Iterate over children using an ES6 iterator

Author: Joris-van-der-Wel

lib/SymbolTree.js

@@ -303,6 +303,36 @@ class SymbolTree {
                 return array;
         }
 
+        childrenIterator(parent) {
+                const _node = this._node.bind(this);
+
+                let nextObject = this._node(parent).first;
+                const iterator = {};
+
+                iterator.next = function() {
+                        if (!nextObject) {
+                                return {
+                                        done  : true,
+                                        value : parent
+                                };
+                        }
+
+                        const value = nextObject;
+                        nextObject = _node(nextObject).next;
+
+                        return {
+                                done  : false,
+                                value : value
+                        };
+                };
+
+                iterator[Symbol.iterator] = function() {
+                        return iterator;
+                };
+
+                return iterator;
+        }
+
         /**
          * Remove the object from this tree.
          * Has no effect if already removed.

test/SymbolTree.js

@@ -673,6 +673,57 @@ test('childrenToArray with filter', function(t) {
         t.end();
 });
 
+test('children iterator', 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)) {
+                results.push(object);
+        }
+        t.deepEqual([aa, ab, ac], results);
+
+        t.end();
+});
+
+test('children iterator return value using a generator', function(t) {
+        const tree = new SymbolTree();
+        const a = {};
+        const aa = {};
+        const ab = {};
+        const ac = {};
+
+        tree.insertLast(aa, a);
+        tree.insertLast(ab, a);
+        tree.insertLast(ac, a);
+
+        function* generator(it) {
+                const returnValue = yield* it;
+                t.equal(a, returnValue);
+        }
+
+        const results = [];
+
+        for (const object of generator(tree.childrenIterator(a))) {
+                results.push(object);
+        }
+        t.deepEqual([aa, ab, ac], results);
+
+        t.end();
+});
+
 test('treeToArray', function(t) {
         const tree = new SymbolTree();
         const a = {};