From 44e36e32727475c199b028f91c5610aa2aec6374 Mon Sep 17 00:00:00 2001
From: leandromoh <leandromoh@hotmail.com>
Date: Mon, 24 Dec 2018 18:13:18 -0200
Subject: [PATCH 1/2] removed duplicated

---
 MoreLinq/Traverse.cs | 45 ++++++++++++++++++++++----------------------
 1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/MoreLinq/Traverse.cs b/MoreLinq/Traverse.cs
index 4fb46b5b8..87cc58bf9 100644
--- a/MoreLinq/Traverse.cs
+++ b/MoreLinq/Traverse.cs
@@ -18,6 +18,7 @@
 namespace MoreLinq
 {
     using System;
+    using System.Collections;
     using System.Collections.Generic;
     using System.Linq;
 
@@ -46,21 +47,8 @@ public partial class MoreEnumerable
 
         public static IEnumerable<T> TraverseBreadthFirst<T>(T root, Func<T, IEnumerable<T>> childrenSelector)
         {
-            if (childrenSelector == null) throw new ArgumentNullException(nameof(childrenSelector));
-
-            return _(); IEnumerable<T> _()
-            {
-                var queue = new Queue<T>();
-                queue.Enqueue(root);
-
-                while (queue.Count != 0)
-                {
-                    var current = queue.Dequeue();
-                    yield return current;
-                    foreach (var child in childrenSelector(current))
-                        queue.Enqueue(child);
-                }
-            }
+            var queue = new Queue<T>();
+            return TraverseImpl(root, childrenSelector, queue.Enqueue, queue.Dequeue, queue);
         }
 
         /// <summary>
@@ -85,22 +73,33 @@ public static IEnumerable<T> TraverseBreadthFirst<T>(T root, Func<T, IEnumerable
         /// </remarks>
 
         public static IEnumerable<T> TraverseDepthFirst<T>(T root, Func<T, IEnumerable<T>> childrenSelector)
+        {
+            // because a stack pops the elements out in LIFO order, we need to push them in reverse
+            // if we want to traverse the returned list in the same order as was returned to us
+
+            var stack = new Stack<T>();
+            return TraverseImpl(root, x => childrenSelector(x).Reverse(), stack.Push, stack.Pop, stack);
+        }
+
+        static IEnumerable<T> TraverseImpl<T>(
+            T root,
+            Func<T, IEnumerable<T>> childrenSelector,
+            Action<T> Push,
+            Func<T> Pop,
+            ICollection collection)
         {
             if (childrenSelector == null) throw new ArgumentNullException(nameof(childrenSelector));
 
             return _(); IEnumerable<T> _()
             {
-                var stack = new Stack<T>();
-                stack.Push(root);
+                Push(root);
 
-                while (stack.Count != 0)
+                while (collection.Count != 0)
                 {
-                    var current = stack.Pop();
+                    var current = Pop();
                     yield return current;
-                    // because a stack pops the elements out in LIFO order, we need to push them in reverse
-                    // if we want to traverse the returned list in the same order as was returned to us
-                    foreach (var child in childrenSelector(current).Reverse())
-                        stack.Push(child);
+                    foreach (var child in childrenSelector(current))
+                        Push(child);
                 }
             }
         }

From 60ee09de9b4e8735ebd745b012a1dcc4a2a76e69 Mon Sep 17 00:00:00 2001
From: leandromoh <leandromoh@hotmail.com>
Date: Mon, 24 Dec 2018 18:54:20 -0200
Subject: [PATCH 2/2] fix validation

---
 MoreLinq/Traverse.cs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/MoreLinq/Traverse.cs b/MoreLinq/Traverse.cs
index 87cc58bf9..2745ab653 100644
--- a/MoreLinq/Traverse.cs
+++ b/MoreLinq/Traverse.cs
@@ -47,6 +47,8 @@ public partial class MoreEnumerable
 
         public static IEnumerable<T> TraverseBreadthFirst<T>(T root, Func<T, IEnumerable<T>> childrenSelector)
         {
+            if (childrenSelector == null) throw new ArgumentNullException(nameof(childrenSelector));
+
             var queue = new Queue<T>();
             return TraverseImpl(root, childrenSelector, queue.Enqueue, queue.Dequeue, queue);
         }
@@ -74,6 +76,8 @@ public static IEnumerable<T> TraverseBreadthFirst<T>(T root, Func<T, IEnumerable
 
         public static IEnumerable<T> TraverseDepthFirst<T>(T root, Func<T, IEnumerable<T>> childrenSelector)
         {
+            if (childrenSelector == null) throw new ArgumentNullException(nameof(childrenSelector));
+
             // because a stack pops the elements out in LIFO order, we need to push them in reverse
             // if we want to traverse the returned list in the same order as was returned to us
 
@@ -88,8 +92,6 @@ static IEnumerable<T> TraverseImpl<T>(
             Func<T> Pop,
             ICollection collection)
         {
-            if (childrenSelector == null) throw new ArgumentNullException(nameof(childrenSelector));
-
             return _(); IEnumerable<T> _()
             {
                 Push(root);