Allow to chain subcommands using `command.Use(subcommandName, subcommand)`.

commands/args.go

@@ -72,6 +72,10 @@ func (a *Args) LastParam() string {
 	return a.Params[a.ParamsSize()-1]
 }
 
+func (a *Args) HasSubcommand() bool {
+	return !a.IsParamsEmpty() && a.Params[0][0] != '-'
+}
+
 func (a *Args) InsertParam(i int, items ...string) {
 	if i < 0 || (i != 0 && i > a.ParamsSize()-1) {
 		panic(fmt.Sprintf("Index %d is out of bound", i))

commands/commands.go

@@ -3,6 +3,7 @@ package commands
 import (
 	"flag"
 	"fmt"
+	"os"
 	"strings"
 )
 
@@ -20,6 +21,50 @@ type Command struct {
 	Short        string
 	Long         string
 	GitExtension bool
+
+	subCommands map[string]*Command
+}
+
+func (c *Command) Call(args *Args) (err error) {
+	runCommand := c
+	if len(c.subCommands) > 0 && args.HasSubcommand() {
+		subCommandName := args.FirstParam()
+		if subCommand, ok := c.subCommands[subCommandName]; ok {
+			runCommand = subCommand
+			args.Params = args.Params[1:]
+		} else {
+			fmt.Printf("error: Unknown subcommand: %s\n", subCommandName)
+			c.PrintUsage()
+			os.Exit(1)
+		}
+	}
+
+	if err = c.parseArguments(args); err != nil {
+		return
+	}
+
+	runCommand.Run(runCommand, args)
+	return
+}
+
+func (c *Command) parseArguments(args *Args) (err error) {
+	if err := c.Flag.Parse(args.Params); err != nil {
+		if err == flag.ErrHelp {
+			return nil
+		} else {
+			return err
+		}
+	}
+
+	args.Params = c.Flag.Args()
+	return
+}
+
+func (c *Command) Use(name string, subCommand *Command) {
+	if c.subCommands == nil {
+		c.subCommands = make(map[string]*Command)
+	}
+	c.subCommands[name] = subCommand
 }
 
 func (c *Command) PrintUsage() {
@@ -77,7 +122,6 @@ var GitHub = []*Command{
 	cmdCiStatus,
 	cmdBrowse,
 	cmdCompare,
-	cmdReleases,
 	cmdRelease,
 	cmdIssue,
 }

commands/release.go

@@ -16,15 +16,15 @@ import (
 )
 
 var (
-	cmdReleases = &Command{
-		Run:   releases,
-		Usage: "releases",
+	cmdRelease = &Command{
+		Run:   release,
+		Usage: "release",
 		Short: "Retrieve releases from GitHub",
 		Long:  `Retrieve releases from GitHub for the project that the "origin" remote points to.`}
 
-	cmdRelease = &Command{
-		Run:   release,
-		Usage: "release [-d] [-p] [-a <ASSETS_DIR>] [-m <MESSAGE>|-f <FILE>] TAG",
+	cmdCreateRelease = &Command{
+		Run:   createRelease,
+		Usage: "release create [-d] [-p] [-a <ASSETS_DIR>] [-m <MESSAGE>|-f <FILE>] TAG",
 		Short: "Create a new release in GitHub",
 		Long: `Create a new release in GitHub for the project that the "origin" remote points to.
 - It requires the name of the tag to release as a first argument.
@@ -42,6 +42,8 @@ var (
 )
 
 func init() {
+	cmdRelease.Use("create", cmdCreateRelease)
+
 	cmdRelease.Flag.BoolVar(&flagReleaseDraft, "d", false, "DRAFT")
 	cmdRelease.Flag.BoolVar(&flagReleasePrerelease, "p", false, "PRERELEASE")
 	cmdRelease.Flag.StringVar(&flagReleaseAssetsDir, "a", "", "ASSETS_DIR")
@@ -49,7 +51,7 @@ func init() {
 	cmdRelease.Flag.StringVar(&flagReleaseFile, "f", "", "FILE")
 }
 
-func releases(cmd *Command, args *Args) {
+func release(cmd *Command, args *Args) {
 	runInLocalRepo(func(localRepo *github.GitHubRepo, project *github.Project, gh *github.Client) {
 		if args.Noop {
 			fmt.Printf("Would request list of releases for %s\n", project)
@@ -67,7 +69,7 @@ func releases(cmd *Command, args *Args) {
 	})
 }
 
-func release(cmd *Command, args *Args) {
+func createRelease(cmd *Command, args *Args) {
 	if args.IsParamsEmpty() {
 		utils.Check(fmt.Errorf("Missed argument TAG"))
 		return

commands/runner.go

@@ -1,7 +1,6 @@
 package commands
 
 import (
-	"flag"
 	"fmt"
 	"github.com/jingweno/gh/cmd"
 	"github.com/jingweno/gh/git"
@@ -59,21 +58,14 @@ func (r *Runner) Execute() ExecError {
 				cmd.Flag.Usage = func() {
 					cmd.PrintUsage()
 				}
-				if err := cmd.Flag.Parse(args.Params); err != nil {
-					if err == flag.ErrHelp {
-						return newExecError(nil)
-					} else {
-						return newExecError(err)
-					}
-				}
-
-				args.Params = cmd.Flag.Args()
 			}
 
-			cmd.Run(cmd, args)
+			err := cmd.Call(args)
+			if err != nil {
+				return newExecError(err)
+			}
 
 			cmds := args.Commands()
-			var err error
 			if args.Noop {
 				printCommands(cmds)
 			} else {