flag.go

Documentation: cmd/internal/objabi

     1  // Copyright 2015 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 objabi
     6  
     7  import (
     8  	"flag"
     9  	"fmt"
    10  	"io"
    11  	"io/ioutil"
    12  	"log"
    13  	"os"
    14  	"strconv"
    15  	"strings"
    16  )
    17  
    18  func Flagcount(name, usage string, val *int) {
    19  	flag.Var((*count)(val), name, usage)
    20  }
    21  
    22  func Flagfn1(name, usage string, f func(string)) {
    23  	flag.Var(fn1(f), name, usage)
    24  }
    25  
    26  func Flagprint(w io.Writer) {
    27  	flag.CommandLine.SetOutput(w)
    28  	flag.PrintDefaults()
    29  }
    30  
    31  func Flagparse(usage func()) {
    32  	flag.Usage = usage
    33  	os.Args = expandArgs(os.Args)
    34  	flag.Parse()
    35  }
    36  
    37  // expandArgs expands "response files" arguments in the provided slice.
    38  //
    39  // A "response file" argument starts with '@' and the rest of that
    40  // argument is a filename with CR-or-CRLF-separated arguments. Each
    41  // argument in the named files can also contain response file
    42  // arguments. See Issue 18468.
    43  //
    44  // The returned slice 'out' aliases 'in' iff the input did not contain
    45  // any response file arguments.
    46  //
    47  // TODO: handle relative paths of recursive expansions in different directories?
    48  // Is there a spec for this? Are relative paths allowed?
    49  func expandArgs(in []string) (out []string) {
    50  	// out is nil until we see a "@" argument.
    51  	for i, s := range in {
    52  		if strings.HasPrefix(s, "@") {
    53  			if out == nil {
    54  				out = make([]string, 0, len(in)*2)
    55  				out = append(out, in[:i]...)
    56  			}
    57  			slurp, err := ioutil.ReadFile(s[1:])
    58  			if err != nil {
    59  				log.Fatal(err)
    60  			}
    61  			args := strings.Split(strings.TrimSpace(strings.Replace(string(slurp), "\r", "", -1)), "\n")
    62  			out = append(out, expandArgs(args)...)
    63  		} else if out != nil {
    64  			out = append(out, s)
    65  		}
    66  	}
    67  	if out == nil {
    68  		return in
    69  	}
    70  	return
    71  }
    72  
    73  func AddVersionFlag() {
    74  	flag.Var(versionFlag{}, "V", "print version and exit")
    75  }
    76  
    77  var buildID string // filled in by linker
    78  
    79  type versionFlag struct{}
    80  
    81  func (versionFlag) IsBoolFlag() bool { return true }
    82  func (versionFlag) Get() interface{} { return nil }
    83  func (versionFlag) String() string   { return "" }
    84  func (versionFlag) Set(s string) error {
    85  	name := os.Args[0]
    86  	name = name[strings.LastIndex(name, `/`)+1:]
    87  	name = name[strings.LastIndex(name, `\`)+1:]
    88  	name = strings.TrimSuffix(name, ".exe")
    89  	p := Expstring()
    90  	if p == DefaultExpstring() {
    91  		p = ""
    92  	}
    93  	sep := ""
    94  	if p != "" {
    95  		sep = " "
    96  	}
    97  
    98  	// The go command invokes -V=full to get a unique identifier
    99  	// for this tool. It is assumed that the release version is sufficient
   100  	// for releases, but during development we include the full
   101  	// build ID of the binary, so that if the compiler is changed and
   102  	// rebuilt, we notice and rebuild all packages.
   103  	if s == "full" && strings.HasPrefix(Version, "devel") {
   104  		p += " buildID=" + buildID
   105  	}
   106  	fmt.Printf("%s version %s%s%s\n", name, Version, sep, p)
   107  	os.Exit(0)
   108  	return nil
   109  }
   110  
   111  // count is a flag.Value that is like a flag.Bool and a flag.Int.
   112  // If used as -name, it increments the count, but -name=x sets the count.
   113  // Used for verbose flag -v.
   114  type count int
   115  
   116  func (c *count) String() string {
   117  	return fmt.Sprint(int(*c))
   118  }
   119  
   120  func (c *count) Set(s string) error {
   121  	switch s {
   122  	case "true":
   123  		*c++
   124  	case "false":
   125  		*c = 0
   126  	default:
   127  		n, err := strconv.Atoi(s)
   128  		if err != nil {
   129  			return fmt.Errorf("invalid count %q", s)
   130  		}
   131  		*c = count(n)
   132  	}
   133  	return nil
   134  }
   135  
   136  func (c *count) Get() interface{} {
   137  	return int(*c)
   138  }
   139  
   140  func (c *count) IsBoolFlag() bool {
   141  	return true
   142  }
   143  
   144  func (c *count) IsCountFlag() bool {
   145  	return true
   146  }
   147  
   148  type fn1 func(string)
   149  
   150  func (f fn1) Set(s string) error {
   151  	f(s)
   152  	return nil
   153  }
   154  
   155  func (f fn1) String() string { return "" }
   156
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