/usr/share/go-1.8/src/flag/flag.go is in golang-1.8-src 1.8.3-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 | // Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/*
Package flag implements command-line flag parsing.
Usage:
Define flags using flag.String(), Bool(), Int(), etc.
This declares an integer flag, -flagname, stored in the pointer ip, with type *int.
import "flag"
var ip = flag.Int("flagname", 1234, "help message for flagname")
If you like, you can bind the flag to a variable using the Var() functions.
var flagvar int
func init() {
flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname")
}
Or you can create custom flags that satisfy the Value interface (with
pointer receivers) and couple them to flag parsing by
flag.Var(&flagVal, "name", "help message for flagname")
For such flags, the default value is just the initial value of the variable.
After all flags are defined, call
flag.Parse()
to parse the command line into the defined flags.
Flags may then be used directly. If you're using the flags themselves,
they are all pointers; if you bind to variables, they're values.
fmt.Println("ip has value ", *ip)
fmt.Println("flagvar has value ", flagvar)
After parsing, the arguments following the flags are available as the
slice flag.Args() or individually as flag.Arg(i).
The arguments are indexed from 0 through flag.NArg()-1.
Command line flag syntax:
-flag
-flag=x
-flag x // non-boolean flags only
One or two minus signs may be used; they are equivalent.
The last form is not permitted for boolean flags because the
meaning of the command
cmd -x *
will change if there is a file called 0, false, etc. You must
use the -flag=false form to turn off a boolean flag.
Flag parsing stops just before the first non-flag argument
("-" is a non-flag argument) or after the terminator "--".
Integer flags accept 1234, 0664, 0x1234 and may be negative.
Boolean flags may be:
1, 0, t, f, T, F, true, false, TRUE, FALSE, True, False
Duration flags accept any input valid for time.ParseDuration.
The default set of command-line flags is controlled by
top-level functions. The FlagSet type allows one to define
independent sets of flags, such as to implement subcommands
in a command-line interface. The methods of FlagSet are
analogous to the top-level functions for the command-line
flag set.
*/
package flag
import (
"errors"
"fmt"
"io"
"os"
"reflect"
"sort"
"strconv"
"time"
)
// ErrHelp is the error returned if the -help or -h flag is invoked
// but no such flag is defined.
var ErrHelp = errors.New("flag: help requested")
// -- bool Value
type boolValue bool
func newBoolValue(val bool, p *bool) *boolValue {
*p = val
return (*boolValue)(p)
}
func (b *boolValue) Set(s string) error {
v, err := strconv.ParseBool(s)
*b = boolValue(v)
return err
}
func (b *boolValue) Get() interface{} { return bool(*b) }
func (b *boolValue) String() string { return strconv.FormatBool(bool(*b)) }
func (b *boolValue) IsBoolFlag() bool { return true }
// optional interface to indicate boolean flags that can be
// supplied without "=value" text
type boolFlag interface {
Value
IsBoolFlag() bool
}
// -- int Value
type intValue int
func newIntValue(val int, p *int) *intValue {
*p = val
return (*intValue)(p)
}
func (i *intValue) Set(s string) error {
v, err := strconv.ParseInt(s, 0, 64)
*i = intValue(v)
return err
}
func (i *intValue) Get() interface{} { return int(*i) }
func (i *intValue) String() string { return strconv.Itoa(int(*i)) }
// -- int64 Value
type int64Value int64
func newInt64Value(val int64, p *int64) *int64Value {
*p = val
return (*int64Value)(p)
}
func (i *int64Value) Set(s string) error {
v, err := strconv.ParseInt(s, 0, 64)
*i = int64Value(v)
return err
}
func (i *int64Value) Get() interface{} { return int64(*i) }
func (i *int64Value) String() string { return strconv.FormatInt(int64(*i), 10) }
// -- uint Value
type uintValue uint
func newUintValue(val uint, p *uint) *uintValue {
*p = val
return (*uintValue)(p)
}
func (i *uintValue) Set(s string) error {
v, err := strconv.ParseUint(s, 0, 64)
*i = uintValue(v)
return err
}
func (i *uintValue) Get() interface{} { return uint(*i) }
func (i *uintValue) String() string { return strconv.FormatUint(uint64(*i), 10) }
// -- uint64 Value
type uint64Value uint64
func newUint64Value(val uint64, p *uint64) *uint64Value {
*p = val
return (*uint64Value)(p)
}
func (i *uint64Value) Set(s string) error {
v, err := strconv.ParseUint(s, 0, 64)
*i = uint64Value(v)
return err
}
func (i *uint64Value) Get() interface{} { return uint64(*i) }
func (i *uint64Value) String() string { return strconv.FormatUint(uint64(*i), 10) }
// -- string Value
type stringValue string
func newStringValue(val string, p *string) *stringValue {
*p = val
return (*stringValue)(p)
}
func (s *stringValue) Set(val string) error {
*s = stringValue(val)
return nil
}
func (s *stringValue) Get() interface{} { return string(*s) }
func (s *stringValue) String() string { return string(*s) }
// -- float64 Value
type float64Value float64
func newFloat64Value(val float64, p *float64) *float64Value {
*p = val
return (*float64Value)(p)
}
func (f *float64Value) Set(s string) error {
v, err := strconv.ParseFloat(s, 64)
*f = float64Value(v)
return err
}
func (f *float64Value) Get() interface{} { return float64(*f) }
func (f *float64Value) String() string { return strconv.FormatFloat(float64(*f), 'g', -1, 64) }
// -- time.Duration Value
type durationValue time.Duration
func newDurationValue(val time.Duration, p *time.Duration) *durationValue {
*p = val
return (*durationValue)(p)
}
func (d *durationValue) Set(s string) error {
v, err := time.ParseDuration(s)
*d = durationValue(v)
return err
}
func (d *durationValue) Get() interface{} { return time.Duration(*d) }
func (d *durationValue) String() string { return (*time.Duration)(d).String() }
// Value is the interface to the dynamic value stored in a flag.
// (The default value is represented as a string.)
//
// If a Value has an IsBoolFlag() bool method returning true,
// the command-line parser makes -name equivalent to -name=true
// rather than using the next command-line argument.
//
// Set is called once, in command line order, for each flag present.
// The flag package may call the String method with a zero-valued receiver,
// such as a nil pointer.
type Value interface {
String() string
Set(string) error
}
// Getter is an interface that allows the contents of a Value to be retrieved.
// It wraps the Value interface, rather than being part of it, because it
// appeared after Go 1 and its compatibility rules. All Value types provided
// by this package satisfy the Getter interface.
type Getter interface {
Value
Get() interface{}
}
// ErrorHandling defines how FlagSet.Parse behaves if the parse fails.
type ErrorHandling int
// These constants cause FlagSet.Parse to behave as described if the parse fails.
const (
ContinueOnError ErrorHandling = iota // Return a descriptive error.
ExitOnError // Call os.Exit(2).
PanicOnError // Call panic with a descriptive error.
)
// A FlagSet represents a set of defined flags. The zero value of a FlagSet
// has no name and has ContinueOnError error handling.
type FlagSet struct {
// Usage is the function called when an error occurs while parsing flags.
// The field is a function (not a method) that may be changed to point to
// a custom error handler.
Usage func()
name string
parsed bool
actual map[string]*Flag
formal map[string]*Flag
args []string // arguments after flags
errorHandling ErrorHandling
output io.Writer // nil means stderr; use out() accessor
}
// A Flag represents the state of a flag.
type Flag struct {
Name string // name as it appears on command line
Usage string // help message
Value Value // value as set
DefValue string // default value (as text); for usage message
}
// sortFlags returns the flags as a slice in lexicographical sorted order.
func sortFlags(flags map[string]*Flag) []*Flag {
list := make(sort.StringSlice, len(flags))
i := 0
for _, f := range flags {
list[i] = f.Name
i++
}
list.Sort()
result := make([]*Flag, len(list))
for i, name := range list {
result[i] = flags[name]
}
return result
}
func (f *FlagSet) out() io.Writer {
if f.output == nil {
return os.Stderr
}
return f.output
}
// SetOutput sets the destination for usage and error messages.
// If output is nil, os.Stderr is used.
func (f *FlagSet) SetOutput(output io.Writer) {
f.output = output
}
// VisitAll visits the flags in lexicographical order, calling fn for each.
// It visits all flags, even those not set.
func (f *FlagSet) VisitAll(fn func(*Flag)) {
for _, flag := range sortFlags(f.formal) {
fn(flag)
}
}
// VisitAll visits the command-line flags in lexicographical order, calling
// fn for each. It visits all flags, even those not set.
func VisitAll(fn func(*Flag)) {
CommandLine.VisitAll(fn)
}
// Visit visits the flags in lexicographical order, calling fn for each.
// It visits only those flags that have been set.
func (f *FlagSet) Visit(fn func(*Flag)) {
for _, flag := range sortFlags(f.actual) {
fn(flag)
}
}
// Visit visits the command-line flags in lexicographical order, calling fn
// for each. It visits only those flags that have been set.
func Visit(fn func(*Flag)) {
CommandLine.Visit(fn)
}
// Lookup returns the Flag structure of the named flag, returning nil if none exists.
func (f *FlagSet) Lookup(name string) *Flag {
return f.formal[name]
}
// Lookup returns the Flag structure of the named command-line flag,
// returning nil if none exists.
func Lookup(name string) *Flag {
return CommandLine.formal[name]
}
// Set sets the value of the named flag.
func (f *FlagSet) Set(name, value string) error {
flag, ok := f.formal[name]
if !ok {
return fmt.Errorf("no such flag -%v", name)
}
err := flag.Value.Set(value)
if err != nil {
return err
}
if f.actual == nil {
f.actual = make(map[string]*Flag)
}
f.actual[name] = flag
return nil
}
// Set sets the value of the named command-line flag.
func Set(name, value string) error {
return CommandLine.Set(name, value)
}
// isZeroValue guesses whether the string represents the zero
// value for a flag. It is not accurate but in practice works OK.
func isZeroValue(flag *Flag, value string) bool {
// Build a zero value of the flag's Value type, and see if the
// result of calling its String method equals the value passed in.
// This works unless the Value type is itself an interface type.
typ := reflect.TypeOf(flag.Value)
var z reflect.Value
if typ.Kind() == reflect.Ptr {
z = reflect.New(typ.Elem())
} else {
z = reflect.Zero(typ)
}
if value == z.Interface().(Value).String() {
return true
}
switch value {
case "false":
return true
case "":
return true
case "0":
return true
}
return false
}
// UnquoteUsage extracts a back-quoted name from the usage
// string for a flag and returns it and the un-quoted usage.
// Given "a `name` to show" it returns ("name", "a name to show").
// If there are no back quotes, the name is an educated guess of the
// type of the flag's value, or the empty string if the flag is boolean.
func UnquoteUsage(flag *Flag) (name string, usage string) {
// Look for a back-quoted name, but avoid the strings package.
usage = flag.Usage
for i := 0; i < len(usage); i++ {
if usage[i] == '`' {
for j := i + 1; j < len(usage); j++ {
if usage[j] == '`' {
name = usage[i+1 : j]
usage = usage[:i] + name + usage[j+1:]
return name, usage
}
}
break // Only one back quote; use type name.
}
}
// No explicit name, so use type if we can find one.
name = "value"
switch flag.Value.(type) {
case boolFlag:
name = ""
case *durationValue:
name = "duration"
case *float64Value:
name = "float"
case *intValue, *int64Value:
name = "int"
case *stringValue:
name = "string"
case *uintValue, *uint64Value:
name = "uint"
}
return
}
// PrintDefaults prints to standard error the default values of all
// defined command-line flags in the set. See the documentation for
// the global function PrintDefaults for more information.
func (f *FlagSet) PrintDefaults() {
f.VisitAll(func(flag *Flag) {
s := fmt.Sprintf(" -%s", flag.Name) // Two spaces before -; see next two comments.
name, usage := UnquoteUsage(flag)
if len(name) > 0 {
s += " " + name
}
// Boolean flags of one ASCII letter are so common we
// treat them specially, putting their usage on the same line.
if len(s) <= 4 { // space, space, '-', 'x'.
s += "\t"
} else {
// Four spaces before the tab triggers good alignment
// for both 4- and 8-space tab stops.
s += "\n \t"
}
s += usage
if !isZeroValue(flag, flag.DefValue) {
if _, ok := flag.Value.(*stringValue); ok {
// put quotes on the value
s += fmt.Sprintf(" (default %q)", flag.DefValue)
} else {
s += fmt.Sprintf(" (default %v)", flag.DefValue)
}
}
fmt.Fprint(f.out(), s, "\n")
})
}
// PrintDefaults prints, to standard error unless configured otherwise,
// a usage message showing the default settings of all defined
// command-line flags.
// For an integer valued flag x, the default output has the form
// -x int
// usage-message-for-x (default 7)
// The usage message will appear on a separate line for anything but
// a bool flag with a one-byte name. For bool flags, the type is
// omitted and if the flag name is one byte the usage message appears
// on the same line. The parenthetical default is omitted if the
// default is the zero value for the type. The listed type, here int,
// can be changed by placing a back-quoted name in the flag's usage
// string; the first such item in the message is taken to be a parameter
// name to show in the message and the back quotes are stripped from
// the message when displayed. For instance, given
// flag.String("I", "", "search `directory` for include files")
// the output will be
// -I directory
// search directory for include files.
func PrintDefaults() {
CommandLine.PrintDefaults()
}
// defaultUsage is the default function to print a usage message.
func (f *FlagSet) defaultUsage() {
if f.name == "" {
fmt.Fprintf(f.out(), "Usage:\n")
} else {
fmt.Fprintf(f.out(), "Usage of %s:\n", f.name)
}
f.PrintDefaults()
}
// NOTE: Usage is not just defaultUsage(CommandLine)
// because it serves (via godoc flag Usage) as the example
// for how to write your own usage function.
// Usage prints to standard error a usage message documenting all defined command-line flags.
// It is called when an error occurs while parsing flags.
// The function is a variable that may be changed to point to a custom function.
// By default it prints a simple header and calls PrintDefaults; for details about the
// format of the output and how to control it, see the documentation for PrintDefaults.
var Usage = func() {
fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
PrintDefaults()
}
// NFlag returns the number of flags that have been set.
func (f *FlagSet) NFlag() int { return len(f.actual) }
// NFlag returns the number of command-line flags that have been set.
func NFlag() int { return len(CommandLine.actual) }
// Arg returns the i'th argument. Arg(0) is the first remaining argument
// after flags have been processed. Arg returns an empty string if the
// requested element does not exist.
func (f *FlagSet) Arg(i int) string {
if i < 0 || i >= len(f.args) {
return ""
}
return f.args[i]
}
// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument
// after flags have been processed. Arg returns an empty string if the
// requested element does not exist.
func Arg(i int) string {
return CommandLine.Arg(i)
}
// NArg is the number of arguments remaining after flags have been processed.
func (f *FlagSet) NArg() int { return len(f.args) }
// NArg is the number of arguments remaining after flags have been processed.
func NArg() int { return len(CommandLine.args) }
// Args returns the non-flag arguments.
func (f *FlagSet) Args() []string { return f.args }
// Args returns the non-flag command-line arguments.
func Args() []string { return CommandLine.args }
// BoolVar defines a bool flag with specified name, default value, and usage string.
// The argument p points to a bool variable in which to store the value of the flag.
func (f *FlagSet) BoolVar(p *bool, name string, value bool, usage string) {
f.Var(newBoolValue(value, p), name, usage)
}
// BoolVar defines a bool flag with specified name, default value, and usage string.
// The argument p points to a bool variable in which to store the value of the flag.
func BoolVar(p *bool, name string, value bool, usage string) {
CommandLine.Var(newBoolValue(value, p), name, usage)
}
// Bool defines a bool flag with specified name, default value, and usage string.
// The return value is the address of a bool variable that stores the value of the flag.
func (f *FlagSet) Bool(name string, value bool, usage string) *bool {
p := new(bool)
f.BoolVar(p, name, value, usage)
return p
}
// Bool defines a bool flag with specified name, default value, and usage string.
// The return value is the address of a bool variable that stores the value of the flag.
func Bool(name string, value bool, usage string) *bool {
return CommandLine.Bool(name, value, usage)
}
// IntVar defines an int flag with specified name, default value, and usage string.
// The argument p points to an int variable in which to store the value of the flag.
func (f *FlagSet) IntVar(p *int, name string, value int, usage string) {
f.Var(newIntValue(value, p), name, usage)
}
// IntVar defines an int flag with specified name, default value, and usage string.
// The argument p points to an int variable in which to store the value of the flag.
func IntVar(p *int, name string, value int, usage string) {
CommandLine.Var(newIntValue(value, p), name, usage)
}
// Int defines an int flag with specified name, default value, and usage string.
// The return value is the address of an int variable that stores the value of the flag.
func (f *FlagSet) Int(name string, value int, usage string) *int {
p := new(int)
f.IntVar(p, name, value, usage)
return p
}
// Int defines an int flag with specified name, default value, and usage string.
// The return value is the address of an int variable that stores the value of the flag.
func Int(name string, value int, usage string) *int {
return CommandLine.Int(name, value, usage)
}
// Int64Var defines an int64 flag with specified name, default value, and usage string.
// The argument p points to an int64 variable in which to store the value of the flag.
func (f *FlagSet) Int64Var(p *int64, name string, value int64, usage string) {
f.Var(newInt64Value(value, p), name, usage)
}
// Int64Var defines an int64 flag with specified name, default value, and usage string.
// The argument p points to an int64 variable in which to store the value of the flag.
func Int64Var(p *int64, name string, value int64, usage string) {
CommandLine.Var(newInt64Value(value, p), name, usage)
}
// Int64 defines an int64 flag with specified name, default value, and usage string.
// The return value is the address of an int64 variable that stores the value of the flag.
func (f *FlagSet) Int64(name string, value int64, usage string) *int64 {
p := new(int64)
f.Int64Var(p, name, value, usage)
return p
}
// Int64 defines an int64 flag with specified name, default value, and usage string.
// The return value is the address of an int64 variable that stores the value of the flag.
func Int64(name string, value int64, usage string) *int64 {
return CommandLine.Int64(name, value, usage)
}
// UintVar defines a uint flag with specified name, default value, and usage string.
// The argument p points to a uint variable in which to store the value of the flag.
func (f *FlagSet) UintVar(p *uint, name string, value uint, usage string) {
f.Var(newUintValue(value, p), name, usage)
}
// UintVar defines a uint flag with specified name, default value, and usage string.
// The argument p points to a uint variable in which to store the value of the flag.
func UintVar(p *uint, name string, value uint, usage string) {
CommandLine.Var(newUintValue(value, p), name, usage)
}
// Uint defines a uint flag with specified name, default value, and usage string.
// The return value is the address of a uint variable that stores the value of the flag.
func (f *FlagSet) Uint(name string, value uint, usage string) *uint {
p := new(uint)
f.UintVar(p, name, value, usage)
return p
}
// Uint defines a uint flag with specified name, default value, and usage string.
// The return value is the address of a uint variable that stores the value of the flag.
func Uint(name string, value uint, usage string) *uint {
return CommandLine.Uint(name, value, usage)
}
// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
// The argument p points to a uint64 variable in which to store the value of the flag.
func (f *FlagSet) Uint64Var(p *uint64, name string, value uint64, usage string) {
f.Var(newUint64Value(value, p), name, usage)
}
// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
// The argument p points to a uint64 variable in which to store the value of the flag.
func Uint64Var(p *uint64, name string, value uint64, usage string) {
CommandLine.Var(newUint64Value(value, p), name, usage)
}
// Uint64 defines a uint64 flag with specified name, default value, and usage string.
// The return value is the address of a uint64 variable that stores the value of the flag.
func (f *FlagSet) Uint64(name string, value uint64, usage string) *uint64 {
p := new(uint64)
f.Uint64Var(p, name, value, usage)
return p
}
// Uint64 defines a uint64 flag with specified name, default value, and usage string.
// The return value is the address of a uint64 variable that stores the value of the flag.
func Uint64(name string, value uint64, usage string) *uint64 {
return CommandLine.Uint64(name, value, usage)
}
// StringVar defines a string flag with specified name, default value, and usage string.
// The argument p points to a string variable in which to store the value of the flag.
func (f *FlagSet) StringVar(p *string, name string, value string, usage string) {
f.Var(newStringValue(value, p), name, usage)
}
// StringVar defines a string flag with specified name, default value, and usage string.
// The argument p points to a string variable in which to store the value of the flag.
func StringVar(p *string, name string, value string, usage string) {
CommandLine.Var(newStringValue(value, p), name, usage)
}
// String defines a string flag with specified name, default value, and usage string.
// The return value is the address of a string variable that stores the value of the flag.
func (f *FlagSet) String(name string, value string, usage string) *string {
p := new(string)
f.StringVar(p, name, value, usage)
return p
}
// String defines a string flag with specified name, default value, and usage string.
// The return value is the address of a string variable that stores the value of the flag.
func String(name string, value string, usage string) *string {
return CommandLine.String(name, value, usage)
}
// Float64Var defines a float64 flag with specified name, default value, and usage string.
// The argument p points to a float64 variable in which to store the value of the flag.
func (f *FlagSet) Float64Var(p *float64, name string, value float64, usage string) {
f.Var(newFloat64Value(value, p), name, usage)
}
// Float64Var defines a float64 flag with specified name, default value, and usage string.
// The argument p points to a float64 variable in which to store the value of the flag.
func Float64Var(p *float64, name string, value float64, usage string) {
CommandLine.Var(newFloat64Value(value, p), name, usage)
}
// Float64 defines a float64 flag with specified name, default value, and usage string.
// The return value is the address of a float64 variable that stores the value of the flag.
func (f *FlagSet) Float64(name string, value float64, usage string) *float64 {
p := new(float64)
f.Float64Var(p, name, value, usage)
return p
}
// Float64 defines a float64 flag with specified name, default value, and usage string.
// The return value is the address of a float64 variable that stores the value of the flag.
func Float64(name string, value float64, usage string) *float64 {
return CommandLine.Float64(name, value, usage)
}
// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
// The argument p points to a time.Duration variable in which to store the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func (f *FlagSet) DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
f.Var(newDurationValue(value, p), name, usage)
}
// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
// The argument p points to a time.Duration variable in which to store the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
CommandLine.Var(newDurationValue(value, p), name, usage)
}
// Duration defines a time.Duration flag with specified name, default value, and usage string.
// The return value is the address of a time.Duration variable that stores the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time.Duration {
p := new(time.Duration)
f.DurationVar(p, name, value, usage)
return p
}
// Duration defines a time.Duration flag with specified name, default value, and usage string.
// The return value is the address of a time.Duration variable that stores the value of the flag.
// The flag accepts a value acceptable to time.ParseDuration.
func Duration(name string, value time.Duration, usage string) *time.Duration {
return CommandLine.Duration(name, value, usage)
}
// Var defines a flag with the specified name and usage string. The type and
// value of the flag are represented by the first argument, of type Value, which
// typically holds a user-defined implementation of Value. For instance, the
// caller could create a flag that turns a comma-separated string into a slice
// of strings by giving the slice the methods of Value; in particular, Set would
// decompose the comma-separated string into the slice.
func (f *FlagSet) Var(value Value, name string, usage string) {
// Remember the default value as a string; it won't change.
flag := &Flag{name, usage, value, value.String()}
_, alreadythere := f.formal[name]
if alreadythere {
var msg string
if f.name == "" {
msg = fmt.Sprintf("flag redefined: %s", name)
} else {
msg = fmt.Sprintf("%s flag redefined: %s", f.name, name)
}
fmt.Fprintln(f.out(), msg)
panic(msg) // Happens only if flags are declared with identical names
}
if f.formal == nil {
f.formal = make(map[string]*Flag)
}
f.formal[name] = flag
}
// Var defines a flag with the specified name and usage string. The type and
// value of the flag are represented by the first argument, of type Value, which
// typically holds a user-defined implementation of Value. For instance, the
// caller could create a flag that turns a comma-separated string into a slice
// of strings by giving the slice the methods of Value; in particular, Set would
// decompose the comma-separated string into the slice.
func Var(value Value, name string, usage string) {
CommandLine.Var(value, name, usage)
}
// failf prints to standard error a formatted error and usage message and
// returns the error.
func (f *FlagSet) failf(format string, a ...interface{}) error {
err := fmt.Errorf(format, a...)
fmt.Fprintln(f.out(), err)
f.usage()
return err
}
// usage calls the Usage method for the flag set if one is specified,
// or the appropriate default usage function otherwise.
func (f *FlagSet) usage() {
if f.Usage == nil {
f.defaultUsage()
} else {
f.Usage()
}
}
// parseOne parses one flag. It reports whether a flag was seen.
func (f *FlagSet) parseOne() (bool, error) {
if len(f.args) == 0 {
return false, nil
}
s := f.args[0]
if len(s) == 0 || s[0] != '-' || len(s) == 1 {
return false, nil
}
numMinuses := 1
if s[1] == '-' {
numMinuses++
if len(s) == 2 { // "--" terminates the flags
f.args = f.args[1:]
return false, nil
}
}
name := s[numMinuses:]
if len(name) == 0 || name[0] == '-' || name[0] == '=' {
return false, f.failf("bad flag syntax: %s", s)
}
// it's a flag. does it have an argument?
f.args = f.args[1:]
hasValue := false
value := ""
for i := 1; i < len(name); i++ { // equals cannot be first
if name[i] == '=' {
value = name[i+1:]
hasValue = true
name = name[0:i]
break
}
}
m := f.formal
flag, alreadythere := m[name] // BUG
if !alreadythere {
if name == "help" || name == "h" { // special case for nice help message.
f.usage()
return false, ErrHelp
}
return false, f.failf("flag provided but not defined: -%s", name)
}
if fv, ok := flag.Value.(boolFlag); ok && fv.IsBoolFlag() { // special case: doesn't need an arg
if hasValue {
if err := fv.Set(value); err != nil {
return false, f.failf("invalid boolean value %q for -%s: %v", value, name, err)
}
} else {
if err := fv.Set("true"); err != nil {
return false, f.failf("invalid boolean flag %s: %v", name, err)
}
}
} else {
// It must have a value, which might be the next argument.
if !hasValue && len(f.args) > 0 {
// value is the next arg
hasValue = true
value, f.args = f.args[0], f.args[1:]
}
if !hasValue {
return false, f.failf("flag needs an argument: -%s", name)
}
if err := flag.Value.Set(value); err != nil {
return false, f.failf("invalid value %q for flag -%s: %v", value, name, err)
}
}
if f.actual == nil {
f.actual = make(map[string]*Flag)
}
f.actual[name] = flag
return true, nil
}
// Parse parses flag definitions from the argument list, which should not
// include the command name. Must be called after all flags in the FlagSet
// are defined and before flags are accessed by the program.
// The return value will be ErrHelp if -help or -h were set but not defined.
func (f *FlagSet) Parse(arguments []string) error {
f.parsed = true
f.args = arguments
for {
seen, err := f.parseOne()
if seen {
continue
}
if err == nil {
break
}
switch f.errorHandling {
case ContinueOnError:
return err
case ExitOnError:
os.Exit(2)
case PanicOnError:
panic(err)
}
}
return nil
}
// Parsed reports whether f.Parse has been called.
func (f *FlagSet) Parsed() bool {
return f.parsed
}
// Parse parses the command-line flags from os.Args[1:]. Must be called
// after all flags are defined and before flags are accessed by the program.
func Parse() {
// Ignore errors; CommandLine is set for ExitOnError.
CommandLine.Parse(os.Args[1:])
}
// Parsed reports whether the command-line flags have been parsed.
func Parsed() bool {
return CommandLine.Parsed()
}
// CommandLine is the default set of command-line flags, parsed from os.Args.
// The top-level functions such as BoolVar, Arg, and so on are wrappers for the
// methods of CommandLine.
var CommandLine = NewFlagSet(os.Args[0], ExitOnError)
func init() {
// Override generic FlagSet default Usage with call to global Usage.
// Note: This is not CommandLine.Usage = Usage,
// because we want any eventual call to use any updated value of Usage,
// not the value it has when this line is run.
CommandLine.Usage = commandLineUsage
}
func commandLineUsage() {
Usage()
}
// NewFlagSet returns a new, empty flag set with the specified name and
// error handling property.
func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet {
f := &FlagSet{
name: name,
errorHandling: errorHandling,
}
f.Usage = f.defaultUsage
return f
}
// Init sets the name and error handling property for a flag set.
// By default, the zero FlagSet uses an empty name and the
// ContinueOnError error handling policy.
func (f *FlagSet) Init(name string, errorHandling ErrorHandling) {
f.name = name
f.errorHandling = errorHandling
}
|