[improvement] mixins typescript (#3690)

src/mixins/relation.js

@@ -1,68 +0,0 @@
-export function ChildrenMixin(parent, options = {}) {
-  const indexKey = options.indexKey || 'index';
-
-  return {
-    inject: {
-      [parent]: {
-        default: null
-      }
-    },
-
-    computed: {
-      parent() {
-        return this[parent];
-      },
-
-      [indexKey]() {
-        this.bindRelation();
-        return this.parent.children.indexOf(this);
-      }
-    },
-
-    created() {
-      this.bindRelation();
-    },
-
-    beforeDestroy() {
-      if (this.parent) {
-        this.parent.children = this.parent.children.filter(item => item !== this);
-      }
-    },
-
-    methods: {
-      bindRelation() {
-        if (!this.parent) {
-          return;
-        }
-
-        const { children } = this.parent;
-
-        if (children.indexOf(this) === -1) {
-          const vnodeIndex = this.parent.slots().indexOf(this.$vnode);
-
-          if (vnodeIndex === -1) {
-            children.push(this);
-          } else {
-            children.splice(vnodeIndex, 0, this);
-          }
-        }
-      }
-    }
-  };
-}
-
-export function ParentMixin(parent) {
-  return {
-    provide() {
-      return {
-        [parent]: this
-      };
-    },
-
-    data() {
-      return {
-        children: []
-      };
-    }
-  };
-}