-
Notifications
You must be signed in to change notification settings - Fork 0
/
flag.go
693 lines (606 loc) · 20.3 KB
/
flag.go
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
// 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.
/*
pflag is a drop-in replacement for Go's flag package, implementing
POSIX/GNU-style --flags.
pflag is compatible with the GNU extensions to the POSIX recommendations
for command-line options. See
http://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html
Usage:
pflag is a drop-in replacement of Go's native flag package. If you import
pflag under the name "flag" then all code should continue to function
with no changes.
import flag "github.com/ogier/pflag"
There is one exception to this: if you directly instantiate the Flag struct
there is one more field "Shorthand" that you will need to set.
Most code never instantiates this struct directly, and instead uses
functions such as String(), BoolVar(), and Var(), and is therefore
unaffected.
Define flags using flag.String(), Bool(), Int(), etc.
This declares an integer flag, -flagname, stored in the pointer ip, with type *int.
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 after the flag are available as the
slice flag.Args() or individually as flag.Arg(i).
The arguments are indexed from 0 through flag.NArg()-1.
The pflag package also defines some new functions that are not in flag,
that give one-letter shorthands for flags. You can use these by appending
'P' to the name of any function that defines a flag.
var ip = flag.IntP("flagname", "f", 1234, "help message")
var flagvar bool
func init() {
flag.BoolVarP("boolname", "b", true, "help message")
}
flag.VarP(&flagVar, "varname", "v", 1234, "help message")
Shorthand letters can be used with single dashes on the command line.
Boolean shorthand flags can be combined with other shorthand flags.
Command line flag syntax:
--flag // boolean flags only
--flag=x
Unlike the flag package, a single dash before an option means something
different than a double dash. Single dashes signify a series of shorthand
letters for flags. All but the last shorthand letter must be boolean flags.
// boolean flags
-f
-abc
// non-boolean flags
-n 1234
-Ifile
// mixed
-abcs "hello"
-abcn1234
Flag parsing stops after the terminator "--". Unlike the flag package,
flags can be interspersed with arguments anywhere on the command line
before this terminator.
Integer flags accept 1234, 0664, 0x1234 and may be negative.
Boolean flags (in their long form) accept 1, 0, 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 pflag
import (
"bytes"
"errors"
"fmt"
"io"
"os"
"sort"
"strings"
)
// ErrHelp is the error returned if the flag -help is invoked but no such flag is defined.
var ErrHelp = errors.New("pflag: help requested")
// ErrorHandling defines how to handle flag parsing errors.
type ErrorHandling int
const (
ContinueOnError ErrorHandling = iota
ExitOnError
PanicOnError
)
// NormalizedName is a flag name that has been normalized according to rules
// for the FlagSet (e.g. making '-' and '_' equivalent).
type NormalizedName string
// A FlagSet represents a set of defined flags.
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[NormalizedName]*Flag
formal map[NormalizedName]*Flag
shorthands map[byte]*Flag
args []string // arguments after flags
exitOnError bool // does the program exit if there's an error?
errorHandling ErrorHandling
output io.Writer // nil means stderr; use out() accessor
interspersed bool // allow interspersed option/non-option args
normalizeNameFunc func(f *FlagSet, name string) NormalizedName
}
// A Flag represents the state of a flag.
type Flag struct {
Name string // name as it appears on command line
Shorthand string // one-letter abbreviated flag
Usage string // help message
Value Value // value as set
DefValue string // default value (as text); for usage message
Changed bool // If the user set the value (or if left to default)
Deprecated string // If this flag is deprecated, this string is the new or now thing to use
Annotations map[string][]string // used by cobra.Command bash autocomple code
}
// Value is the interface to the dynamic value stored in a flag.
// (The default value is represented as a string.)
type Value interface {
String() string
Set(string) error
Type() string
}
// sortFlags returns the flags as a slice in lexicographical sorted order.
func sortFlags(flags map[NormalizedName]*Flag) []*Flag {
list := make(sort.StringSlice, len(flags))
i := 0
for k := range flags {
list[i] = string(k)
i++
}
list.Sort()
result := make([]*Flag, len(list))
for i, name := range list {
result[i] = flags[NormalizedName(name)]
}
return result
}
func (f *FlagSet) SetNormalizeFunc(n func(f *FlagSet, name string) NormalizedName) {
f.normalizeNameFunc = n
for k, v := range f.formal {
delete(f.formal, k)
nname := f.normalizeFlagName(string(k))
f.formal[nname] = v
v.Name = string(nname)
}
}
func (f *FlagSet) GetNormalizeFunc() func(f *FlagSet, name string) NormalizedName {
if f.normalizeNameFunc != nil {
return f.normalizeNameFunc
}
return func(f *FlagSet, name string) NormalizedName { return NormalizedName(name) }
}
func (f *FlagSet) normalizeFlagName(name string) NormalizedName {
n := f.GetNormalizeFunc()
return n(f, name)
}
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)
}
}
func (f *FlagSet) HasFlags() bool {
return len(f.formal) > 0
}
// 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.lookup(f.normalizeFlagName(name))
}
// lookup returns the Flag structure of the named flag, returning nil if none exists.
func (f *FlagSet) lookup(name NormalizedName) *Flag {
return f.formal[name]
}
// Mark a flag deprecated in your program
func (f *FlagSet) MarkDeprecated(name string, usageMessage string) error {
flag := f.Lookup(name)
if flag == nil {
return fmt.Errorf("flag %q does not exist", name)
}
flag.Deprecated = usageMessage
return nil
}
// Lookup returns the Flag structure of the named command-line flag,
// returning nil if none exists.
func Lookup(name string) *Flag {
return CommandLine.Lookup(name)
}
// Set sets the value of the named flag.
func (f *FlagSet) Set(name, value string) error {
normalName := f.normalizeFlagName(name)
flag, ok := f.formal[normalName]
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[NormalizedName]*Flag)
}
f.actual[normalName] = flag
flag.Changed = true
if len(flag.Deprecated) > 0 {
fmt.Fprintf(os.Stderr, "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated)
}
return nil
}
// Set sets the value of the named command-line flag.
func Set(name, value string) error {
return CommandLine.Set(name, value)
}
// PrintDefaults prints, to standard error unless configured
// otherwise, the default values of all defined flags in the set.
func (f *FlagSet) PrintDefaults() {
f.VisitAll(func(flag *Flag) {
if len(flag.Deprecated) > 0 {
return
}
format := "--%s=%s: %s\n"
if _, ok := flag.Value.(*stringValue); ok {
// put quotes on the value
format = "--%s=%q: %s\n"
}
if len(flag.Shorthand) > 0 {
format = " -%s, " + format
} else {
format = " %s " + format
}
fmt.Fprintf(f.out(), format, flag.Shorthand, flag.Name, flag.DefValue, flag.Usage)
})
}
func (f *FlagSet) FlagUsages() string {
x := new(bytes.Buffer)
f.VisitAll(func(flag *Flag) {
if len(flag.Deprecated) > 0 {
return
}
format := "--%s=%s: %s\n"
if _, ok := flag.Value.(*stringValue); ok {
// put quotes on the value
format = "--%s=%q: %s\n"
}
if len(flag.Shorthand) > 0 {
format = " -%s, " + format
} else {
format = " %s " + format
}
fmt.Fprintf(x, format, flag.Shorthand, flag.Name, flag.DefValue, flag.Usage)
})
return x.String()
}
// PrintDefaults prints to standard error the default values of all defined command-line flags.
func PrintDefaults() {
CommandLine.PrintDefaults()
}
// defaultUsage is the default function to print a usage message.
func defaultUsage(f *FlagSet) {
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.
// The function is a variable that may be changed to point to a custom function.
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.
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.
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 }
// 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) {
f.VarP(value, name, "", usage)
}
// Like Var, but accepts a shorthand letter that can be used after a single dash.
func (f *FlagSet) VarP(value Value, name, shorthand, usage string) {
// Remember the default value as a string; it won't change.
flag := &Flag{
Name: name,
Shorthand: shorthand,
Usage: usage,
Value: value,
DefValue: value.String(),
}
f.AddFlag(flag)
}
func (f *FlagSet) AddFlag(flag *Flag) {
// Call normalizeFlagName function only once
var normalizedFlagName NormalizedName = f.normalizeFlagName(flag.Name)
_, alreadythere := f.formal[normalizedFlagName]
if alreadythere {
msg := fmt.Sprintf("%s flag redefined: %s", f.name, flag.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[NormalizedName]*Flag)
}
flag.Name = string(normalizedFlagName)
f.formal[normalizedFlagName] = flag
if len(flag.Shorthand) == 0 {
return
}
if len(flag.Shorthand) > 1 {
fmt.Fprintf(f.out(), "%s shorthand more than ASCII character: %s\n", f.name, flag.Shorthand)
panic("shorthand is more than one character")
}
if f.shorthands == nil {
f.shorthands = make(map[byte]*Flag)
}
c := flag.Shorthand[0]
old, alreadythere := f.shorthands[c]
if alreadythere {
fmt.Fprintf(f.out(), "%s shorthand reused: %q for %s already used for %s\n", f.name, c, flag.Name, old.Name)
panic("shorthand redefinition")
}
f.shorthands[c] = 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.VarP(value, name, "", usage)
}
// Like Var, but accepts a shorthand letter that can be used after a single dash.
func VarP(value Value, name, shorthand, usage string) {
CommandLine.VarP(value, name, shorthand, 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, or the usage function if
// the flag set is CommandLine.
func (f *FlagSet) usage() {
if f == CommandLine {
Usage()
} else if f.Usage == nil {
defaultUsage(f)
} else {
f.Usage()
}
}
func (f *FlagSet) setFlag(flag *Flag, value string, origArg string) error {
if err := flag.Value.Set(value); err != nil {
return f.failf("invalid argument %q for %s: %v", value, origArg, err)
}
// mark as visited for Visit()
if f.actual == nil {
f.actual = make(map[NormalizedName]*Flag)
}
f.actual[f.normalizeFlagName(flag.Name)] = flag
flag.Changed = true
if len(flag.Deprecated) > 0 {
fmt.Fprintf(os.Stderr, "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated)
}
return nil
}
func (f *FlagSet) parseLongArg(s string, args []string) (a []string, err error) {
a = args
name := s[2:]
if len(name) == 0 || name[0] == '-' || name[0] == '=' {
err = f.failf("bad flag syntax: %s", s)
return
}
split := strings.SplitN(name, "=", 2)
name = split[0]
flag, alreadythere := f.formal[f.normalizeFlagName(name)]
if !alreadythere {
if name == "help" { // special case for nice help message.
f.usage()
return a, ErrHelp
}
err = f.failf("unknown flag: --%s", name)
return
}
var value string
if len(split) == 1 {
if bv, ok := flag.Value.(boolFlag); !ok || !bv.IsBoolFlag() {
err = f.failf("flag needs an argument: %s", s)
return
}
value = "true"
} else {
value = split[1]
}
err = f.setFlag(flag, value, s)
return
}
func (f *FlagSet) parseSingleShortArg(shorthands string, args []string) (outShorts string, outArgs []string, err error) {
outArgs = args
outShorts = shorthands[1:]
c := shorthands[0]
flag, alreadythere := f.shorthands[c]
if !alreadythere {
if c == 'h' { // special case for nice help message.
f.usage()
err = ErrHelp
return
}
//TODO continue on error
err = f.failf("unknown shorthand flag: %q in -%s", c, shorthands)
return
}
var value string
if len(shorthands) > 2 && shorthands[1] == '=' {
value = shorthands[2:]
outShorts = ""
} else if bv, ok := flag.Value.(boolFlag); ok && bv.IsBoolFlag() {
value = "true"
} else if len(shorthands) > 1 {
value = shorthands[1:]
outShorts = ""
} else if len(args) > 0 {
value = args[0]
outArgs = args[1:]
} else {
err = f.failf("flag needs an argument: %q in -%s", c, shorthands)
return
}
err = f.setFlag(flag, value, shorthands)
return
}
func (f *FlagSet) parseShortArg(s string, args []string) (a []string, err error) {
a = args
shorthands := s[1:]
for len(shorthands) > 0 {
shorthands, a, err = f.parseSingleShortArg(shorthands, args)
if err != nil {
return
}
}
return
}
func (f *FlagSet) parseArgs(args []string) (err error) {
for len(args) > 0 {
s := args[0]
args = args[1:]
if len(s) == 0 || s[0] != '-' || len(s) == 1 {
if !f.interspersed {
f.args = append(f.args, s)
f.args = append(f.args, args...)
return nil
}
f.args = append(f.args, s)
continue
}
if s[1] == '-' {
if len(s) == 2 { // "--" terminates the flags
f.args = append(f.args, args...)
break
}
args, err = f.parseLongArg(s, args)
} else {
args, err = f.parseShortArg(s, args)
}
if err != nil {
return
}
}
return
}
// 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 was set but not defined.
func (f *FlagSet) Parse(arguments []string) error {
f.parsed = true
f.args = make([]string, 0, len(arguments))
err := f.parseArgs(arguments)
if err != nil {
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:])
}
// Whether to support interspersed option/non-option arguments.
func SetInterspersed(interspersed bool) {
CommandLine.SetInterspersed(interspersed)
}
// Parsed returns true if the command-line flags have been parsed.
func Parsed() bool {
return CommandLine.Parsed()
}
// The default set of command-line flags, parsed from os.Args.
var CommandLine = NewFlagSet(os.Args[0], ExitOnError)
// 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,
interspersed: true,
}
return f
}
// Whether to support interspersed option/non-option arguments.
func (f *FlagSet) SetInterspersed(interspersed bool) {
f.interspersed = interspersed
}
// 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
}