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Simple DOM node traversal in golang using a very useful collector/matcher function
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| package main | |
| import ( | |
| "bytes" | |
| "fmt" | |
| "io" | |
| "strings" | |
| "unicode" | |
| "golang.org/x/net/html" | |
| "golang.org/x/net/html/atom" | |
| ) | |
| const htm = `<!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title></title> | |
| </head> | |
| <body> | |
| body content | |
| <p>more <a href="">content</a></p> | |
| <p>This <a href="/foo"><em>important</em> link <br> to | |
| foo</a> is here</p> | |
| <p>Call at <a href="mailto:[email protected]">[email protected]</a></p> | |
| <div> | |
| <span>[email protected]</span></div> | |
| <p>Hello and <a href="">example.com</a>.</span></p> | |
| <em>are all valid. You can email "john" if you need me.</em> | |
| </body> | |
| </html>` | |
| func main() { | |
| doc, err := html.Parse(strings.NewReader(htm)) | |
| if err != nil { | |
| fmt.Println(err) | |
| return | |
| } | |
| // Find all the text nodes that are not children of a <p> | |
| matcher := func(node *html.Node) (keep bool, exit bool) { | |
| if node.Type == html.TextNode && strings.TrimSpace(node.Data) != "" { | |
| keep = true | |
| } | |
| if node.DataAtom == atom.P { | |
| exit = true | |
| } | |
| return | |
| } | |
| nodes = TraverseNode(doc, matcher) | |
| for i, node := range nodes { | |
| fmt.Println(i, renderNode(node)) | |
| } | |
| } | |
| // TraverseNode collecting the nodes that match the given function | |
| func TraverseNode(doc *html.Node, matcher func(node *html.Node) (bool, bool)) (nodes []*html.Node) { | |
| var keep, exit bool | |
| var f func(*html.Node) | |
| f = func(n *html.Node) { | |
| keep, exit = matcher(n) | |
| if keep { | |
| nodes = append(nodes, n) | |
| } | |
| if exit { | |
| return | |
| } | |
| for c := n.FirstChild; c != nil; c = c.NextSibling { | |
| f(c) | |
| } | |
| } | |
| f(doc) | |
| return nodes | |
| } | |
| // Works better than: https://github.com/yhat/scrape/blob/master/scrape.go#L129 | |
| // because you can cut the search short from the matcher function | |
| func renderNode(n *html.Node) string { | |
| var buf bytes.Buffer | |
| w := io.Writer(&buf) | |
| html.Render(w, n) | |
| return buf.String() | |
| } |
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