diff --git a/node_generate.go b/node_generate.go
index 91b8bb5..0ea1c91 100644
--- a/node_generate.go
+++ b/node_generate.go
@@ -8,34 +8,33 @@ import (
 )
 
 type rootGenerator struct {
-	r  io.Reader
-	st spaceType
+	counter  *counter
+	scanner  *bufio.Scanner
+	strategy nodeGenerateStrategy
 }
 
 func newRootGenerator(r io.Reader, st spaceType) *rootGenerator {
 	return &rootGenerator{
-		r:  r,
-		st: st,
+		counter:  newCounter(),
+		scanner:  bufio.NewScanner(r),
+		strategy: newStrategy(st),
 	}
 }
 
 func (rg *rootGenerator) generate() ([]*Node, error) {
 	var (
-		scanner          = bufio.NewScanner(rg.r)
-		stack            *stack
-		counter          = newCounter()
-		generateNodeFunc = rg.st.decideGenerateFunc()
-		roots            []*Node
+		stack *stack
+		roots []*Node
 	)
 
-	for scanner.Scan() {
-		currentNode := generateNodeFunc(scanner.Text(), counter.next())
+	for rg.scanner.Scan() {
+		currentNode := rg.strategy.generate(rg.scanner.Text(), rg.counter.next())
 		if err := currentNode.validate(); err != nil {
 			return nil, err
 		}
 
 		if currentNode.isRoot() {
-			counter.reset()
+			rg.counter.reset()
 			roots = append(roots, currentNode)
 			stack = newStack()
 			stack.push(currentNode)
@@ -49,7 +48,7 @@ func (rg *rootGenerator) generate() ([]*Node, error) {
 		stack.dfs(currentNode)
 	}
 
-	if err := scanner.Err(); err != nil {
+	if err := rg.scanner.Err(); err != nil {
 		return nil, err
 	}
 	return roots, nil
@@ -69,147 +68,3 @@ func (n *Node) validate() error {
 	}
 	return nil
 }
-
-type generateFunc func(row string, idx uint) *Node
-
-type spaceType int
-
-const (
-	spacesTab spaceType = iota
-	spacesTwo
-	spacesFour
-)
-
-func (st spaceType) decideGenerateFunc() generateFunc {
-	switch st {
-	case spacesTwo:
-		return generateFuncTwoSpaces
-	case spacesFour:
-		return generateFuncFourSpaces
-	default:
-		return generateFuncTab
-	}
-}
-
-// https://ja.wikipedia.org/wiki/ASCII
-const (
-	hyphen = 45
-	space  = 32
-	tab    = 9
-)
-
-const (
-	rootHierarchyNum = uint(1)
-)
-
-func generateFuncTab(row string, idx uint) *Node {
-	var (
-		text      = ""
-		hierarchy = rootHierarchyNum
-	)
-	var (
-		isPrevChar = false
-		isRoot     = false
-	)
-
-	for i, r := range row {
-		switch r {
-		case hyphen:
-			if i == 0 {
-				isRoot = true
-			}
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-			isPrevChar = false
-		case space:
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-		case tab:
-			hierarchy++
-		default: // directry or file text char
-			text += string(r)
-			isPrevChar = true
-		}
-	}
-	if !isRoot && hierarchy == rootHierarchyNum {
-		hierarchy = 0
-	}
-
-	return newNode(text, hierarchy, idx)
-}
-
-func generateFuncTwoSpaces(row string, idx uint) *Node {
-	var (
-		text      = ""
-		hierarchy = rootHierarchyNum
-	)
-	var (
-		spaceCnt   = uint(0)
-		isPrevChar = false
-	)
-
-	for _, r := range row {
-		switch r {
-		case hyphen:
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-			if spaceCnt%2 == 0 {
-				hierarchy += spaceCnt / 2
-			}
-			isPrevChar = false
-		case space:
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-			spaceCnt++
-		default: // directry or file text char
-			text += string(r)
-			isPrevChar = true
-		}
-	}
-
-	return newNode(text, hierarchy, idx)
-}
-
-func generateFuncFourSpaces(row string, idx uint) *Node {
-	var (
-		text      = ""
-		hierarchy = rootHierarchyNum
-	)
-	var (
-		spaceCnt   = uint(0)
-		isPrevChar = false
-	)
-
-	for _, r := range row {
-		switch r {
-		case hyphen:
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-			if spaceCnt%4 == 0 {
-				hierarchy += spaceCnt / 4
-			}
-			isPrevChar = false
-		case space:
-			if isPrevChar {
-				text += string(r)
-				continue
-			}
-			spaceCnt++
-		default: // directry or file text char
-			text += string(r)
-			isPrevChar = true
-		}
-	}
-
-	return newNode(text, hierarchy, idx)
-}
diff --git a/node_generate_strategy.go b/node_generate_strategy.go
new file mode 100644
index 0000000..5a5fa43
--- /dev/null
+++ b/node_generate_strategy.go
@@ -0,0 +1,153 @@
+package gtree
+
+type spaceType int
+
+const (
+	spacesTab spaceType = iota
+	spacesTwo
+	spacesFour
+)
+
+type nodeGenerateStrategy interface {
+	generate(row string, idx uint) *Node
+}
+
+func newStrategy(st spaceType) nodeGenerateStrategy {
+	switch st {
+	case spacesTwo:
+		return &twoSpacesStrategy{}
+	case spacesFour:
+		return &fourSpacesStrategy{}
+	default:
+		return &tabStrategy{}
+	}
+}
+
+// https://ja.wikipedia.org/wiki/ASCII
+const (
+	hyphen = 45
+	space  = 32
+	tab    = 9
+)
+
+const (
+	rootHierarchyNum = uint(1)
+)
+
+type tabStrategy struct{}
+
+func (*tabStrategy) generate(row string, idx uint) *Node {
+	var (
+		text      = ""
+		hierarchy = rootHierarchyNum
+	)
+	var (
+		isPrevChar = false
+		isRoot     = false
+	)
+
+	for i, r := range row {
+		switch r {
+		case hyphen:
+			if i == 0 {
+				isRoot = true
+			}
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+			isPrevChar = false
+		case space:
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+		case tab:
+			hierarchy++
+		default: // directry or file text char
+			text += string(r)
+			isPrevChar = true
+		}
+	}
+	if !isRoot && hierarchy == rootHierarchyNum {
+		hierarchy = 0
+	}
+
+	return newNode(text, hierarchy, idx)
+}
+
+type twoSpacesStrategy struct{}
+
+func (*twoSpacesStrategy) generate(row string, idx uint) *Node {
+	var (
+		text      = ""
+		hierarchy = rootHierarchyNum
+	)
+	var (
+		spaceCnt   = uint(0)
+		isPrevChar = false
+	)
+
+	for _, r := range row {
+		switch r {
+		case hyphen:
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+			if spaceCnt%2 == 0 {
+				hierarchy += spaceCnt / 2
+			}
+			isPrevChar = false
+		case space:
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+			spaceCnt++
+		default: // directry or file text char
+			text += string(r)
+			isPrevChar = true
+		}
+	}
+
+	return newNode(text, hierarchy, idx)
+}
+
+type fourSpacesStrategy struct{}
+
+func (*fourSpacesStrategy) generate(row string, idx uint) *Node {
+	var (
+		text      = ""
+		hierarchy = rootHierarchyNum
+	)
+	var (
+		spaceCnt   = uint(0)
+		isPrevChar = false
+	)
+
+	for _, r := range row {
+		switch r {
+		case hyphen:
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+			if spaceCnt%4 == 0 {
+				hierarchy += spaceCnt / 4
+			}
+			isPrevChar = false
+		case space:
+			if isPrevChar {
+				text += string(r)
+				continue
+			}
+			spaceCnt++
+		default: // directry or file text char
+			text += string(r)
+			isPrevChar = true
+		}
+	}
+
+	return newNode(text, hierarchy, idx)
+}