MD Bookmarks: Proof-of-concept reimplementation of data storage/binding layer

chrome/browser/resources/md_bookmarks/util.js

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Utility functions for the Bookmarks page.
+ */
+
+cr.define('bookmarks.util', function() {
+  /**
+   * @param {BookmarksPageState} state
+   * @return {!Array<string>}
+   */
+  function getDisplayedList(state) {
+    if (state.selectedFolder)
+      return assert(state.nodes[state.selectedFolder].children);
+
+    return state.search.results;
+  }
+
+  /**
+   * @param {BookmarkTreeNode} rootNode
+   * @return {NodeList}
+   */
+  function normalizeNodes(rootNode) {
+    /** @type {NodeList} */
+    var nodeMap = {};
+    var queue = [];
+    queue.push(rootNode);
+
+    while (queue.length > 0) {
+      var node = queue.pop();
+      // Node index is not necessary and not kept up-to-date. Remove it from the
+      // data structure so we don't accidentally depend on the incorrect
+      // information.
+      delete node.index;
+      nodeMap[node.id] = node;
+      if (node.children) {
+        var childIds = [];
+        node.children.forEach(function(child) {
+          childIds.push(child.id);
+          queue.push(child);
+        });
+        node.children = childIds;
+      }
+    }
+
+    return nodeMap;
+  }
+
+  /** @return {BookmarksPageState} */
+  function createEmptyState() {
+    return {
+      nodes: {},
+      selectedFolder: '0',
+      closedFolders: {},
+      search: {
+        term: '',
+        inProgress: false,
+        results: [],
+      },
+      selection: {
+        items: {},
+        anchor: null,
+        count: 0,
+      },
+    };
+  }
+
+  return {
+    createEmptyState: createEmptyState,
+    getDisplayedList: getDisplayedList,
+    normalizeNodes: normalizeNodes,
+  };
+});