feat: add (*cliz.Command).Next() (#133)

Author: ginokent

exp/cli/cli.go

@@ -109,8 +109,30 @@ func Default[T interface{}](v T) *T { return ptr[T](v) }
 
 func ptr[T interface{}](v T) *T { return &v }
 
-// GetSubcommand returns the subcommand if cmd contains the subcommand.
-func (cmd *Command) GetSubcommand(arg string) (subcmd *Command) {
+func (cmd *Command) GetName() string {
+	if cmd == nil {
+		return ""
+	}
+	return cmd.Name
+}
+
+func (cmd *Command) Next() *Command {
+	if cmd == nil {
+		return nil
+	}
+	if len(cmd.calledCommands) == 0 {
+		return nil
+	}
+	for _, subcmd := range cmd.SubCommands {
+		if len(subcmd.calledCommands) > 0 {
+			return subcmd
+		}
+	}
+	return nil
+}
+
+// getSubcommand returns the subcommand if cmd contains the subcommand.
+func (cmd *Command) getSubcommand(arg string) (subcmd *Command) {
 	for _, subcmd := range cmd.SubCommands {
 		if subcmd.Name == arg {
 			return subcmd
@@ -243,7 +265,7 @@ argsLoop:
 			}
 			return nil, nil, errorz.Errorf("%s: %w", arg, ErrUnknownOption)
 		default:
-			subcmd := cmd.GetSubcommand(arg)
+			subcmd := cmd.getSubcommand(arg)
 			// If subcmd is nil, it is not a subcommand.
 			if subcmd == nil {
 				cmd.remainingArgs = append(cmd.remainingArgs, arg)

exp/cli/cli_test.go

@@ -184,6 +184,34 @@ func TestCommand(t *testing.T) {
 			t.Fatalf("❌: %v: %+v", args, err)
 		}
 
+		if (*Command)(nil).Next() != nil {
+			t.Errorf("❌: expect != actual: %v != %v", nil, (*Command)(nil).Next())
+		}
+		if (&Command{}).Next() != nil {
+			t.Errorf("❌: expect != actual: %v != %v", nil, (&Command{}).Next())
+		}
+		switch c.GetName() {
+		case "my-cli":
+			switch c := c.Next(); c.GetName() {
+			case "sub-cmd":
+				switch c := c.Next(); c.GetName() {
+				case "sub-sub-cmd":
+					switch c := c.Next(); c.GetName() {
+					case "":
+						// OK
+					default:
+						t.Errorf("❌: expect != actual: %v != %v", "", c.GetName())
+					}
+				default:
+					t.Errorf("❌: expect != actual: %v != %v", "sub-sub-cmd", c.GetName())
+				}
+			default:
+				t.Errorf("❌: expect != actual: %v != %v", "sub-cmd", c.GetName())
+			}
+		default:
+			t.Errorf("❌: expect != actual: %v != %v", "my-cli", c.GetName())
+		}
+
 		if expect, actual := []string{"my-cli", "sub-cmd", "sub-sub-cmd"}, calledCommands; !reflect.DeepEqual(expect, actual) {
 			t.Errorf("❌: expect != actual: %v != %v", expect, actual)
 		}