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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/flag/flag.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.tar.xz golang-1.20-43a123c1ae6613b3efeed291fa552ecd909d3acf.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/flag/flag.go')
-rw-r--r-- | src/flag/flag.go | 1182 |
1 files changed, 1182 insertions, 0 deletions
diff --git a/src/flag/flag.go b/src/flag/flag.go new file mode 100644 index 0000000..ef3cf29 --- /dev/null +++ b/src/flag/flag.go @@ -0,0 +1,1182 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +/* +Package flag implements command-line flag parsing. + +# Usage + +Define flags using flag.String(), Bool(), Int(), etc. + +This declares an integer flag, -n, stored in the pointer nFlag, with type *int: + + import "flag" + var nFlag = flag.Int("n", 1234, "help message for flag n") + +If you like, you can bind the flag to a variable using the Var() functions. + + var flagvar int + func init() { + flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname") + } + +Or you can create custom flags that satisfy the Value interface (with +pointer receivers) and couple them to flag parsing by + + flag.Var(&flagVal, "name", "help message for flagname") + +For such flags, the default value is just the initial value of the variable. + +After all flags are defined, call + + flag.Parse() + +to parse the command line into the defined flags. + +Flags may then be used directly. If you're using the flags themselves, +they are all pointers; if you bind to variables, they're values. + + fmt.Println("ip has value ", *ip) + fmt.Println("flagvar has value ", flagvar) + +After parsing, the arguments following the flags are available as the +slice flag.Args() or individually as flag.Arg(i). +The arguments are indexed from 0 through flag.NArg()-1. + +# Command line flag syntax + +The following forms are permitted: + + -flag + --flag // double dashes are also permitted + -flag=x + -flag x // non-boolean flags only + +One or two dashes may be used; they are equivalent. +The last form is not permitted for boolean flags because the +meaning of the command + + cmd -x * + +where * is a Unix shell wildcard, will change if there is a file +called 0, false, etc. You must use the -flag=false form to turn +off a boolean flag. + +Flag parsing stops just before the first non-flag argument +("-" is a non-flag argument) or after the terminator "--". + +Integer flags accept 1234, 0664, 0x1234 and may be negative. +Boolean flags may be: + + 1, 0, t, f, T, F, true, false, TRUE, FALSE, True, False + +Duration flags accept any input valid for time.ParseDuration. + +The default set of command-line flags is controlled by +top-level functions. The FlagSet type allows one to define +independent sets of flags, such as to implement subcommands +in a command-line interface. The methods of FlagSet are +analogous to the top-level functions for the command-line +flag set. +*/ +package flag + +import ( + "encoding" + "errors" + "fmt" + "io" + "os" + "reflect" + "sort" + "strconv" + "strings" + "time" +) + +// ErrHelp is the error returned if the -help or -h flag is invoked +// but no such flag is defined. +var ErrHelp = errors.New("flag: help requested") + +// errParse is returned by Set if a flag's value fails to parse, such as with an invalid integer for Int. +// It then gets wrapped through failf to provide more information. +var errParse = errors.New("parse error") + +// errRange is returned by Set if a flag's value is out of range. +// It then gets wrapped through failf to provide more information. +var errRange = errors.New("value out of range") + +func numError(err error) error { + ne, ok := err.(*strconv.NumError) + if !ok { + return err + } + if ne.Err == strconv.ErrSyntax { + return errParse + } + if ne.Err == strconv.ErrRange { + return errRange + } + return err +} + +// -- 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) + if err != nil { + err = errParse + } + *b = boolValue(v) + return err +} + +func (b *boolValue) Get() any { return bool(*b) } + +func (b *boolValue) String() string { return strconv.FormatBool(bool(*b)) } + +func (b *boolValue) IsBoolFlag() bool { return true } + +// optional interface to indicate boolean flags that can be +// supplied without "=value" text +type boolFlag interface { + Value + IsBoolFlag() bool +} + +// -- int Value +type intValue int + +func newIntValue(val int, p *int) *intValue { + *p = val + return (*intValue)(p) +} + +func (i *intValue) Set(s string) error { + v, err := strconv.ParseInt(s, 0, strconv.IntSize) + if err != nil { + err = numError(err) + } + *i = intValue(v) + return err +} + +func (i *intValue) Get() any { return int(*i) } + +func (i *intValue) String() string { return strconv.Itoa(int(*i)) } + +// -- int64 Value +type int64Value int64 + +func newInt64Value(val int64, p *int64) *int64Value { + *p = val + return (*int64Value)(p) +} + +func (i *int64Value) Set(s string) error { + v, err := strconv.ParseInt(s, 0, 64) + if err != nil { + err = numError(err) + } + *i = int64Value(v) + return err +} + +func (i *int64Value) Get() any { return int64(*i) } + +func (i *int64Value) String() string { return strconv.FormatInt(int64(*i), 10) } + +// -- uint Value +type uintValue uint + +func newUintValue(val uint, p *uint) *uintValue { + *p = val + return (*uintValue)(p) +} + +func (i *uintValue) Set(s string) error { + v, err := strconv.ParseUint(s, 0, strconv.IntSize) + if err != nil { + err = numError(err) + } + *i = uintValue(v) + return err +} + +func (i *uintValue) Get() any { return uint(*i) } + +func (i *uintValue) String() string { return strconv.FormatUint(uint64(*i), 10) } + +// -- uint64 Value +type uint64Value uint64 + +func newUint64Value(val uint64, p *uint64) *uint64Value { + *p = val + return (*uint64Value)(p) +} + +func (i *uint64Value) Set(s string) error { + v, err := strconv.ParseUint(s, 0, 64) + if err != nil { + err = numError(err) + } + *i = uint64Value(v) + return err +} + +func (i *uint64Value) Get() any { return uint64(*i) } + +func (i *uint64Value) String() string { return strconv.FormatUint(uint64(*i), 10) } + +// -- string Value +type stringValue string + +func newStringValue(val string, p *string) *stringValue { + *p = val + return (*stringValue)(p) +} + +func (s *stringValue) Set(val string) error { + *s = stringValue(val) + return nil +} + +func (s *stringValue) Get() any { return string(*s) } + +func (s *stringValue) String() string { return string(*s) } + +// -- float64 Value +type float64Value float64 + +func newFloat64Value(val float64, p *float64) *float64Value { + *p = val + return (*float64Value)(p) +} + +func (f *float64Value) Set(s string) error { + v, err := strconv.ParseFloat(s, 64) + if err != nil { + err = numError(err) + } + *f = float64Value(v) + return err +} + +func (f *float64Value) Get() any { return float64(*f) } + +func (f *float64Value) String() string { return strconv.FormatFloat(float64(*f), 'g', -1, 64) } + +// -- time.Duration Value +type durationValue time.Duration + +func newDurationValue(val time.Duration, p *time.Duration) *durationValue { + *p = val + return (*durationValue)(p) +} + +func (d *durationValue) Set(s string) error { + v, err := time.ParseDuration(s) + if err != nil { + err = errParse + } + *d = durationValue(v) + return err +} + +func (d *durationValue) Get() any { return time.Duration(*d) } + +func (d *durationValue) String() string { return (*time.Duration)(d).String() } + +// -- encoding.TextUnmarshaler Value +type textValue struct{ p encoding.TextUnmarshaler } + +func newTextValue(val encoding.TextMarshaler, p encoding.TextUnmarshaler) textValue { + ptrVal := reflect.ValueOf(p) + if ptrVal.Kind() != reflect.Ptr { + panic("variable value type must be a pointer") + } + defVal := reflect.ValueOf(val) + if defVal.Kind() == reflect.Ptr { + defVal = defVal.Elem() + } + if defVal.Type() != ptrVal.Type().Elem() { + panic(fmt.Sprintf("default type does not match variable type: %v != %v", defVal.Type(), ptrVal.Type().Elem())) + } + ptrVal.Elem().Set(defVal) + return textValue{p} +} + +func (v textValue) Set(s string) error { + return v.p.UnmarshalText([]byte(s)) +} + +func (v textValue) Get() interface{} { + return v.p +} + +func (v textValue) String() string { + if m, ok := v.p.(encoding.TextMarshaler); ok { + if b, err := m.MarshalText(); err == nil { + return string(b) + } + } + return "" +} + +// -- func Value +type funcValue func(string) error + +func (f funcValue) Set(s string) error { return f(s) } + +func (f funcValue) String() string { return "" } + +// Value is the interface to the dynamic value stored in a flag. +// (The default value is represented as a string.) +// +// If a Value has an IsBoolFlag() bool method returning true, +// the command-line parser makes -name equivalent to -name=true +// rather than using the next command-line argument. +// +// Set is called once, in command line order, for each flag present. +// The flag package may call the String method with a zero-valued receiver, +// such as a nil pointer. +type Value interface { + String() string + Set(string) error +} + +// Getter is an interface that allows the contents of a Value to be retrieved. +// It wraps the Value interface, rather than being part of it, because it +// appeared after Go 1 and its compatibility rules. All Value types provided +// by this package satisfy the Getter interface, except the type used by Func. +type Getter interface { + Value + Get() any +} + +// ErrorHandling defines how FlagSet.Parse behaves if the parse fails. +type ErrorHandling int + +// These constants cause FlagSet.Parse to behave as described if the parse fails. +const ( + ContinueOnError ErrorHandling = iota // Return a descriptive error. + ExitOnError // Call os.Exit(2) or for -h/-help Exit(0). + PanicOnError // Call panic with a descriptive error. +) + +// A FlagSet represents a set of defined flags. The zero value of a FlagSet +// has no name and has ContinueOnError error handling. +// +// Flag names must be unique within a FlagSet. An attempt to define a flag whose +// name is already in use will cause a panic. +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. What happens after Usage is called depends + // on the ErrorHandling setting; for the command line, this defaults + // to ExitOnError, which exits the program after calling Usage. + Usage func() + + name string + parsed bool + actual map[string]*Flag + formal map[string]*Flag + args []string // arguments after flags + errorHandling ErrorHandling + output io.Writer // nil means stderr; use Output() 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 { + result := make([]*Flag, len(flags)) + i := 0 + for _, f := range flags { + result[i] = f + i++ + } + sort.Slice(result, func(i, j int) bool { + return result[i].Name < result[j].Name + }) + return result +} + +// Output returns the destination for usage and error messages. os.Stderr is returned if +// output was not set or was set to nil. +func (f *FlagSet) Output() io.Writer { + if f.output == nil { + return os.Stderr + } + return f.output +} + +// Name returns the name of the flag set. +func (f *FlagSet) Name() string { + return f.name +} + +// ErrorHandling returns the error handling behavior of the flag set. +func (f *FlagSet) ErrorHandling() ErrorHandling { + return f.errorHandling +} + +// SetOutput sets the destination for usage and error messages. +// If output is nil, os.Stderr is used. +func (f *FlagSet) SetOutput(output io.Writer) { + f.output = output +} + +// VisitAll visits the flags in lexicographical order, calling fn for each. +// It visits all flags, even those not set. +func (f *FlagSet) VisitAll(fn func(*Flag)) { + for _, flag := range sortFlags(f.formal) { + fn(flag) + } +} + +// VisitAll visits the command-line flags in lexicographical order, calling +// fn for each. It visits all flags, even those not set. +func VisitAll(fn func(*Flag)) { + CommandLine.VisitAll(fn) +} + +// Visit visits the flags in lexicographical order, calling fn for each. +// It visits only those flags that have been set. +func (f *FlagSet) Visit(fn func(*Flag)) { + for _, flag := range sortFlags(f.actual) { + fn(flag) + } +} + +// Visit visits the command-line flags in lexicographical order, calling fn +// for each. It visits only those flags that have been set. +func Visit(fn func(*Flag)) { + CommandLine.Visit(fn) +} + +// Lookup returns the Flag structure of the named flag, returning nil if none exists. +func (f *FlagSet) Lookup(name string) *Flag { + return f.formal[name] +} + +// Lookup returns the Flag structure of the named command-line flag, +// returning nil if none exists. +func Lookup(name string) *Flag { + return CommandLine.formal[name] +} + +// Set sets the value of the named flag. +func (f *FlagSet) Set(name, value string) error { + flag, ok := f.formal[name] + if !ok { + return fmt.Errorf("no such flag -%v", name) + } + err := flag.Value.Set(value) + if err != nil { + return err + } + if f.actual == nil { + f.actual = make(map[string]*Flag) + } + f.actual[name] = flag + return nil +} + +// Set sets the value of the named command-line flag. +func Set(name, value string) error { + return CommandLine.Set(name, value) +} + +// isZeroValue determines whether the string represents the zero +// value for a flag. +func isZeroValue(flag *Flag, value string) (ok bool, err error) { + // Build a zero value of the flag's Value type, and see if the + // result of calling its String method equals the value passed in. + // This works unless the Value type is itself an interface type. + typ := reflect.TypeOf(flag.Value) + var z reflect.Value + if typ.Kind() == reflect.Pointer { + z = reflect.New(typ.Elem()) + } else { + z = reflect.Zero(typ) + } + // Catch panics calling the String method, which shouldn't prevent the + // usage message from being printed, but that we should report to the + // user so that they know to fix their code. + defer func() { + if e := recover(); e != nil { + if typ.Kind() == reflect.Pointer { + typ = typ.Elem() + } + err = fmt.Errorf("panic calling String method on zero %v for flag %s: %v", typ, flag.Name, e) + } + }() + return value == z.Interface().(Value).String(), nil +} + +// UnquoteUsage extracts a back-quoted name from the usage +// string for a flag and returns it and the un-quoted usage. +// Given "a `name` to show" it returns ("name", "a name to show"). +// If there are no back quotes, the name is an educated guess of the +// type of the flag's value, or the empty string if the flag is boolean. +func UnquoteUsage(flag *Flag) (name string, usage string) { + // Look for a back-quoted name, but avoid the strings package. + usage = flag.Usage + for i := 0; i < len(usage); i++ { + if usage[i] == '`' { + for j := i + 1; j < len(usage); j++ { + if usage[j] == '`' { + name = usage[i+1 : j] + usage = usage[:i] + name + usage[j+1:] + return name, usage + } + } + break // Only one back quote; use type name. + } + } + // No explicit name, so use type if we can find one. + name = "value" + switch fv := flag.Value.(type) { + case boolFlag: + if fv.IsBoolFlag() { + name = "" + } + case *durationValue: + name = "duration" + case *float64Value: + name = "float" + case *intValue, *int64Value: + name = "int" + case *stringValue: + name = "string" + case *uintValue, *uint64Value: + name = "uint" + } + return +} + +// PrintDefaults prints, to standard error unless configured otherwise, the +// default values of all defined command-line flags in the set. See the +// documentation for the global function PrintDefaults for more information. +func (f *FlagSet) PrintDefaults() { + var isZeroValueErrs []error + f.VisitAll(func(flag *Flag) { + var b strings.Builder + fmt.Fprintf(&b, " -%s", flag.Name) // Two spaces before -; see next two comments. + name, usage := UnquoteUsage(flag) + if len(name) > 0 { + b.WriteString(" ") + b.WriteString(name) + } + // Boolean flags of one ASCII letter are so common we + // treat them specially, putting their usage on the same line. + if b.Len() <= 4 { // space, space, '-', 'x'. + b.WriteString("\t") + } else { + // Four spaces before the tab triggers good alignment + // for both 4- and 8-space tab stops. + b.WriteString("\n \t") + } + b.WriteString(strings.ReplaceAll(usage, "\n", "\n \t")) + + // Print the default value only if it differs to the zero value + // for this flag type. + if isZero, err := isZeroValue(flag, flag.DefValue); err != nil { + isZeroValueErrs = append(isZeroValueErrs, err) + } else if !isZero { + if _, ok := flag.Value.(*stringValue); ok { + // put quotes on the value + fmt.Fprintf(&b, " (default %q)", flag.DefValue) + } else { + fmt.Fprintf(&b, " (default %v)", flag.DefValue) + } + } + fmt.Fprint(f.Output(), b.String(), "\n") + }) + // If calling String on any zero flag.Values triggered a panic, print + // the messages after the full set of defaults so that the programmer + // knows to fix the panic. + if errs := isZeroValueErrs; len(errs) > 0 { + fmt.Fprintln(f.Output()) + for _, err := range errs { + fmt.Fprintln(f.Output(), err) + } + } +} + +// PrintDefaults prints, to standard error unless configured otherwise, +// a usage message showing the default settings of all defined +// command-line flags. +// For an integer valued flag x, the default output has the form +// +// -x int +// usage-message-for-x (default 7) +// +// The usage message will appear on a separate line for anything but +// a bool flag with a one-byte name. For bool flags, the type is +// omitted and if the flag name is one byte the usage message appears +// on the same line. The parenthetical default is omitted if the +// default is the zero value for the type. The listed type, here int, +// can be changed by placing a back-quoted name in the flag's usage +// string; the first such item in the message is taken to be a parameter +// name to show in the message and the back quotes are stripped from +// the message when displayed. For instance, given +// +// flag.String("I", "", "search `directory` for include files") +// +// the output will be +// +// -I directory +// search directory for include files. +// +// To change the destination for flag messages, call CommandLine.SetOutput. +func PrintDefaults() { + CommandLine.PrintDefaults() +} + +// defaultUsage is the default function to print a usage message. +func (f *FlagSet) defaultUsage() { + if f.name == "" { + fmt.Fprintf(f.Output(), "Usage:\n") + } else { + fmt.Fprintf(f.Output(), "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 a usage message documenting all defined command-line flags +// to CommandLine's output, which by default is os.Stderr. +// It is called when an error occurs while parsing flags. +// The function is a variable that may be changed to point to a custom function. +// By default it prints a simple header and calls PrintDefaults; for details about the +// format of the output and how to control it, see the documentation for PrintDefaults. +// Custom usage functions may choose to exit the program; by default exiting +// happens anyway as the command line's error handling strategy is set to +// ExitOnError. +var Usage = func() { + fmt.Fprintf(CommandLine.Output(), "Usage of %s:\n", os.Args[0]) + PrintDefaults() +} + +// NFlag returns the number of flags that have been set. +func (f *FlagSet) NFlag() int { return len(f.actual) } + +// NFlag returns the number of command-line flags that have been set. +func NFlag() int { return len(CommandLine.actual) } + +// Arg returns the i'th argument. Arg(0) is the first remaining argument +// after flags have been processed. Arg returns an empty string if the +// requested element does not exist. +func (f *FlagSet) Arg(i int) string { + if i < 0 || i >= len(f.args) { + return "" + } + return f.args[i] +} + +// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument +// after flags have been processed. Arg returns an empty string if the +// requested element does not exist. +func Arg(i int) string { + return CommandLine.Arg(i) +} + +// NArg is the number of arguments remaining after flags have been processed. +func (f *FlagSet) NArg() int { return len(f.args) } + +// NArg is the number of arguments remaining after flags have been processed. +func NArg() int { return len(CommandLine.args) } + +// Args returns the non-flag arguments. +func (f *FlagSet) Args() []string { return f.args } + +// Args returns the non-flag command-line arguments. +func Args() []string { return CommandLine.args } + +// BoolVar defines a bool flag with specified name, default value, and usage string. +// The argument p points to a bool variable in which to store the value of the flag. +func (f *FlagSet) BoolVar(p *bool, name string, value bool, usage string) { + f.Var(newBoolValue(value, p), name, usage) +} + +// BoolVar defines a bool flag with specified name, default value, and usage string. +// The argument p points to a bool variable in which to store the value of the flag. +func BoolVar(p *bool, name string, value bool, usage string) { + CommandLine.Var(newBoolValue(value, p), name, usage) +} + +// Bool defines a bool flag with specified name, default value, and usage string. +// The return value is the address of a bool variable that stores the value of the flag. +func (f *FlagSet) Bool(name string, value bool, usage string) *bool { + p := new(bool) + f.BoolVar(p, name, value, usage) + return p +} + +// Bool defines a bool flag with specified name, default value, and usage string. +// The return value is the address of a bool variable that stores the value of the flag. +func Bool(name string, value bool, usage string) *bool { + return CommandLine.Bool(name, value, usage) +} + +// IntVar defines an int flag with specified name, default value, and usage string. +// The argument p points to an int variable in which to store the value of the flag. +func (f *FlagSet) IntVar(p *int, name string, value int, usage string) { + f.Var(newIntValue(value, p), name, usage) +} + +// IntVar defines an int flag with specified name, default value, and usage string. +// The argument p points to an int variable in which to store the value of the flag. +func IntVar(p *int, name string, value int, usage string) { + CommandLine.Var(newIntValue(value, p), name, usage) +} + +// Int defines an int flag with specified name, default value, and usage string. +// The return value is the address of an int variable that stores the value of the flag. +func (f *FlagSet) Int(name string, value int, usage string) *int { + p := new(int) + f.IntVar(p, name, value, usage) + return p +} + +// Int defines an int flag with specified name, default value, and usage string. +// The return value is the address of an int variable that stores the value of the flag. +func Int(name string, value int, usage string) *int { + return CommandLine.Int(name, value, usage) +} + +// Int64Var defines an int64 flag with specified name, default value, and usage string. +// The argument p points to an int64 variable in which to store the value of the flag. +func (f *FlagSet) Int64Var(p *int64, name string, value int64, usage string) { + f.Var(newInt64Value(value, p), name, usage) +} + +// Int64Var defines an int64 flag with specified name, default value, and usage string. +// The argument p points to an int64 variable in which to store the value of the flag. +func Int64Var(p *int64, name string, value int64, usage string) { + CommandLine.Var(newInt64Value(value, p), name, usage) +} + +// Int64 defines an int64 flag with specified name, default value, and usage string. +// The return value is the address of an int64 variable that stores the value of the flag. +func (f *FlagSet) Int64(name string, value int64, usage string) *int64 { + p := new(int64) + f.Int64Var(p, name, value, usage) + return p +} + +// Int64 defines an int64 flag with specified name, default value, and usage string. +// The return value is the address of an int64 variable that stores the value of the flag. +func Int64(name string, value int64, usage string) *int64 { + return CommandLine.Int64(name, value, usage) +} + +// UintVar defines a uint flag with specified name, default value, and usage string. +// The argument p points to a uint variable in which to store the value of the flag. +func (f *FlagSet) UintVar(p *uint, name string, value uint, usage string) { + f.Var(newUintValue(value, p), name, usage) +} + +// UintVar defines a uint flag with specified name, default value, and usage string. +// The argument p points to a uint variable in which to store the value of the flag. +func UintVar(p *uint, name string, value uint, usage string) { + CommandLine.Var(newUintValue(value, p), name, usage) +} + +// Uint defines a uint flag with specified name, default value, and usage string. +// The return value is the address of a uint variable that stores the value of the flag. +func (f *FlagSet) Uint(name string, value uint, usage string) *uint { + p := new(uint) + f.UintVar(p, name, value, usage) + return p +} + +// Uint defines a uint flag with specified name, default value, and usage string. +// The return value is the address of a uint variable that stores the value of the flag. +func Uint(name string, value uint, usage string) *uint { + return CommandLine.Uint(name, value, usage) +} + +// Uint64Var defines a uint64 flag with specified name, default value, and usage string. +// The argument p points to a uint64 variable in which to store the value of the flag. +func (f *FlagSet) Uint64Var(p *uint64, name string, value uint64, usage string) { + f.Var(newUint64Value(value, p), name, usage) +} + +// Uint64Var defines a uint64 flag with specified name, default value, and usage string. +// The argument p points to a uint64 variable in which to store the value of the flag. +func Uint64Var(p *uint64, name string, value uint64, usage string) { + CommandLine.Var(newUint64Value(value, p), name, usage) +} + +// Uint64 defines a uint64 flag with specified name, default value, and usage string. +// The return value is the address of a uint64 variable that stores the value of the flag. +func (f *FlagSet) Uint64(name string, value uint64, usage string) *uint64 { + p := new(uint64) + f.Uint64Var(p, name, value, usage) + return p +} + +// Uint64 defines a uint64 flag with specified name, default value, and usage string. +// The return value is the address of a uint64 variable that stores the value of the flag. +func Uint64(name string, value uint64, usage string) *uint64 { + return CommandLine.Uint64(name, value, usage) +} + +// StringVar defines a string flag with specified name, default value, and usage string. +// The argument p points to a string variable in which to store the value of the flag. +func (f *FlagSet) StringVar(p *string, name string, value string, usage string) { + f.Var(newStringValue(value, p), name, usage) +} + +// StringVar defines a string flag with specified name, default value, and usage string. +// The argument p points to a string variable in which to store the value of the flag. +func StringVar(p *string, name string, value string, usage string) { + CommandLine.Var(newStringValue(value, p), name, usage) +} + +// String defines a string flag with specified name, default value, and usage string. +// The return value is the address of a string variable that stores the value of the flag. +func (f *FlagSet) String(name string, value string, usage string) *string { + p := new(string) + f.StringVar(p, name, value, usage) + return p +} + +// String defines a string flag with specified name, default value, and usage string. +// The return value is the address of a string variable that stores the value of the flag. +func String(name string, value string, usage string) *string { + return CommandLine.String(name, value, usage) +} + +// Float64Var defines a float64 flag with specified name, default value, and usage string. +// The argument p points to a float64 variable in which to store the value of the flag. +func (f *FlagSet) Float64Var(p *float64, name string, value float64, usage string) { + f.Var(newFloat64Value(value, p), name, usage) +} + +// Float64Var defines a float64 flag with specified name, default value, and usage string. +// The argument p points to a float64 variable in which to store the value of the flag. +func Float64Var(p *float64, name string, value float64, usage string) { + CommandLine.Var(newFloat64Value(value, p), name, usage) +} + +// Float64 defines a float64 flag with specified name, default value, and usage string. +// The return value is the address of a float64 variable that stores the value of the flag. +func (f *FlagSet) Float64(name string, value float64, usage string) *float64 { + p := new(float64) + f.Float64Var(p, name, value, usage) + return p +} + +// Float64 defines a float64 flag with specified name, default value, and usage string. +// The return value is the address of a float64 variable that stores the value of the flag. +func Float64(name string, value float64, usage string) *float64 { + return CommandLine.Float64(name, value, usage) +} + +// DurationVar defines a time.Duration flag with specified name, default value, and usage string. +// The argument p points to a time.Duration variable in which to store the value of the flag. +// The flag accepts a value acceptable to time.ParseDuration. +func (f *FlagSet) DurationVar(p *time.Duration, name string, value time.Duration, usage string) { + f.Var(newDurationValue(value, p), name, usage) +} + +// DurationVar defines a time.Duration flag with specified name, default value, and usage string. +// The argument p points to a time.Duration variable in which to store the value of the flag. +// The flag accepts a value acceptable to time.ParseDuration. +func DurationVar(p *time.Duration, name string, value time.Duration, usage string) { + CommandLine.Var(newDurationValue(value, p), name, usage) +} + +// Duration defines a time.Duration flag with specified name, default value, and usage string. +// The return value is the address of a time.Duration variable that stores the value of the flag. +// The flag accepts a value acceptable to time.ParseDuration. +func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time.Duration { + p := new(time.Duration) + f.DurationVar(p, name, value, usage) + return p +} + +// Duration defines a time.Duration flag with specified name, default value, and usage string. +// The return value is the address of a time.Duration variable that stores the value of the flag. +// The flag accepts a value acceptable to time.ParseDuration. +func Duration(name string, value time.Duration, usage string) *time.Duration { + return CommandLine.Duration(name, value, usage) +} + +// TextVar defines a flag with a specified name, default value, and usage string. +// The argument p must be a pointer to a variable that will hold the value +// of the flag, and p must implement encoding.TextUnmarshaler. +// If the flag is used, the flag value will be passed to p's UnmarshalText method. +// The type of the default value must be the same as the type of p. +func (f *FlagSet) TextVar(p encoding.TextUnmarshaler, name string, value encoding.TextMarshaler, usage string) { + f.Var(newTextValue(value, p), name, usage) +} + +// TextVar defines a flag with a specified name, default value, and usage string. +// The argument p must be a pointer to a variable that will hold the value +// of the flag, and p must implement encoding.TextUnmarshaler. +// If the flag is used, the flag value will be passed to p's UnmarshalText method. +// The type of the default value must be the same as the type of p. +func TextVar(p encoding.TextUnmarshaler, name string, value encoding.TextMarshaler, usage string) { + CommandLine.Var(newTextValue(value, p), name, usage) +} + +// Func defines a flag with the specified name and usage string. +// Each time the flag is seen, fn is called with the value of the flag. +// If fn returns a non-nil error, it will be treated as a flag value parsing error. +func (f *FlagSet) Func(name, usage string, fn func(string) error) { + f.Var(funcValue(fn), name, usage) +} + +// Func defines a flag with the specified name and usage string. +// Each time the flag is seen, fn is called with the value of the flag. +// If fn returns a non-nil error, it will be treated as a flag value parsing error. +func Func(name, usage string, fn func(string) error) { + CommandLine.Func(name, usage, fn) +} + +// 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) { + // Flag must not begin "-" or contain "=". + if strings.HasPrefix(name, "-") { + panic(f.sprintf("flag %q begins with -", name)) + } else if strings.Contains(name, "=") { + panic(f.sprintf("flag %q contains =", name)) + } + + // 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 = f.sprintf("flag redefined: %s", name) + } else { + msg = f.sprintf("%s flag redefined: %s", f.name, name) + } + 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) +} + +// sprintf formats the message, prints it to output, and returns it. +func (f *FlagSet) sprintf(format string, a ...any) string { + msg := fmt.Sprintf(format, a...) + fmt.Fprintln(f.Output(), msg) + return msg +} + +// failf prints to standard error a formatted error and usage message and +// returns the error. +func (f *FlagSet) failf(format string, a ...any) error { + msg := f.sprintf(format, a...) + f.usage() + return errors.New(msg) +} + +// usage calls the Usage method for the flag set if one is specified, +// or the appropriate default usage function otherwise. +func (f *FlagSet) usage() { + if f.Usage == nil { + f.defaultUsage() + } else { + f.Usage() + } +} + +// parseOne parses one flag. It reports whether a flag was seen. +func (f *FlagSet) parseOne() (bool, error) { + if len(f.args) == 0 { + return false, nil + } + s := f.args[0] + if len(s) < 2 || s[0] != '-' { + return false, nil + } + numMinuses := 1 + if s[1] == '-' { + numMinuses++ + if len(s) == 2 { // "--" terminates the flags + f.args = f.args[1:] + return false, nil + } + } + name := s[numMinuses:] + if len(name) == 0 || name[0] == '-' || name[0] == '=' { + return false, f.failf("bad flag syntax: %s", s) + } + + // it's a flag. does it have an argument? + f.args = f.args[1:] + hasValue := false + value := "" + for i := 1; i < len(name); i++ { // equals cannot be first + if name[i] == '=' { + value = name[i+1:] + hasValue = true + name = name[0:i] + break + } + } + + flag, ok := f.formal[name] + if !ok { + if name == "help" || name == "h" { // special case for nice help message. + f.usage() + return false, ErrHelp + } + return false, f.failf("flag provided but not defined: -%s", name) + } + + if fv, ok := flag.Value.(boolFlag); ok && fv.IsBoolFlag() { // special case: doesn't need an arg + if hasValue { + if err := fv.Set(value); err != nil { + return false, f.failf("invalid boolean value %q for -%s: %v", value, name, err) + } + } else { + if err := fv.Set("true"); err != nil { + return false, f.failf("invalid boolean flag %s: %v", name, err) + } + } + } else { + // It must have a value, which might be the next argument. + if !hasValue && len(f.args) > 0 { + // value is the next arg + hasValue = true + value, f.args = f.args[0], f.args[1:] + } + if !hasValue { + return false, f.failf("flag needs an argument: -%s", name) + } + if err := flag.Value.Set(value); err != nil { + return false, f.failf("invalid value %q for flag -%s: %v", value, name, err) + } + } + if f.actual == nil { + f.actual = make(map[string]*Flag) + } + f.actual[name] = flag + return true, nil +} + +// Parse parses flag definitions from the argument list, which should not +// include the command name. Must be called after all flags in the FlagSet +// are defined and before flags are accessed by the program. +// The return value will be ErrHelp if -help or -h were set but not defined. +func (f *FlagSet) Parse(arguments []string) error { + f.parsed = true + f.args = arguments + for { + seen, err := f.parseOne() + if seen { + continue + } + if err == nil { + break + } + switch f.errorHandling { + case ContinueOnError: + return err + case ExitOnError: + if err == ErrHelp { + os.Exit(0) + } + os.Exit(2) + case PanicOnError: + panic(err) + } + } + return nil +} + +// Parsed reports whether f.Parse has been called. +func (f *FlagSet) Parsed() bool { + return f.parsed +} + +// Parse parses the command-line flags from os.Args[1:]. Must be called +// after all flags are defined and before flags are accessed by the program. +func Parse() { + // Ignore errors; CommandLine is set for ExitOnError. + CommandLine.Parse(os.Args[1:]) +} + +// Parsed reports whether the command-line flags have been parsed. +func Parsed() bool { + return CommandLine.Parsed() +} + +// CommandLine is the default set of command-line flags, parsed from os.Args. +// The top-level functions such as BoolVar, Arg, and so on are wrappers for the +// methods of CommandLine. +var CommandLine = NewFlagSet(os.Args[0], ExitOnError) + +func init() { + // Override generic FlagSet default Usage with call to global Usage. + // Note: This is not CommandLine.Usage = Usage, + // because we want any eventual call to use any updated value of Usage, + // not the value it has when this line is run. + CommandLine.Usage = commandLineUsage +} + +func commandLineUsage() { + Usage() +} + +// NewFlagSet returns a new, empty flag set with the specified name and +// error handling property. If the name is not empty, it will be printed +// in the default usage message and in error messages. +func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet { + f := &FlagSet{ + name: name, + errorHandling: errorHandling, + } + f.Usage = f.defaultUsage + return f +} + +// Init sets the name and error handling property for a flag set. +// By default, the zero FlagSet uses an empty name and the +// ContinueOnError error handling policy. +func (f *FlagSet) Init(name string, errorHandling ErrorHandling) { + f.name = name + f.errorHandling = errorHandling +} |