libgo/go/hash/example_test.go

   1 // Copyright 2017 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build ignore
   6
   7 package hash_test
   8
   9 import (
  10         "bytes"
  11         "crypto/sha256"
  12         "encoding"
  13         "fmt"
  14         "log"
  15 )
  16
  17 func Example_binaryMarshaler() {
  18         const (
  19                 input1 = "The tunneling gopher digs downwards, "
  20                 input2 = "unaware of what he will find."
  21         )
  22
  23         first := sha256.New()
  24         first.Write([]byte(input1))
  25
  26         marshaler, ok := first.(encoding.BinaryMarshaler)
  27         if !ok {
  28                 log.Fatal("first does not implement encoding.BinaryMarshaler")
  29         }
  30         state, err := marshaler.MarshalBinary()
  31         if err != nil {
  32                 log.Fatal("unable to marshal hash:", err)
  33         }
  34
  35         second := sha256.New()
  36
  37         unmarshaler, ok := second.(encoding.BinaryUnmarshaler)
  38         if !ok {
  39                 log.Fatal("second does not implement encoding.BinaryUnmarshaler")
  40         }
  41         if err := unmarshaler.UnmarshalBinary(state); err != nil {
  42                 log.Fatal("unable to unmarshal hash:", err)
  43         }
  44
  45         first.Write([]byte(input2))
  46         second.Write([]byte(input2))
  47
  48         fmt.Printf("%x\n", first.Sum(nil))
  49         fmt.Println(bytes.Equal(first.Sum(nil), second.Sum(nil)))
  50         // Output:
  51         // 57d51a066f3a39942649cd9a76c77e97ceab246756ff3888659e6aa5a07f4a52
  52         // true
  53 }