urfave-cli/flag_generic.go

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package cli
import (
"flag"
"fmt"
)
// Generic is a generic parseable type identified by a specific flag
type Generic interface {
Set(value string) error
String() string
}
type stringGeneric struct {
value string
}
func (s *stringGeneric) Set(value string) error {
s.value = value
return nil
}
func (s *stringGeneric) String() string {
return s.value
}
// GetValue returns the flags value as string representation and an empty
// string if the flag takes no value at all.
func (f *GenericFlag) GetValue() string {
if f.Value != nil {
return f.Value.String()
}
return ""
}
// GetDefaultText returns the default text for this flag
func (f *GenericFlag) GetDefaultText() string {
if f.DefaultText != "" {
return f.DefaultText
}
if f.defaultValue != nil {
return f.defaultValue.String()
}
return ""
}
// Apply takes the flagset and calls Set on the generic flag with the value
// provided by the user for parsing by the flag
func (f *GenericFlag) Apply(set *flag.FlagSet) error {
// set default value so that environment wont be able to overwrite it
if f.Value != nil {
f.defaultValue = &stringGeneric{value: f.Value.String()}
}
if val, source, found := flagFromEnvOrFile(f.EnvVars, f.FilePath); found {
if val != "" {
if err := f.Value.Set(val); err != nil {
return fmt.Errorf("could not parse %q from %s as value for flag %s: %s", val, source, f.Name, err)
}
f.HasBeenSet = true
}
}
for _, name := range f.Names() {
if f.Destination != nil {
set.Var(f.Destination, name, f.Usage)
continue
}
set.Var(f.Value, name, f.Usage)
}
return nil
}
// Get returns the flags value in the given Context.
func (f *GenericFlag) Get(ctx *Context) interface{} {
return ctx.Generic(f.Name)
}
// RunAction executes flag action if set
func (f *GenericFlag) RunAction(c *Context) error {
if f.Action != nil {
return f.Action(c, c.Generic(f.Name))
}
return nil
}
// Generic looks up the value of a local GenericFlag, returns
// nil if not found
func (cCtx *Context) Generic(name string) interface{} {
if fs := cCtx.lookupFlagSet(name); fs != nil {
return lookupGeneric(name, fs)
}
return nil
}
func lookupGeneric(name string, set *flag.FlagSet) interface{} {
f := set.Lookup(name)
if f != nil {
parsed, err := f.Value, error(nil)
if err != nil {
return nil
}
return parsed
}
return nil
}