chore: implement part of html renderer

plugin/gomark/ast/node.go

@@ -1,7 +1,36 @@
 package ast
 
 type Node interface {
+	// Type returns a node type.
 	Type() NodeType
+
+	// String returns a string representation of this node.
+	// This method is used for debugging.
+	String() string
+
+	// GetParent returns a parent node of this node.
+	GetParent() Node
+
+	// GetPrevSibling returns a previous sibling node of this node.
+	GetPrevSibling() Node
+
+	// GetNextSibling returns a next sibling node of this node.
+	GetNextSibling() Node
+
+	// GetChildren returns children nodes of this node.
+	GetChildren() []Node
+
+	// SetParent sets a parent node to this node.
+	SetParent(Node)
+
+	// SetPrevSibling sets a previous sibling node to this node.
+	SetPrevSibling(Node)
+
+	// SetNextSibling sets a next sibling node to this node.
+	SetNextSibling(Node)
+
+	// SetChildren sets children nodes to this node.
+	SetChildren([]Node)
 }
 
 type NodeType int
@@ -18,3 +47,45 @@ func NewNodeType(name string) NodeType {
 	nodeTypeIndex++
 	return nodeTypeIndex
 }
+
+type BaseNode struct {
+	parent Node
+
+	prevSibling Node
+
+	nextSibling Node
+
+	children []Node
+}
+
+func (n *BaseNode) GetParent() Node {
+	return n.parent
+}
+
+func (n *BaseNode) GetPrevSibling() Node {
+	return n.prevSibling
+}
+
+func (n *BaseNode) GetNextSibling() Node {
+	return n.nextSibling
+}
+
+func (n *BaseNode) GetChildren() []Node {
+	return n.children
+}
+
+func (n *BaseNode) SetParent(node Node) {
+	n.parent = node
+}
+
+func (n *BaseNode) SetPrevSibling(node Node) {
+	n.prevSibling = node
+}
+
+func (n *BaseNode) SetNextSibling(node Node) {
+	n.nextSibling = node
+}
+
+func (n *BaseNode) SetChildren(nodes []Node) {
+	n.children = nodes
+}