move computed value parentSubmenuNum from .vue to mixin.js

src/components/menu/menu-item.vue

@@ -3,12 +3,13 @@
 </template>
 <script>
     import Emitter from '../../mixins/emitter';
-    import { findComponentUpward, findComponentsUpward } from '../../utils/assist';
+    import { findComponentUpward } from '../../utils/assist';
     const prefixCls = 'ivu-menu';
+    import mixin from './mixin';
 
     export default {
         name: 'MenuItem',
-        mixins: [ Emitter ],
+        mixins: [ Emitter, mixin ],
         props: {
             name: {
                 type: [String, Number],
@@ -35,9 +36,6 @@
                     }
                 ];
             },
-            parentSubmenuNum () {
-                return findComponentsUpward(this, 'Submenu').length;
-            },
             itemStyle () {
                 return this.hasParentSubmenu ? {
                     paddingLeft: 43 + (this.parentSubmenuNum - 1) * 24 + 'px'

src/components/menu/mixin.js

@@ -0,0 +1,8 @@
+import { findComponentsUpward } from '../../utils/assist';
+export default {
+    computed: {
+        parentSubmenuNum () {
+            return findComponentsUpward(this, 'Submenu').length;
+        }
+    }
+}

src/components/menu/submenu.vue

@@ -21,14 +21,15 @@
     import Drop from '../select/dropdown.vue';
     import Icon from '../icon/icon.vue';
     import CollapseTransition from '../base/collapse-transition';
-    import { getStyle, findComponentUpward, findComponentsUpward, findComponentsDownward } from '../../utils/assist';
+    import { getStyle, findComponentUpward, findComponentsDownward } from '../../utils/assist';
     import Emitter from '../../mixins/emitter';
+    import mixin from './mixin';
 
     const prefixCls = 'ivu-menu';
 
     export default {
         name: 'Submenu',
-        mixins: [ Emitter ],
+        mixins: [ Emitter, mixin ],
         components: { Icon, Drop, CollapseTransition },
         props: {
             name: {
@@ -77,9 +78,6 @@
             hasParentSubmenu () {
                 return findComponentUpward(this, 'Submenu');
             },
-            parentSubmenuNum () {
-                return findComponentsUpward(this, 'Submenu').length;
-            },
             titleStyle () {
                 return this.hasParentSubmenu ? {
                     paddingLeft: 43 + (this.parentSubmenuNum - 1) * 24 + 'px'