parser.go

package main

import (
  "go/ast"
  "go/parser"
  "go/token"
  "log"
)

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

import "fmt"

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

  fset := token.NewFileSet()

  file, err := parser.ParseFile(fset, "", src, 0)
  if err != nil {
     log.Fatal(err)
  }

  ast.Print(fset, file)
}