add HTML utility functions

html.go

@@ -0,0 +1,104 @@
+package goutil
+
+import (
+	"golang.org/x/net/html"
+	"strings"
+)
+
+type HtmlNode html.Node
+
+func (n *HtmlNode) GetAttribute(key string) ([]string, bool) {
+	if n != nil {
+		for _, attr := range n.Attr {
+			if attr.Key == key {
+				return strings.Split(attr.Val, " "), true
+			}
+		}
+	}
+	return []string{}, false
+}
+
+func (n *HtmlNode) CheckAttribute(attr string, val string) bool {
+	if n != nil && n.Type == html.ElementNode {
+		attrvals, ok := n.GetAttribute(attr)
+		if ok {
+			for _, v := range attrvals {
+				if v == val {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func (n *HtmlNode) Find(f func(n *HtmlNode) bool) *HtmlNode {
+	if n != nil {
+		if f(n) {
+			return n
+		}
+		for c := (*HtmlNode)(n.FirstChild); c != nil; c = (*HtmlNode)(c.NextSibling) {
+			result := c.Find(f)
+			if result != nil {
+				return result
+			}
+		}
+	}
+	return nil
+}
+
+func (n *HtmlNode) FindAll(f func(n *HtmlNode) bool) []*HtmlNode {
+	all := []*HtmlNode{}
+	if n != nil {
+		if f(n) {
+			return []*HtmlNode{n}
+		}
+		for c := (*HtmlNode)(n.FirstChild); c != nil; c = (*HtmlNode)(c.NextSibling) {
+			result := c.FindAll(f)
+			if len(result) > 0 {
+				all = append(all, result...)
+			}
+		}
+	}
+	return all
+}
+
+func (n *HtmlNode) GetElementById(id string) *HtmlNode {
+	if n != nil {
+		return n.Find(func(n *HtmlNode) bool { return n.CheckAttribute("id", id) })
+	} else {
+		return nil
+	}
+}
+
+func (n *HtmlNode) GetElementsByClass(class string) []*HtmlNode {
+	if n != nil {
+		return n.FindAll(func(n *HtmlNode) bool { return n.CheckAttribute("class", class) })
+	} else {
+		return nil
+	}
+}
+
+func (n *HtmlNode) text() string {
+	if n == nil {
+		return ""
+	}
+	textNodes := n.FindAll(func(n *HtmlNode) bool { return n.Type == html.TextNode })
+	texts := []string{}
+	for _, n := range textNodes {
+		t := strings.TrimSpace(n.Data)
+		if t != "" {
+			texts = append(texts, t)
+		}
+	}
+	if len(texts) > 0 {
+		return strings.Join(texts, " ")
+	} else {
+		return ""
+	}
+}
+
+func (n *HtmlNode) firstText() string {
+	text := n.Find(func(n *HtmlNode) bool { return n.Type == html.TextNode })
+	return strings.TrimSpace(text.Data)
+}