Support xpath query

example_test.go

@@ -52,6 +52,35 @@ func ExampleNode_GetChildren() {
 	// testcase: name = ExampleParse
 }
 
+func ExampleNode_Query() {
+	node := xmldom.Must(xmldom.ParseXML(ExampleXml)).Root
+	// xpath expr: https://github.com/antchfx/xpath
+
+	// find all children
+	fmt.Printf("children = %v\n", len(node.Query("//*")))
+
+	// find node matched tag name
+	nodeList := node.Query("//testcase")
+	for _, c := range nodeList {
+		fmt.Printf("%v: name = %v\n", c.Name, c.GetAttributeValue("name"))
+	}
+	// Output:
+	// children = 5
+	// testcase: name = ExampleParseXML
+	// testcase: name = ExampleParse
+}
+
+func ExampleNode_QueryOne() {
+	node := xmldom.Must(xmldom.ParseXML(ExampleXml)).Root
+	// xpath expr: https://github.com/antchfx/xpath
+
+	// find node matched attr name
+	c := node.QueryOne("//testcase[@name='ExampleParseXML']")
+	fmt.Printf("%v: name = %v\n", c.Name, c.GetAttributeValue("name"))
+	// Output:
+	// testcase: name = ExampleParseXML
+}
+
 func ExampleDocument_XML() {
 	doc := xmldom.Must(xmldom.ParseXML(ExampleXml))
 	fmt.Println(doc.XML())

node.go

@@ -143,6 +143,18 @@ func (n *Node) FindByID(id string) *Node {
 	return nil
 }
 
+func (n *Node) Query(xpath string) []*Node {
+	return xpathQuery(n, xpath)
+}
+
+func (n *Node) QueryOne(xpath string) *Node {
+	return xpathQueryOne(n, xpath)
+}
+
+func (n *Node) QueryEach(xpath string, cb func(int, *Node)) {
+	xpathQueryEach(n, xpath, cb)
+}
+
 func (n *Node) XML() string {
 	buf := new(bytes.Buffer)
 	printXML(buf, n, 0, "")

query.go

@@ -0,0 +1,150 @@
+package xmldom
+
+import (
+	"github.com/antchfx/xpath"
+)
+
+// createXPathNavigator creates a new xpath.NodeNavigator for the specified xmldom.Node.
+func createXPathNavigator(top *Node) xpath.NodeNavigator {
+	return &xmlNodeNavigator{curr: top, attrIndex: -1}
+}
+
+// xpathQuery searches the Node that matches by the specified XPath expr.
+func xpathQuery(top *Node, expr string) []*Node {
+	t := xpath.Select(createXPathNavigator(top), expr)
+	var nodes []*Node
+	for t.MoveNext() {
+		nodes = append(nodes, (t.Current().(*xmlNodeNavigator)).curr)
+	}
+	return nodes
+}
+
+// xpathQueryOne searches the Node that matches by the specified XPath expr,
+// and returns first element of matched.
+func xpathQueryOne(top *Node, expr string) *Node {
+	t := xpath.Select(createXPathNavigator(top), expr)
+	if t.MoveNext() {
+		return (t.Current().(*xmlNodeNavigator)).curr
+	}
+	return nil
+}
+
+// xpathQueryEach searches the xmldom.Node and calls functions cb.
+func xpathQueryEach(top *Node, expr string, cb func(int, *Node)) {
+	t := xpath.Select(createXPathNavigator(top), expr)
+	var i int
+	for t.MoveNext() {
+		cb(i, (t.Current().(*xmlNodeNavigator)).curr)
+		i++
+	}
+}
+
+type xmlNodeNavigator struct {
+	curr      *Node
+	attrIndex int
+}
+
+func (x *xmlNodeNavigator) NodeType() xpath.NodeType {
+	if x.curr == x.curr.Root() {
+		return xpath.RootNode
+	}
+	if x.attrIndex != -1 {
+		return xpath.AttributeNode
+	}
+	return xpath.ElementNode
+}
+
+func (x *xmlNodeNavigator) LocalName() string {
+	if x.attrIndex != -1 {
+		return x.curr.Attributes[x.attrIndex].Name
+	}
+	return x.curr.Name
+}
+
+func (x *xmlNodeNavigator) Prefix() string {
+	return ""
+}
+
+func (x *xmlNodeNavigator) Value() string {
+	if x.attrIndex != -1 {
+		return x.curr.Attributes[x.attrIndex].Value
+	}
+	return x.curr.Text
+}
+
+func (x *xmlNodeNavigator) Copy() xpath.NodeNavigator {
+	n := *x
+	return &n
+}
+
+func (x *xmlNodeNavigator) MoveToRoot() {
+	x.curr = x.curr.Root()
+}
+
+func (x *xmlNodeNavigator) MoveToParent() bool {
+	if node := x.curr.Parent; node != nil {
+		x.curr = node
+		return true
+	}
+	return false
+}
+
+func (x *xmlNodeNavigator) MoveToNextAttribute() bool {
+	if x.attrIndex >= len(x.curr.Attributes)-1 {
+		return false
+	}
+	x.attrIndex++
+	return true
+}
+
+func (x *xmlNodeNavigator) MoveToChild() bool {
+	if node := x.curr.FirstChild(); node != nil {
+		x.curr = node
+		return true
+	}
+	return false
+}
+
+func (x *xmlNodeNavigator) MoveToFirst() bool {
+	if x.curr.Parent != nil {
+		node := x.curr.Parent.FirstChild()
+		if node != nil {
+			x.curr = node
+			return true
+		}
+	}
+	return false
+}
+
+func (x *xmlNodeNavigator) MoveToPrevious() bool {
+	node := x.curr.PrevSibling()
+	if node != nil {
+		x.curr = node
+		return true
+	}
+	return false
+}
+
+func (x *xmlNodeNavigator) MoveToNext() bool {
+	node := x.curr.NextSibling()
+	if node != nil {
+		x.curr = node
+		return true
+	}
+	return false
+}
+
+func (x *xmlNodeNavigator) MoveTo(other xpath.NodeNavigator) bool {
+	node, ok := other.(*xmlNodeNavigator)
+	if !ok || node.curr.Root() != x.curr.Root() {
+		return false
+	}
+
+	x.curr = node.curr
+	x.attrIndex = node.attrIndex
+	return true
+}
+
+func (x *xmlNodeNavigator) String() string {
+	return x.Value()
+}