Go: How would you "Pretty Print"/"Prettify" HTML?

In Python, PHP, and many other languages, it is possible to convert a html document and "prettify" it. In Go, this is very easily done for JSON and XML (from a struct/interface) using the MarshIndent function.

Example for XML in Go:

http://play.golang.org/p/aBNfNxTEG1

package main

import (
    "encoding/xml"
    "fmt"
    "os"
)

func main() {
    type Address struct {
        City, State string
    }
    type Person struct {
        XMLName   xml.Name `xml:"person"`
        Id        int      `xml:"id,attr"`
        FirstName string   `xml:"name>first"`
        LastName  string   `xml:"name>last"`
        Age       int      `xml:"age"`
        Height    float32  `xml:"height,omitempty"`
        Married   bool
        Address
        Comment string `xml:",comment"`
    }

    v := &Person{Id: 13, FirstName: "John", LastName: "Doe", Age: 42}
    v.Comment = " Need more details. "
    v.Address = Address{"Hanga Roa", "Easter Island"}

    output, err := xml.MarshalIndent(v, "  ", "    ")
    if err != nil {
        fmt.Printf("error: %v\n", err)
    }

    os.Stdout.Write(output)
}

However, this only works for converting struct/interface into a []byte. What I want is convert a string of html code and indent automatically. Example:

Raw HTML

<!doctype html><html><head>
<title>Website Title</title>
</head><body>
<div class="random-class">
<h1>I like pie</h1><p>It's true!</p></div>
</body></html>

Prettified HTML

<!doctype html>
<html>
    <head>
        <title>Website Title</title>
    </head>
    <body>
        <div class="random-class">
            <h1>I like pie</h1>
            <p>It's true!</p>
        </div>
    </body>
</html>

How would this be done just using a string?

Solution

I faced a same problem and I just solved it by creating an HTML formatting package in Go by myself.

Here it is:

GoHTML - HTML formatter for Go

Please check this package out.

Thanks,

Keiji