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package cli
import (
"errors"
"flag"
"fmt"
"io"
"strings"
)
var ErrUnknownCommand = errors.New("error: unknown command")
type SubcommandFunc = func(*flag.FlagSet) error
type Subcommand struct {
FlagSet *flag.FlagSet
Usage string
Func SubcommandFunc
}
type SubcommandGroup struct {
subcommands map[string]Subcommand
output io.Writer
errorHandling flag.ErrorHandling
}
func NewSubcommandGroup(output io.Writer, errorHandling flag.ErrorHandling) SubcommandGroup {
return SubcommandGroup{subcommands: make(map[string]Subcommand), output: output, errorHandling: errorHandling}
}
func (sg *SubcommandGroup) AddSubcommand(name string, usage string, fn SubcommandFunc) {
fs := flag.NewFlagSet(name, sg.errorHandling)
fs.SetOutput(sg.output)
sg.subcommands[name] = Subcommand{
FlagSet: fs,
Usage: usage,
Func: fn,
}
}
func (sg SubcommandGroup) ExecSubcommand(name string) error {
cmd, ok := sg.subcommands[name]
if !ok {
return ErrUnknownCommand
}
return cmd.Func(cmd.FlagSet)
}
func (sg SubcommandGroup) Usage() string {
var b strings.Builder
b.WriteString(" subcommands:\n")
for _, cmd := range sg.subcommands {
fmt.Fprintf(&b, " %s: %s\n", cmd.FlagSet.Name(), cmd.Usage)
}
return b.String()
}
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