github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/math/bits/make_examples.go (about)

     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  }