libgo/go/math/bits/make_examples.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 //go:build ignore
   6 // +build ignore
   7
   8 // This program generates example_test.go.
   9
  10 package main
  11
  12 import (
  13         "bytes"
  14         "fmt"
  15         "log"
  16         "math/bits"
  17         "os"
  18 )
  19
  20 const header = `// Copyright 2017 The Go Authors. All rights reserved.
  21 // Use of this source code is governed by a BSD-style
  22 // license that can be found in the LICENSE file.
  23
  24 // Code generated by go run make_examples.go. DO NOT EDIT.
  25
  26 package bits_test
  27
  28 import (
  29         "fmt"
  30         "math/bits"
  31 )
  32 `
  33
  34 func main() {
  35         w := bytes.NewBuffer([]byte(header))
  36
  37         for _, e := range []struct {
  38                 name string
  39                 in   int
  40                 out  [4]any
  41                 out2 [4]any
  42         }{
  43                 {
  44                         name: "LeadingZeros",
  45                         in:   1,
  46                         out:  [4]any{bits.LeadingZeros8(1), bits.LeadingZeros16(1), bits.LeadingZeros32(1), bits.LeadingZeros64(1)},
  47                 },
  48                 {
  49                         name: "TrailingZeros",
  50                         in:   14,
  51                         out:  [4]any{bits.TrailingZeros8(14), bits.TrailingZeros16(14), bits.TrailingZeros32(14), bits.TrailingZeros64(14)},
  52                 },
  53                 {
  54                         name: "OnesCount",
  55                         in:   14,
  56                         out:  [4]any{bits.OnesCount8(14), bits.OnesCount16(14), bits.OnesCount32(14), bits.OnesCount64(14)},
  57                 },
  58                 {
  59                         name: "RotateLeft",
  60                         in:   15,
  61                         out:  [4]any{bits.RotateLeft8(15, 2), bits.RotateLeft16(15, 2), bits.RotateLeft32(15, 2), bits.RotateLeft64(15, 2)},
  62                         out2: [4]any{bits.RotateLeft8(15, -2), bits.RotateLeft16(15, -2), bits.RotateLeft32(15, -2), bits.RotateLeft64(15, -2)},
  63                 },
  64                 {
  65                         name: "Reverse",
  66                         in:   19,
  67                         out:  [4]any{bits.Reverse8(19), bits.Reverse16(19), bits.Reverse32(19), bits.Reverse64(19)},
  68                 },
  69                 {
  70                         name: "ReverseBytes",
  71                         in:   15,
  72                         out:  [4]any{nil, bits.ReverseBytes16(15), bits.ReverseBytes32(15), bits.ReverseBytes64(15)},
  73                 },
  74                 {
  75                         name: "Len",
  76                         in:   8,
  77                         out:  [4]any{bits.Len8(8), bits.Len16(8), bits.Len32(8), bits.Len64(8)},
  78                 },
  79         } {
  80                 for i, size := range []int{8, 16, 32, 64} {
  81                         if e.out[i] == nil {
  82                                 continue // function doesn't exist
  83                         }
  84                         f := fmt.Sprintf("%s%d", e.name, size)
  85                         fmt.Fprintf(w, "\nfunc Example%s() {\n", f)
  86                         switch e.name {
  87                         case "RotateLeft", "Reverse", "ReverseBytes":
  88                                 fmt.Fprintf(w, "\tfmt.Printf(\"%%0%db\\n\", %d)\n", size, e.in)
  89                                 if e.name == "RotateLeft" {
  90                                         fmt.Fprintf(w, "\tfmt.Printf(\"%%0%db\\n\", bits.%s(%d, 2))\n", size, f, e.in)
  91                                         fmt.Fprintf(w, "\tfmt.Printf(\"%%0%db\\n\", bits.%s(%d, -2))\n", size, f, e.in)
  92                                 } else {
  93                                         fmt.Fprintf(w, "\tfmt.Printf(\"%%0%db\\n\", bits.%s(%d))\n", size, f, e.in)
  94                                 }
  95                                 fmt.Fprintf(w, "\t// Output:\n")
  96                                 fmt.Fprintf(w, "\t// %0*b\n", size, e.in)
  97                                 fmt.Fprintf(w, "\t// %0*b\n", size, e.out[i])
  98                                 if e.name == "RotateLeft" && e.out2[i] != nil {
  99                                         fmt.Fprintf(w, "\t// %0*b\n", size, e.out2[i])
 100                                 }
 101                         default:
 102                                 fmt.Fprintf(w, "\tfmt.Printf(\"%s(%%0%db) = %%d\\n\", %d, bits.%s(%d))\n", f, size, e.in, f, e.in)
 103                                 fmt.Fprintf(w, "\t// Output:\n")
 104                                 fmt.Fprintf(w, "\t// %s(%0*b) = %d\n", f, size, e.in, e.out[i])
 105                         }
 106                         fmt.Fprintf(w, "}\n")
 107                 }
 108         }
 109
 110         if err := os.WriteFile("example_test.go", w.Bytes(), 0666); err != nil {
 111                 log.Fatal(err)
 112         }
 113 }