MD Bookmarks: Remove deleted nodes from state tree

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() {
   /**
@@ skipping 49 matching lines @@
         inProgress: false,
         results: [],
       },
       selection: {
         items: {},
         anchor: null,
       },
     };
   }
 
+  /**
+   * Get all descendants of a node, including the node itself.
+   * @param {NodeList} nodes
+   * @param {string} baseId
+   * @return {!Set<string>}
+   */
+  function getDescendants(nodes, baseId) {
+    var descendants = new Set();
+    var stack = [];
+    stack.push(baseId);
+
+    while (stack.length > 0) {
+      var id = stack.pop();
+      var node = nodes[id];
+
+      if (!node)
+        continue;
+
+      descendants.add(id);
+
+      if (!node.children)
+        continue;
+
+      node.children.forEach(function(childId) {
+        stack.push(childId);
+      });
+    }
+
+    return descendants;
+  }
+
+  /**
+   * @param {!Object<string, T>} map
+   * @param {!Set<string>} nodes
+   * @return {!Object<string, T>}
+   * @template T
+   */
+  function removeNodesFromMap(map, nodes) {

[calamity, 2017/04/03 06:54:24]

Maybe genericize further into removeKeysFromMap? At the moment this is
overloading Nodes in a confusing way. Another alternative is removeIdsFromMap.

[tsergeant, 2017/04/04 04:42:28]

Done, with removeIdsFromMap (and removeIdsFromSet)

+    var newMap = Object.assign({}, map);
+    nodes.forEach(function(id) {
+      delete newMap[id];
+    });
+    return newMap;
+  };
+
   return {
     createEmptyState: createEmptyState,
+    getDescendants: getDescendants,
     getDisplayedList: getDisplayedList,
     normalizeNodes: normalizeNodes,
+    removeNodesFromMap: removeNodesFromMap,
   };
 });