From 634a0734c429850a4679b2f220b14a896536a7fb Mon Sep 17 00:00:00 2001
From: Evan You <yyx990803@gmail.com>
Date: Tue, 21 Jun 2016 03:03:49 -0400
Subject: [PATCH] support sync watcher as internal flag

---
 build/karma.cover.config.js  | 3 ++-
 src/core/observer/watcher.js | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/build/karma.cover.config.js b/build/karma.cover.config.js
index 950f40a1c..c03003570 100644
--- a/build/karma.cover.config.js
+++ b/build/karma.cover.config.js
@@ -19,7 +19,8 @@ module.exports = function (config) {
       ignore: [
         'test/',
         'src/compiler/parser/html-parser.js',
-        'src/core/instance/proxy.js'
+        'src/core/instance/proxy.js',
+        'src/sfc/deindent.js'
       ]
     }]]
   }
diff --git a/src/core/observer/watcher.js b/src/core/observer/watcher.js
index 6c649e76a..95c7e7c97 100644
--- a/src/core/observer/watcher.js
+++ b/src/core/observer/watcher.js
@@ -27,6 +27,7 @@ export default class Watcher {
   deep: boolean;
   user: boolean;
   lazy: boolean;
+  sync: boolean;
   dirty: boolean;
   active: boolean;
   deps: Array<Dep>;
@@ -48,6 +49,7 @@ export default class Watcher {
     this.deep = !!options.deep
     this.user = !!options.user
     this.lazy = !!options.lazy
+    this.sync = !!options.sync
     this.expression = expOrFn.toString()
     this.cb = cb
     this.id = ++uid // uid for batching
@@ -167,8 +169,11 @@ export default class Watcher {
    * Will be called when a dependency changes.
    */
   update () {
+    /* istanbul ignore else */
     if (this.lazy) {
       this.dirty = true
+    } else if (this.sync) {
+      this.run()
     } else {
       queueWatcher(this)
     }