added tree stacking

.gitignore

@@ -1,3 +1,5 @@
+.idea
+
 # Binaries for programs and plugins
 *.exe
 *.exe~
@@ -11,4 +13,4 @@
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
 
-image
+image

filetree.go

@@ -3,31 +3,108 @@ package main
 import (
 	"errors"
 	"strings"
+	"fmt"
 )
 
 type FileTree interface {
-	AddPath(string, interface{})
-	RemovePath(string)
-	Visit(Visiter)
+	AddPath(string, interface{}) *Node
+	RemovePath(string) error
+	Visit(Visiter) error
+	// Diff(*Tree) error
+	Stack(*Tree) (Tree, error)
 }
 
-type Visiter func(*Node)
+type Visiter func(*Node) error
 
-func (tree *Tree) Visit(visiter Visiter) {
-	tree.root.Visit(visiter)
+func (tree *Tree) Visit(visiter Visiter) error {
+	return tree.root.Visit(visiter)
 }
 
-func (node *Node) Visit(visiter Visiter) {
+func (node *Node) Visit(visiter Visiter) error {
 	for _, child := range node.children {
-		child.Visit(visiter)
+		err := child.Visit(visiter)
+		if err != nil {
+			return err
+		}
 	}
-	visiter(node)
+	return visiter(node)
+}
+
+func (node *Node) IsWhiteout() bool {
+	return strings.HasPrefix(node.name, ".wh.")
+}
+
+func (node *Node) Path() string {
+	path := []string{}
+	curNode := node
+	for {
+		if curNode.parent == nil{
+			break
+		}
+		path = append([]string{curNode.name}, path...)
+		curNode = curNode.parent
+	}
+	return "/" + strings.Join(path, "/")
+}
+
+
+func (node *Node) WhiteoutPath() string {
+	path := []string{}
+	curNode := node
+	for {
+		if curNode.parent == nil{
+			break
+		}
+
+		name := curNode.name
+		if curNode == node {
+			name = strings.TrimPrefix(name, ".wh.")
+		}
+
+		path = append([]string{name}, path...)
+		curNode = curNode.parent
+	}
+	return "/" + strings.Join(path, "/")
+}
+
+
+
+func (tree *Tree) Stack(upper *Tree) (error) {
+	graft := func(node *Node) error {
+		if node.IsWhiteout() {
+			err := tree.RemovePath(node.WhiteoutPath())
+			if err != nil {
+				return fmt.Errorf("Cannot remove node %s: %v", node.Path(), err.Error())
+			}
+		} else {
+			newNode, err := tree.AddPath(node.Path(), node.data)
+			if err != nil {
+				return fmt.Errorf("Cannot add node %s: %v", newNode.Path(), err.Error())
+			}
+		}
+		return nil
+	}
+	return upper.Visit(graft)
+}
+
+func (tree *Tree) GetNode(path string) (*Node, error) {
+	nodeNames := strings.Split(path, "/")
+	node := tree.Root()
+	for _, name := range nodeNames {
+		if name == "" {
+			continue
+		}
+		if node.children[name] == nil {
+			return nil, errors.New("Path does not exist")
+		}
+		node = node.children[name]
+	}
+	return node, nil
 }
 
 func (tree *Tree) AddPath(path string, data interface{}) (*Node, error) {
 	nodeNames := strings.Split(path, "/")
 	node := tree.Root()
-	var err error
 	for idx, name := range nodeNames {
 		if name == "" {
 			continue
@@ -36,15 +113,12 @@ func (tree *Tree) AddPath(path string, data interface{}) (*Node, error) {
 		if node.children[name] != nil {
 			node = node.children[name]
 		} else {
-
-			node, _ = node.AddChild(name, nil)
-			if err != nil {
-
-				return node, err
-			}
+			// don't attach the payload. The payload is destined for the
+			// path's end node, not any intermediary node.
+			node = node.AddChild(name, nil)
 		}
 
-		// attach payload
+		// attach payload to the last specified node
 		if idx == len(nodeNames)-1 {
 			node.data = data
 		}
@@ -54,17 +128,9 @@ func (tree *Tree) AddPath(path string, data interface{}) (*Node, error) {
 }
 
 func (tree *Tree) RemovePath(path string) error {
-	nodeNames := strings.Split(path, "/")
-	node := tree.Root()
-	for _, name := range nodeNames {
-		if name == "" {
-			continue
-		}
-		if node.children[name] == nil {
-			return errors.New("Path does not exist")
-		}
-		node = node.children[name]
+	node, err := tree.GetNode(path)
+	if err != nil {
+		return err
 	}
-	// this node's parent should be a leaf
 	return node.Remove()
 }

filetree_test.go

@@ -59,3 +59,83 @@ func TestRemovePath(t *testing.T) {
 	}
 
 }
+
+func TestPath(t *testing.T) {
+	expected := "/etc/nginx/nginx.conf"
+	tree := NewTree()
+	node, _ := tree.AddPath(expected, nil)
+
+	actual := node.Path()
+	if expected != actual {
+		t.Errorf("Expected path '%s' got '%s'", expected, actual)
+	}
+}
+
+func TestIsWhiteout(t *testing.T) {
+	tree1 := NewTree()
+	p1, _ := tree1.AddPath("/etc/nginx/public1", 2)
+	p2, _ := tree1.AddPath("/etc/nginx/.wh.public2", 2)
+
+	if p1.IsWhiteout() != false {
+		t.Errorf("Expected path '%s' to **not** be a whiteout file", p1.name)
+	}
+
+	if p2.IsWhiteout() != true {
+		t.Errorf("Expected path '%s' to be a whiteout file", p2.name)
+	}
+}
+
+
+func TestStack(t *testing.T) {
+	payloadKey := "/var/run/systemd"
+	payloadValue := 1263487
+
+	tree1 := NewTree()
+
+	tree1.AddPath("/etc/nginx/public", 2)
+	tree1.AddPath(payloadKey, 3)
+	tree1.AddPath("/var/run/bashful", 4)
+	tree1.AddPath("/tmp", 5)
+	tree1.AddPath("/tmp/nonsense", 6)
+
+	tree2 := NewTree()
+	// add new files
+	tree2.AddPath("/etc/nginx/nginx.conf", 1)
+	// modify current files
+	tree2.AddPath(payloadKey, payloadValue)
+	// whiteout the following files
+	tree2.AddPath("/var/run/.wh.bashful", nil)
+	tree2.AddPath("/.wh.tmp", nil)
+
+	err := tree1.Stack(tree2)
+
+	if err != nil {
+		t.Errorf("Could not stack trees: %v", err)
+	}
+
+	expected := `.
+├── etc
+│   └── nginx
+│       ├── nginx.conf
+│       └── public
+└── var
+    └── run
+        └── systemd
+`
+
+	node, err := tree1.GetNode(payloadKey)
+	if err != nil {
+		t.Errorf("Expected '%s' to still exist, but it doesn't", payloadKey)
+	}
+
+	if node.data != payloadValue {
+		t.Errorf("Expected '%s' value to be %d but got %d", payloadKey, payloadValue, node.data.(int))
+	}
+
+	actual := tree1.String()
+
+	if expected != actual {
+		t.Errorf("Expected tree string:\n--->%s<---\nGot:\n--->%s<---", expected, actual)
+	}
+
+}

main.go

@@ -55,7 +55,7 @@ func saveImage(readCloser io.ReadCloser) {
 	}
 }
 
-func main() {
+func demo() {
 	ctx := context.Background()
 	cli, err := client.NewEnvClient()
 	if err != nil {

tree.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"errors"
 	"sort"
 )
 
@@ -14,7 +13,7 @@ const (
 )
 
 type Tree struct {
-	root Node
+	root *Node
 	size int
 }
 
@@ -29,10 +28,9 @@ type Node struct {
 func NewTree() (tree *Tree) {
 	tree = new(Tree)
 	tree.size = 0
-	root := &tree.root
-	root.tree = tree
-	root.name = ""
-	root.children = make(map[string]*Node)
+	tree.root = new(Node)
+	tree.root.tree = tree
+	tree.root.children = make(map[string]*Node)
 	return tree
 }
 
@@ -47,17 +45,19 @@ func NewNode(parent *Node, name string, data interface{}) (node *Node) {
 }
 
 func (tree *Tree) Root() *Node {
-	return &tree.root
+	return tree.root
 }
 
-func (node *Node) AddChild(name string, data interface{}) (child *Node, error error) {
-	if node.children[name] != nil {
-		return nil, errors.New("Tree node already exists")
-	}
+func (node *Node) AddChild(name string, data interface{}) (child *Node) {
 	child = NewNode(node, name, data)
-	node.children[name] = child
-	node.tree.size++
-	return child, nil
+	if node.children[name] != nil {
+		// tree node already exists, replace the payload, keep the children
+		node.children[name].data = data
+	} else {
+		node.children[name] = child
+		node.tree.size++
+	}
+	return child
 }
 
 func (node *Node) Remove() error {
@@ -116,3 +116,23 @@ func (tree *Tree) String() string {
 
 	return "." + newLine + walkTree(tree.Root(), []bool{})
 }
+
+func (node *Node) Copy() *Node {
+	// newNode := new(Node)
+	// *newNode = *node
+	// return newNode
+	newNode := NewNode(node.parent, node.name, node.data)
+	for name, child := range node.children {
+		newNode.children[name] = child.Copy()
+	}
+	return newNode
+}
+
+func (tree *Tree) Copy() *Tree {
+	newTree := NewTree()
+	*newTree = *tree
+	newTree.root = tree.Root().Copy()
+
+	return newTree
+}
+

tree_test.go

@@ -6,24 +6,14 @@ func TestAddChild(t *testing.T) {
 	var expected, actual int
 	tree := NewTree()
 
-	_, err := tree.Root().AddChild("first node!", 1)
-	if err != nil {
-		t.Errorf("Adding valued child should not result in error.")
-	}
+	one := tree.Root().AddChild("first node!", 1)
 
-	two, err := tree.Root().AddChild("nil node!", nil)
-	if err != nil {
-		t.Errorf("Adding nil child should not result in error.")
-	}
+	two := tree.Root().AddChild("nil node!", nil)
 
 	tree.Root().AddChild("third node!", 3)
 	two.AddChild("forth, one level down...", 4)
 	two.AddChild("fifth, one level down...", 5)
-
-	_, err = two.AddChild("fifth, one level down...", 5)
-	if err == nil {
-		t.Errorf("Expected an error when adding duplicate nodes, no error given.")
-	}
+	two.AddChild("fifth, one level down...", 5)
 
 	expected, actual = 5, tree.size
 	if expected != actual {
@@ -40,6 +30,15 @@ func TestAddChild(t *testing.T) {
 		t.Errorf("Expected 'twos' number of children to be %d got %d.", expected, actual)
 	}
 
+	if two.data != nil {
+		t.Errorf("Expected 'ones' payload to be nil got %d.", two.data)
+	}
+
+	expected, actual = 1, one.data.(int)
+	if expected != actual {
+		t.Errorf("Expected 'ones' payload to be %d got %d.", expected, actual)
+	}
+
 }
 
 func TestRemoveChild(t *testing.T) {
@@ -47,9 +46,9 @@ func TestRemoveChild(t *testing.T) {
 
 	tree := NewTree()
 	tree.Root().AddChild("first", 1)
-	two, _ := tree.Root().AddChild("nil", nil)
+	two := tree.Root().AddChild("nil", nil)
 	tree.Root().AddChild("third", 3)
-	forth, _ := two.AddChild("forth", 4)
+	forth := two.AddChild("forth", 4)
 	two.AddChild("fifth", 5)
 
 	forth.Remove()
@@ -79,7 +78,7 @@ func TestRemoveChild(t *testing.T) {
 func TestPrintTree(t *testing.T) {
 	tree := NewTree()
 	tree.Root().AddChild("first node!", nil)
-	two, _ := tree.Root().AddChild("second node!", nil)
+	two := tree.Root().AddChild("second node!", nil)
 	tree.Root().AddChild("third node!", nil)
 	two.AddChild("forth, one level down...", nil)