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      1 // run
      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 // Test simple type switches, including chans, maps etc.
      8 
      9 package main
     10 
     11 import "os"
     12 
     13 const (
     14 	Bool = iota
     15 	Int
     16 	Float
     17 	String
     18 	Struct
     19 	Chan
     20 	Array
     21 	Map
     22 	Func
     23 	Last
     24 )
     25 
     26 type S struct {
     27 	a int
     28 }
     29 
     30 var s S = S{1234}
     31 
     32 var c = make(chan int)
     33 
     34 var a = []int{0, 1, 2, 3}
     35 
     36 var m = make(map[string]int)
     37 
     38 func assert(b bool, s string) {
     39 	if !b {
     40 		println(s)
     41 		os.Exit(1)
     42 	}
     43 }
     44 
     45 func f(i int) interface{} {
     46 	switch i {
     47 	case Bool:
     48 		return true
     49 	case Int:
     50 		return 7
     51 	case Float:
     52 		return 7.4
     53 	case String:
     54 		return "hello"
     55 	case Struct:
     56 		return s
     57 	case Chan:
     58 		return c
     59 	case Array:
     60 		return a
     61 	case Map:
     62 		return m
     63 	case Func:
     64 		return f
     65 	}
     66 	panic("bad type number")
     67 }
     68 
     69 func main() {
     70 	for i := Bool; i < Last; i++ {
     71 		switch x := f(i).(type) {
     72 		case bool:
     73 			assert(x == true && i == Bool, "bool")
     74 		case int:
     75 			assert(x == 7 && i == Int, "int")
     76 		case float64:
     77 			assert(x == 7.4 && i == Float, "float64")
     78 		case string:
     79 			assert(x == "hello" && i == String, "string")
     80 		case S:
     81 			assert(x.a == 1234 && i == Struct, "struct")
     82 		case chan int:
     83 			assert(x == c && i == Chan, "chan")
     84 		case []int:
     85 			assert(x[3] == 3 && i == Array, "array")
     86 		case map[string]int:
     87 			assert(x != nil && i == Map, "map")
     88 		case func(i int) interface{}:
     89 			assert(x != nil && i == Func, "fun")
     90 		default:
     91 			assert(false, "unknown")
     92 		}
     93 	}
     94 
     95 	// boolean switch (has had bugs in past; worth writing down)
     96 	switch {
     97 	case true:
     98 		assert(true, "switch 2 bool")
     99 	default:
    100 		assert(false, "switch 2 unknown")
    101 	}
    102 
    103 	switch true {
    104 	case true:
    105 		assert(true, "switch 3 bool")
    106 	default:
    107 		assert(false, "switch 3 unknown")
    108 	}
    109 
    110 	switch false {
    111 	case false:
    112 		assert(true, "switch 4 bool")
    113 	default:
    114 		assert(false, "switch 4 unknown")
    115 	}
    116 }
    117