120 lines
2.5 KiB
Go
120 lines
2.5 KiB
Go
// Handler to make management of subcommands easier.
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"flag"
|
|
"os"
|
|
)
|
|
|
|
type (
|
|
Command struct {
|
|
Use string // command name (used for matching)
|
|
Short string // a short description to display
|
|
Long string // a long help text
|
|
Example string // an example string
|
|
Run func(*Command, []string) // the command to run
|
|
|
|
flagSet *flag.FlagSet // internal flagset with all flags
|
|
commands []*Command // the list of subcommands
|
|
}
|
|
)
|
|
|
|
// This function adds a new sub command.
|
|
func (c *Command) AddCommand(cmds... *Command) {
|
|
res := c.commands
|
|
for _, cmd := range cmds {
|
|
res = append(res, cmd)
|
|
}
|
|
c.commands = res
|
|
}
|
|
|
|
// Evaluate the arguments and call either the subcommand or parse it as flags.
|
|
func (c *Command) eval(args []string) error {
|
|
var name string = ""
|
|
var rest []string = []string{}
|
|
|
|
if len(args) > 0 {
|
|
name = args[0]
|
|
}
|
|
if len(args) > 1 {
|
|
rest = args[1:]
|
|
}
|
|
|
|
if name == "help" {
|
|
c.Help(rest)
|
|
return nil
|
|
}
|
|
|
|
for _, cmd := range c.commands {
|
|
if cmd.Use == name {
|
|
return cmd.eval(rest)
|
|
}
|
|
}
|
|
if err := c.Flags().Parse(args); err != nil { return err }
|
|
if c.Run != nil {
|
|
c.Run(c, rest)
|
|
} else {
|
|
c.Help(rest)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Execute the command. It will fetch os.Args[1:] itself.
|
|
func (c *Command) Execute() error {
|
|
return c.eval(os.Args[1:])
|
|
}
|
|
|
|
// Return the flagset currently in use.
|
|
func (c *Command) Flags() *flag.FlagSet {
|
|
if c.flagSet == nil {
|
|
c.flagSet = flag.NewFlagSet(c.Use, flag.ContinueOnError)
|
|
}
|
|
return c.flagSet
|
|
}
|
|
|
|
// Print the help for the current command or a subcommand.
|
|
func (c *Command) Help(args []string) {
|
|
if len(args) > 0 {
|
|
for _, cmd := range c.commands {
|
|
if args[0] == cmd.Use {
|
|
cmd.Help([]string{})
|
|
return
|
|
}
|
|
}
|
|
}
|
|
if c.Long != "" { fmt.Println(c.Long, "\n") }
|
|
c.Usage()
|
|
}
|
|
|
|
// Print the usage information.
|
|
func (c *Command) Usage() {
|
|
usage := ""
|
|
if c.Use != "" {
|
|
usage = usage + " " + c.Use
|
|
}
|
|
if len(c.commands) > 0 {
|
|
usage = usage + " command"
|
|
}
|
|
if c.flagSet != nil {
|
|
usage = usage + " [flags]"
|
|
}
|
|
fmt.Printf("Usage: %s%s\n", os.Args[0], usage)
|
|
|
|
if len(c.commands) > 0 {
|
|
fmt.Printf("\nwhere command is one of:\n")
|
|
for _, cmd := range c.commands {
|
|
fmt.Printf("\t%s\t\t%s\n", cmd.Use, cmd.Short)
|
|
}
|
|
}
|
|
if c.flagSet != nil {
|
|
fmt.Printf("\nwhere flags is any of:\n")
|
|
c.Flags().SetOutput(os.Stdout)
|
|
c.Flags().PrintDefaults()
|
|
}
|
|
if c.Example != "" {
|
|
fmt.Println("\nexample:")
|
|
fmt.Printf("\t%s\n", c.Example)
|
|
}
|
|
}
|