accompanies the blog post: Comparing JSON and XML as DataFormats… Again http://xampl.com/so/2012/06/22/1164/

bmark_test.go

package main

// run from the command line as:
//    go test -bench=".*

import (
	"testing"
)

func BenchmarkJSON(b *testing.B) {
	json_bytes := []byte(`{ "book":{"type":"textbook","pages":"256","title":"Programming Pearls 2nd Edition","description":"The first edition of Programming Pearls was one of the most influential books I read early in my career...","rating":"4.5","coverType":"paperback","genre":"Computer Science","author":"Jon Bentley","publisher":"Addison-Wesley Professional","copyright":"1999"}}`)
	for i := 0; i < b.N; i++ {
		//book := load_json_book(json_bytes)
		_, err := load_json_book(json_bytes)
		if nil != err {
			b.Fatalf("JSON parsing failed: %q", err)
		}
	}
}

func BenchmarkXML(b *testing.B) {
	xml_bytes := []byte(`<book type='textbook' pages='256' title='Programming Pearls 2nd Edition' rating='4.5' coverType='paperback' genre='Computer Science' author='Jon Bentley' publisher='Addison-Wesley Professional' copyright='1999'><description>The first edition of Programming Pearls was one of the most influential books I read early in my career...</description></book>`)
	for i := 0; i < b.N; i++ {
		//book := load_xml_book(xml_bytes)
		_, err := load_xml_book(xml_bytes)
		if nil != err {
			b.Fatalf("XML parsing failed: %q", err)
		}
	}
}

func BenchmarkPP(b *testing.B) {
	xml_bytes := []byte(`<book type='textbook' pages='256' title='Programming Pearls 2nd Edition' rating='4.5' coverType='paperback' genre='Computer Science' author='Jon Bentley' publisher='Addison-Wesley Professional' copyright='1999'><description>The first edition of Programming Pearls was one of the most influential books I read early in my career...</description></book>`)
	for i := 0; i < b.N; i++ {
		_, err := load_xml_by_pull_parser(xml_bytes)
		if nil != err {
			b.Fatalf("XML PP parsing failed: %q", err)
		}
	}
}

book.json

{
 "book": {
     "type": "textbook",
     "pages": "256",
     "title": "Programming Pearls 2nd Edition",
     "description": "The first edition of Programming Pearls was one of the most influential books I read early in my career...",
     "rating": "4.5",
     "coverType": "paperback",
     "genre": "Computer Science",
     "author": "Jon Bentley",
     "publisher": "Addison-Wesley Professional",
     "copyright": "1999"
     }
}

book.xml

<book>
  <type>textbook</type>
  <pages>256</pages>
  <title>Programming Pearls 2nd Edition</title>
  <description>The first edition of Programming Pearls was one of the most influential books I read early in my career...</description>
  <rating>4.5</rating>
  <coverType>paperback</coverType>
  <genre>Computer Science</genre>
  <author>Jon Bentley</author>
  <publisher>Addison-Wesley Professional</publisher>
  <copyright>1999</copyright>
</book>

main.go

package main

import (
	"bytes"
	"encoding/json"
	"encoding/xml"
	"fmt"
	"io"
)

type BookRef struct {
	Book BookInfo
}
type BookInfo struct {
	Type        string `xml:"type,attr"`
	Pages       string `xml:"pages,attr"`
	Title       string `xml:"title,attr"`
	Description string `xml:"description"`
	Rating      string `xml:"rating,attr"`
	CoverType   string `xml:"coverType,attr"`
	Genre       string `xml:"genre,attr"`
	Author      string `xml:"author,attr"`
	Publisher   string `xml:"publisher,attr"`
	Copyright   string `xml:"copyright,attr"`
}

func load_json_book(bytes []byte) (book *BookRef, err error) {
	book = new(BookRef)
	err = json.Unmarshal(bytes, book)
	return
}

func load_xml_book(bytes []byte) (book *BookInfo, err error) {
	book = new(BookInfo)
	err = xml.Unmarshal(bytes, book)
	return
}

func load_xml_by_pull_parser(xml_bytes []byte) (book *BookInfo, err error) {
	book = new(BookInfo)
	decoder := xml.NewDecoder(bytes.NewReader(xml_bytes))
	collectingDescription := false

	for {
		in_token, err := decoder.Token()
		if io.EOF == err {
			break
		}
		if (nil == in_token) && (nil == err) {
			break
		}

		switch token := in_token.(type) {
		case xml.StartElement:
			collectingDescription = false

			switch token.Name.Local {
			case "book":
				for i := range token.Attr {
					switch token.Attr[i].Name.Local {
					case "type":
						book.Type = token.Attr[i].Value
					case "pages":
						book.Pages = token.Attr[i].Value
					case "title":
						book.Title = token.Attr[i].Value
					case "rating":
						book.Rating = token.Attr[i].Value
					case "coverType":
						book.CoverType = token.Attr[i].Value
					case "genre":
						book.Genre = token.Attr[i].Value
					case "author":
						book.Author = token.Attr[i].Value
					case "publisher":
						book.Publisher = token.Attr[i].Value
					case "copyright":
						book.Copyright = token.Attr[i].Value
					}
				}
			case "description":
				book.Description = ""
				collectingDescription = true
			}
		case xml.EndElement:
			collectingDescription = false
		case xml.CharData:
			if collectingDescription {
				//book.Description += string(token.Copy())
				book.Description += string(token)
			}
		}

		if nil != err {
			break
		}
	}

	return
}

func main() {
	json_bytes := []byte(`{"book":{"type":"textbook","pages":"256","title":"Programming Pearls 2nd Edition","description":"The first edition of Programming Pearls was one of the most influential books I read early in my career...","rating":"4.5","coverType":"paperback","genre":"Computer Science","author":"Jon Bentley","publisher":"Addison-Wesley Professional","copyright":"1999"}}`)
	xml_bytes := []byte(`<book type='textbook' pages='256' title='Programming Pearls 2nd Edition' rating='4.5' coverType='paperback' genre='Computer Science' author='Jon Bentley' publisher='Addison-Wesley Professional' copyright='1999'><description>The first edition of Programming Pearls was one of the most influential books I read early in my career...</description></book>`)

	fmt.Printf("JSON `%v`\n", string(json_bytes))
	fmt.Printf("the size of the JSON string in bytes: %v\n", len(json_bytes))
	json_book, err := load_json_book(json_bytes)
	if nil != err {
		fmt.Printf("load_json_book:: that didn't work: %v\n", err)
	} else {
		fmt.Printf("the JSON book is \n%#v\n", json_book)
	}

	fmt.Println()

	fmt.Printf("XML `%v`\n", string(xml_bytes))
	fmt.Printf("the size of the XML string in bytes: %v\n", len(xml_bytes))
	xml_book, err := load_xml_book(xml_bytes)
	if nil != err {
		fmt.Printf("load_xml_book:: that didn't work: %v\n", err)
	} else {
		fmt.Printf("the XML book is \n%#v\n", xml_book)
	}

	fmt.Println()

	pp_xml_book, err := load_xml_by_pull_parser(xml_bytes)
	if nil != err {
		fmt.Printf("pp:: that didn't work: %v\n", err)
	} else {
		fmt.Printf("the pulled XML book is \n%#v\n", pp_xml_book)
	}
}

nicer-book.xml

<book type='textbook'
      pages='256'
      title='Programming Pearls 2nd Edition'
      rating='4.5'
      coverType='paperback'
      genre='Computer Science'
      author='Jon Bentley'
      publisher='Addison-Wesley Professional'
      copyright='1999'>
  <description>The first edition of Programming Pearls was one of the most influential books I read early in my career...</description>
</book>