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Copy pathflag_impl.go
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264 lines (228 loc) · 8.74 KB
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package cli
import (
"context"
"flag"
"fmt"
"reflect"
)
// Value represents a value as used by cli.
// For now it implements the golang flag.Value interface
type Value interface {
flag.Value
flag.Getter
}
type boolFlag interface {
IsBoolFlag() bool
}
type fnValue struct {
fn func(string) error
isBool bool
v Value
}
func (f *fnValue) Get() any { return f.v.Get() }
func (f *fnValue) Set(s string) error { return f.fn(s) }
func (f *fnValue) String() string {
if f.v == nil {
return ""
}
return f.v.String()
}
func (f *fnValue) IsBoolFlag() bool { return f.isBool }
func (f *fnValue) Count() int {
if s, ok := f.v.(Countable); ok {
return s.Count()
}
return 0
}
// ValueCreator is responsible for creating a flag.Value emulation
// as well as custom formatting
//
// T specifies the type
// C specifies the config for the type
type ValueCreator[T any, C any] interface {
Create(T, *T, C) Value
ToString(T) string
}
// NoConfig is for flags which dont need a custom configuration
type NoConfig struct{}
// FlagBase [T,C,VC] is a generic flag base which can be used
// as a boilerplate to implement the most common interfaces
// used by urfave/cli.
//
// T specifies the type
// C specifies the configuration required(if any for that flag type)
// VC specifies the value creator which creates the flag.Value emulation
type FlagBase[T any, C any, VC ValueCreator[T, C]] struct {
Name string `json:"name"` // name of the flag
Category string `json:"category"` // category of the flag, if any
DefaultText string `json:"defaultText"` // default text of the flag for usage purposes
HideDefault bool `json:"hideDefault"` // whether to hide the default value in output
Usage string `json:"usage"` // usage string for help output
Sources ValueSourceChain `json:"-"` // sources to load flag value from
Required bool `json:"required"` // whether the flag is required or not
Hidden bool `json:"hidden"` // whether to hide the flag in help output
Local bool `json:"local"` // whether the flag needs to be applied to subcommands as well
Value T `json:"defaultValue"` // default value for this flag if not set by from any source
Destination *T `json:"-"` // destination pointer for value when set
Aliases []string `json:"aliases"` // Aliases that are allowed for this flag
TakesFile bool `json:"takesFileArg"` // whether this flag takes a file argument, mainly for shell completion purposes
Action func(context.Context, *Command, T) error `json:"-"` // Action callback to be called when flag is set
Config C `json:"config"` // Additional/Custom configuration associated with this flag type
OnlyOnce bool `json:"onlyOnce"` // whether this flag can be duplicated on the command line
Validator func(T) error `json:"-"` // custom function to validate this flag value
ValidateDefaults bool `json:"validateDefaults"` // whether to validate defaults or not
// unexported fields for internal use
count int // number of times the flag has been set
hasBeenSet bool // whether the flag has been set from env or file
applied bool // whether the flag has been applied to a flag set already
creator VC // value creator for this flag type
value Value // value representing this flag's value
}
// GetValue returns the flags value as string representation and an empty
// string if the flag takes no value at all.
func (f *FlagBase[T, C, V]) GetValue() string {
if !f.TakesValue() {
return ""
}
return fmt.Sprintf("%v", f.Value)
}
// Apply populates the flag given the flag set and environment
func (f *FlagBase[T, C, V]) Apply(set *flag.FlagSet) error {
tracef("apply (flag=%[1]q)", f.Name)
// TODO move this phase into a separate flag initialization function
// if flag has been applied previously then it would have already been set
// from env or file. So no need to apply the env set again. However
// lots of units tests prior to persistent flags assumed that the
// flag can be applied to different flag sets multiple times while still
// keeping the env set.
if !f.applied || f.Local {
newVal := f.Value
if val, source, found := f.Sources.LookupWithSource(); found {
tmpVal := f.creator.Create(f.Value, new(T), f.Config)
if val != "" || reflect.TypeOf(f.Value).Kind() == reflect.String {
if err := tmpVal.Set(val); err != nil {
return fmt.Errorf(
"could not parse %[1]q as %[2]T value from %[3]s for flag %[4]s: %[5]s",
val, f.Value, source, f.Name, err,
)
}
} else if val == "" && reflect.TypeOf(f.Value).Kind() == reflect.Bool {
_ = tmpVal.Set("false")
}
newVal = tmpVal.Get().(T)
f.hasBeenSet = true
}
if f.Destination == nil {
f.value = f.creator.Create(newVal, new(T), f.Config)
} else {
f.value = f.creator.Create(newVal, f.Destination, f.Config)
}
// Validate the given default or values set from external sources as well
if f.Validator != nil && f.ValidateDefaults {
if err := f.Validator(f.value.Get().(T)); err != nil {
return err
}
}
}
isBool := false
if b, ok := f.value.(boolFlag); ok && b.IsBoolFlag() {
isBool = true
}
for _, name := range f.Names() {
set.Var(&fnValue{
fn: func(val string) error {
if f.count == 1 && f.OnlyOnce {
return fmt.Errorf("cant duplicate this flag")
}
f.count++
if err := f.value.Set(val); err != nil {
return err
}
f.hasBeenSet = true
if f.Validator != nil {
if err := f.Validator(f.value.Get().(T)); err != nil {
return err
}
}
return nil
},
isBool: isBool,
v: f.value,
}, name, f.Usage)
}
f.applied = true
return nil
}
// IsDefaultVisible returns true if the flag is not hidden, otherwise false
func (f *FlagBase[T, C, V]) IsDefaultVisible() bool {
return !f.HideDefault
}
// String returns a readable representation of this value (for usage defaults)
func (f *FlagBase[T, C, V]) String() string {
return FlagStringer(f)
}
// IsSet returns whether or not the flag has been set through env or file
func (f *FlagBase[T, C, V]) IsSet() bool {
return f.hasBeenSet
}
// Names returns the names of the flag
func (f *FlagBase[T, C, V]) Names() []string {
return FlagNames(f.Name, f.Aliases)
}
// IsRequired returns whether or not the flag is required
func (f *FlagBase[T, C, V]) IsRequired() bool {
return f.Required
}
// IsVisible returns true if the flag is not hidden, otherwise false
func (f *FlagBase[T, C, V]) IsVisible() bool {
return !f.Hidden
}
// GetCategory returns the category of the flag
func (f *FlagBase[T, C, V]) GetCategory() string {
return f.Category
}
func (f *FlagBase[T, C, V]) SetCategory(c string) {
f.Category = c
}
// GetUsage returns the usage string for the flag
func (f *FlagBase[T, C, V]) GetUsage() string {
return f.Usage
}
// GetEnvVars returns the env vars for this flag
func (f *FlagBase[T, C, V]) GetEnvVars() []string {
return f.Sources.EnvKeys()
}
// TakesValue returns true if the flag takes a value, otherwise false
func (f *FlagBase[T, C, V]) TakesValue() bool {
var t T
return reflect.TypeOf(t) == nil || reflect.TypeOf(t).Kind() != reflect.Bool
}
// GetDefaultText returns the default text for this flag
func (f *FlagBase[T, C, V]) GetDefaultText() string {
if f.DefaultText != "" {
return f.DefaultText
}
var v V
return v.ToString(f.Value)
}
// RunAction executes flag action if set
func (f *FlagBase[T, C, V]) RunAction(ctx context.Context, cmd *Command) error {
if f.Action != nil {
return f.Action(ctx, cmd, cmd.Value(f.Name).(T))
}
return nil
}
// IsMultiValueFlag returns true if the value type T can take multiple
// values from cmd line. This is true for slice and map type flags
func (f *FlagBase[T, C, VC]) IsMultiValueFlag() bool {
// TBD how to specify
if reflect.TypeOf(f.Value) == nil {
return false
}
kind := reflect.TypeOf(f.Value).Kind()
return kind == reflect.Slice || kind == reflect.Map
}
// IsLocal returns false if flag needs to be persistent across subcommands
func (f *FlagBase[T, C, VC]) IsLocal() bool {
return f.Local
}