Iterate over children in reverse

Author: Joris-van-der-Wel

lib/SymbolTree.js

@@ -358,12 +358,14 @@ class SymbolTree {
          * @method childrenIterator
          * @memberOf module:symbol-tree#
          * @param {Object} parent
+         * @param {Boolean} [reverse=false]
          * @return {Object} An iterable iterator (ES6)
          */
-        childrenIterator(parent) {
+        childrenIterator(parent, reverse) {
                 const _node = this._node.bind(this);
 
-                let nextObject = this._node(parent).first;
+                let nextObject = this._node(parent)[reverse ? 'last' : 'first'];
+
                 const iterator = {};
 
                 iterator.next = function() {
@@ -375,7 +377,7 @@ class SymbolTree {
                         }
 
                         const value = nextObject;
-                        nextObject = _node(nextObject).next;
+                        nextObject = _node(nextObject)[reverse ? 'prev' : 'next'];
 
                         return {
                                 done  : false,

test/SymbolTree.js

@@ -698,6 +698,32 @@ test('children iterator', function(t) {
         t.end();
 });
 
+test('children iterator reverse', function(t) {
+        const tree = new SymbolTree();
+        const a = {};
+        const aa = {};
+        const ab = {};
+        const aba = {};
+        const ac = {};
+        const b = {};
+
+        tree.insertLast(aa, a);
+        tree.insertLast(ab, a);
+        tree.insertLast(aba, ab);
+        tree.insertLast(ac, a);
+        tree.insertAfter(b, a);
+
+        const results = [];
+
+        for (const object of tree.childrenIterator(a, true)) {
+                results.push(object);
+        }
+        t.deepEqual([ac, ab, aa], results);
+
+        t.end();
+});
+
+
 test('children iterator return value using a generator', function(t) {
         const tree = new SymbolTree();
         const a = {};