glock.go

package main

import (
	"flag"
	"fmt"
	"io"
	"os"
	"strings"
	"text/template"
)

// Used in vcs.go and http.go to print detailed stuff about go get.
// Also used to enable output from the debug() function declared in util.go.
var buildV bool

type Command struct {
	Run       func(cmd *Command, args []string)
	UsageLine string
	Short     string
	Long      string
	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)
}

// Runnable reports whether the command can be run; otherwise
// it is a documentation pseudo-command such as importpath.
func (c *Command) Runnable() bool {
	return c.Run != nil
}

// 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{
	cmdSave,
	cmdApply,
	cmdInstall,
	cmdSync,
	cmdCmd,
}

func main() {
	flag.BoolVar(&buildV, "v", false, "Verbose")
	flag.Usage = usage
	flag.Parse()

	args := flag.Args()
	if len(args) < 1 {
		usage()
	}

	if args[0] == "help" {
		usage()
		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)
			os.Exit(0)
			return
		}
	}

	usage()
}

func usage() {
	printUsage(os.Stderr)
	os.Exit(2)
}

func printUsage(w io.Writer) {
	tmpl(w, usageTemplate, commands)
}

func perror(err error) {
	fmt.Fprintln(os.Stderr, err)
	os.Exit(1)
}

// 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, "capitalize": capitalize})
	template.Must(t.Parse(text))
	if err := t.Execute(w, data); err != nil {
		panic(err)
	}
}

func envForDir(dir string) []string {
	env := os.Environ()
	// Internally we only use rooted paths, so dir is rooted.
	// Even if dir is not rooted, no harm done.
	return mergeEnvLists([]string{"PWD=" + dir}, env)
}

func mergeEnvLists(in, out []string) []string {
NextVar:
	for _, inkv := range in {
		k := strings.SplitAfterN(inkv, "=", 2)[0]
		for i, outkv := range out {
			if strings.HasPrefix(outkv, k) {
				out[i] = inkv
				continue NextVar
			}
		}
		out = append(out, inkv)
	}
	return out
}

var usageTemplate = `Glock is a tool for managing Go dependencies.

Usage:

	glock command [arguments]

The commands are:
{{range .}}
    {{.Name | printf "%-11s"}} {{.Short}}{{end}}

`