libgo/go/sort/example_wrapper_test.go

   1 // Copyright 2011 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 package sort_test
   6
   7 import (
   8         "fmt"
   9         "sort"
  10 )
  11
  12 type Grams int
  13
  14 func (g Grams) String() string { return fmt.Sprintf("%dg", int(g)) }
  15
  16 type Organ struct {
  17         Name   string
  18         Weight Grams
  19 }
  20
  21 type Organs []*Organ
  22
  23 func (s Organs) Len() int      { return len(s) }
  24 func (s Organs) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
  25
  26 // ByName implements sort.Interface by providing Less and using the Len and
  27 // Swap methods of the embedded Organs value.
  28 type ByName struct{ Organs }
  29
  30 func (s ByName) Less(i, j int) bool { return s.Organs[i].Name < s.Organs[j].Name }
  31
  32 // ByWeight implements sort.Interface by providing Less and using the Len and
  33 // Swap methods of the embedded Organs value.
  34 type ByWeight struct{ Organs }
  35
  36 func (s ByWeight) Less(i, j int) bool { return s.Organs[i].Weight < s.Organs[j].Weight }
  37
  38 func Example_sortWrapper() {
  39         s := []*Organ{
  40                 {"brain", 1340},
  41                 {"heart", 290},
  42                 {"liver", 1494},
  43                 {"pancreas", 131},
  44                 {"prostate", 62},
  45                 {"spleen", 162},
  46         }
  47
  48         sort.Sort(ByWeight{s})
  49         fmt.Println("Organs by weight:")
  50         printOrgans(s)
  51
  52         sort.Sort(ByName{s})
  53         fmt.Println("Organs by name:")
  54         printOrgans(s)
  55
  56         // Output:
  57         // Organs by weight:
  58         // prostate (62g)
  59         // pancreas (131g)
  60         // spleen   (162g)
  61         // heart    (290g)
  62         // brain    (1340g)
  63         // liver    (1494g)
  64         // Organs by name:
  65         // brain    (1340g)
  66         // heart    (290g)
  67         // liver    (1494g)
  68         // pancreas (131g)
  69         // prostate (62g)
  70         // spleen   (162g)
  71 }
  72
  73 func printOrgans(s []*Organ) {
  74         for _, o := range s {
  75                 fmt.Printf("%-8s (%v)\n", o.Name, o.Weight)
  76         }
  77 }