Merge branch 'vapor' into edison/feat/vaporTransition

packages/compiler-vapor/__tests__/__snapshots__/compile.spec.ts.snap

@@ -149,17 +149,17 @@ export function render(_ctx, $props, $emit, $attrs, $slots) {
 `;
 
 exports[`compile > directives > v-pre > should not affect siblings after it 1`] = `
-"import { resolveComponent as _resolveComponent, createComponentWithFallback as _createComponentWithFallback, createTextNode as _createTextNode, insert as _insert, toDisplayString as _toDisplayString, setText as _setText, setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
+"import { resolveComponent as _resolveComponent, child as _child, createComponentWithFallback as _createComponentWithFallback, prepend as _prepend, toDisplayString as _toDisplayString, setText as _setText, setProp as _setProp, renderEffect as _renderEffect, template as _template } from 'vue';
 const t0 = _template("<div :id=\\"foo\\"><Comp></Comp>{{ bar }}</div>")
-const t1 = _template("<div></div>")
+const t1 = _template("<div> </div>")
 
 export function render(_ctx, $props, $emit, $attrs, $slots) {
   const _component_Comp = _resolveComponent("Comp")
   const n0 = t0()
   const n3 = t1()
+  const n2 = _child(n3)
   const n1 = _createComponentWithFallback(_component_Comp)
-  const n2 = _createTextNode()
+  _prepend(n3, n1)
-  _insert([n1, n2], n3)
   _renderEffect(() => {
     _setText(n2, _toDisplayString(_ctx.bar))
     _setProp(n3, "id", _ctx.foo)
@@ -169,10 +169,12 @@ export function render(_ctx, $props, $emit, $attrs, $slots) {
 `;
 
 exports[`compile > dynamic root 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
-  const n0 = _createTextNode(_toDisplayString(1) + _toDisplayString(2))
+  const n0 = t0()
+  _setText(n0, _toDisplayString(1) + _toDisplayString(2))
   return n0
 }"
 `;
@@ -197,7 +199,7 @@ export function render(_ctx) {
 
 exports[`compile > expression parsing > interpolation 1`] = `
 "
-  const n0 = _createTextNode()
+  const n0 = t0()
   _renderEffect(() => _setText(n0, _toDisplayString(a + b.value)))
   return n0
 "
@@ -229,10 +231,12 @@ export function render(_ctx) {
 `;
 
 exports[`compile > static + dynamic root 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
-  const n0 = _createTextNode(_toDisplayString(1) + _toDisplayString(2) + "3" + _toDisplayString(4) + _toDisplayString(5) + "6" + _toDisplayString(7) + _toDisplayString(8) + "9" + 'A' + 'B')
+  const n0 = t0()
+  _setText(n0, _toDisplayString(1) + _toDisplayString(2) + "3" + _toDisplayString(4) + _toDisplayString(5) + "6" + _toDisplayString(7) + _toDisplayString(8) + "9" + 'A' + 'B')
   return n0
 }"
 `;

packages/compiler-vapor/__tests__/transforms/__snapshots__/expression.spec.ts.snap

@@ -1,30 +1,33 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
 exports[`compiler: expression > basic 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
-  const n0 = _createTextNode()
+  const n0 = t0()
   _renderEffect(() => _setText(n0, _toDisplayString(_ctx.a)))
   return n0
 }"
 `;
 
 exports[`compiler: expression > props 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx, $props, $emit, $attrs, $slots) {
-  const n0 = _createTextNode()
+  const n0 = t0()
   _renderEffect(() => _setText(n0, _toDisplayString($props.foo)))
   return n0
 }"
 `;
 
 exports[`compiler: expression > props aliased 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx, $props, $emit, $attrs, $slots) {
-  const n0 = _createTextNode()
+  const n0 = t0()
   _renderEffect(() => _setText(n0, _toDisplayString($props['bar'])))
   return n0
 }"

packages/compiler-vapor/__tests__/transforms/__snapshots__/transformChildren.spec.ts.snap

@@ -1,24 +1,22 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
 exports[`compiler: children transform > children & sibling references 1`] = `
-"import { child as _child, nthChild as _nthChild, next as _next, createTextNode as _createTextNode, insert as _insert, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
+"import { child as _child, next as _next, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
-const t0 = _template("<div><p> </p> <!><p> </p></div>", true)
+const t0 = _template("<div><p> </p> <p> </p></div>", true)
 
 export function render(_ctx) {
-  const n4 = t0()
+  const n3 = t0()
-  const n0 = _child(n4)
+  const n0 = _child(n3)
-  const n3 = _nthChild(n4, 2)
+  const n1 = _next(n0)
-  const n2 = _next(n3)
+  const n2 = _next(n1)
   const x0 = _child(n0)
-  const n1 = _createTextNode()
   const x2 = _child(n2)
-  _insert(n1, n4, n3)
   _renderEffect(() => {
     _setText(x0, _toDisplayString(_ctx.first))
-    _setText(n1, _toDisplayString(_ctx.second) + " " + _toDisplayString(_ctx.third) + " ")
+    _setText(n1, " " + _toDisplayString(_ctx.second) + " " + _toDisplayString(_ctx.third) + " ")
     _setText(x2, _toDisplayString(_ctx.forth))
   })
-  return n4
+  return n3
 }"
 `;
 

packages/compiler-vapor/__tests__/transforms/__snapshots__/transformText.spec.ts.snap

@@ -1,20 +1,23 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
 exports[`compiler: text transform > consecutive text 1`] = `
-"import { createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect } from 'vue';
+"import { toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
-  const n0 = _createTextNode()
+  const n0 = t0()
   _renderEffect(() => _setText(n0, _toDisplayString(_ctx.msg)))
   return n0
 }"
 `;
 
 exports[`compiler: text transform > no consecutive text 1`] = `
-"import { createTextNode as _createTextNode } from 'vue';
+"import { setText as _setText, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
-  const n0 = _createTextNode("hello world")
+  const n0 = t0()
+  _setText(n0, "hello world")
   return n0
 }"
 `;

packages/compiler-vapor/__tests__/transforms/__snapshots__/vOnce.spec.ts.snap

@@ -12,15 +12,15 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: v-once > basic 1`] = `
-"import { child as _child, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setClass as _setClass, prepend as _prepend, template as _template } from 'vue';
+"import { child as _child, next as _next, toDisplayString as _toDisplayString, setText as _setText, setClass as _setClass, template as _template } from 'vue';
-const t0 = _template("<div><span></span></div>", true)
+const t0 = _template("<div> <span></span></div>", true)
 
 export function render(_ctx, $props, $emit, $attrs, $slots) {
   const n2 = t0()
-  const n1 = _child(n2)
+  const n0 = _child(n2)
-  const n0 = _createTextNode(_toDisplayString(_ctx.msg) + " ")
+  const n1 = _next(n0)
+  _setText(n0, _toDisplayString(_ctx.msg) + " ")
   _setClass(n1, _ctx.clz)
-  _prepend(n2, n0)
   return n2
 }"
 `;

packages/compiler-vapor/__tests__/transforms/__snapshots__/vSlot.spec.ts.snap

@@ -22,7 +22,8 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: transform slot > dynamic slots name w/ v-for 1`] = `
-"import { resolveComponent as _resolveComponent, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createForSlots as _createForSlots, createComponentWithFallback as _createComponentWithFallback } from 'vue';
+"import { resolveComponent as _resolveComponent, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createForSlots as _createForSlots, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
   const _component_Comp = _resolveComponent("Comp")
@@ -31,7 +32,7 @@ export function render(_ctx) {
       () => (_createForSlots(_ctx.list, (item) => ({
         name: item, 
         fn: (_slotProps0) => {
-          const n0 = _createTextNode()
+          const n0 = t0()
           _renderEffect(() => _setText(n0, _toDisplayString(_slotProps0["bar"])))
           return n0
         }
@@ -158,7 +159,7 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: transform slot > nested slots scoping 1`] = `
-"import { resolveComponent as _resolveComponent, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
+"import { resolveComponent as _resolveComponent, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
 const t0 = _template(" ")
 
 export function render(_ctx) {
@@ -166,17 +167,16 @@ export function render(_ctx) {
   const _component_Comp = _resolveComponent("Comp")
   const n5 = _createComponentWithFallback(_component_Comp, null, {
     "default": (_slotProps0) => {
-      const n2 = t0()
+      const n3 = t0()
       const n1 = _createComponentWithFallback(_component_Inner, null, {
         "default": (_slotProps1) => {
-          const n0 = _createTextNode()
+          const n0 = t0()
           _renderEffect(() => _setText(n0, _toDisplayString(_slotProps0["foo"] + _slotProps1["bar"] + _ctx.baz)))
           return n0
         }
       })
-      const n3 = _createTextNode()
+      _renderEffect(() => _setText(n3, " " + _toDisplayString(_slotProps0["foo"] + _ctx.bar + _ctx.baz)))
-      _renderEffect(() => _setText(n3, _toDisplayString(_slotProps0["foo"] + _ctx.bar + _ctx.baz)))
+      return [n1, n3]
-      return [n1, n2, n3]
     }
   }, true)
   return n5
@@ -184,7 +184,8 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: transform slot > on component dynamically named slot 1`] = `
-"import { resolveComponent as _resolveComponent, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback } from 'vue';
+"import { resolveComponent as _resolveComponent, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
   const _component_Comp = _resolveComponent("Comp")
@@ -193,7 +194,7 @@ export function render(_ctx) {
       () => ({
         name: _ctx.named, 
         fn: (_slotProps0) => {
-          const n0 = _createTextNode()
+          const n0 = t0()
           _renderEffect(() => _setText(n0, _toDisplayString(_slotProps0["foo"] + _ctx.bar)))
           return n0
         }
@@ -205,13 +206,14 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: transform slot > on component named slot 1`] = `
-"import { resolveComponent as _resolveComponent, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback } from 'vue';
+"import { resolveComponent as _resolveComponent, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
   const _component_Comp = _resolveComponent("Comp")
   const n1 = _createComponentWithFallback(_component_Comp, null, {
     "named": (_slotProps0) => {
-      const n0 = _createTextNode()
+      const n0 = t0()
       _renderEffect(() => _setText(n0, _toDisplayString(_slotProps0["foo"] + _ctx.bar)))
       return n0
     }
@@ -221,13 +223,14 @@ export function render(_ctx) {
 `;
 
 exports[`compiler: transform slot > on-component default slot 1`] = `
-"import { resolveComponent as _resolveComponent, createTextNode as _createTextNode, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback } from 'vue';
+"import { resolveComponent as _resolveComponent, toDisplayString as _toDisplayString, setText as _setText, renderEffect as _renderEffect, createComponentWithFallback as _createComponentWithFallback, template as _template } from 'vue';
+const t0 = _template(" ")
 
 export function render(_ctx) {
   const _component_Comp = _resolveComponent("Comp")
   const n1 = _createComponentWithFallback(_component_Comp, null, {
     "default": (_slotProps0) => {
-      const n0 = _createTextNode()
+      const n0 = t0()
       _renderEffect(() => _setText(n0, _toDisplayString(_slotProps0["foo"] + _ctx.bar)))
       return n0
     }

packages/compiler-vapor/__tests__/transforms/transformChildren.spec.ts

@@ -27,10 +27,11 @@ describe('compiler: children transform', () => {
     )
     expect(code).toMatchSnapshot()
     expect(Array.from(helpers)).containSubset([
+      'child',
+      'toDisplayString',
+      'renderEffect',
       'next',
       'setText',
-      'createTextNode',
-      'insert',
       'template',
     ])
   })

packages/compiler-vapor/__tests__/transforms/transformText.spec.ts

@@ -1,4 +1,5 @@
 // TODO: add tests for this transform
+import { NodeTypes } from '@vue/compiler-dom'
 import {
   IRNodeTypes,
   transformChildren,
@@ -24,14 +25,14 @@ describe('compiler: text transform', () => {
       '{{ "hello world" }}',
     )
     expect(code).toMatchSnapshot()
-    expect(helpers).contains.all.keys('createTextNode')
+    expect(helpers).contains.all.keys('setText', 'template')
     expect(ir.block.operation).toMatchObject([
       {
-        type: IRNodeTypes.CREATE_TEXT_NODE,
+        type: IRNodeTypes.SET_TEXT,
-        id: 0,
+        element: 0,
         values: [
           {
-            type: IRNodeTypes.SET_TEXT,
+            type: NodeTypes.SIMPLE_EXPRESSION,
             content: '"hello world"',
             isStatic: false,
           },
@@ -43,14 +44,8 @@ describe('compiler: text transform', () => {
   it('consecutive text', () => {
     const { code, ir, helpers } = compileWithTextTransform('{{ msg }}')
     expect(code).toMatchSnapshot()
-    expect(helpers).contains.all.keys('createTextNode')
+    expect(helpers).contains.all.keys('setText', 'template')
-    expect(ir.block.operation).toMatchObject([
+    expect(ir.block.operation).toMatchObject([])
-      {
-        type: IRNodeTypes.CREATE_TEXT_NODE,
-        id: 0,
-        values: undefined,
-      },
-    ])
     expect(ir.block.effect.length).toBe(1)
   })
 })

packages/compiler-vapor/__tests__/transforms/vOnce.spec.ts

@@ -28,8 +28,8 @@ describe('compiler: v-once', () => {
     expect(ir.block.effect).lengthOf(0)
     expect(ir.block.operation).toMatchObject([
       {
-        type: IRNodeTypes.CREATE_TEXT_NODE,
+        type: IRNodeTypes.SET_TEXT,
-        id: 0,
+        element: 0,
         values: [
           {
             type: NodeTypes.SIMPLE_EXPRESSION,
@@ -61,11 +61,6 @@ describe('compiler: v-once', () => {
           ],
         },
       },
-      {
-        type: IRNodeTypes.PREPEND_NODE,
-        elements: [0],
-        parent: 2,
-      },
     ])
   })
 

packages/compiler-vapor/src/generators/template.ts

@@ -66,11 +66,10 @@ export function genChildren(
     push(NEWLINE, `const ${variable} = `)
 
     if (prev) {
-      const offset = elementIndex - prev[1]
+      if (elementIndex - prev[1] === 1) {
-      if (offset === 1) {
         push(...genCall(helper('next'), prev[0]))
       } else {
-        push(...genCall(helper('nthChild'), from, String(offset)))
+        push(...genCall(helper('nthChild'), from, String(elementIndex)))
       }
     } else {
       if (newPath.length === 1 && newPath[0] === 0) {

packages/compiler-vapor/src/transforms/transformText.ts

@@ -30,32 +30,71 @@ export const transformText: NodeTransform = (node, context) => {
     return
   }
 
+  const isFragment =
+    node.type === NodeTypes.ROOT ||
+    (node.type === NodeTypes.ELEMENT &&
+      (node.tagType === ElementTypes.TEMPLATE ||
+        node.tagType === ElementTypes.COMPONENT))
+
   if (
-    node.type === NodeTypes.ELEMENT &&
+    (isFragment ||
-    node.tagType === ElementTypes.ELEMENT &&
+      (node.type === NodeTypes.ELEMENT &&
-    isAllTextLike(node.children)
+        node.tagType === ElementTypes.ELEMENT)) &&
+    node.children.length
   ) {
-    processTextLikeContainer(
+    let hasInterp = false
-      node.children,
+    let isAllTextLike = true
+    for (const c of node.children) {
+      if (c.type === NodeTypes.INTERPOLATION) {
+        hasInterp = true
+      } else if (c.type !== NodeTypes.TEXT) {
+        isAllTextLike = false
+      }
+    }
+    // all text like with interpolation
+    if (!isFragment && isAllTextLike && hasInterp) {
+      processTextContainer(
+        node.children as TextLike[],
         context as TransformContext<ElementNode>,
       )
+    } else if (hasInterp) {
+      // check if there's any text before interpolation, it needs to be merged
+      for (let i = 0; i < node.children.length; i++) {
+        const c = node.children[i]
+        const prev = node.children[i - 1]
+        if (
+          c.type === NodeTypes.INTERPOLATION &&
+          prev &&
+          prev.type === NodeTypes.TEXT
+        ) {
+          // mark leading text node for skipping
+          seen.get(context.root)!.add(prev)
+        }
+      }
+    }
   } else if (node.type === NodeTypes.INTERPOLATION) {
-    processTextLike(context as TransformContext<InterpolationNode>)
+    processInterpolation(context as TransformContext<InterpolationNode>)
   } else if (node.type === NodeTypes.TEXT) {
     context.template += node.content
   }
 }
 
-function processTextLike(context: TransformContext<InterpolationNode>) {
+function processInterpolation(context: TransformContext<InterpolationNode>) {
-  const nexts = context.parent!.node.children.slice(context.index)
+  const children = context.parent!.node.children
+  const nexts = children.slice(context.index)
   const idx = nexts.findIndex(n => !isTextLike(n))
   const nodes = (idx > -1 ? nexts.slice(0, idx) : nexts) as Array<TextLike>
 
+  // merge leading text
+  const prev = children[context.index - 1]
+  if (prev && prev.type === NodeTypes.TEXT) {
+    nodes.unshift(prev)
+  }
+
+  context.template += ' '
   const id = context.reference()
   const values = nodes.map(node => createTextLikeExpression(node, context))
 
-  context.dynamic.flags |= DynamicFlag.INSERT | DynamicFlag.NON_TEMPLATE
-
   const nonConstantExps = values.filter(v => !isConstantExpression(v))
   const isStatic =
     !nonConstantExps.length ||
@@ -64,12 +103,13 @@ function processTextLike(context: TransformContext<InterpolationNode>) {
     ) ||
     context.inVOnce
 
+  if (isStatic) {
     context.registerOperation({
-    type: IRNodeTypes.CREATE_TEXT_NODE,
+      type: IRNodeTypes.SET_TEXT,
-    id,
+      element: id,
-    values: isStatic ? values : undefined,
+      values,
     })
-  if (!isStatic) {
+  } else {
     context.registerEffect(values, {
       type: IRNodeTypes.SET_TEXT,
       element: id,
@@ -78,7 +118,7 @@ function processTextLike(context: TransformContext<InterpolationNode>) {
   }
 }
 
-function processTextLikeContainer(
+function processTextContainer(
   children: TextLike[],
   context: TransformContext<ElementNode>,
 ) {
@@ -111,15 +151,6 @@ function createTextLikeExpression(node: TextLike, context: TransformContext) {
   }
 }
 
-function isAllTextLike(children: TemplateChildNode[]): children is TextLike[] {
-  return (
-    !!children.length &&
-    children.every(isTextLike) &&
-    // at least one an interpolation
-    children.some(n => n.type === NodeTypes.INTERPOLATION)
-  )
-}
-
 function isTextLike(node: TemplateChildNode): node is TextLike {
   return node.type === NodeTypes.INTERPOLATION || node.type === NodeTypes.TEXT
 }

packages/runtime-vapor/__tests__/apiCreateVaporApp.spec.ts

@@ -35,8 +35,10 @@ describe('api: createVaporApp', () => {
     const root1 = document.createElement('div')
     createVaporApp(Comp).mount(root1)
     expect(root1.innerHTML).toBe(`0`)
+
     //#5571 mount multiple apps to the same host element
     createVaporApp(Comp).mount(root1)
+    expect(`mount target container is not empty`).toHaveBeenWarned()
     expect(
       `There is already an app instance mounted on the host container`,
     ).toHaveBeenWarned()

packages/runtime-vapor/src/apiCreateApp.ts

@@ -7,6 +7,7 @@ import {
   unmountComponent,
 } from './component'
 import {
+  type App,
   type AppMountFn,
   type AppUnmountFn,
   type CreateAppFunction,
@@ -20,6 +21,7 @@ import {
 import type { RawProps } from './componentProps'
 import { getGlobalThis } from '@vue/shared'
 import { optimizePropertyLookup } from './dom/prop'
+import { withHydration } from './dom/hydration'
 
 let _createApp: CreateAppFunction<ParentNode, VaporComponent>
 
@@ -28,6 +30,9 @@ const mountApp: AppMountFn<ParentNode> = (app, container) => {
 
   // clear content before mounting
   if (container.nodeType === 1 /* Node.ELEMENT_NODE */) {
+    if (__DEV__ && container.childNodes.length) {
+      warn('mount target container is not empty and will be cleared.')
+    }
     container.textContent = ''
   }
 
@@ -38,21 +43,38 @@ const mountApp: AppMountFn<ParentNode> = (app, container) => {
     false,
     app._context,
   )
-
   mountComponent(instance, container)
   flushOnAppMount()
 
-  return instance
+  return instance!
+}
+
+let _hydrateApp: CreateAppFunction<ParentNode, VaporComponent>
+
+const hydrateApp: AppMountFn<ParentNode> = (app, container) => {
+  optimizePropertyLookup()
+
+  let instance: VaporComponentInstance
+  withHydration(container, () => {
+    instance = createComponent(
+      app._component,
+      app._props as RawProps,
+      null,
+      false,
+      app._context,
+    )
+    mountComponent(instance, container)
+    flushOnAppMount()
+  })
+
+  return instance!
 }
 
 const unmountApp: AppUnmountFn = app => {
   unmountComponent(app._instance as VaporComponentInstance, app._container)
 }
 
-export const createVaporApp: CreateAppFunction<ParentNode, VaporComponent> = (
+function prepareApp() {
-  comp,
-  props,
-) => {
   // compile-time feature flags check
   if (__ESM_BUNDLER__ && !__TEST__) {
     initFeatureFlags()
@@ -63,10 +85,9 @@ export const createVaporApp: CreateAppFunction<ParentNode, VaporComponent> = (
   if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
     setDevtoolsHook(target.__VUE_DEVTOOLS_GLOBAL_HOOK__, target)
   }
+}
 
-  if (!_createApp) _createApp = createAppAPI(mountApp, unmountApp, getExposed)
+function postPrepareApp(app: App) {
-  const app = _createApp(comp, props)
-
   if (__DEV__) {
     app.config.globalProperties = new Proxy(
       {},
@@ -84,5 +105,27 @@ export const createVaporApp: CreateAppFunction<ParentNode, VaporComponent> = (
     container = normalizeContainer(container) as ParentNode
     return mount(container, ...args)
   }
+}
+
+export const createVaporApp: CreateAppFunction<ParentNode, VaporComponent> = (
+  comp,
+  props,
+) => {
+  prepareApp()
+  if (!_createApp) _createApp = createAppAPI(mountApp, unmountApp, getExposed)
+  const app = _createApp(comp, props)
+  postPrepareApp(app)
+  return app
+}
+
+export const createVaporSSRApp: CreateAppFunction<
+  ParentNode,
+  VaporComponent
+> = (comp, props) => {
+  prepareApp()
+  if (!_hydrateApp)
+    _hydrateApp = createAppAPI(hydrateApp, unmountApp, getExposed)
+  const app = _hydrateApp(comp, props)
+  postPrepareApp(app)
   return app
 }

packages/runtime-vapor/src/block.ts

@@ -7,6 +7,7 @@ import {
 } from './component'
 import { createComment, createTextNode } from './dom/node'
 import { EffectScope, pauseTracking, resetTracking } from '@vue/reactivity'
+import { isHydrating } from './dom/hydration'
 import {
   type TransitionHooks,
   type TransitionProps,
@@ -154,6 +155,7 @@ export function insert(
 ): void {
   anchor = anchor === 0 ? parent.firstChild : anchor
   if (block instanceof Node) {
+    if (!isHydrating) {
       // don't apply transition on text or comment nodes
       if ((block as TransitionBlock).$transition && block instanceof Element) {
         performTransitionEnter(
@@ -165,15 +167,21 @@ export function insert(
       } else {
         parent.insertBefore(block, anchor)
       }
+    }
   } else if (isVaporComponent(block)) {
+    if (block.isMounted) {
+      insert(block.block!, parent, anchor)
+    } else {
       mountComponent(block, parent, anchor)
+    }
   } else if (isArray(block)) {
-    for (let i = 0; i < block.length; i++) {
+    for (const b of block) {
-      insert(block[i], parent, anchor)
+      insert(b, parent, anchor)
     }
   } else {
     // fragment
     if (block.insert) {
+      // TODO handle hydration for vdom interop
       block.insert(parent, anchor, (block as TransitionBlock).$transition)
     } else {
       insert(block.nodes, parent, anchor, parentSuspense)
@@ -182,6 +190,8 @@ export function insert(
   }
 }
 
+export type InsertFn = typeof insert
+
 export function prepend(parent: ParentNode, ...blocks: Block[]): void {
   let i = blocks.length
   while (i--) insert(blocks[i], parent, 0)

packages/runtime-vapor/src/component.ts

@@ -480,14 +480,10 @@ export function mountComponent(
   if (__DEV__) {
     startMeasure(instance, `mount`)
   }
-  if (!instance.isMounted) {
   if (instance.bm) invokeArrayFns(instance.bm)
   insert(instance.block, parent, anchor)
   if (instance.m) queuePostFlushCb(() => invokeArrayFns(instance.m!))
   instance.isMounted = true
-  } else {
-    insert(instance.block, parent, anchor)
-  }
   if (__DEV__) {
     endMeasure(instance, `mount`)
   }

packages/runtime-vapor/src/dom/hydration.ts

@@ -0,0 +1,125 @@
+import { child, next } from './node'
+
+export let isHydrating = false
+export let currentHydrationNode: Node | null = null
+
+export function setCurrentHydrationNode(node: Node | null): void {
+  currentHydrationNode = node
+}
+
+let isOptimized = false
+
+export function withHydration(container: ParentNode, fn: () => void): void {
+  adoptHydrationNode = adoptHydrationNodeImpl
+  if (!isOptimized) {
+    // optimize anchor cache lookup
+    const proto = Comment.prototype as any
+    proto.$p = proto.$e = undefined
+    isOptimized = true
+  }
+  isHydrating = true
+  currentHydrationNode = child(container)
+  const res = fn()
+  isHydrating = false
+  currentHydrationNode = null
+  return res
+}
+
+export let adoptHydrationNode: (
+  node: Node | null,
+  template?: string,
+) => Node | null
+
+type Anchor = Comment & {
+  // previous open anchor
+  $p?: Anchor
+  // matching end anchor
+  $e?: Anchor
+}
+
+const isComment = (node: Node, data: string): node is Anchor =>
+  node.nodeType === 8 && (node as Comment).data === data
+
+/**
+ * Locate the first non-fragment-comment node and locate the next node
+ * while handling potential fragments.
+ */
+function adoptHydrationNodeImpl(
+  node: Node | null,
+  template?: string,
+): Node | null {
+  if (!isHydrating || !node) {
+    return node
+  }
+
+  let adopted: Node | undefined
+  let end: Node | undefined | null
+
+  if (template) {
+    if (template[0] !== '<' && template[1] !== '!') {
+      while (node.nodeType === 8) node = next(node)
+    }
+    adopted = end = node
+  } else if (isComment(node, '[')) {
+    // fragment
+    let start = node
+    let cur: Node = node
+    let fragmentDepth = 1
+    // previously recorded fragment end
+    if (!end && node.$e) {
+      end = node.$e
+    }
+    while (true) {
+      cur = next(cur)
+      if (isComment(cur, '[')) {
+        // previously recorded fragment end
+        if (!end && node.$e) {
+          end = node.$e
+        }
+        fragmentDepth++
+        cur.$p = start
+        start = cur
+      } else if (isComment(cur, ']')) {
+        fragmentDepth--
+        // record fragment end on start node for later traversal
+        start.$e = cur
+        start = start.$p!
+        if (!fragmentDepth) {
+          // fragment end
+          end = cur
+          break
+        }
+      } else if (!adopted) {
+        adopted = cur
+        if (end) {
+          break
+        }
+      }
+    }
+    if (!adopted) {
+      throw new Error('hydration mismatch')
+    }
+  } else {
+    adopted = end = node
+  }
+
+  if (__DEV__ && template) {
+    const type = adopted.nodeType
+    if (
+      (type === 8 && !template.startsWith('<!')) ||
+      (type === 1 &&
+        !template.startsWith(
+          `<` + (adopted as Element).tagName.toLowerCase(),
+        )) ||
+      (type === 3 &&
+        template.trim() &&
+        !template.startsWith((adopted as Text).data))
+    ) {
+      // TODO recover and provide more info
+      throw new Error('hydration mismatch!')
+    }
+  }
+
+  currentHydrationNode = next(end!)
+  return adopted
+}

packages/runtime-vapor/src/dom/template.ts

@@ -1,13 +1,33 @@
+import {
+  adoptHydrationNode,
+  currentHydrationNode,
+  isHydrating,
+} from './hydration'
+import { child, createTextNode } from './node'
+
+let t: HTMLTemplateElement
+
 /*! #__NO_SIDE_EFFECTS__ */
 export function template(html: string, root?: boolean) {
-  let node: ChildNode
+  let node: Node
-  const create = () => {
-    const t = document.createElement('template')
-    t.innerHTML = html
-    return t.content.firstChild!
-  }
   return (): Node & { $root?: true } => {
-    const ret = (node || (node = create())).cloneNode(true)
+    if (isHydrating) {
+      if (__DEV__ && !currentHydrationNode) {
+        // TODO this should not happen
+        throw new Error('No current hydration node')
+      }
+      return adoptHydrationNode(currentHydrationNode, html)!
+    }
+    // fast path for text nodes
+    if (html[0] !== '<') {
+      return createTextNode(html)
+    }
+    if (!node) {
+      t = t || document.createElement('template')
+      t.innerHTML = html
+      node = child(t.content)
+    }
+    const ret = node.cloneNode(true)
     if (root) (ret as any).$root = true
     return ret
   }

packages/runtime-vapor/src/index.ts

@@ -1,5 +1,5 @@
 // public APIs
-export { createVaporApp } from './apiCreateApp'
+export { createVaporApp, createVaporSSRApp } from './apiCreateApp'
 export { defineVaporComponent } from './apiDefineComponent'
 export { vaporInteropPlugin } from './vdomInterop'
 export type { VaporDirective } from './directives/custom'