fix example run error on playground. #110

Author: zhengchun

doc_test.go

@@ -1,32 +1,235 @@
 package xpath_test
 
 import (
+	"bytes"
 	"fmt"
 
 	"github.com/antchfx/xpath"
 )
 
-// XPath package example.
+type NodeType uint
+
+const (
+	DocumentNode NodeType = iota
+	ElementNode
+	TextNode
+)
+
+type Node struct {
+	Parent, FirstChild, LastChild, PrevSibling, NextSibling *Node
+
+	Type NodeType
+	Data string
+}
+
+func (n *Node) Value() string {
+	if n.Type == TextNode {
+		return n.Data
+	}
+
+	var buff bytes.Buffer
+	var output func(*Node)
+	output = func(node *Node) {
+		if node.Type == TextNode {
+			buff.WriteString(node.Data)
+		}
+		for child := node.FirstChild; child != nil; child = child.NextSibling {
+			output(child)
+		}
+	}
+	output(n)
+	return buff.String()
+}
+
+func (parent *Node) AddChild(n *Node) {
+	n.Parent = parent
+	n.NextSibling = nil
+	if parent.FirstChild == nil {
+		parent.FirstChild = n
+		n.PrevSibling = nil
+	} else {
+		parent.LastChild.NextSibling = n
+		n.PrevSibling = parent.LastChild
+	}
+
+	parent.LastChild = n
+}
+
+type NodeNavigator struct {
+	curr, root *Node
+}
+
+func (n *NodeNavigator) NodeType() xpath.NodeType {
+	switch n.curr.Type {
+	case TextNode:
+		return xpath.TextNode
+	case DocumentNode:
+		return xpath.RootNode
+	}
+	return xpath.ElementNode
+}
+
+func (n *NodeNavigator) LocalName() string {
+	return n.curr.Data
+}
+
+func (n *NodeNavigator) Prefix() string {
+	return ""
+}
+
+func (n *NodeNavigator) NamespaceURL() string {
+	return ""
+}
+
+func (n *NodeNavigator) Value() string {
+	switch n.curr.Type {
+	case ElementNode:
+		return n.curr.Value()
+	case TextNode:
+		return n.curr.Data
+	}
+	return ""
+}
+
+func (n *NodeNavigator) Copy() xpath.NodeNavigator {
+	n2 := *n
+	return &n2
+}
+
+func (n *NodeNavigator) MoveToRoot() {
+	n.curr = n.root
+}
+
+func (n *NodeNavigator) MoveToParent() bool {
+	if node := n.curr.Parent; node != nil {
+		n.curr = node
+		return true
+	}
+	return false
+}
+
+func (n *NodeNavigator) MoveToNextAttribute() bool {
+	return true
+}
+
+func (n *NodeNavigator) MoveToChild() bool {
+	if node := n.curr.FirstChild; node != nil {
+		n.curr = node
+		return true
+	}
+	return false
+}
+
+func (n *NodeNavigator) MoveToFirst() bool {
+	for {
+		node := n.curr.PrevSibling
+		if node == nil {
+			break
+		}
+		n.curr = node
+	}
+	return true
+}
+
+func (n *NodeNavigator) String() string {
+	return n.Value()
+}
+
+func (n *NodeNavigator) MoveToNext() bool {
+	if node := n.curr.NextSibling; node != nil {
+		n.curr = node
+		return true
+	}
+	return false
+}
+
+func (n *NodeNavigator) MoveToPrevious() bool {
+	if node := n.curr.PrevSibling; node != nil {
+		n.curr = node
+		return true
+	}
+	return false
+}
+
+func (n *NodeNavigator) MoveTo(other xpath.NodeNavigator) bool {
+	node, ok := other.(*NodeNavigator)
+	if !ok || node.root != n.root {
+		return false
+	}
+
+	n.curr = node.curr
+	return true
+}
+
+// XPath package example. See more xpath implements package:
+// https://github.com/antchfx/htmlquery
+// https://github.com/antchfx/xmlquery
+// https://github.com/antchfx/jsonquery
 func Example() {
+	/***
+	?xml version="1.0" encoding="UTF-8"?>
+	<bookstore>
+		<book>
+			<title>Everyday Italian</title>
+			<author>Giada De Laurentiis</author>
+			<year>2005</year>
+			<price>30.00</price>
+		</book>
+		<book>
+			<title>Harry Potter</title>
+			<author>J K. Rowling</author>
+			<year>2005</year>
+			<price>29.99</price>
+		</book>
+	</bookstore>
+	**/
+
+	// Here, for begin test, we should create a document
+	books := []struct {
+		title  string
+		author string
+		year   int
+		price  float64
+	}{
+		{title: "Everyday Italian", author: "Giada De Laurentiis", year: 2005, price: 30.00},
+		{title: "Harry Potter", author: "J K. Rowling", year: 2005, price: 29.99},
+	}
+	bookstore := &Node{Data: "bookstore", Type: ElementNode}
+	for _, v := range books {
+		book := &Node{Data: "book", Type: ElementNode}
+		title := &Node{Data: "title", Type: ElementNode}
+		title.AddChild(&Node{Data: v.title, Type: TextNode})
+		book.AddChild(title)
+		author := &Node{Data: "author", Type: ElementNode}
+		author.AddChild(&Node{Data: v.author, Type: TextNode})
+		book.AddChild(author)
+		year := &Node{Data: "year", Type: ElementNode}
+		year.AddChild(&Node{Data: fmt.Sprintf("%d", v.year), Type: TextNode})
+		book.AddChild(year)
+		price := &Node{Data: "price", Type: ElementNode}
+		price.AddChild(&Node{Data: fmt.Sprintf("%f", v.price), Type: TextNode})
+		book.AddChild(price)
+		bookstore.AddChild(book)
+	}
+	var doc = &Node{}
+	doc.AddChild(bookstore)
+	var root xpath.NodeNavigator = &NodeNavigator{curr: doc, root: doc}
 	expr, err := xpath.Compile("count(//book)")
+	// using Evaluate() method
 	if err != nil {
 		panic(err)
 	}
-	var root xpath.NodeNavigator
-	// using Evaluate() method
 	val := expr.Evaluate(root) // it returns float64 type
 	fmt.Println(val.(float64))
 
 	// using Evaluate() method
-	expr = xpath.MustCompile("//book")
-	val = expr.Evaluate(root) // it returns NodeIterator type.
-	iter := val.(*xpath.NodeIterator)
-	for iter.MoveNext() {
-		fmt.Println(iter.Current().Value())
-	}
+	expr = xpath.MustCompile("sum(//price)")
+	val = expr.Evaluate(root) // output total price
+	fmt.Println(val.(float64))
 
 	// using Select() method
-	iter = expr.Select(root) // it always returns NodeIterator object.
+	expr = xpath.MustCompile("//book")
+	iter := expr.Select(root) // it always returns NodeIterator object.
 	for iter.MoveNext() {
 		fmt.Println(iter.Current().Value())
 	}