SSR: eliminate closure in render.js implementation

flow/options.js

@@ -57,7 +57,9 @@ declare type ComponentOptions = {
   _propKeys?: Array<string>;
   _parentVnode?: VNode;
   _parentListeners?: ?Object;
-  _renderChildren?: ?VNodeChildren
+  _renderChildren?: ?VNodeChildren;
+  _componentTag: ?string;
+  _scopeId: ?string;
 }
 
 declare type PropOptions = {

flow/ssr.js

@@ -0,0 +1,21 @@
+declare type ComponentWithCacheContext = {
+  type: 'ComponentWithCache';
+  bufferIndex: number;
+  buffer: Array<string>;
+  key: string;
+}
+
+declare type ElementContext = {
+  type: 'Element';
+  children: Array<VNode>;
+  rendered: number;
+  endTag: string;
+  total: number;
+}
+
+declare type ComponentContext = {
+  type: 'Component';
+  prevActive: Component;
+}
+
+declare type RenderState = ComponentContext | ComponentWithCacheContext | ElementContext

package.json

@@ -67,7 +67,7 @@
     "eslint-loader": "^1.3.0",
     "eslint-plugin-flowtype": "^2.16.0",
     "eslint-plugin-html": "^1.5.2",
-    "flow-bin": "^0.32.0",
+    "flow-bin": "^0.33.0",
     "he": "^1.1.0",
     "http-server": "^0.9.0",
     "jasmine": "2.4.x",

src/compiler/codegen/index.js

@@ -53,9 +53,10 @@ function genElement (el: ASTElement): string {
     // component or element
     let code
     if (el.component) {
-      code = genComponent(el)
+      code = genComponent(el.component, el)
     } else {
-      const data = genData(el)
+      const data = el.plain ? undefined : genData(el)
+
       const children = el.inlineTemplate ? null : genChildren(el)
       code = `_h('${el.tag}'${
         data ? `,${data}` : '' // data
@@ -95,11 +96,7 @@ function genFor (el: any): string {
     '})'
 }
 
-function genData (el: ASTElement): string | void {
-  if (el.plain) {
-    return
-  }
-
+function genData (el: ASTElement): string {
   let data = '{'
 
   // directives first.
@@ -229,9 +226,10 @@ function genSlot (el: ASTElement): string {
     : `_t(${slotName})`
 }
 
-function genComponent (el: any): string {
+// componentName is el.component, take it as argument to shun flow's pessimistic refinement
+function genComponent (componentName, el): string {
   const children = el.inlineTemplate ? null : genChildren(el)
-  return `_h(${el.component},${genData(el)}${
+  return `_h(${componentName},${genData(el)}${
     children ? `,${children}` : ''
   })`
 }

src/core/util/props.js

@@ -126,7 +126,7 @@ function assertProp (
  */
 function assertType (value: any, type: Function): {
   valid: boolean,
-  expectedType: string
+  expectedType: ?string
 } {
   let valid
   let expectedType = getType(type)

src/server/render-stream.js

@@ -13,9 +13,8 @@ import { createWriteFunction } from './write'
 
 export default class RenderStream extends stream.Readable {
   buffer: string;
-  render: Function;
+  render: (write: Function, done: Function) => void;
   expectedSize: number;
-  stackDepth: number;
   write: Function;
   next: Function;
   end: Function;
@@ -26,7 +25,6 @@ export default class RenderStream extends stream.Readable {
     this.buffer = ''
     this.render = render
     this.expectedSize = 0
-    this.stackDepth = 0
 
     this.write = createWriteFunction((text, next) => {
       const n = this.expectedSize