diff --git a/ast/node.go b/ast/node.go
index f3fda90..5c5f032 100644
--- a/ast/node.go
+++ b/ast/node.go
@@ -37,9 +37,12 @@ const (
 type Node interface {
 	AsTreeNode() *TreeNode
 	GetParent() Node
+	SetParent(newParent Node)
 	GetChildren() []Node
+	SetChildren(newChildren []Node)
 	FirstChild() Node
 	LastChild() Node
+	SetContent(c []byte)
 }
 
 // TreeNode is a common part of all nodes, used to represent tree and contain
@@ -64,11 +67,75 @@ func (n *TreeNode) GetParent() Node {
 	return n.Parent
 }
 
+// SetParent sets the parent
+func (n *TreeNode) SetParent(newParent Node) {
+	n.Parent = newParent
+}
+
 // GetChildren returns children
 func (n *TreeNode) GetChildren() []Node {
 	return n.Children
 }
 
+// SetChildren sets children
+func (n *TreeNode) SetChildren(newChildren []Node) {
+	n.Children = newChildren
+}
+
+// SetContent sets content of the node
+func (n *TreeNode) SetContent(c []byte) {
+	n.Content = c
+}
+
+// LeafNode is a common part of all nodes, used to represent tree and contain
+// data that all nodes have in common
+type LeafNode struct {
+	Parent Node
+
+	Literal []byte // Text contents of the leaf nodes
+	Content []byte // Markdown content of the block nodes
+}
+
+// AsTreeNode returns itself as *TreeNode
+func (n *LeafNode) AsTreeNode() *TreeNode {
+	return nil
+}
+
+// GetParent returns parent
+func (n *LeafNode) GetParent() Node {
+	return n.Parent
+}
+
+// SetParent sets the parent
+func (n *LeafNode) SetParent(newParent Node) {
+	n.Parent = newParent
+}
+
+// GetChildren returns children
+func (n *LeafNode) GetChildren() []Node {
+	return nil
+}
+
+// SetChildren sets children
+func (n *LeafNode) SetChildren(newChildren []Node) {
+	// do nothing, LeafNode has no children
+}
+
+// FirstChild returns children
+func (n *LeafNode) FirstChild() Node {
+	return nil
+}
+
+// LastChild returns children
+func (n *LeafNode) LastChild() Node {
+	return nil
+}
+
+// SetContent sets content of the node
+func (n *LeafNode) SetContent(c []byte) {
+	n.Content = c
+}
+
 // PanicIfTreeNode will panic if node is *TreeNode
 func PanicIfTreeNode(node Node) {
 	if _, ok := node.(*TreeNode); ok {
@@ -135,7 +202,7 @@ type Heading struct {
 
 // HorizontalRule represents data for horizontal rule node
 type HorizontalRule struct {
-	TreeNode
+	LeafNode
 }
 
 // Emph represents data for emp node
@@ -173,17 +240,17 @@ type Image struct {
 
 // Text represents data for text node
 type Text struct {
-	TreeNode
+	LeafNode
 }
 
 // HTMLBlock represents data for html node
 type HTMLBlock struct {
-	TreeNode
+	LeafNode
 }
 
 // CodeBlock contains fields relevant to a CodeBlock node type.
 type CodeBlock struct {
-	TreeNode
+	LeafNode
 
 	IsFenced    bool   // Specifies whether it's a fenced code block or an indented one
 	Info        []byte // This holds the info string
@@ -195,22 +262,22 @@ type CodeBlock struct {
 // Softbreak represents data for softbreak node
 // Note: not used currently
 type Softbreak struct {
-	TreeNode
+	LeafNode
 }
 
 // Hardbreak represents data for hard break node
 type Hardbreak struct {
-	TreeNode
+	LeafNode
 }
 
 // Code represents data for code node
 type Code struct {
-	TreeNode
+	LeafNode
 }
 
 // HTMLSpan represents data for html span node
 type HTMLSpan struct {
-	TreeNode
+	LeafNode
 }
 
 // Table represents data for table node
@@ -265,27 +332,29 @@ func removeNodeFromArray(a []Node, node Node) []Node {
 
 // RemoveFromTree removes this node from tree
 func RemoveFromTree(n Node) {
-	nt := n.AsTreeNode()
-	if nt.Parent == nil {
+	if n.GetParent() == nil {
 		return
 	}
 	// important: don't clear n.Children if n has no parent
 	// we're called from AppendChild and that might happen on a node
 	// that accumulated Children but hasn't been inserted into the tree
-	p := nt.Parent.AsTreeNode()
-	p.Children = removeNodeFromArray(p.Children, n)
-	nt.Parent = nil
-	nt.Children = nil
+	p := n.GetParent()
+	newChildren := removeNodeFromArray(p.GetChildren(), n)
+	p.SetChildren(newChildren)
+	n.SetChildren(nil)
 }
 
 // AppendChild adds a node 'child' as a child of 'n'.
 // It panics if either node is nil.
 func AppendChild(n Node, child Node) {
-	childTN := child.AsTreeNode()
 	RemoveFromTree(child)
-	childTN.Parent = n
-	nTN := n.AsTreeNode()
-	nTN.Children = append(nTN.Children, child)
+	child.SetParent(n)
+	newChildren := append(n.GetChildren(), child)
+	n.SetChildren(newChildren)
+}
+
+func isContainer(n Node) bool {
+	return n.AsTreeNode() != nil
 }
 
 // LastChild returns last child of this node
@@ -336,16 +405,6 @@ func PrevNode(n Node) Node {
 	return nil
 }
 
-func isContainer(n Node) bool {
-	// list of non-containers is smaller so we check against that for speed
-	switch n.(type) {
-	case *HorizontalRule, *Text, *HTMLBlock, *CodeBlock, *Softbreak, *Hardbreak, *Code, *HTMLSpan:
-		return false
-	default:
-		return true
-	}
-}
-
 // WalkStatus allows NodeVisitor to have some control over the tree traversal.
 // It is returned from NodeVisitor and different values allow Node.Walk to
 // decide which node to go to next.
diff --git a/parser/block.go b/parser/block.go
index 43921c4..29b4bb4 100644
--- a/parser/block.go
+++ b/parser/block.go
@@ -253,7 +253,7 @@ func (p *Parser) block(data []byte) {
 func (p *Parser) addBlock(n ast.Node, content []byte) ast.Node {
 	p.closeUnmatchedBlocks()
 	container := p.addChild(n, 0)
-	container.AsTreeNode().Content = content
+	container.SetContent(content)
 	return container
 }
 
@@ -455,14 +455,15 @@ func (p *Parser) html(data []byte, doRender bool) int {
 	if doRender {
 		// trim newlines
 		end := backChar(data, i, '\n')
-		finalizeHTMLBlock(p.addBlock(&ast.HTMLBlock{}, data[:end]))
+		htmlBlock := &ast.HTMLBlock{}
+		p.addBlock(htmlBlock, data[:end])
+		finalizeHTMLBlock(htmlBlock)
 	}
 
 	return i
 }
 
-func finalizeHTMLBlock(blockNode ast.Node) {
-	block := blockNode.AsTreeNode()
+func finalizeHTMLBlock(block *ast.HTMLBlock) {
 	block.Literal = block.Content
 	block.Content = nil
 }
@@ -476,8 +477,9 @@ func (p *Parser) htmlComment(data []byte, doRender bool) int {
 		if doRender {
 			// trim trailing newlines
 			end := backChar(data, size, '\n')
-			block := p.addBlock(&ast.HTMLBlock{}, data[:end])
-			finalizeHTMLBlock(block)
+			htmlBLock := &ast.HTMLBlock{}
+			p.addBlock(htmlBLock, data[:end])
+			finalizeHTMLBlock(htmlBLock)
 		}
 		return size
 	}
@@ -507,7 +509,9 @@ func (p *Parser) htmlHr(data []byte, doRender bool) int {
 			if doRender {
 				// trim newlines
 				end := backChar(data, size, '\n')
-				finalizeHTMLBlock(p.addBlock(&ast.HTMLBlock{}, data[:end]))
+				htmlBlock := &ast.HTMLBlock{}
+				p.addBlock(htmlBlock, data[:end])
+				finalizeHTMLBlock(htmlBlock)
 			}
 			return size
 		}
@@ -742,11 +746,11 @@ func (p *Parser) fencedCodeBlock(data []byte, doRender bool) int {
 	}
 
 	if doRender {
-		d := &ast.CodeBlock{
+		codeBlock := &ast.CodeBlock{
 			IsFenced: true,
 		}
-		block := p.addBlock(d, work.Bytes()) // TODO: get rid of temp buffer
-		finalizeCodeBlock(block, d)
+		p.addBlock(codeBlock, work.Bytes()) // TODO: get rid of temp buffer
+		finalizeCodeBlock(codeBlock)
 	}
 
 	return beg
@@ -766,18 +770,18 @@ func unescapeString(str []byte) []byte {
 	return str
 }
 
-func finalizeCodeBlock(blockNode ast.Node, code *ast.CodeBlock) {
-	block := blockNode.AsTreeNode()
+func finalizeCodeBlock(code *ast.CodeBlock) {
+	c := code.Content
 	if code.IsFenced {
-		newlinePos := bytes.IndexByte(block.Content, '\n')
-		firstLine := block.Content[:newlinePos]
-		rest := block.Content[newlinePos+1:]
+		newlinePos := bytes.IndexByte(c, '\n')
+		firstLine := c[:newlinePos]
+		rest := c[newlinePos+1:]
 		code.Info = unescapeString(bytes.Trim(firstLine, "\n"))
-		block.Literal = rest
+		code.Literal = rest
 	} else {
-		block.Literal = block.Content
+		code.Literal = c
 	}
-	block.Content = nil
+	code.Content = nil
 }
 
 func (p *Parser) table(data []byte) int {
@@ -1087,11 +1091,11 @@ func (p *Parser) code(data []byte) int {
 
 	work.WriteByte('\n')
 
-	d := &ast.CodeBlock{
+	codeBlock := &ast.CodeBlock{
 		IsFenced: false,
 	}
-	block := p.addBlock(d, work.Bytes()) // TODO: get rid of temp buffer
-	finalizeCodeBlock(block, d)
+	p.addBlock(codeBlock, work.Bytes()) // TODO: get rid of temp buffer
+	finalizeCodeBlock(codeBlock)
 
 	return i
 }
diff --git a/parser/inline.go b/parser/inline.go
index e32ddde..dbd4c9d 100644
--- a/parser/inline.go
+++ b/parser/inline.go
@@ -1181,7 +1181,7 @@ func helperTripleEmphasis(p *Parser, data []byte, offset int, c byte) (int, ast.
 }
 
 func newTextNode(d []byte) *ast.Text {
-	return &ast.Text{ast.TreeNode{Literal: d}}
+	return &ast.Text{ast.LeafNode{Literal: d}}
 }
 
 func normalizeURI(s []byte) []byte {