gcc/testsuite/go.test/test/typeswitch1.go

   1 // $G $D/$F.go && $L $F.$A && ./$A.out
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 package main
   8
   9 import "fmt"
  10
  11 const (
  12         a = iota
  13         b
  14         c
  15         d
  16         e
  17 )
  18
  19 var x = []int{1, 2, 3}
  20
  21 func f(x int, len *byte) {
  22         *len = byte(x)
  23 }
  24
  25 func whatis(x interface{}) string {
  26         switch xx := x.(type) {
  27         default:
  28                 return fmt.Sprint("default ", xx)
  29         case int, int8, int16, int32:
  30                 return fmt.Sprint("signed ", xx)
  31         case int64:
  32                 return fmt.Sprint("signed64 ", int64(xx))
  33         case uint, uint8, uint16, uint32:
  34                 return fmt.Sprint("unsigned ", xx)
  35         case uint64:
  36                 return fmt.Sprint("unsigned64 ", uint64(xx))
  37         case nil:
  38                 return fmt.Sprint("nil ", xx)
  39         }
  40         panic("not reached")
  41 }
  42
  43 func whatis1(x interface{}) string {
  44         xx := x
  45         switch xx.(type) {
  46         default:
  47                 return fmt.Sprint("default ", xx)
  48         case int, int8, int16, int32:
  49                 return fmt.Sprint("signed ", xx)
  50         case int64:
  51                 return fmt.Sprint("signed64 ", xx.(int64))
  52         case uint, uint8, uint16, uint32:
  53                 return fmt.Sprint("unsigned ", xx)
  54         case uint64:
  55                 return fmt.Sprint("unsigned64 ", xx.(uint64))
  56         case nil:
  57                 return fmt.Sprint("nil ", xx)
  58         }
  59         panic("not reached")
  60 }
  61
  62 func check(x interface{}, s string) {
  63         w := whatis(x)
  64         if w != s {
  65                 fmt.Println("whatis", x, "=>", w, "!=", s)
  66                 panic("fail")
  67         }
  68
  69         w = whatis1(x)
  70         if w != s {
  71                 fmt.Println("whatis1", x, "=>", w, "!=", s)
  72                 panic("fail")
  73         }
  74 }
  75
  76 func main() {
  77         check(1, "signed 1")
  78         check(uint(1), "unsigned 1")
  79         check(int64(1), "signed64 1")
  80         check(uint64(1), "unsigned64 1")
  81         check(1.5, "default 1.5")
  82         check(nil, "nil <nil>")
  83 }