moby/pkg/mflag/flag.go
Phil Estes 34a83f9f2c Merge pull request #19517 from calavera/validate_config_keys
Verify that the configuration keys in the file are valid.
2016-01-22 15:01:29 -05:00

1280 lines
39 KiB
Go

// Copyright 2014-2016 The Docker & 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 mflag implements command-line flag parsing.
//
// Usage:
//
// Define flags using flag.String(), Bool(), Int(), etc.
//
// This declares an integer flag, -f or --flagname, stored in the pointer ip, with type *int.
// import "flag /github.com/docker/docker/pkg/mflag"
// var ip = flag.Int([]string{"f", "-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() {
// // -flaghidden will work, but will be hidden from the usage
// flag.IntVar(&flagvar, []string{"f", "#flaghidden", "-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, []string{"name"}, "help message for flagname")
// For such flags, the default value is just the initial value of the variable.
//
// You can also add "deprecated" flags, they are still usable, but are not shown
// in the usage and will display a warning when you try to use them. `#` before
// an option means this option is deprecated, if there is an following option
// without `#` ahead, then that's the replacement, if not, it will just be removed:
// var ip = flag.Int([]string{"#f", "#flagname", "-flagname"}, 1234, "help message for flagname")
// this will display: `Warning: '-f' is deprecated, it will be replaced by '--flagname' soon. See usage.` or
// this will display: `Warning: '-flagname' is deprecated, it will be replaced by '--flagname' soon. See usage.`
// var ip = flag.Int([]string{"f", "#flagname"}, 1234, "help message for flagname")
// will display: `Warning: '-flagname' is deprecated, it will be removed soon. See usage.`
// so you can only use `-f`.
//
// You can also group one letter flags, bif you declare
// var v = flag.Bool([]string{"v", "-verbose"}, false, "help message for verbose")
// var s = flag.Bool([]string{"s", "-slow"}, false, "help message for slow")
// you will be able to use the -vs or -sv
//
// 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.
//
// Command line flag syntax:
// -flag
// -flag=x
// -flag="x"
// -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, 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 mflag
import (
"errors"
"fmt"
"io"
"os"
"runtime"
"sort"
"strconv"
"strings"
"text/tabwriter"
"time"
"github.com/docker/docker/pkg/homedir"
)
// ErrHelp is the error returned if the flag -help is invoked but no such flag is defined.
var ErrHelp = errors.New("flag: help requested")
// ErrRetry is the error returned if you need to try letter by letter
var ErrRetry = errors.New("flag: retry")
// -- 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 fmt.Sprintf("%v", *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 fmt.Sprintf("%v", *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 fmt.Sprintf("%v", *i) }
// -- 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 fmt.Sprintf("%v", *i) }
// -- 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 fmt.Sprintf("%v", *i) }
// -- uint16 Value
type uint16Value uint16
func newUint16Value(val uint16, p *uint16) *uint16Value {
*p = val
return (*uint16Value)(p)
}
func (i *uint16Value) Set(s string) error {
v, err := strconv.ParseUint(s, 0, 16)
*i = uint16Value(v)
return err
}
func (i *uint16Value) Get() interface{} { return uint16(*i) }
func (i *uint16Value) String() string { return fmt.Sprintf("%v", *i) }
// -- 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 fmt.Sprintf("%s", *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 fmt.Sprintf("%v", *f) }
// -- 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.
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 to handle flag parsing errors.
type ErrorHandling int
// ErrorHandling strategies available when a flag parsing error occurs
const (
ContinueOnError ErrorHandling = iota
ExitOnError
PanicOnError
)
// 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()
ShortUsage 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
nArgRequirements []nArgRequirement
}
// A Flag represents the state of a flag.
type Flag struct {
Names []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
}
type flagSlice []string
func (p flagSlice) Len() int { return len(p) }
func (p flagSlice) Less(i, j int) bool {
pi, pj := strings.TrimPrefix(p[i], "-"), strings.TrimPrefix(p[j], "-")
lpi, lpj := strings.ToLower(pi), strings.ToLower(pj)
if lpi != lpj {
return lpi < lpj
}
return pi < pj
}
func (p flagSlice) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
// sortFlags returns the flags as a slice in lexicographical sorted order.
func sortFlags(flags map[string]*Flag) []*Flag {
var list flagSlice
// The sorted list is based on the first name, when flag map might use the other names.
nameMap := make(map[string]string)
for n, f := range flags {
fName := strings.TrimPrefix(f.Names[0], "#")
nameMap[fName] = n
if len(f.Names) == 1 {
list = append(list, fName)
continue
}
found := false
for _, name := range list {
if name == fName {
found = true
break
}
}
if !found {
list = append(list, fName)
}
}
sort.Sort(list)
result := make([]*Flag, len(list))
for i, name := range list {
result[i] = flags[nameMap[name]]
}
return result
}
// Name returns the name of the FlagSet.
func (fs *FlagSet) Name() string {
return fs.name
}
// Out returns the destination for usage and error messages.
func (fs *FlagSet) Out() io.Writer {
if fs.output == nil {
return os.Stderr
}
return fs.output
}
// SetOutput sets the destination for usage and error messages.
// If output is nil, os.Stderr is used.
func (fs *FlagSet) SetOutput(output io.Writer) {
fs.output = output
}
// VisitAll visits the flags in lexicographical order, calling fn for each.
// It visits all flags, even those not set.
func (fs *FlagSet) VisitAll(fn func(*Flag)) {
for _, flag := range sortFlags(fs.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 (fs *FlagSet) Visit(fn func(*Flag)) {
for _, flag := range sortFlags(fs.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 (fs *FlagSet) Lookup(name string) *Flag {
return fs.formal[name]
}
// IsSet indicates whether the specified flag is set in the given FlagSet
func (fs *FlagSet) IsSet(name string) bool {
return fs.actual[name] != nil
}
// 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]
}
// IsSet indicates whether the specified flag was specified at all on the cmd line.
func IsSet(name string) bool {
return CommandLine.IsSet(name)
}
type nArgRequirementType int
// Indicator used to pass to BadArgs function
const (
Exact nArgRequirementType = iota
Max
Min
)
type nArgRequirement struct {
Type nArgRequirementType
N int
}
// Require adds a requirement about the number of arguments for the FlagSet.
// The first parameter can be Exact, Max, or Min to respectively specify the exact,
// the maximum, or the minimal number of arguments required.
// The actual check is done in FlagSet.CheckArgs().
func (fs *FlagSet) Require(nArgRequirementType nArgRequirementType, nArg int) {
fs.nArgRequirements = append(fs.nArgRequirements, nArgRequirement{nArgRequirementType, nArg})
}
// CheckArgs uses the requirements set by FlagSet.Require() to validate
// the number of arguments. If the requirements are not met,
// an error message string is returned.
func (fs *FlagSet) CheckArgs() (message string) {
for _, req := range fs.nArgRequirements {
var arguments string
if req.N == 1 {
arguments = "1 argument"
} else {
arguments = fmt.Sprintf("%d arguments", req.N)
}
str := func(kind string) string {
return fmt.Sprintf("%q requires %s%s", fs.name, kind, arguments)
}
switch req.Type {
case Exact:
if fs.NArg() != req.N {
return str("")
}
case Max:
if fs.NArg() > req.N {
return str("a maximum of ")
}
case Min:
if fs.NArg() < req.N {
return str("a minimum of ")
}
}
}
return ""
}
// Set sets the value of the named flag.
func (fs *FlagSet) Set(name, value string) error {
flag, ok := fs.formal[name]
if !ok {
return fmt.Errorf("no such flag -%v", name)
}
if err := flag.Value.Set(value); err != nil {
return err
}
if fs.actual == nil {
fs.actual = make(map[string]*Flag)
}
fs.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(value string) bool {
switch value {
case "false":
return true
case "":
return true
case "0":
return true
}
return false
}
// PrintDefaults prints, to standard error unless configured
// otherwise, the default values of all defined flags in the set.
func (fs *FlagSet) PrintDefaults() {
writer := tabwriter.NewWriter(fs.Out(), 20, 1, 3, ' ', 0)
home := homedir.Get()
// Don't substitute when HOME is /
if runtime.GOOS != "windows" && home == "/" {
home = ""
}
// Add a blank line between cmd description and list of options
if fs.FlagCount() > 0 {
fmt.Fprintln(writer, "")
}
fs.VisitAll(func(flag *Flag) {
names := []string{}
for _, name := range flag.Names {
if name[0] != '#' {
names = append(names, name)
}
}
if len(names) > 0 && len(flag.Usage) > 0 {
val := flag.DefValue
if home != "" && strings.HasPrefix(val, home) {
val = homedir.GetShortcutString() + val[len(home):]
}
if isZeroValue(val) {
format := " -%s"
fmt.Fprintf(writer, format, strings.Join(names, ", -"))
} else {
format := " -%s=%s"
fmt.Fprintf(writer, format, strings.Join(names, ", -"), val)
}
for _, line := range strings.Split(flag.Usage, "\n") {
fmt.Fprintln(writer, "\t", line)
}
}
})
writer.Flush()
}
// 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(fs *FlagSet) {
if fs.name == "" {
fmt.Fprintf(fs.Out(), "Usage:\n")
} else {
fmt.Fprintf(fs.Out(), "Usage of %s:\n", fs.name)
}
fs.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(CommandLine.Out(), "Usage of %s:\n", os.Args[0])
PrintDefaults()
}
// ShortUsage prints to standard error a usage message documenting the standard command layout
// The function is a variable that may be changed to point to a custom function.
var ShortUsage = func() {
fmt.Fprintf(CommandLine.output, "Usage of %s:\n", os.Args[0])
}
// FlagCount returns the number of flags that have been defined.
func (fs *FlagSet) FlagCount() int { return len(sortFlags(fs.formal)) }
// FlagCountUndeprecated returns the number of undeprecated flags that have been defined.
func (fs *FlagSet) FlagCountUndeprecated() int {
count := 0
for _, flag := range sortFlags(fs.formal) {
for _, name := range flag.Names {
if name[0] != '#' {
count++
break
}
}
}
return count
}
// NFlag returns the number of flags that have been set.
func (fs *FlagSet) NFlag() int { return len(fs.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 (fs *FlagSet) Arg(i int) string {
if i < 0 || i >= len(fs.args) {
return ""
}
return fs.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 (fs *FlagSet) NArg() int { return len(fs.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 (fs *FlagSet) Args() []string { return fs.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 (fs *FlagSet) BoolVar(p *bool, names []string, value bool, usage string) {
fs.Var(newBoolValue(value, p), names, 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, names []string, value bool, usage string) {
CommandLine.Var(newBoolValue(value, p), names, 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 (fs *FlagSet) Bool(names []string, value bool, usage string) *bool {
p := new(bool)
fs.BoolVar(p, names, 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(names []string, value bool, usage string) *bool {
return CommandLine.Bool(names, 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 (fs *FlagSet) IntVar(p *int, names []string, value int, usage string) {
fs.Var(newIntValue(value, p), names, 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, names []string, value int, usage string) {
CommandLine.Var(newIntValue(value, p), names, 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 (fs *FlagSet) Int(names []string, value int, usage string) *int {
p := new(int)
fs.IntVar(p, names, 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(names []string, value int, usage string) *int {
return CommandLine.Int(names, 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 (fs *FlagSet) Int64Var(p *int64, names []string, value int64, usage string) {
fs.Var(newInt64Value(value, p), names, 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, names []string, value int64, usage string) {
CommandLine.Var(newInt64Value(value, p), names, 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 (fs *FlagSet) Int64(names []string, value int64, usage string) *int64 {
p := new(int64)
fs.Int64Var(p, names, 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(names []string, value int64, usage string) *int64 {
return CommandLine.Int64(names, 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 (fs *FlagSet) UintVar(p *uint, names []string, value uint, usage string) {
fs.Var(newUintValue(value, p), names, 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, names []string, value uint, usage string) {
CommandLine.Var(newUintValue(value, p), names, 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 (fs *FlagSet) Uint(names []string, value uint, usage string) *uint {
p := new(uint)
fs.UintVar(p, names, 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(names []string, value uint, usage string) *uint {
return CommandLine.Uint(names, 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 (fs *FlagSet) Uint64Var(p *uint64, names []string, value uint64, usage string) {
fs.Var(newUint64Value(value, p), names, 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, names []string, value uint64, usage string) {
CommandLine.Var(newUint64Value(value, p), names, 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 (fs *FlagSet) Uint64(names []string, value uint64, usage string) *uint64 {
p := new(uint64)
fs.Uint64Var(p, names, 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(names []string, value uint64, usage string) *uint64 {
return CommandLine.Uint64(names, value, usage)
}
// Uint16Var defines a uint16 flag with specified name, default value, and usage string.
// The argument p points to a uint16 variable in which to store the value of the flag.
func (fs *FlagSet) Uint16Var(p *uint16, names []string, value uint16, usage string) {
fs.Var(newUint16Value(value, p), names, usage)
}
// Uint16Var defines a uint16 flag with specified name, default value, and usage string.
// The argument p points to a uint16 variable in which to store the value of the flag.
func Uint16Var(p *uint16, names []string, value uint16, usage string) {
CommandLine.Var(newUint16Value(value, p), names, usage)
}
// Uint16 defines a uint16 flag with specified name, default value, and usage string.
// The return value is the address of a uint16 variable that stores the value of the flag.
func (fs *FlagSet) Uint16(names []string, value uint16, usage string) *uint16 {
p := new(uint16)
fs.Uint16Var(p, names, value, usage)
return p
}
// Uint16 defines a uint16 flag with specified name, default value, and usage string.
// The return value is the address of a uint16 variable that stores the value of the flag.
func Uint16(names []string, value uint16, usage string) *uint16 {
return CommandLine.Uint16(names, 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 (fs *FlagSet) StringVar(p *string, names []string, value string, usage string) {
fs.Var(newStringValue(value, p), names, 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, names []string, value string, usage string) {
CommandLine.Var(newStringValue(value, p), names, 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 (fs *FlagSet) String(names []string, value string, usage string) *string {
p := new(string)
fs.StringVar(p, names, 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(names []string, value string, usage string) *string {
return CommandLine.String(names, 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 (fs *FlagSet) Float64Var(p *float64, names []string, value float64, usage string) {
fs.Var(newFloat64Value(value, p), names, 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, names []string, value float64, usage string) {
CommandLine.Var(newFloat64Value(value, p), names, 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 (fs *FlagSet) Float64(names []string, value float64, usage string) *float64 {
p := new(float64)
fs.Float64Var(p, names, 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(names []string, value float64, usage string) *float64 {
return CommandLine.Float64(names, 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.
func (fs *FlagSet) DurationVar(p *time.Duration, names []string, value time.Duration, usage string) {
fs.Var(newDurationValue(value, p), names, 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.
func DurationVar(p *time.Duration, names []string, value time.Duration, usage string) {
CommandLine.Var(newDurationValue(value, p), names, 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.
func (fs *FlagSet) Duration(names []string, value time.Duration, usage string) *time.Duration {
p := new(time.Duration)
fs.DurationVar(p, names, 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.
func Duration(names []string, value time.Duration, usage string) *time.Duration {
return CommandLine.Duration(names, 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 (fs *FlagSet) Var(value Value, names []string, usage string) {
// Remember the default value as a string; it won't change.
flag := &Flag{names, usage, value, value.String()}
for _, name := range names {
name = strings.TrimPrefix(name, "#")
_, alreadythere := fs.formal[name]
if alreadythere {
var msg string
if fs.name == "" {
msg = fmt.Sprintf("flag redefined: %s", name)
} else {
msg = fmt.Sprintf("%s flag redefined: %s", fs.name, name)
}
fmt.Fprintln(fs.Out(), msg)
panic(msg) // Happens only if flags are declared with identical names
}
if fs.formal == nil {
fs.formal = make(map[string]*Flag)
}
fs.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, names []string, usage string) {
CommandLine.Var(value, names, usage)
}
// failf prints to standard error a formatted error and usage message and
// returns the error.
func (fs *FlagSet) failf(format string, a ...interface{}) error {
err := fmt.Errorf(format, a...)
fmt.Fprintln(fs.Out(), err)
if os.Args[0] == fs.name {
fmt.Fprintf(fs.Out(), "See '%s --help'.\n", os.Args[0])
} else {
fmt.Fprintf(fs.Out(), "See '%s %s --help'.\n", os.Args[0], fs.name)
}
return err
}
// usage calls the Usage method for the flag set, or the usage function if
// the flag set is CommandLine.
func (fs *FlagSet) usage() {
if fs == CommandLine {
Usage()
} else if fs.Usage == nil {
defaultUsage(fs)
} else {
fs.Usage()
}
}
func trimQuotes(str string) string {
if len(str) == 0 {
return str
}
type quote struct {
start, end byte
}
// All valid quote types.
quotes := []quote{
// Double quotes
{
start: '"',
end: '"',
},
// Single quotes
{
start: '\'',
end: '\'',
},
}
for _, quote := range quotes {
// Only strip if outermost match.
if str[0] == quote.start && str[len(str)-1] == quote.end {
str = str[1 : len(str)-1]
break
}
}
return str
}
// parseOne parses one flag. It reports whether a flag was seen.
func (fs *FlagSet) parseOne() (bool, string, error) {
if len(fs.args) == 0 {
return false, "", nil
}
s := fs.args[0]
if len(s) == 0 || s[0] != '-' || len(s) == 1 {
return false, "", nil
}
if s[1] == '-' && len(s) == 2 { // "--" terminates the flags
fs.args = fs.args[1:]
return false, "", nil
}
name := s[1:]
if len(name) == 0 || name[0] == '=' {
return false, "", fs.failf("bad flag syntax: %s", s)
}
// it's a flag. does it have an argument?
fs.args = fs.args[1:]
hasValue := false
value := ""
if i := strings.Index(name, "="); i != -1 {
value = trimQuotes(name[i+1:])
hasValue = true
name = name[:i]
}
m := fs.formal
flag, alreadythere := m[name] // BUG
if !alreadythere {
if name == "-help" || name == "help" || name == "h" { // special case for nice help message.
fs.usage()
return false, "", ErrHelp
}
if len(name) > 0 && name[0] == '-' {
return false, "", fs.failf("flag provided but not defined: -%s", name)
}
return false, name, ErrRetry
}
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, "", fs.failf("invalid boolean value %q for -%s: %v", value, name, err)
}
} else {
fv.Set("true")
}
} else {
// It must have a value, which might be the next argument.
if !hasValue && len(fs.args) > 0 {
// value is the next arg
hasValue = true
value, fs.args = fs.args[0], fs.args[1:]
}
if !hasValue {
return false, "", fs.failf("flag needs an argument: -%s", name)
}
if err := flag.Value.Set(value); err != nil {
return false, "", fs.failf("invalid value %q for flag -%s: %v", value, name, err)
}
}
if fs.actual == nil {
fs.actual = make(map[string]*Flag)
}
fs.actual[name] = flag
for i, n := range flag.Names {
if n == fmt.Sprintf("#%s", name) {
replacement := ""
for j := i; j < len(flag.Names); j++ {
if flag.Names[j][0] != '#' {
replacement = flag.Names[j]
break
}
}
if replacement != "" {
fmt.Fprintf(fs.Out(), "Warning: '-%s' is deprecated, it will be replaced by '-%s' soon. See usage.\n", name, replacement)
} else {
fmt.Fprintf(fs.Out(), "Warning: '-%s' is deprecated, it will be removed soon. See usage.\n", name)
}
}
}
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 was set but not defined.
func (fs *FlagSet) Parse(arguments []string) error {
fs.parsed = true
fs.args = arguments
for {
seen, name, err := fs.parseOne()
if seen {
continue
}
if err == nil {
break
}
if err == ErrRetry {
if len(name) > 1 {
err = nil
for _, letter := range strings.Split(name, "") {
fs.args = append([]string{"-" + letter}, fs.args...)
seen2, _, err2 := fs.parseOne()
if seen2 {
continue
}
if err2 != nil {
err = fs.failf("flag provided but not defined: -%s", name)
break
}
}
if err == nil {
continue
}
} else {
err = fs.failf("flag provided but not defined: -%s", name)
}
}
switch fs.errorHandling {
case ContinueOnError:
return err
case ExitOnError:
os.Exit(125)
case PanicOnError:
panic(err)
}
}
return nil
}
// ParseFlags is a utility function that adds a help flag if withHelp is true,
// calls fs.Parse(args) and prints a relevant error message if there are
// incorrect number of arguments. It returns error only if error handling is
// set to ContinueOnError and parsing fails. If error handling is set to
// ExitOnError, it's safe to ignore the return value.
func (fs *FlagSet) ParseFlags(args []string, withHelp bool) error {
var help *bool
if withHelp {
help = fs.Bool([]string{"#help", "-help"}, false, "Print usage")
}
if err := fs.Parse(args); err != nil {
return err
}
if help != nil && *help {
fs.SetOutput(os.Stdout)
fs.Usage()
os.Exit(0)
}
if str := fs.CheckArgs(); str != "" {
fs.SetOutput(os.Stderr)
fs.ReportError(str, withHelp)
fs.ShortUsage()
os.Exit(1)
}
return nil
}
// ReportError is a utility method that prints a user-friendly message
// containing the error that occurred during parsing and a suggestion to get help
func (fs *FlagSet) ReportError(str string, withHelp bool) {
if withHelp {
if os.Args[0] == fs.Name() {
str += ".\nSee '" + os.Args[0] + " --help'"
} else {
str += ".\nSee '" + os.Args[0] + " " + fs.Name() + " --help'"
}
}
fmt.Fprintf(fs.Out(), "%s: %s.\n", os.Args[0], str)
}
// Parsed reports whether fs.Parse has been called.
func (fs *FlagSet) Parsed() bool {
return fs.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 returns true if 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 on are wrappers for the
// methods of CommandLine.
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,
}
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 (fs *FlagSet) Init(name string, errorHandling ErrorHandling) {
fs.name = name
fs.errorHandling = errorHandling
}
type mergeVal struct {
Value
key string
fset *FlagSet
}
func (v mergeVal) Set(s string) error {
return v.fset.Set(v.key, s)
}
func (v mergeVal) IsBoolFlag() bool {
if b, ok := v.Value.(boolFlag); ok {
return b.IsBoolFlag()
}
return false
}
// Name returns the name of a mergeVal.
// If the original value had a name, return the original name,
// otherwise, return the key asinged to this mergeVal.
func (v mergeVal) Name() string {
type namedValue interface {
Name() string
}
if nVal, ok := v.Value.(namedValue); ok {
return nVal.Name()
}
return v.key
}
// Merge is an helper function that merges n FlagSets into a single dest FlagSet
// In case of name collision between the flagsets it will apply
// the destination FlagSet's errorHandling behavior.
func Merge(dest *FlagSet, flagsets ...*FlagSet) error {
for _, fset := range flagsets {
if fset.formal == nil {
continue
}
for k, f := range fset.formal {
if _, ok := dest.formal[k]; ok {
var err error
if fset.name == "" {
err = fmt.Errorf("flag redefined: %s", k)
} else {
err = fmt.Errorf("%s flag redefined: %s", fset.name, k)
}
fmt.Fprintln(fset.Out(), err.Error())
// Happens only if flags are declared with identical names
switch dest.errorHandling {
case ContinueOnError:
return err
case ExitOnError:
os.Exit(2)
case PanicOnError:
panic(err)
}
}
newF := *f
newF.Value = mergeVal{f.Value, k, fset}
if dest.formal == nil {
dest.formal = make(map[string]*Flag)
}
dest.formal[k] = &newF
}
}
return nil
}
// IsEmpty reports if the FlagSet is actually empty.
func (fs *FlagSet) IsEmpty() bool {
return len(fs.actual) == 0
}