays.
      mountChildren(
        n2.children,
        container,
        fragmentEndAnchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    } else {
      if (
        patchFlag > 0 &&
        patchFlag & 64 /* PatchFlags.STABLE_FRAGMENT */ &&
        dynamicChildren &&
        // #2715 the previous fragment could've been a BAILed one as a result
        // of renderSlot() with no valid children
        n1.dynamicChildren
      ) {
        // a stable fragment (template root or <template v-for>) doesn't need to
        // patch children order, but it may contain dynamicChildren.
        patchBlockChildren(
          n1.dynamicChildren,
          dynamicChildren,
          container,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds
        )
        if (parentComponent && parentComponent.type.__hmrId) {
          traverseStaticChildren(n1, n2)
        } else if (
          // #2080 if the stable fragment has a key, it's a <template v-for> that may
          //  get moved around. Make sure all root level vnodes inherit el.
          // #2134 or if it's a component root, it may also get moved around
          // as the component is being moved.
          n2.key != null ||
          (parentComponent && n2 === parentComponent.subTree)
        ) {
          traverseStaticChildren(n1, n2, true /* shallow */)
        }
      } else {
        // keyed / unkeyed, or manual fragments.
        // for keyed & unkeyed, since they are compiler generated from v-for,
        // each child is guaranteed to be a block so the fragment will never
        // have dynamicChildren.
        patchChildren(
          n1,
          n2,
          container,
          fragmentEndAnchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      }
    }
  }
  const processComponent = (
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    n2.slotScopeIds = slotScopeIds
    if (n1 == null) {
      if (n2.shapeFlag & 512 /* ShapeFlags.COMPONENT_KEPT_ALIVE */) {
        parentComponent.ctx.activate(n2, container, anchor, isSVG, optimized)
      } else {
        mountComponent(
          n2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          optimized
        )
      }
    } else {
      updateComponent(n1, n2, optimized)
    }
  }
  const mountComponent = (
    initialVNode,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    const instance = (initialVNode.component = createComponentInstance(
      initialVNode,
      parentComponent,
      parentSuspense
    ))
    if (instance.type.__hmrId) {
      registerHMR(instance)
    }
    {
      pushWarningContext(initialVNode)
      startMeasure(instance, `mount`)
    }
    // inject renderer internals for keepAlive
    if (isKeepAlive(initialVNode)) {
      instance.ctx.renderer = internals
    }
    // resolve props and slots for setup context
    {
      {
        startMeasure(instance, `init`)
      }
      setupComponent(instance)
      {
        endMeasure(instance, `init`)
      }
    }
    // setup() is async. This component relies on async logic to be resolved
    // before proceeding
    if (instance.asyncDep) {
      parentSuspense && parentSuspense.registerDep(instance, setupRenderEffect)
      // Give it a placeholder if this is not hydration
      // TODO handle self-defined fallback
      if (!initialVNode.el) {
        const placeholder = (instance.subTree = createVNode(Comment))
        processCommentNode(null, placeholder, container, anchor)
      }
      return
    }
    setupRenderEffect(
      instance,
      initialVNode,
      container,
      anchor,
      parentSuspense,
      isSVG,
      optimized
    )
    {
      popWarningContext()
      endMeasure(instance, `mount`)
    }
  }
  const updateComponent = (n1, n2, optimized) => {
    const instance = (n2.component = n1.component)
    if (shouldUpdateComponent(n1, n2, optimized)) {
      if (instance.asyncDep && !instance.asyncResolved) {
        // async & still pending - just update props and slots
        // since the component's reactive effect for render isn't set-up yet
        {
          pushWarningContext(n2)
        }
        updateComponentPreRender(instance, n2, optimized)
        {
          popWarningContext()
        }
        return
      } else {
        // normal update
        instance.next = n2
        // in case the child component is also queued, remove it to avoid
        // double updating the same child component in the same flush.
        invalidateJob(instance.update)
        // instance.update is the reactive effect.
        instance.update()
      }
    } else {
      // no update needed. just copy over properties
      n2.el = n1.el
      instance.vnode = n2
    }
  }
  const setupRenderEffect = (
    instance,
    initialVNode,
    container,
    anchor,
    parentSuspense,
    isSVG,
    optimized
  ) => {
    const componentUpdateFn = () => {
      if (!instance.isMounted) {
        let vnodeHook
        const { el, props } = initialVNode
        const { bm, m, parent } = instance
        const isAsyncWrapperVNode = isAsyncWrapper(initialVNode)
        toggleRecurse(instance, false)
        // beforeMount hook
        if (bm) {
          invokeArrayFns(bm)
        }
        // onVnodeBeforeMount
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeBeforeMount)
        ) {
          invokeVNodeHook(vnodeHook, parent, initialVNode)
        }
        toggleRecurse(instance, true)
        if (el && hydrateNode) {
          // vnode has adopted host node - perform hydration instead of mount.
          const hydrateSubTree = () => {
            {
              startMeasure(instance, `render`)
            }
            instance.subTree = renderComponentRoot(instance)
            {
              endMeasure(instance, `render`)
            }
            {
              startMeasure(instance, `hydrate`)
            }
            hydrateNode(el, instance.subTree, instance, parentSuspense, null)
            {
              endMeasure(instance, `hydrate`)
            }
          }
          if (isAsyncWrapperVNode) {
            initialVNode.type.__asyncLoader().then(
              // note: we are moving the render call into an async callback,
              // which means it won't track dependencies - but it's ok because
              // a server-rendered async wrapper is already in resolved state
              // and it will never need to change.
              () => !instance.isUnmounted && hydrateSubTree()
            )
          } else {
            hydrateSubTree()
          }
        } else {
          {
            startMeasure(instance, `render`)
          }
          const subTree = (instance.subTree = renderComponentRoot(instance))
          {
            endMeasure(instance, `render`)
          }
          {
            startMeasure(instance, `patch`)
          }
          patch(
            null,
            subTree,
            container,
            anchor,
            instance,
            parentSuspense,
            isSVG
          )
          {
            endMeasure(instance, `patch`)
          }
          initialVNode.el = subTree.el
        }
        // mounted hook
        if (m) {
          queuePostRenderEffect(m, parentSuspense)
        }
        // onVnodeMounted
        if (
          !isAsyncWrapperVNode &&
          (vnodeHook = props && props.onVnodeMounted)
        ) {
          const scopedInitialVNode = initialVNode
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook, parent, scopedInitialVNode),
            parentSuspense
          )
        }
        // activated hook for keep-alive roots.
        // #1742 activated hook must be accessed after first render
        // since the hook may be injected by a child keep-alive
        if (
          initialVNode.shapeFlag &
            256 /* ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE */ ||
          (parent &&
            isAsyncWrapper(parent.vnode) &&
            parent.vnode.shapeFlag &
              256) /* ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE */
        ) {
          instance.a && queuePostRenderEffect(instance.a, parentSuspense)
        }
        instance.isMounted = true
        {
          devtoolsComponentAdded(instance)
        }
        // #2458: deference mount-only object parameters to prevent memleaks
        initialVNode = container = anchor = null
      } else {
        // updateComponent
        // This is triggered by mutation of component's own state (next: null)
        // OR parent calling processComponent (next: VNode)
        let { next, bu, u, parent, vnode } = instance
        let originNext = next
        let vnodeHook
        {
          pushWarningContext(next || instance.vnode)
        }
        // Disallow component effect recursion during pre-lifecycle hooks.
        toggleRecurse(instance, false)
        if (next) {
          next.el = vnode.el
          updateComponentPreRender(instance, next, optimized)
        } else {
          next = vnode
        }
        // beforeUpdate hook
        if (bu) {
          invokeArrayFns(bu)
        }
        // onVnodeBeforeUpdate
        if ((vnodeHook = next.props && next.props.onVnodeBeforeUpdate)) {
          invokeVNodeHook(vnodeHook, parent, next, vnode)
        }
        toggleRecurse(instance, true)
        // render
        {
          startMeasure(instance, `render`)
        }
        const nextTree = renderComponentRoot(instance)
        {
          endMeasure(instance, `render`)
        }
        const prevTree = instance.subTree
        instance.subTree = nextTree
        {
          startMeasure(instance, `patch`)
        }
        patch(
          prevTree,
          nextTree,
          // parent may have changed if it's in a teleport
          hostParentNode(prevTree.el),
          // anchor may have changed if it's in a fragment
          getNextHostNode(prevTree),
          instance,
          parentSuspense,
          isSVG
        )
        {
          endMeasure(instance, `patch`)
        }
        next.el = nextTree.el
        if (originNext === null) {
          // self-triggered update. In case of HOC, update parent component
          // vnode el. HOC is indicated by parent instance's subTree pointing
          // to child component's vnode
          updateHOCHostEl(instance, nextTree.el)
        }
        // updated hook
        if (u) {
          queuePostRenderEffect(u, parentSuspense)
        }
        // onVnodeUpdated
        if ((vnodeHook = next.props && next.props.onVnodeUpdated)) {
          queuePostRenderEffect(
            () => invokeVNodeHook(vnodeHook, parent, next, vnode),
            parentSuspense
          )
        }
        {
          devtoolsComponentUpdated(instance)
        }
        {
          popWarningContext()
        }
      }
    }
    // create reactive effect for rendering
    const effect = (instance.effect = new ReactiveEffect(
      componentUpdateFn,
      () => queueJob(update),
      instance.scope // track it in component's effect scope
    ))
    const update = (instance.update = () => effect.run())
    update.id = instance.uid
    // allowRecurse
    // #1801, #2043 component render effects should allow recursive updates
    toggleRecurse(instance, true)
    {
      effect.onTrack = instance.rtc
        ? (e) => invokeArrayFns(instance.rtc, e)
        : void 0
      effect.onTrigger = instance.rtg
        ? (e) => invokeArrayFns(instance.rtg, e)
        : void 0
      update.ownerInstance = instance
    }
    update()
  }
  const updateComponentPreRender = (instance, nextVNode, optimized) => {
    nextVNode.component = instance
    const prevProps = instance.vnode.props
    instance.vnode = nextVNode
    instance.next = null
    updateProps(instance, nextVNode.props, prevProps, optimized)
    updateSlots(instance, nextVNode.children, optimized)
    pauseTracking()
    // props update may have triggered pre-flush watchers.
    // flush them before the render update.
    flushPreFlushCbs()
    resetTracking()
  }
  const patchChildren = (
    n1,
    n2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized = false
  ) => {
    const c1 = n1 && n1.children
    const prevShapeFlag = n1 ? n1.shapeFlag : 0
    const c2 = n2.children
    const { patchFlag, shapeFlag } = n2
    // fast path
    if (patchFlag > 0) {
      if (patchFlag & 128 /* PatchFlags.KEYED_FRAGMENT */) {
        // this could be either fully-keyed or mixed (some keyed some not)
        // presence of patchFlag means children are guaranteed to be arrays
        patchKeyedChildren(
          c1,
          c2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        return
      } else if (patchFlag & 256 /* PatchFlags.UNKEYED_FRAGMENT */) {
        // unkeyed
        patchUnkeyedChildren(
          c1,
          c2,
          container,
          anchor,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
        return
      }
    }
    // children has 3 possibilities: text, array or no children.
    if (shapeFlag & 8 /* ShapeFlags.TEXT_CHILDREN */) {
      // text children fast path
      if (prevShapeFlag & 16 /* ShapeFlags.ARRAY_CHILDREN */) {
        unmountChildren(c1, parentComponent, parentSuspense)
      }
      if (c2 !== c1) {
        hostSetElementText(container, c2)
      }
    } else {
      if (prevShapeFlag & 16 /* ShapeFlags.ARRAY_CHILDREN */) {
        // prev children was array
        if (shapeFlag & 16 /* ShapeFlags.ARRAY_CHILDREN */) {
          // two arrays, cannot assume anything, do full diff
          patchKeyedChildren(
            c1,
            c2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else {
          // no new children, just unmount old
          unmountChildren(c1, parentComponent, parentSuspense, true)
        }
      } else {
        // prev children was text OR null
        // new children is array OR null
        if (prevShapeFlag & 8 /* ShapeFlags.TEXT_CHILDREN */) {
          hostSetElementText(container, "")
        }
        // mount new if array
        if (shapeFlag & 16 /* ShapeFlags.ARRAY_CHILDREN */) {
          mountChildren(
            c2,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        }
      }
    }
  }
  const patchUnkeyedChildren = (
    c1,
    c2,
    container,
    anchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    c1 = c1 || EMPTY_ARR
    c2 = c2 || EMPTY_ARR
    const oldLength = c1.length
    const newLength = c2.length
    const commonLength = Math.min(oldLength, newLength)
    let i
    for (i = 0; i < commonLength; i++) {
      const nextChild = (c2[i] = optimized
        ? cloneIfMounted(c2[i])
        : normalizeVNode(c2[i]))
      patch(
        c1[i],
        nextChild,
        container,
        null,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized
      )
    }
    if (oldLength > newLength) {
      // remove old
      unmountChildren(
        c1,
        parentComponent,
        parentSuspense,
        true,
        false,
        commonLength
      )
    } else {
      // mount new
      mountChildren(
        c2,
        container,
        anchor,
        parentComponent,
        parentSuspense,
        isSVG,
        slotScopeIds,
        optimized,
        commonLength
      )
    }
  }
  // can be all-keyed or mixed
  const patchKeyedChildren = (
    c1,
    c2,
    container,
    parentAnchor,
    parentComponent,
    parentSuspense,
    isSVG,
    slotScopeIds,
    optimized
  ) => {
    let i = 0
    const l2 = c2.length
    let e1 = c1.length - 1 // prev ending index
    let e2 = l2 - 1 // next ending index
    // 1. sync from start
    // (a b) c
    // (a b) d e
    while (i <= e1 && i <= e2) {
      const n1 = c1[i]
      const n2 = (c2[i] = optimized
        ? cloneIfMounted(c2[i])
        : normalizeVNode(c2[i]))
      if (isSameVNodeType(n1, n2)) {
        patch(
          n1,
          n2,
          container,
          null,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      } else {
        break
      }
      i++
    }
    // 2. sync from end
    // a (b c)
    // d e (b c)
    while (i <= e1 && i <= e2) {
      const n1 = c1[e1]
      const n2 = (c2[e2] = optimized
        ? cloneIfMounted(c2[e2])
        : normalizeVNode(c2[e2]))
      if (isSameVNodeType(n1, n2)) {
        patch(
          n1,
          n2,
          container,
          null,
          parentComponent,
          parentSuspense,
          isSVG,
          slotScopeIds,
          optimized
        )
      } else {
        break
      }
      e1--
      e2--
    }
    // 3. common sequence + mount
    // (a b)
    // (a b) c
    // i = 2, e1 = 1, e2 = 2
    // (a b)
    // c (a b)
    // i = 0, e1 = -1, e2 = 0
    if (i > e1) {
      if (i <= e2) {
        const nextPos = e2 + 1
        const anchor = nextPos < l2 ? c2[nextPos].el : parentAnchor
        while (i <= e2) {
          patch(
            null,
            (c2[i] = optimized ? cloneIfMounted(c2[i]) : normalizeVNode(c2[i])),
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
          i++
        }
      }
    }
    // 4. common sequence + unmount
    // (a b) c
    // (a b)
    // i = 2, e1 = 2, e2 = 1
    // a (b c)
    // (b c)
    // i = 0, e1 = 0, e2 = -1
    else if (i > e2) {
      while (i <= e1) {
        unmount(c1[i], parentComponent, parentSuspense, true)
        i++
      }
    }
    // 5. unknown sequence
    // [i ... e1 + 1]: a b [c d e] f g
    // [i ... e2 + 1]: a b [e d c h] f g
    // i = 2, e1 = 4, e2 = 5
    else {
      const s1 = i // prev starting index
      const s2 = i // next starting index
      // 5.1 build key:index map for newChildren
      const keyToNewIndexMap = new Map()
      for (i = s2; i <= e2; i++) {
        const nextChild = (c2[i] = optimized
          ? cloneIfMounted(c2[i])
          : normalizeVNode(c2[i]))
        if (nextChild.key != null) {
          if (keyToNewIndexMap.has(nextChild.key)) {
            warn$1(
              `Duplicate keys found during update:`,
              JSON.stringify(nextChild.key),
              `Make sure keys are unique.`
            )
          }
          keyToNewIndexMap.set(nextChild.key, i)
        }
      }
      // 5.2 loop through old children left to be patched and try to patch
      // matching nodes & remove nodes that are no longer present
      let j
      let patched = 0
      const toBePatched = e2 - s2 + 1
      let moved = false
      // used to track whether any node has moved
      let maxNewIndexSoFar = 0
      // works as Map<newIndex, oldIndex>
      // Note that oldIndex is offset by +1
      // and oldIndex = 0 is a special value indicating the new node has
      // no corresponding old node.
      // used for determining longest stable subsequence
      const newIndexToOldIndexMap = new Array(toBePatched)
      for (i = 0; i < toBePatched; i++) newIndexToOldIndexMap[i] = 0
      for (i = s1; i <= e1; i++) {
        const prevChild = c1[i]
        if (patched >= toBePatched) {
          // all new children have been patched so this can only be a removal
          unmount(prevChild, parentComponent, parentSuspense, true)
          continue
        }
        let newIndex
        if (prevChild.key != null) {
          newIndex = keyToNewIndexMap.get(prevChild.key)
        } else {
          // key-less node, try to locate a key-less node of the same type
          for (j = s2; j <= e2; j++) {
            if (
              newIndexToOldIndexMap[j - s2] === 0 &&
              isSameVNodeType(prevChild, c2[j])
            ) {
              newIndex = j
              break
            }
          }
        }
        if (newIndex === undefined) {
          unmount(prevChild, parentComponent, parentSuspense, true)
        } else {
          newIndexToOldIndexMap[newIndex - s2] = i + 1
          if (newIndex >= maxNewIndexSoFar) {
            maxNewIndexSoFar = newIndex
          } else {
            moved = true
          }
          patch(
            prevChild,
            c2[newIndex],
            container,
            null,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
          patched++
        }
      }
      // 5.3 move and mount
      // generate longest stable subsequence only when nodes have moved
      const increasingNewIndexSequence = moved
        ? getSequence(newIndexToOldIndexMap)
        : EMPTY_ARR
      j = increasingNewIndexSequence.length - 1
      // looping backwards so that we can use last patched node as anchor
      for (i = toBePatched - 1; i >= 0; i--) {
        const nextIndex = s2 + i
        const nextChild = c2[nextIndex]
        const anchor = nextIndex + 1 < l2 ? c2[nextIndex + 1].el : parentAnchor
        if (newIndexToOldIndexMap[i] === 0) {
          // mount new
          patch(
            null,
            nextChild,
            container,
            anchor,
            parentComponent,
            parentSuspense,
            isSVG,
            slotScopeIds,
            optimized
          )
        } else if (moved) {
          // move if:
          // There is no stable subsequence (e.g. a reverse)
          // OR current node is not among the stable sequence
          if (j < 0 || i !== increasingNewIndexSequence[j]) {
            move(nextChild, container, anchor, 2 /* MoveType.REORDER */)
          } else {
            j--
          }
        }
      }
    }
  }
  const move = (vnode, container, anchor, moveType, parentSuspense = null) => {
    const { el, type, transition, children, shapeFlag } = vnode
    if (shapeFlag & 6 /* ShapeFlags.COMPONENT */) {
      move(vnode.component.subTree, container, anchor, moveType)
      return
    }
    if (shapeFlag & 128 /* ShapeFlags.SUSPENSE */) {
      vnode.suspense.move(container, anchor, moveType)
      return
    }
    if (shapeFlag & 64 /* ShapeFlags.TELEPORT */) {
      type.move(vnode, container, anchor, internals)
      return
    }
    if (type === Fragment) {
      hostInsert(el, container, anchor)
      for (let i = 0; i < children.length; i++) {
        move(children[i], container, anchor, moveType)
      }
      hostInsert(vnode.anchor, container, anchor)
      return
    }
    if (type === Static) {
      moveStaticNode(vnode, container, anchor)
      return
    }
    // single nodes
    const needTransition =
      moveType !== 2 /* MoveType.REORDER */ &&
      shapeFlag & 1 /* ShapeFlags.ELEMENT */ &&
      transition
    if (needTransition) {
      if (moveType === 0 /* MoveType.ENTER */) {
        transition.beforeEnter(el)
        hostInsert(el, container, anchor)
        queuePostRenderEffect(() => transition.enter(el), parentSuspense)
      } else {
        const { leave, delayLeave, afterLeave } = transition
        const remove = () => hostInsert(el, container, anchor)
        const performLeave = () => {
          leave(el, () => {
            remove()
            afterLeave && afterLeave()
          })
        }
        if (delayLeave) {
          delayLeave(el, remove, performLeave)
        } else {
          performLeave()
        }
      }
    } else {
      hostInsert(el, container, anchor)
    }
  }
  const unmount = (
    vnode,
    parentComponent,
    parentSuspense,
    doRemove = false,
    optimized = false
  ) => {
    const {
      type,
      props,
      ref,
      children,
      dynamicChildren,
      shapeFlag,
      patchFlag,
      dirs,
    } = vnode
    // unset ref
    if (ref != null) {
      setRef(ref, null, parentSuspense, vnode, true)
    }
    if (shapeFlag & 256 /* ShapeFlags.COMPONENT_SHOULD_KEEP_ALIVE */) {
      parentComponent.ctx.deactivate(vnode)
      return
    }
    const shouldInvokeDirs = shapeFlag & 1 /* ShapeFlags.ELEMENT */ && dirs
    const shouldInvokeVnodeHook = !isAsyncWrapper(vnode)
    let vnodeHook
    if (
      shouldInvokeVnodeHook &&
      (vnodeHook = props && props.onVnodeBeforeUnmount)
    ) {
      invokeVNodeHook(vnodeHook, parentComponent, vnode)
    }
    if (shapeFlag & 6 /* ShapeFlags.COMPONENT */) {
      unmountComponent(vnode.component, parentSuspense, doRemove)
    } else {
      if (shapeFlag & 128 /* ShapeFlags.SUSPENSE */) {
        vnode.suspense.unmount(parentSuspense, doRemove)
        return
      }
      if (shouldInvokeDirs) {
        invokeDirectiveHook(vnode, null, parentComponent, "beforeUnmount")
      }
      if (shapeFlag & 64 /* ShapeFlags.TELEPORT */) {
        vnode.type.remove(
          vnode,
          parentComponent,
          parentSuspense,
          optimized,
          internals,
          doRemove
        )
      } else if (
        dynamicChildren &&
        // #1153: fast path should not be taken for non-stable (v-for) fragments
        (type !== Fragment ||
          (patchFlag > 0 && patchFlag & 64)) /* PatchFlags.STABLE_FRAGMENT */
      ) {
        // fast path for block nodes: only need to unmount dynamic children.
        unmountChildren(
          dynamicChildren,
          parentComponent,
          parentSuspense,
          false,
          true
        )
      } else if (
        (type === Fragment &&
          patchFlag &
            (128 /* PatchFlags.KEYED_FRAGMENT */ |
              256)) /* PatchFlags.UNKEYED_FRAGMENT */ ||
        (!optimized && shapeFlag & 16) /* ShapeFlags.ARRAY_CHILDREN */
      ) {
        unmountChildren(children, parentComponent, parentSuspense)
      }
      if (doRemove) {
        remove(vnode)
      }
    }
    if (
      (shouldInvokeVnodeHook &&
        (vnodeHook = props && props.onVnodeUnmounted)) ||
      shouldInvokeDirs
    ) {
      queuePostRenderEffect(() => {
        vnodeHook && invokeVNodeHook(vnodeHook, parentComponent, vnode)
        shouldInvokeDirs &&
          invokeDirectiveHook(vnode, null, parentComponent, "unmounted")
      }, parentSuspense)
    }
  }
  const remove = (vnode) => {
    const { type, el, anchor, transition } = vnode
    if (type === Fragment) {
      if (
        vnode.patchFlag > 0 &&
        vnode.patchFlag & 2048 /* PatchFlags.DEV_ROOT_FRAGMENT */ &&
        transition &&
        !transition.persisted
      ) {
        vnode.children.forEach((child) => {
          if (child.type === Comment) {
            hostRemove(child.el)
          } else {
            remove(child)
          }
        })
      } else {
        removeFragment(el, anchor)
      }
      return
    }
    if (type === Static) {
      removeStaticNode(vnode)
      return
    }
    const performRemove = () => {
      hostRemove(el)
      if (transition && !transition.persisted && transition.afterLeave) {
        transition.afterLeave()
      }
    }
    if (
      vnode.shapeFlag & 1 /* ShapeFlags.ELEMENT */ &&
      transition &&
      !transition.persisted
    ) {
      const { leave, delayLeave } = transition
      const performLeave = () => leave(el, performRemove)
      if (delayLeave) {
        delayLeave(vnode.el, performRemove, performLeave)
      } else {
        performLeave()
      }
    } else {
      performRemove()
    }
  }
  const removeFragment = (cur, end) => {
    // For fragments, directly remove all contained DOM nodes.
    // (fragment child nodes cannot have transition)
    let next
    while (cur !== end) {
      next = hostNextSibling(cur)
      hostRemove(cur)
      cur = next
    }
    hostRemove(end)
  }
  const unmountComponent = (instance, parentSuspense, doRemove) => {
    if (instance.type.__hmrId) {
      unregisterHMR(instance)
    }
    const { bum, scope, update, subTree, um } = instance
    // beforeUnmount hook
    if (bum) {
      invokeArrayFns(bum)
    }
    // stop effects in component scope
    scope.stop()
    // update may be null if a component is unmounted before its async
    // setup has resolved.
    if (update) {
      // so that scheduler will no longer invoke it
      update.active = false
      unmount(subTree, instance, parentSuspense, doRemove)
    }
    // unmounted hook
    if (um) {
      queuePostRenderEffect(um, parentSuspense)
    }
    queuePostRenderEffect(() => {
      instance.isUnmounted = true
    }, parentSuspense)
    // A component with async dep inside a pending suspense is unmounted before
    // its async dep resolves. This should remove the dep from the suspense, and
    // cause the suspense to resolve immediately if that was the last dep.
    if (
      parentSuspense &&
      parentSuspense.pendingBranch &&
      !parentSuspense.isUnmounted &&
      instance.asyncDep &&
      !instance.asyncResolved &&
      instance.suspenseId === parentSuspense.pendingId
    ) {
      parentSuspense.deps--
      if (parentSuspense.deps === 0) {
        parentSuspense.resolve()
      }
    }
    {
      devtoolsComponentRemoved(instance)
    }
  }
  const unmountChildren = (
    children,
    parentComponent,
    parentSuspense,
    doRemove = false,
    optimized = false,
    start = 0
  ) => {
    for (let i = start; i < children.length; i++) {
      unmount(children[i], parentComponent, parentSuspense, doRemove, optimized)
    }
  }
  const getNextHostNode = (vnode) => {
    if (vnode.shapeFlag & 6 /* ShapeFlags.COMPONENT */) {
      return getNextHostNode(vnode.component.subTree)
    }
    if (vnode.shapeFlag & 128 /* ShapeFlags.SUSPENSE */) {
      return vnode.suspense.next()
    }
    return hostNextSibling(vnode.anchor || vnode.el)
  }
  const render = (vnode, container, isSVG) => {
    if (vnode == null) {
      if (container._vnode) {
        unmount(container._vnode, null, null, true)
      }
    } else {
      patch(container._vnode || null, vnode, container, null, null, null, isSVG)
    }
    flushPreFlushCbs()
    flushPostFlushCbs()
    container._vnode = vnode
  }
  const internals = {
    p: patch,
    um: unmount,
    m: move,
    r: remove,
    mt: mountComponent,
    mc: mountChildren,
    pc: patchChildren,
    pbc: patchBlockChildren,
    n: getNextHostNode,
    o: options,
  }
  let hydrate
  let hydrateNode
  if (createHydrationFns) {
    ;[hydrate, hydrateNode] = createHydrationFns(internals)
  }
  return {
    render,
    hydrate,
    createApp: createAppAPI(render, hydrate),
  }
}

function createAppAPI(render, hydrate) {
  return function createApp(rootComponent, rootProps = null) {
    if (!isFunction(rootComponent)) {
      rootComponent = Object.assign({}, rootComponent)
    }
    if (rootProps != null && !isObject(rootProps)) {
      warn$1(`root props passed to app.mount() must be an object.`)
      rootProps = null
    }
    const context = createAppContext()
    const installedPlugins = new Set()
    let isMounted = false
    const app = (context.app = {
      _uid: uid++,
      _component: rootComponent,
      _props: rootProps,
      _container: null,
      _context: context,
      _instance: null,
      version,
      get config() {
        return context.config
      },
      set config(v) {
        {
          warn$1(
            `app.config cannot be replaced. Modify individual options instead.`
          )
        }
      },
      use(plugin, ...options) {
        if (installedPlugins.has(plugin)) {
          warn$1(`Plugin has already been applied to target app.`)
        } else if (plugin && isFunction(plugin.install)) {
          installedPlugins.add(plugin)
          plugin.install(app, ...options)
        } else if (isFunction(plugin)) {
          installedPlugins.add(plugin)
          plugin(app, ...options)
        } else {
          warn$1(
            `A plugin must either be a function or an object with an "install" ` +
              `function.`
          )
        }
        return app
      },
      mixin(mixin) {
        {
          if (!context.mixins.includes(mixin)) {
            context.mixins.push(mixin)
          } else {
            warn$1(
              "Mixin has already been applied to target app" +
                (mixin.name ? `: ${mixin.name}` : "")
            )
          }
        }
        return app
      },
      component(name, component) {
        {
          validateComponentName(name, context.config)
        }
        if (!component) {
          return context.components[name]
        }
        if (context.components[name]) {
          warn$1(
            `Component "${name}" has already been registered in target app.`
          )
        }
        context.components[name] = component
        return app
      },
      directive(name, directive) {
        {
          validateDirectiveName(name)
        }
        if (!directive) {
          return context.directives[name]
        }
        if (context.directives[name]) {
          warn$1(
            `Directive "${name}" has already been registered in target app.`
          )
        }
        context.directives[name] = directive
        return app
      },
      mount(rootContainer, isHydrate, isSVG) {
        if (!isMounted) {
          // #5571
          if (rootContainer.__vue_app__) {
            warn$1(
              `There is already an app instance mounted on the host container.\n` +
                ` If you want to mount another app on the same host container,` +
                ` you need to unmount the previous app by calling \`app.unmount()\` first.`
            )
          }
          const vnode = createVNode(rootComponent, rootProps)
          // store app context on the root VNode.
          // this will be set on the root instance on initial mount.
          vnode.appContext = context
          // HMR root reload
          {
            context.reload = () => {
              render(cloneVNode(vnode), rootContainer, isSVG)
            }
          }
          if (isHydrate && hydrate) {
            hydrate(vnode, rootContainer)
          } else {
            render(vnode, rootContainer, isSVG)
          }
          isMounted = true
          app._container = rootContainer
          rootContainer.__vue_app__ = app
          {
            app._instance = vnode.component
            devtoolsInitApp(app, version)
          }
          return getExposeProxy(vnode.component) || vnode.component.proxy
        } else {
          warn$1(
            `App has already been mounted.\n` +
              `If you want to remount the same app, move your app creation logic ` +
              `into a factory function and create fresh app instances for each ` +
              `mount - e.g. \`const createMyApp = () => createApp(App)\``
          )
        }
      },
      unmount() {
        if (isMounted) {
          render(null, app._container)
          {
            app._instance = null
            devtoolsUnmountApp(app)
          }
          delete app._container.__vue_app__
        } else {
          warn$1(`Cannot unmount an app that is not mounted.`)
        }
      },
      provide(key, value) {
        if (key in context.provides) {
          warn$1(
            `App already provides property with key "${String(key)}". ` +
              `It will be overwritten with the new value.`
          )
        }
        context.provides[key] = value
        return app
      },
    })
    return app
  }
}

render 的核心作用就是渲染组件或相关节点，将其派发

const render: RootRenderFunction = (vnode, container, isSVG) => {
  if (vnode == null) {
    if (container._vnode) {
      unmount(container._vnode, null, null, true)
    }
  } else {
    patch(container._vnode || null, vnode, container, null, null, null, isSVG)
  }
  flushPostFlushCbs()
  container._vnode = vnode
}

总结

在使用 vue 的createApp时，内部通过createRenderer返回一个对象，这个对象上有createApp对象和render方法，createApp对象为用户提供一系列使用方法(provide、inject、use、component、mount)，render方法为后续渲染做准备

项目中 ​

​

1.Vue 引入 ​

2.根组件 ​

2.1 app ​

2.2 use ​

2.3 mount ​

3.App.vue ​

1.开发使用 vue3.x ​

2.vue3.x 源码内部 ​

2.1 createRenderer ​

2.2 baseCreateRenderer ​

项目中