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jeremybenn |
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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Package flag implements command-line flag parsing.
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Usage:
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Define flags using flag.String(), Bool(), Int(), etc. Example:
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import "flag"
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var ip *int = flag.Int("flagname", 1234, "help message for flagname")
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If you like, you can bind the flag to a variable using the Var() functions.
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var flagvar int
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func init() {
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flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname")
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}
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Or you can create custom flags that satisfy the Value interface (with
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pointer receivers) and couple them to flag parsing by
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flag.Var(&flagVal, "name", "help message for flagname")
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For such flags, the default value is just the initial value of the variable.
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After all flags are defined, call
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flag.Parse()
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to parse the command line into the defined flags.
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Flags may then be used directly. If you're using the flags themselves,
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they are all pointers; if you bind to variables, they're values.
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fmt.Println("ip has value ", *ip);
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fmt.Println("flagvar has value ", flagvar);
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After parsing, the arguments after the flag are available as the
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slice flag.Args() or individually as flag.Arg(i).
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The arguments are indexed from 0 up to flag.NArg().
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Command line flag syntax:
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-flag
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-flag=x
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-flag x // non-boolean flags only
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One or two minus signs may be used; they are equivalent.
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The last form is not permitted for boolean flags because the
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meaning of the command
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cmd -x *
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will change if there is a file called 0, false, etc. You must
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use the -flag=false form to turn off a boolean flag.
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Flag parsing stops just before the first non-flag argument
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("-" is a non-flag argument) or after the terminator "--".
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Integer flags accept 1234, 0664, 0x1234 and may be negative.
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Boolean flags may be 1, 0, t, f, true, false, TRUE, FALSE, True, False.
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Duration flags accept any input valid for time.ParseDuration.
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The default set of command-line flags is controlled by
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top-level functions. The FlagSet type allows one to define
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independent sets of flags, such as to implement subcommands
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in a command-line interface. The methods of FlagSet are
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analogous to the top-level functions for the command-line
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flag set.
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*/
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package flag
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import (
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"errors"
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"fmt"
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"io"
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"os"
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"sort"
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"strconv"
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"time"
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)
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// ErrHelp is the error returned if the flag -help is invoked but no such flag is defined.
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var ErrHelp = errors.New("flag: help requested")
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// -- bool Value
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type boolValue bool
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func newBoolValue(val bool, p *bool) *boolValue {
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*p = val
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return (*boolValue)(p)
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}
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func (b *boolValue) Set(s string) error {
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v, err := strconv.ParseBool(s)
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*b = boolValue(v)
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return err
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}
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func (b *boolValue) String() string { return fmt.Sprintf("%v", *b) }
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// -- int Value
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type intValue int
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func newIntValue(val int, p *int) *intValue {
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*p = val
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return (*intValue)(p)
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}
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func (i *intValue) Set(s string) error {
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v, err := strconv.ParseInt(s, 0, 64)
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*i = intValue(v)
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return err
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}
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func (i *intValue) String() string { return fmt.Sprintf("%v", *i) }
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// -- int64 Value
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type int64Value int64
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func newInt64Value(val int64, p *int64) *int64Value {
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*p = val
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return (*int64Value)(p)
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}
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func (i *int64Value) Set(s string) error {
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v, err := strconv.ParseInt(s, 0, 64)
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*i = int64Value(v)
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return err
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}
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func (i *int64Value) String() string { return fmt.Sprintf("%v", *i) }
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// -- uint Value
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type uintValue uint
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func newUintValue(val uint, p *uint) *uintValue {
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*p = val
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return (*uintValue)(p)
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}
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func (i *uintValue) Set(s string) error {
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v, err := strconv.ParseUint(s, 0, 64)
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*i = uintValue(v)
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return err
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}
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func (i *uintValue) String() string { return fmt.Sprintf("%v", *i) }
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// -- uint64 Value
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type uint64Value uint64
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func newUint64Value(val uint64, p *uint64) *uint64Value {
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*p = val
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return (*uint64Value)(p)
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}
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func (i *uint64Value) Set(s string) error {
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v, err := strconv.ParseUint(s, 0, 64)
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*i = uint64Value(v)
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return err
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}
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func (i *uint64Value) String() string { return fmt.Sprintf("%v", *i) }
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// -- string Value
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type stringValue string
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func newStringValue(val string, p *string) *stringValue {
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*p = val
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return (*stringValue)(p)
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}
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func (s *stringValue) Set(val string) error {
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*s = stringValue(val)
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return nil
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}
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func (s *stringValue) String() string { return fmt.Sprintf("%s", *s) }
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// -- float64 Value
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type float64Value float64
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func newFloat64Value(val float64, p *float64) *float64Value {
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*p = val
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return (*float64Value)(p)
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}
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func (f *float64Value) Set(s string) error {
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v, err := strconv.ParseFloat(s, 64)
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*f = float64Value(v)
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return err
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}
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func (f *float64Value) String() string { return fmt.Sprintf("%v", *f) }
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// -- time.Duration Value
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type durationValue time.Duration
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func newDurationValue(val time.Duration, p *time.Duration) *durationValue {
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*p = val
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return (*durationValue)(p)
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}
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func (d *durationValue) Set(s string) error {
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v, err := time.ParseDuration(s)
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*d = durationValue(v)
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return err
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}
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func (d *durationValue) String() string { return (*time.Duration)(d).String() }
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// Value is the interface to the dynamic value stored in a flag.
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// (The default value is represented as a string.)
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type Value interface {
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String() string
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Set(string) error
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}
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// ErrorHandling defines how to handle flag parsing errors.
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type ErrorHandling int
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const (
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ContinueOnError ErrorHandling = iota
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ExitOnError
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PanicOnError
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)
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// A FlagSet represents a set of defined flags.
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type FlagSet struct {
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// Usage is the function called when an error occurs while parsing flags.
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// The field is a function (not a method) that may be changed to point to
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// a custom error handler.
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Usage func()
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name string
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parsed bool
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actual map[string]*Flag
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formal map[string]*Flag
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args []string // arguments after flags
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exitOnError bool // does the program exit if there's an error?
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errorHandling ErrorHandling
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output io.Writer // nil means stderr; use out() accessor
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}
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// A Flag represents the state of a flag.
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type Flag struct {
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Name string // name as it appears on command line
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Usage string // help message
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Value Value // value as set
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DefValue string // default value (as text); for usage message
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}
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// sortFlags returns the flags as a slice in lexicographical sorted order.
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func sortFlags(flags map[string]*Flag) []*Flag {
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list := make(sort.StringSlice, len(flags))
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i := 0
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for _, f := range flags {
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list[i] = f.Name
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i++
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}
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list.Sort()
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result := make([]*Flag, len(list))
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for i, name := range list {
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result[i] = flags[name]
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}
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return result
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}
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func (f *FlagSet) out() io.Writer {
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if f.output == nil {
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return os.Stderr
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}
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return f.output
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}
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// SetOutput sets the destination for usage and error messages.
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// If output is nil, os.Stderr is used.
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func (f *FlagSet) SetOutput(output io.Writer) {
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f.output = output
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}
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// VisitAll visits the flags in lexicographical order, calling fn for each.
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// It visits all flags, even those not set.
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func (f *FlagSet) VisitAll(fn func(*Flag)) {
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for _, flag := range sortFlags(f.formal) {
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fn(flag)
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}
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}
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// VisitAll visits the command-line flags in lexicographical order, calling
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// fn for each. It visits all flags, even those not set.
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func VisitAll(fn func(*Flag)) {
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commandLine.VisitAll(fn)
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}
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// Visit visits the flags in lexicographical order, calling fn for each.
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// It visits only those flags that have been set.
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func (f *FlagSet) Visit(fn func(*Flag)) {
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for _, flag := range sortFlags(f.actual) {
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fn(flag)
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}
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}
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// Visit visits the command-line flags in lexicographical order, calling fn
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// for each. It visits only those flags that have been set.
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func Visit(fn func(*Flag)) {
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commandLine.Visit(fn)
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}
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// Lookup returns the Flag structure of the named flag, returning nil if none exists.
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func (f *FlagSet) Lookup(name string) *Flag {
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return f.formal[name]
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}
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// Lookup returns the Flag structure of the named command-line flag,
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// returning nil if none exists.
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func Lookup(name string) *Flag {
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return commandLine.formal[name]
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}
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// Set sets the value of the named flag.
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func (f *FlagSet) Set(name, value string) error {
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flag, ok := f.formal[name]
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if !ok {
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return fmt.Errorf("no such flag -%v", name)
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}
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err := flag.Value.Set(value)
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if err != nil {
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return err
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}
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if f.actual == nil {
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f.actual = make(map[string]*Flag)
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}
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f.actual[name] = flag
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return nil
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}
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// Set sets the value of the named command-line flag.
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func Set(name, value string) error {
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return commandLine.Set(name, value)
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}
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// PrintDefaults prints, to standard error unless configured
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// otherwise, the default values of all defined flags in the set.
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func (f *FlagSet) PrintDefaults() {
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f.VisitAll(func(flag *Flag) {
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format := " -%s=%s: %s\n"
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if _, ok := flag.Value.(*stringValue); ok {
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// put quotes on the value
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format = " -%s=%q: %s\n"
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}
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fmt.Fprintf(f.out(), format, flag.Name, flag.DefValue, flag.Usage)
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})
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}
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// PrintDefaults prints to standard error the default values of all defined command-line flags.
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func PrintDefaults() {
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commandLine.PrintDefaults()
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}
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// defaultUsage is the default function to print a usage message.
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func defaultUsage(f *FlagSet) {
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fmt.Fprintf(f.out(), "Usage of %s:\n", f.name)
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f.PrintDefaults()
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}
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// NOTE: Usage is not just defaultUsage(commandLine)
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// because it serves (via godoc flag Usage) as the example
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// for how to write your own usage function.
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// Usage prints to standard error a usage message documenting all defined command-line flags.
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// The function is a variable that may be changed to point to a custom function.
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var Usage = func() {
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fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
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PrintDefaults()
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}
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// NFlag returns the number of flags that have been set.
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func (f *FlagSet) NFlag() int { return len(f.actual) }
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// NFlag returns the number of command-line flags that have been set.
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func NFlag() int { return len(commandLine.actual) }
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// Arg returns the i'th argument. Arg(0) is the first remaining argument
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// after flags have been processed.
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|
|
func (f *FlagSet) Arg(i int) string {
|
378 |
|
|
if i < 0 || i >= len(f.args) {
|
379 |
|
|
return ""
|
380 |
|
|
}
|
381 |
|
|
return f.args[i]
|
382 |
|
|
}
|
383 |
|
|
|
384 |
|
|
// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument
|
385 |
|
|
// after flags have been processed.
|
386 |
|
|
func Arg(i int) string {
|
387 |
|
|
return commandLine.Arg(i)
|
388 |
|
|
}
|
389 |
|
|
|
390 |
|
|
// NArg is the number of arguments remaining after flags have been processed.
|
391 |
|
|
func (f *FlagSet) NArg() int { return len(f.args) }
|
392 |
|
|
|
393 |
|
|
// NArg is the number of arguments remaining after flags have been processed.
|
394 |
|
|
func NArg() int { return len(commandLine.args) }
|
395 |
|
|
|
396 |
|
|
// Args returns the non-flag arguments.
|
397 |
|
|
func (f *FlagSet) Args() []string { return f.args }
|
398 |
|
|
|
399 |
|
|
// Args returns the non-flag command-line arguments.
|
400 |
|
|
func Args() []string { return commandLine.args }
|
401 |
|
|
|
402 |
|
|
// BoolVar defines a bool flag with specified name, default value, and usage string.
|
403 |
|
|
// The argument p points to a bool variable in which to store the value of the flag.
|
404 |
|
|
func (f *FlagSet) BoolVar(p *bool, name string, value bool, usage string) {
|
405 |
|
|
f.Var(newBoolValue(value, p), name, usage)
|
406 |
|
|
}
|
407 |
|
|
|
408 |
|
|
// BoolVar defines a bool flag with specified name, default value, and usage string.
|
409 |
|
|
// The argument p points to a bool variable in which to store the value of the flag.
|
410 |
|
|
func BoolVar(p *bool, name string, value bool, usage string) {
|
411 |
|
|
commandLine.Var(newBoolValue(value, p), name, usage)
|
412 |
|
|
}
|
413 |
|
|
|
414 |
|
|
// Bool defines a bool flag with specified name, default value, and usage string.
|
415 |
|
|
// The return value is the address of a bool variable that stores the value of the flag.
|
416 |
|
|
func (f *FlagSet) Bool(name string, value bool, usage string) *bool {
|
417 |
|
|
p := new(bool)
|
418 |
|
|
f.BoolVar(p, name, value, usage)
|
419 |
|
|
return p
|
420 |
|
|
}
|
421 |
|
|
|
422 |
|
|
// Bool defines a bool flag with specified name, default value, and usage string.
|
423 |
|
|
// The return value is the address of a bool variable that stores the value of the flag.
|
424 |
|
|
func Bool(name string, value bool, usage string) *bool {
|
425 |
|
|
return commandLine.Bool(name, value, usage)
|
426 |
|
|
}
|
427 |
|
|
|
428 |
|
|
// IntVar defines an int flag with specified name, default value, and usage string.
|
429 |
|
|
// The argument p points to an int variable in which to store the value of the flag.
|
430 |
|
|
func (f *FlagSet) IntVar(p *int, name string, value int, usage string) {
|
431 |
|
|
f.Var(newIntValue(value, p), name, usage)
|
432 |
|
|
}
|
433 |
|
|
|
434 |
|
|
// IntVar defines an int flag with specified name, default value, and usage string.
|
435 |
|
|
// The argument p points to an int variable in which to store the value of the flag.
|
436 |
|
|
func IntVar(p *int, name string, value int, usage string) {
|
437 |
|
|
commandLine.Var(newIntValue(value, p), name, usage)
|
438 |
|
|
}
|
439 |
|
|
|
440 |
|
|
// Int defines an int flag with specified name, default value, and usage string.
|
441 |
|
|
// The return value is the address of an int variable that stores the value of the flag.
|
442 |
|
|
func (f *FlagSet) Int(name string, value int, usage string) *int {
|
443 |
|
|
p := new(int)
|
444 |
|
|
f.IntVar(p, name, value, usage)
|
445 |
|
|
return p
|
446 |
|
|
}
|
447 |
|
|
|
448 |
|
|
// Int defines an int flag with specified name, default value, and usage string.
|
449 |
|
|
// The return value is the address of an int variable that stores the value of the flag.
|
450 |
|
|
func Int(name string, value int, usage string) *int {
|
451 |
|
|
return commandLine.Int(name, value, usage)
|
452 |
|
|
}
|
453 |
|
|
|
454 |
|
|
// Int64Var defines an int64 flag with specified name, default value, and usage string.
|
455 |
|
|
// The argument p points to an int64 variable in which to store the value of the flag.
|
456 |
|
|
func (f *FlagSet) Int64Var(p *int64, name string, value int64, usage string) {
|
457 |
|
|
f.Var(newInt64Value(value, p), name, usage)
|
458 |
|
|
}
|
459 |
|
|
|
460 |
|
|
// Int64Var defines an int64 flag with specified name, default value, and usage string.
|
461 |
|
|
// The argument p points to an int64 variable in which to store the value of the flag.
|
462 |
|
|
func Int64Var(p *int64, name string, value int64, usage string) {
|
463 |
|
|
commandLine.Var(newInt64Value(value, p), name, usage)
|
464 |
|
|
}
|
465 |
|
|
|
466 |
|
|
// Int64 defines an int64 flag with specified name, default value, and usage string.
|
467 |
|
|
// The return value is the address of an int64 variable that stores the value of the flag.
|
468 |
|
|
func (f *FlagSet) Int64(name string, value int64, usage string) *int64 {
|
469 |
|
|
p := new(int64)
|
470 |
|
|
f.Int64Var(p, name, value, usage)
|
471 |
|
|
return p
|
472 |
|
|
}
|
473 |
|
|
|
474 |
|
|
// Int64 defines an int64 flag with specified name, default value, and usage string.
|
475 |
|
|
// The return value is the address of an int64 variable that stores the value of the flag.
|
476 |
|
|
func Int64(name string, value int64, usage string) *int64 {
|
477 |
|
|
return commandLine.Int64(name, value, usage)
|
478 |
|
|
}
|
479 |
|
|
|
480 |
|
|
// UintVar defines a uint flag with specified name, default value, and usage string.
|
481 |
|
|
// The argument p points to a uint variable in which to store the value of the flag.
|
482 |
|
|
func (f *FlagSet) UintVar(p *uint, name string, value uint, usage string) {
|
483 |
|
|
f.Var(newUintValue(value, p), name, usage)
|
484 |
|
|
}
|
485 |
|
|
|
486 |
|
|
// UintVar defines a uint flag with specified name, default value, and usage string.
|
487 |
|
|
// The argument p points to a uint variable in which to store the value of the flag.
|
488 |
|
|
func UintVar(p *uint, name string, value uint, usage string) {
|
489 |
|
|
commandLine.Var(newUintValue(value, p), name, usage)
|
490 |
|
|
}
|
491 |
|
|
|
492 |
|
|
// Uint defines a uint flag with specified name, default value, and usage string.
|
493 |
|
|
// The return value is the address of a uint variable that stores the value of the flag.
|
494 |
|
|
func (f *FlagSet) Uint(name string, value uint, usage string) *uint {
|
495 |
|
|
p := new(uint)
|
496 |
|
|
f.UintVar(p, name, value, usage)
|
497 |
|
|
return p
|
498 |
|
|
}
|
499 |
|
|
|
500 |
|
|
// Uint defines a uint flag with specified name, default value, and usage string.
|
501 |
|
|
// The return value is the address of a uint variable that stores the value of the flag.
|
502 |
|
|
func Uint(name string, value uint, usage string) *uint {
|
503 |
|
|
return commandLine.Uint(name, value, usage)
|
504 |
|
|
}
|
505 |
|
|
|
506 |
|
|
// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
|
507 |
|
|
// The argument p points to a uint64 variable in which to store the value of the flag.
|
508 |
|
|
func (f *FlagSet) Uint64Var(p *uint64, name string, value uint64, usage string) {
|
509 |
|
|
f.Var(newUint64Value(value, p), name, usage)
|
510 |
|
|
}
|
511 |
|
|
|
512 |
|
|
// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
|
513 |
|
|
// The argument p points to a uint64 variable in which to store the value of the flag.
|
514 |
|
|
func Uint64Var(p *uint64, name string, value uint64, usage string) {
|
515 |
|
|
commandLine.Var(newUint64Value(value, p), name, usage)
|
516 |
|
|
}
|
517 |
|
|
|
518 |
|
|
// Uint64 defines a uint64 flag with specified name, default value, and usage string.
|
519 |
|
|
// The return value is the address of a uint64 variable that stores the value of the flag.
|
520 |
|
|
func (f *FlagSet) Uint64(name string, value uint64, usage string) *uint64 {
|
521 |
|
|
p := new(uint64)
|
522 |
|
|
f.Uint64Var(p, name, value, usage)
|
523 |
|
|
return p
|
524 |
|
|
}
|
525 |
|
|
|
526 |
|
|
// Uint64 defines a uint64 flag with specified name, default value, and usage string.
|
527 |
|
|
// The return value is the address of a uint64 variable that stores the value of the flag.
|
528 |
|
|
func Uint64(name string, value uint64, usage string) *uint64 {
|
529 |
|
|
return commandLine.Uint64(name, value, usage)
|
530 |
|
|
}
|
531 |
|
|
|
532 |
|
|
// StringVar defines a string flag with specified name, default value, and usage string.
|
533 |
|
|
// The argument p points to a string variable in which to store the value of the flag.
|
534 |
|
|
func (f *FlagSet) StringVar(p *string, name string, value string, usage string) {
|
535 |
|
|
f.Var(newStringValue(value, p), name, usage)
|
536 |
|
|
}
|
537 |
|
|
|
538 |
|
|
// StringVar defines a string flag with specified name, default value, and usage string.
|
539 |
|
|
// The argument p points to a string variable in which to store the value of the flag.
|
540 |
|
|
func StringVar(p *string, name string, value string, usage string) {
|
541 |
|
|
commandLine.Var(newStringValue(value, p), name, usage)
|
542 |
|
|
}
|
543 |
|
|
|
544 |
|
|
// String defines a string flag with specified name, default value, and usage string.
|
545 |
|
|
// The return value is the address of a string variable that stores the value of the flag.
|
546 |
|
|
func (f *FlagSet) String(name string, value string, usage string) *string {
|
547 |
|
|
p := new(string)
|
548 |
|
|
f.StringVar(p, name, value, usage)
|
549 |
|
|
return p
|
550 |
|
|
}
|
551 |
|
|
|
552 |
|
|
// String defines a string flag with specified name, default value, and usage string.
|
553 |
|
|
// The return value is the address of a string variable that stores the value of the flag.
|
554 |
|
|
func String(name string, value string, usage string) *string {
|
555 |
|
|
return commandLine.String(name, value, usage)
|
556 |
|
|
}
|
557 |
|
|
|
558 |
|
|
// Float64Var defines a float64 flag with specified name, default value, and usage string.
|
559 |
|
|
// The argument p points to a float64 variable in which to store the value of the flag.
|
560 |
|
|
func (f *FlagSet) Float64Var(p *float64, name string, value float64, usage string) {
|
561 |
|
|
f.Var(newFloat64Value(value, p), name, usage)
|
562 |
|
|
}
|
563 |
|
|
|
564 |
|
|
// Float64Var defines a float64 flag with specified name, default value, and usage string.
|
565 |
|
|
// The argument p points to a float64 variable in which to store the value of the flag.
|
566 |
|
|
func Float64Var(p *float64, name string, value float64, usage string) {
|
567 |
|
|
commandLine.Var(newFloat64Value(value, p), name, usage)
|
568 |
|
|
}
|
569 |
|
|
|
570 |
|
|
// Float64 defines a float64 flag with specified name, default value, and usage string.
|
571 |
|
|
// The return value is the address of a float64 variable that stores the value of the flag.
|
572 |
|
|
func (f *FlagSet) Float64(name string, value float64, usage string) *float64 {
|
573 |
|
|
p := new(float64)
|
574 |
|
|
f.Float64Var(p, name, value, usage)
|
575 |
|
|
return p
|
576 |
|
|
}
|
577 |
|
|
|
578 |
|
|
// Float64 defines a float64 flag with specified name, default value, and usage string.
|
579 |
|
|
// The return value is the address of a float64 variable that stores the value of the flag.
|
580 |
|
|
func Float64(name string, value float64, usage string) *float64 {
|
581 |
|
|
return commandLine.Float64(name, value, usage)
|
582 |
|
|
}
|
583 |
|
|
|
584 |
|
|
// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
|
585 |
|
|
// The argument p points to a time.Duration variable in which to store the value of the flag.
|
586 |
|
|
func (f *FlagSet) DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
|
587 |
|
|
f.Var(newDurationValue(value, p), name, usage)
|
588 |
|
|
}
|
589 |
|
|
|
590 |
|
|
// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
|
591 |
|
|
// The argument p points to a time.Duration variable in which to store the value of the flag.
|
592 |
|
|
func DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
|
593 |
|
|
commandLine.Var(newDurationValue(value, p), name, usage)
|
594 |
|
|
}
|
595 |
|
|
|
596 |
|
|
// Duration defines a time.Duration flag with specified name, default value, and usage string.
|
597 |
|
|
// The return value is the address of a time.Duration variable that stores the value of the flag.
|
598 |
|
|
func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time.Duration {
|
599 |
|
|
p := new(time.Duration)
|
600 |
|
|
f.DurationVar(p, name, value, usage)
|
601 |
|
|
return p
|
602 |
|
|
}
|
603 |
|
|
|
604 |
|
|
// Duration defines a time.Duration flag with specified name, default value, and usage string.
|
605 |
|
|
// The return value is the address of a time.Duration variable that stores the value of the flag.
|
606 |
|
|
func Duration(name string, value time.Duration, usage string) *time.Duration {
|
607 |
|
|
return commandLine.Duration(name, value, usage)
|
608 |
|
|
}
|
609 |
|
|
|
610 |
|
|
// Var defines a flag with the specified name and usage string. The type and
|
611 |
|
|
// value of the flag are represented by the first argument, of type Value, which
|
612 |
|
|
// typically holds a user-defined implementation of Value. For instance, the
|
613 |
|
|
// caller could create a flag that turns a comma-separated string into a slice
|
614 |
|
|
// of strings by giving the slice the methods of Value; in particular, Set would
|
615 |
|
|
// decompose the comma-separated string into the slice.
|
616 |
|
|
func (f *FlagSet) Var(value Value, name string, usage string) {
|
617 |
|
|
// Remember the default value as a string; it won't change.
|
618 |
|
|
flag := &Flag{name, usage, value, value.String()}
|
619 |
|
|
_, alreadythere := f.formal[name]
|
620 |
|
|
if alreadythere {
|
621 |
|
|
fmt.Fprintf(f.out(), "%s flag redefined: %s\n", f.name, name)
|
622 |
|
|
panic("flag redefinition") // Happens only if flags are declared with identical names
|
623 |
|
|
}
|
624 |
|
|
if f.formal == nil {
|
625 |
|
|
f.formal = make(map[string]*Flag)
|
626 |
|
|
}
|
627 |
|
|
f.formal[name] = flag
|
628 |
|
|
}
|
629 |
|
|
|
630 |
|
|
// Var defines a flag with the specified name and usage string. The type and
|
631 |
|
|
// value of the flag are represented by the first argument, of type Value, which
|
632 |
|
|
// typically holds a user-defined implementation of Value. For instance, the
|
633 |
|
|
// caller could create a flag that turns a comma-separated string into a slice
|
634 |
|
|
// of strings by giving the slice the methods of Value; in particular, Set would
|
635 |
|
|
// decompose the comma-separated string into the slice.
|
636 |
|
|
func Var(value Value, name string, usage string) {
|
637 |
|
|
commandLine.Var(value, name, usage)
|
638 |
|
|
}
|
639 |
|
|
|
640 |
|
|
// failf prints to standard error a formatted error and usage message and
|
641 |
|
|
// returns the error.
|
642 |
|
|
func (f *FlagSet) failf(format string, a ...interface{}) error {
|
643 |
|
|
err := fmt.Errorf(format, a...)
|
644 |
|
|
fmt.Fprintln(f.out(), err)
|
645 |
|
|
f.usage()
|
646 |
|
|
return err
|
647 |
|
|
}
|
648 |
|
|
|
649 |
|
|
// usage calls the Usage method for the flag set, or the usage function if
|
650 |
|
|
// the flag set is commandLine.
|
651 |
|
|
func (f *FlagSet) usage() {
|
652 |
|
|
if f == commandLine {
|
653 |
|
|
Usage()
|
654 |
|
|
} else if f.Usage == nil {
|
655 |
|
|
defaultUsage(f)
|
656 |
|
|
} else {
|
657 |
|
|
f.Usage()
|
658 |
|
|
}
|
659 |
|
|
}
|
660 |
|
|
|
661 |
|
|
// parseOne parses one flag. It returns whether a flag was seen.
|
662 |
|
|
func (f *FlagSet) parseOne() (bool, error) {
|
663 |
|
|
if len(f.args) == 0 {
|
664 |
|
|
return false, nil
|
665 |
|
|
}
|
666 |
|
|
s := f.args[0]
|
667 |
|
|
if len(s) == 0 || s[0] != '-' || len(s) == 1 {
|
668 |
|
|
return false, nil
|
669 |
|
|
}
|
670 |
|
|
num_minuses := 1
|
671 |
|
|
if s[1] == '-' {
|
672 |
|
|
num_minuses++
|
673 |
|
|
if len(s) == 2 { // "--" terminates the flags
|
674 |
|
|
f.args = f.args[1:]
|
675 |
|
|
return false, nil
|
676 |
|
|
}
|
677 |
|
|
}
|
678 |
|
|
name := s[num_minuses:]
|
679 |
|
|
if len(name) == 0 || name[0] == '-' || name[0] == '=' {
|
680 |
|
|
return false, f.failf("bad flag syntax: %s", s)
|
681 |
|
|
}
|
682 |
|
|
|
683 |
|
|
// it's a flag. does it have an argument?
|
684 |
|
|
f.args = f.args[1:]
|
685 |
|
|
has_value := false
|
686 |
|
|
value := ""
|
687 |
|
|
for i := 1; i < len(name); i++ { // equals cannot be first
|
688 |
|
|
if name[i] == '=' {
|
689 |
|
|
value = name[i+1:]
|
690 |
|
|
has_value = true
|
691 |
|
|
name = name[0:i]
|
692 |
|
|
break
|
693 |
|
|
}
|
694 |
|
|
}
|
695 |
|
|
m := f.formal
|
696 |
|
|
flag, alreadythere := m[name] // BUG
|
697 |
|
|
if !alreadythere {
|
698 |
|
|
if name == "help" || name == "h" { // special case for nice help message.
|
699 |
|
|
f.usage()
|
700 |
|
|
return false, ErrHelp
|
701 |
|
|
}
|
702 |
|
|
return false, f.failf("flag provided but not defined: -%s", name)
|
703 |
|
|
}
|
704 |
|
|
if fv, ok := flag.Value.(*boolValue); ok { // special case: doesn't need an arg
|
705 |
|
|
if has_value {
|
706 |
|
|
if err := fv.Set(value); err != nil {
|
707 |
|
|
f.failf("invalid boolean value %q for -%s: %v", value, name, err)
|
708 |
|
|
}
|
709 |
|
|
} else {
|
710 |
|
|
fv.Set("true")
|
711 |
|
|
}
|
712 |
|
|
} else {
|
713 |
|
|
// It must have a value, which might be the next argument.
|
714 |
|
|
if !has_value && len(f.args) > 0 {
|
715 |
|
|
// value is the next arg
|
716 |
|
|
has_value = true
|
717 |
|
|
value, f.args = f.args[0], f.args[1:]
|
718 |
|
|
}
|
719 |
|
|
if !has_value {
|
720 |
|
|
return false, f.failf("flag needs an argument: -%s", name)
|
721 |
|
|
}
|
722 |
|
|
if err := flag.Value.Set(value); err != nil {
|
723 |
|
|
return false, f.failf("invalid value %q for flag -%s: %v", value, name, err)
|
724 |
|
|
}
|
725 |
|
|
}
|
726 |
|
|
if f.actual == nil {
|
727 |
|
|
f.actual = make(map[string]*Flag)
|
728 |
|
|
}
|
729 |
|
|
f.actual[name] = flag
|
730 |
|
|
return true, nil
|
731 |
|
|
}
|
732 |
|
|
|
733 |
|
|
// Parse parses flag definitions from the argument list, which should not
|
734 |
|
|
// include the command name. Must be called after all flags in the FlagSet
|
735 |
|
|
// are defined and before flags are accessed by the program.
|
736 |
|
|
// The return value will be ErrHelp if -help was set but not defined.
|
737 |
|
|
func (f *FlagSet) Parse(arguments []string) error {
|
738 |
|
|
f.parsed = true
|
739 |
|
|
f.args = arguments
|
740 |
|
|
for {
|
741 |
|
|
seen, err := f.parseOne()
|
742 |
|
|
if seen {
|
743 |
|
|
continue
|
744 |
|
|
}
|
745 |
|
|
if err == nil {
|
746 |
|
|
break
|
747 |
|
|
}
|
748 |
|
|
switch f.errorHandling {
|
749 |
|
|
case ContinueOnError:
|
750 |
|
|
return err
|
751 |
|
|
case ExitOnError:
|
752 |
|
|
os.Exit(2)
|
753 |
|
|
case PanicOnError:
|
754 |
|
|
panic(err)
|
755 |
|
|
}
|
756 |
|
|
}
|
757 |
|
|
return nil
|
758 |
|
|
}
|
759 |
|
|
|
760 |
|
|
// Parsed reports whether f.Parse has been called.
|
761 |
|
|
func (f *FlagSet) Parsed() bool {
|
762 |
|
|
return f.parsed
|
763 |
|
|
}
|
764 |
|
|
|
765 |
|
|
// Parse parses the command-line flags from os.Args[1:]. Must be called
|
766 |
|
|
// after all flags are defined and before flags are accessed by the program.
|
767 |
|
|
func Parse() {
|
768 |
|
|
// Ignore errors; commandLine is set for ExitOnError.
|
769 |
|
|
commandLine.Parse(os.Args[1:])
|
770 |
|
|
}
|
771 |
|
|
|
772 |
|
|
// Parsed returns true if the command-line flags have been parsed.
|
773 |
|
|
func Parsed() bool {
|
774 |
|
|
return commandLine.Parsed()
|
775 |
|
|
}
|
776 |
|
|
|
777 |
|
|
// The default set of command-line flags, parsed from os.Args.
|
778 |
|
|
var commandLine = NewFlagSet(os.Args[0], ExitOnError)
|
779 |
|
|
|
780 |
|
|
// NewFlagSet returns a new, empty flag set with the specified name and
|
781 |
|
|
// error handling property.
|
782 |
|
|
func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet {
|
783 |
|
|
f := &FlagSet{
|
784 |
|
|
name: name,
|
785 |
|
|
errorHandling: errorHandling,
|
786 |
|
|
}
|
787 |
|
|
return f
|
788 |
|
|
}
|
789 |
|
|
|
790 |
|
|
// Init sets the name and error handling property for a flag set.
|
791 |
|
|
// By default, the zero FlagSet uses an empty name and the
|
792 |
|
|
// ContinueOnError error handling policy.
|
793 |
|
|
func (f *FlagSet) Init(name string, errorHandling ErrorHandling) {
|
794 |
|
|
f.name = name
|
795 |
|
|
f.errorHandling = errorHandling
|
796 |
|
|
}
|