292 lines
5.8 KiB
Go
292 lines
5.8 KiB
Go
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/*
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Package htmlquery provides extract data from HTML documents using XPath expression.
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*/
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package htmlquery
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import (
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"bytes"
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"fmt"
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"io"
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"net/http"
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"github.com/antchfx/xpath"
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"golang.org/x/net/html"
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"golang.org/x/net/html/charset"
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)
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var _ xpath.NodeNavigator = &NodeNavigator{}
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// CreateXPathNavigator creates a new xpath.NodeNavigator for the specified html.Node.
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func CreateXPathNavigator(top *html.Node) *NodeNavigator {
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return &NodeNavigator{curr: top, root: top, attr: -1}
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}
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// Find searches the html.Node that matches by the specified XPath expr.
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func Find(top *html.Node, expr string) []*html.Node {
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exp, err := xpath.Compile(expr)
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if err != nil {
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panic(err)
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}
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var elems []*html.Node
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t := exp.Select(CreateXPathNavigator(top))
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for t.MoveNext() {
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nav := t.Current().(*NodeNavigator)
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n := getCurrentNode(nav)
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// avoid adding duplicate nodes.
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if len(elems) > 0 && (elems[0] == n || (nav.NodeType() == xpath.AttributeNode &&
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nav.LocalName() == elems[0].Data && nav.Value() == InnerText(elems[0]))) {
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continue
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}
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elems = append(elems, n)
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}
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return elems
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}
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// FindOne searches the html.Node that matches by the specified XPath expr,
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// and returns first element of matched html.Node.
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func FindOne(top *html.Node, expr string) *html.Node {
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var elem *html.Node
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exp, err := xpath.Compile(expr)
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if err != nil {
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panic(err)
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}
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t := exp.Select(CreateXPathNavigator(top))
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if t.MoveNext() {
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elem = getCurrentNode(t.Current().(*NodeNavigator))
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}
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return elem
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}
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// LoadURL loads the HTML document from the specified URL.
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func LoadURL(url string) (*html.Node, error) {
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resp, err := http.Get(url)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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r, err := charset.NewReader(resp.Body, resp.Header.Get("Content-Type"))
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if err != nil {
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return nil, err
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}
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return html.Parse(r)
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}
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func getCurrentNode(n *NodeNavigator) *html.Node {
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if n.NodeType() == xpath.AttributeNode {
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childNode := &html.Node{
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Type: html.TextNode,
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Data: n.Value(),
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}
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return &html.Node{
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Type: html.ElementNode,
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Data: n.LocalName(),
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FirstChild: childNode,
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LastChild: childNode,
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}
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}
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return n.curr
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}
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// Parse returns the parse tree for the HTML from the given Reader.
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func Parse(r io.Reader) (*html.Node, error) {
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return html.Parse(r)
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}
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// InnerText returns the text between the start and end tags of the object.
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func InnerText(n *html.Node) string {
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var output func(*bytes.Buffer, *html.Node)
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output = func(buf *bytes.Buffer, n *html.Node) {
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switch n.Type {
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case html.TextNode:
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buf.WriteString(n.Data)
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return
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case html.CommentNode:
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return
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}
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for child := n.FirstChild; child != nil; child = child.NextSibling {
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output(buf, child)
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}
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}
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var buf bytes.Buffer
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output(&buf, n)
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return buf.String()
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}
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// SelectAttr returns the attribute value with the specified name.
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func SelectAttr(n *html.Node, name string) (val string) {
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if n == nil {
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return
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}
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if n.Type == html.ElementNode && n.Parent == nil && name == n.Data {
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return InnerText(n)
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}
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for _, attr := range n.Attr {
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if attr.Key == name {
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val = attr.Val
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break
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}
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}
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return
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}
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// OutputHTML returns the text including tags name.
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func OutputHTML(n *html.Node, self bool) string {
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var buf bytes.Buffer
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if self {
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html.Render(&buf, n)
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} else {
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for n := n.FirstChild; n != nil; n = n.NextSibling {
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html.Render(&buf, n)
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}
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}
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return buf.String()
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}
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type NodeNavigator struct {
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root, curr *html.Node
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attr int
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}
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func (h *NodeNavigator) Current() *html.Node {
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return h.curr
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}
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func (h *NodeNavigator) NodeType() xpath.NodeType {
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switch h.curr.Type {
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case html.CommentNode:
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return xpath.CommentNode
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case html.TextNode:
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return xpath.TextNode
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case html.DocumentNode:
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return xpath.RootNode
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case html.ElementNode:
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if h.attr != -1 {
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return xpath.AttributeNode
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}
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return xpath.ElementNode
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case html.DoctypeNode:
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// ignored <!DOCTYPE HTML> declare and as Root-Node type.
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return xpath.RootNode
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}
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panic(fmt.Sprintf("unknown HTML node type: %v", h.curr.Type))
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}
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func (h *NodeNavigator) LocalName() string {
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if h.attr != -1 {
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return h.curr.Attr[h.attr].Key
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}
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return h.curr.Data
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}
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func (*NodeNavigator) Prefix() string {
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return ""
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}
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func (h *NodeNavigator) Value() string {
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switch h.curr.Type {
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case html.CommentNode:
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return h.curr.Data
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case html.ElementNode:
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if h.attr != -1 {
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return h.curr.Attr[h.attr].Val
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}
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return InnerText(h.curr)
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case html.TextNode:
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return h.curr.Data
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}
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return ""
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}
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func (h *NodeNavigator) Copy() xpath.NodeNavigator {
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n := *h
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return &n
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}
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func (h *NodeNavigator) MoveToRoot() {
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h.curr = h.root
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}
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func (h *NodeNavigator) MoveToParent() bool {
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if h.attr != -1 {
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h.attr = -1
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return true
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} else if node := h.curr.Parent; node != nil {
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h.curr = node
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return true
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}
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return false
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}
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func (h *NodeNavigator) MoveToNextAttribute() bool {
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if h.attr >= len(h.curr.Attr)-1 {
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return false
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}
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h.attr++
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return true
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}
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func (h *NodeNavigator) MoveToChild() bool {
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if h.attr != -1 {
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return false
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}
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if node := h.curr.FirstChild; node != nil {
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h.curr = node
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return true
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}
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return false
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}
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func (h *NodeNavigator) MoveToFirst() bool {
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if h.attr != -1 || h.curr.PrevSibling == nil {
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return false
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}
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for {
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node := h.curr.PrevSibling
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if node == nil {
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break
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}
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h.curr = node
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}
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return true
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}
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func (h *NodeNavigator) String() string {
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return h.Value()
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}
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func (h *NodeNavigator) MoveToNext() bool {
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if h.attr != -1 {
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return false
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}
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if node := h.curr.NextSibling; node != nil {
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h.curr = node
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return true
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}
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return false
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}
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func (h *NodeNavigator) MoveToPrevious() bool {
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if h.attr != -1 {
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return false
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}
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if node := h.curr.PrevSibling; node != nil {
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h.curr = node
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return true
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}
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return false
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}
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func (h *NodeNavigator) MoveTo(other xpath.NodeNavigator) bool {
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node, ok := other.(*NodeNavigator)
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if !ok || node.root != h.root {
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return false
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}
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h.curr = node.curr
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h.attr = node.attr
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return true
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}
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