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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"flag"
"fmt"
"io"
"os"
"strings"
"template"
)
// A Command is an implementation of a go command
// like go build or go fix.
type Command struct {
// Run runs the command.
// The args are the arguments after the command name.
Run func(cmd *Command, args []string)
// UsageLine is the one-line usage message.
// The first word in the line is taken to be the command name.
UsageLine string
// Short is the short description shown in the 'go help' output.
Short string
// Long is the long message shown in the 'go help <this-command>' output.
Long string
// Flag is a set of flags specific to this command.
Flag flag.FlagSet
}
// Name returns the command's name: the first word in the usage line.
func (c *Command) Name() string {
name := c.UsageLine
i := strings.Index(name, " ")
if i >= 0 {
name = name[:i]
}
return name
}
func (c *Command) Usage() {
fmt.Fprintf(os.Stderr, "usage: %s\n\n", c.UsageLine)
fmt.Fprintf(os.Stderr, "%s\n", strings.TrimSpace(c.Long))
os.Exit(2)
}
// Commands lists the available commands and help topics.
// The order here is the order in which they are printed by 'go help'.
var commands = []*Command{
cmdBuild,
cmdClean,
cmdFix,
cmdFmt,
cmdGet,
cmdInstall,
cmdList,
cmdTest,
cmdVersion,
cmdVet,
helpGopath,
helpImportpath,
helpRemote,
}
func main() {
flag.Usage = usage
flag.Parse()
args := flag.Args()
if len(args) < 1 {
usage()
}
if args[0] == "help" {
help(args[1:])
return
}
for _, cmd := range commands {
if cmd.Name() == args[0] && cmd.Run != nil {
cmd.Flag.Usage = func() { cmd.Usage() }
cmd.Flag.Parse(args[1:])
args = cmd.Flag.Args()
cmd.Run(cmd, args)
return
}
}
fmt.Fprintf(os.Stderr, "Unknown command %#q\n\n", args[0])
usage()
}
var usageTemplate = `usage: go command [arguments]
go manages Go source code.
The commands are:
{{range .}}{{if .Run}}
{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
Use "go help [command]" for more information about a command.
Additional help topics:
{{range .}}{{if not .Run}}
{{.Name | printf "%-11s"}} {{.Short}}{{end}}{{end}}
Use "go help [topic]" for more information about that topic.
`
var helpTemplate = `{{if .Run}}usage: go {{.UsageLine}}
{{end}}{{.Long | trim}}
`
// tmpl executes the given template text on data, writing the result to w.
func tmpl(w io.Writer, text string, data interface{}) {
t := template.New("top")
t.Funcs(template.FuncMap{"trim": strings.TrimSpace})
template.Must(t.Parse(text))
if err := t.Execute(w, data); err != nil {
panic(err)
}
}
func printUsage(w io.Writer) {
tmpl(w, usageTemplate, commands)
}
func usage() {
printUsage(os.Stderr)
os.Exit(2)
}
// help implements the 'help' command.
func help(args []string) {
if len(args) == 0 {
printUsage(os.Stdout)
// not exit 2: succeeded at 'go help'.
return
}
if len(args) != 1 {
fmt.Fprintf(os.Stderr, "usage: go help command\n\nToo many arguments given.\n")
os.Exit(2) // failed at 'go help'
}
arg := args[0]
for _, cmd := range commands {
if cmd.Name() == arg {
tmpl(os.Stdout, helpTemplate, cmd)
// not exit 2: succeeded at 'go help cmd'.
return
}
}
fmt.Fprintf(os.Stderr, "Unknown help topic %#q. Run 'go help'.\n", arg)
os.Exit(2) // failed at 'go help cmd'
}
// importPaths returns the import paths to use for the given command line.
func importPaths(args []string) []string {
// TODO: "all"
if len(args) == 0 {
return []string{"."}
}
return args
}
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