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|
package flag
import (
"flag"
"fmt"
"strings"
"github.com/posener/complete"
)
// -- VarFlag
type VarFlag struct {
Name string
Aliases []string
Usage string
Default string
EnvVar string
Value flag.Value
Completion complete.Predictor
}
func (f *Set) VarFlag(i *VarFlag) {
f.vars = append(f.vars, i)
// If the flag is marked as hidden, just add it to the set and return to
// avoid unnecessary computations here. We do not want to add completions or
// generate help output for hidden flags.
if v, ok := i.Value.(FlagVisibility); ok && v.Hidden() {
f.Var(i.Value, i.Name, "")
return
}
// Calculate the full usage
usage := i.Usage
if len(i.Aliases) > 0 {
sentence := make([]string, len(i.Aliases))
for i, a := range i.Aliases {
sentence[i] = fmt.Sprintf(`"-%s"`, a)
}
aliases := ""
switch len(sentence) {
case 0:
// impossible...
case 1:
aliases = sentence[0]
case 2:
aliases = sentence[0] + " and " + sentence[1]
default:
sentence[len(sentence)-1] = "and " + sentence[len(sentence)-1]
aliases = strings.Join(sentence, ", ")
}
usage += fmt.Sprintf(" This is aliased as %s.", aliases)
}
if i.Default != "" {
usage += fmt.Sprintf(" The default is %s.", i.Default)
}
if i.EnvVar != "" {
usage += fmt.Sprintf(" This can also be specified via the %s "+
"environment variable.", i.EnvVar)
}
// Add aliases to the main set
for _, a := range i.Aliases {
f.unionSet.Var(i.Value, a, "")
}
f.Var(i.Value, i.Name, usage)
f.completions["-"+i.Name] = i.Completion
}
// Var is a lower-level API for adding something to the flags. It should be used
// wtih caution, since it bypasses all validation. Consider VarFlag instead.
func (f *Set) Var(value flag.Value, name, usage string) {
f.unionSet.Var(value, name, usage)
f.flagSet.Var(value, name, usage)
}
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