From 563d4b3610c3c2214a01685ac9308b7d6e361aef Mon Sep 17 00:00:00 2001
From: Alex Goodman <wagoodman@gmail.com>
Date: Fri, 1 Jun 2018 17:27:47 -0400
Subject: [PATCH] prevent underflow

---
 filetree.go | 4 ++--
 main.go     | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/filetree.go b/filetree.go
index 3f35741..4e2d2c3 100644
--- a/filetree.go
+++ b/filetree.go
@@ -210,9 +210,9 @@ func (tree *FileTree) MarkRemoved(path string) error {
 	return node.AssignDiffType(Removed)
 }
 
-func StackRange(trees []*FileTree, index int) *FileTree {
+func StackRange(trees []*FileTree, index uint) *FileTree {
 	tree := trees[0].Copy()
-	for idx := 1; idx < index; idx++ {
+	for idx := uint(1); idx < index; idx++ {
 		tree.Stack(trees[idx])
 	}
 	return tree
diff --git a/main.go b/main.go
index 8bf7a99..568f1f2 100644
--- a/main.go
+++ b/main.go
@@ -18,8 +18,8 @@ var data struct {
 	tree            *FileTree
 	refTrees        []*FileTree
 	manifest        *Manifest
-	absDFSTreeIndex int
-	layerIndex      int
+	absDFSTreeIndex uint
+	layerIndex      uint
 }
 
 func check(e error) {
@@ -118,7 +118,7 @@ func demo() {
 func getAbsPositionNode() (node *FileNode) {
 	var visiter func(*FileNode) error
 	var evaluator func(*FileNode) bool
-	var dfsCounter int
+	var dfsCounter uint
 
 	visiter = func(curNode *FileNode) error {
 		if dfsCounter == data.absDFSTreeIndex {