scanner.go

package main

import (
  "fmt"
  "go/scanner"
  "go/token"
)

func main() {
  src := []byte(`package main

import "fmt"

func main() {
  fmt.Println("Hello, world!")
}
`)

  var s scanner.Scanner
  fset := token.NewFileSet()
  file := fset.AddFile("", fset.Base(), len(src))
  s.Init(file, src, nil, 0)

  for {
     pos, tok, lit := s.Scan()
     fmt.Printf("%-6s%-8s%q\n", fset.Position(pos), tok, lit)

     if tok == token.EOF {
        break
     }
  }
}