AST

What will be printed when the code below is executed?(Hint: Use the template below)

  1. *ast.File:
  2. ____: ____
  3. *ast.GenDecl:
  4. *ast.ValueSpec:
  5. ____: ____
  6. ____: ____
  1. package main
  3. import (
  4.     "fmt"
  5.     "go/ast"
  6.     "go/parser"
  7.     "go/token"
  8.     "log"
  9.     "strings"
  10. )
  12. func main() {
  13.     fs := token.NewFileSet()
  14.     f, err := parser.ParseFile(fs, "", "package main; var a = 0", parser.AllErrors)
  15.     if err != nil {
  16.         log.Fatal(err)
  17.     }
  18.     var v visitor
  19.     ast.Walk(v, f)
  20. }
  22. type visitor int
  24. func (v visitor) Visit(n ast.Node) ast.Visitor {
  25.     if n == nil {
  26.         return nil
  27.     }
  28.     var s string
  29.     switch node := n.(type) {
  30.     case *ast.Ident:
  31.         s = node.Name
  32.     case *ast.BasicLit:
  33.         s = node.Value
  34.     }
  35.     fmt.Printf("%s%T: %s\n", strings.Repeat("\t", int(v)), n, s)
  36.     return v + 1
  37. }