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+// 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.
+okdaokddadok
+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 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 // 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 flag
+
+import (
+ "bufio"
+ "errors"
+ "fmt"
+ "io"
+ "os"
+ "sort"
+ "strconv"
+ "strings"
+ "time"
+)
+
+// EnvironmentPrefix defines a string that will be implicitely prefixed to a
+// flag name before looking it up in the environment variables.
+var EnvironmentPrefix = ""
+
+// DefaultConfigFlagname defines the flag name of the optional config file
+// path. Used to lookup and parse the config file when a default is set and
+// available on disk.
+var DefaultConfigFlagname = "config"
+
+// ErrHelp is the error returned if the flag -help 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 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) }
+
+// -- 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
+
+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()
+
+ name string
+ parsed bool
+ actual map[string]*Flag
+ formal map[string]*Flag
+ envPrefix string // prefix to all env variable names
+ 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
+}
+
+// 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)
+}
+
+// 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) {
+ format := " -%s=%s: %s\n"
+ if _, ok := flag.Value.(*stringValue); ok {
+ // put quotes on the value
+ format = " -%s=%q: %s\n"
+ }
+ fmt.Fprintf(f.out(), format, flag.Name, flag.DefValue, flag.Usage)
+ })
+}
+
+// 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) {
+ 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.
+// 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 }
+
+// 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.
+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.
+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.
+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.
+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, 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()
+ }
+}
+
+// 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)
+ }
+
+ // ignore go test flags
+ if strings.HasPrefix(name, "test.") {
+ return false, nil
+ }
+
+ // 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 {
+ fv.Set("true")
+ }
+ } 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 was 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)
+ }
+ }
+
+ // Parse environment variables
+ if err := f.ParseEnv(os.Environ()); err != nil {
+ switch f.errorHandling {
+ case ContinueOnError:
+ return err
+ case ExitOnError:
+ os.Exit(2)
+ case PanicOnError:
+ panic(err)
+ }
+ return err
+ }
+
+ // Parse configuration from file
+ var cFile string
+ if cf := f.formal[DefaultConfigFlagname]; cf != nil {
+ cFile = cf.Value.String()
+ }
+ if cf := f.actual[DefaultConfigFlagname]; cf != nil {
+ cFile = cf.Value.String()
+ }
+ if cFile != "" {
+ if err := f.ParseFile(cFile); err != nil {
+ switch f.errorHandling {
+ case ContinueOnError:
+ return err
+ case ExitOnError:
+ os.Exit(2)
+ case PanicOnError:
+ panic(err)
+ }
+ return err
+ }
+ }
+
+ return nil
+}
+
+// ParseEnv parses flags from environment variables.
+// Flags already set will be ignored.
+func (f *FlagSet) ParseEnv(environ []string) error {
+
+ m := f.formal
+
+ env := make(map[string]string)
+ for _, s := range environ {
+ i := strings.Index(s, "=")
+ if i < 1 {
+ continue
+ }
+ env[s[0:i]] = s[i+1 : len(s)]
+ }
+
+ for _, flag := range m {
+ name := flag.Name
+ _, set := f.actual[name]
+ if set {
+ continue
+ }
+
+ flag, alreadythere := m[name]
+ if !alreadythere {
+ if name == "help" || name == "h" { // special case for nice help message.
+ f.usage()
+ return ErrHelp
+ }
+ return f.failf("environment variable provided but not defined: %s", name)
+ }
+
+ envKey := strings.ToUpper(flag.Name)
+ if f.envPrefix != "" {
+ envKey = f.envPrefix + "_" + envKey
+ }
+ envKey = strings.Replace(envKey, "-", "_", -1)
+
+ value, isSet := env[envKey]
+ if !isSet {
+ continue
+ }
+
+ hasValue := false
+ if len(value) > 0 {
+ hasValue = true
+ }
+
+ 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 f.failf("invalid boolean value %q for environment variable %s: %v", value, name, err)
+ }
+ } else {
+ // flag without value is regarded a bool
+ fv.Set("true")
+ }
+ } else {
+ if err := flag.Value.Set(value); err != nil {
+ return f.failf("invalid value %q for environment variable %s: %v", value, name, err)
+ }
+ }
+
+ // update f.actual
+ if f.actual == nil {
+ f.actual = make(map[string]*Flag)
+ }
+ f.actual[name] = flag
+
+ }
+ return nil
+}
+
+// ParseFile parses flags from the file in path.
+// Same format as commandline argumens, newlines and lines beginning with a
+// "#" charater are ignored. Flags already set will be ignored.
+func (f *FlagSet) ParseFile(path string) error {
+
+ // Extract arguments from file
+ fp, err := os.Open(path)
+ if err != nil {
+ return err
+ }
+ defer fp.Close()
+
+ scanner := bufio.NewScanner(fp)
+ for scanner.Scan() {
+ line := scanner.Text()
+
+ // Ignore empty lines
+ if len(line) == 0 {
+ continue
+ }
+
+ // Ignore comments
+ if line[:1] == "#" {
+ continue
+ }
+
+ // Match `key=value` and `key value`
+ var name, value string
+ hasValue := false
+ for i, v := range line {
+ if v == '=' || v == ' ' {
+ hasValue = true
+ name, value = line[:i], line[i+1:]
+ break
+ }
+ }
+
+ if hasValue == false {
+ name = line
+ }
+
+ // Ignore flag when already set; arguments have precedence over file
+ if f.actual[name] != nil {
+ continue
+ }
+
+ m := f.formal
+ flag, alreadythere := m[name]
+ if !alreadythere {
+ if name == "help" || name == "h" { // special case for nice help message.
+ f.usage()
+ return ErrHelp
+ }
+ return f.failf("configuration variable 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 f.failf("invalid boolean value %q for configuration variable %s: %v", value, name, err)
+ }
+ } else {
+ // flag without value is regarded a bool
+ fv.Set("true")
+ }
+ } else {
+ if err := flag.Value.Set(value); err != nil {
+ return f.failf("invalid value %q for configuration variable %s: %v", value, name, err)
+ }
+ }
+
+ // update f.actual
+ if f.actual == nil {
+ f.actual = make(map[string]*Flag)
+ }
+ f.actual[name] = flag
+ }
+
+ if err := scanner.Err(); err != nil {
+ return 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 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
+}
+
+// NewFlagSetWithEnvPrefix returns a new empty flag set with the specified name,
+// environment variable prefix, and error handling property.
+func NewFlagSetWithEnvPrefix(name string, prefix string, errorHandling ErrorHandling) *FlagSet {
+ f := NewFlagSet(name, errorHandling)
+ f.envPrefix = prefix
+ return f
+}
+
+// Init sets the name, environment name prefix, and error handling property
+// for a flag set.
+// By default, the zero FlagSet uses an empty name, EnvironmentPrefix, and the
+// ContinueOnError error handling policy.
+func (f *FlagSet) Init(name string, errorHandling ErrorHandling) {
+ f.name = name
+ f.envPrefix = EnvironmentPrefix
+ f.errorHandling = errorHandling
+}
nihil fit ex nihilo