Add command alias

README.md

@@ -15,8 +15,8 @@ Popular CLI libraries (or better frameworks) have too large and unclear API, in
 
 * Simple API.
 * Dependency-free.
-* Easy to integrate.
 * Clean and tested code.
+* Command aliases.
 * Auto suggesting command.
 * Builtin `help` and `version` commands.
 

acmd.go

@@ -31,9 +31,12 @@ type Runner struct {
 
 // Command specifies a sub-command for a program's command-line interface.
 type Command struct {
-	// Name is just a one-word.
+	// Name of the command, ex: `init`
 	Name string
 
+	// Alias is an optional short second name, ex: `i`.
+	Alias string
+
 	// Description of the command.
 	Description string
 
@@ -158,9 +161,15 @@ func validateCommand(cmd Command) error {
 	case cmd.Name == "help" || cmd.Name == "version":
 		return fmt.Errorf("command %q is reserved", cmd.Name)
 
+	case cmd.Alias == "help" || cmd.Alias == "version":
+		return fmt.Errorf("command alias %q is reserved", cmd.Alias)
+
 	case !cmdNameRE.MatchString(cmd.Name):
 		return fmt.Errorf("command %q must contains only letters, digits, - and _", cmd.Name)
 
+	case cmd.Alias != "" && !cmdNameRE.MatchString(cmd.Alias):
+		return fmt.Errorf("command alias %q must contains only letters, digits, - and _", cmd.Alias)
+
 	case len(cmds) != 0:
 		sort.Slice(cmds, func(i, j int) bool {
 			return cmds[i].Name < cmds[j].Name
@@ -171,7 +180,14 @@ func validateCommand(cmd Command) error {
 			if _, ok := names[cmd.Name]; ok {
 				return fmt.Errorf("duplicate command %q", cmd.Name)
 			}
+			if _, ok := names[cmd.Alias]; ok {
+				return fmt.Errorf("duplicate command alias %q", cmd.Alias)
+			}
+
 			names[cmd.Name] = struct{}{}
+			if cmd.Alias != "" {
+				names[cmd.Alias] = struct{}{}
+			}
 
 			if err := validateCommand(cmd); err != nil {
 				return err
@@ -196,7 +212,7 @@ func run(ctx context.Context, cfg Config, cmds []Command, args []string) error {
 	selected, params := args[0], args[1:]
 
 	for _, c := range cmds {
-		if c.Name == selected {
+		if selected == c.Name || selected == c.Alias {
 			return c.Do(ctx, params)
 		}
 	}

acmd_test.go

@@ -79,10 +79,18 @@ func TestRunnerInit(t *testing.T) {
 		cfg        Config
 		wantErrStr string
 	}{
+		{
+			cmds:       []Command{{Name: "", Do: nopFunc}},
+			wantErrStr: `command "" must contains only letters, digits, - and _`,
+		},
 		{
 			cmds:       []Command{{Name: "foo%", Do: nopFunc}},
 			wantErrStr: `command "foo%" must contains only letters, digits, - and _`,
 		},
+		{
+			cmds:       []Command{{Name: "foo", Alias: "%", Do: nopFunc}},
+			wantErrStr: `command alias "%" must contains only letters, digits, - and _`,
+		},
 		{
 			cmds:       []Command{{Name: "foo%", Do: nil}},
 			wantErrStr: `command "foo%" function cannot be nil`,
@@ -102,10 +110,30 @@ func TestRunnerInit(t *testing.T) {
 			cmds:       []Command{{Name: "version", Do: nopFunc}},
 			wantErrStr: `command "version" is reserved`,
 		},
+		{
+			cmds:       []Command{{Name: "foo", Alias: "help", Do: nopFunc}},
+			wantErrStr: `command alias "help" is reserved`,
+		},
+		{
+			cmds:       []Command{{Name: "foo", Alias: "version", Do: nopFunc}},
+			wantErrStr: `command alias "version" is reserved`,
+		},
 		{
 			cmds:       []Command{{Name: "a", Do: nopFunc}, {Name: "a", Do: nopFunc}},
 			wantErrStr: `duplicate command "a"`,
 		},
+		{
+			cmds:       []Command{{Name: "aaa", Do: nopFunc}, {Name: "b", Alias: "aaa", Do: nopFunc}},
+			wantErrStr: `duplicate command alias "aaa"`,
+		},
+		{
+			cmds:       []Command{{Name: "aaa", Alias: "a", Do: nopFunc}, {Name: "bbb", Alias: "a", Do: nopFunc}},
+			wantErrStr: `duplicate command alias "a"`,
+		},
+		{
+			cmds:       []Command{{Name: "a", Do: nopFunc}, {Name: "b", Alias: "a", Do: nopFunc}},
+			wantErrStr: `duplicate command alias "a"`,
+		},
 	}
 
 	for _, tc := range testCases {

example_test.go

@@ -133,6 +133,44 @@ func ExampleVersion() {
 	// Output: acmd-example version: the best v0.x.y
 }
 
+func ExampleAlias() {
+	testOut := os.Stdout
+	testArgs := []string{"f"}
+
+	cmds := []acmd.Command{
+		{
+			Name:  "foo",
+			Alias: "f",
+			Do: func(ctx context.Context, args []string) error {
+				fmt.Fprint(testOut, "foo")
+				return nil
+			},
+		},
+		{
+			Name:  "bar",
+			Alias: "b",
+			Do: func(ctx context.Context, args []string) error {
+				fmt.Fprint(testOut, "bar")
+				return nil
+			},
+		},
+	}
+
+	r := acmd.RunnerOf(cmds, acmd.Config{
+		AppName:        "acmd-example",
+		AppDescription: "Example of acmd package",
+		Version:        "the best v0.x.y",
+		Output:         testOut,
+		Args:           testArgs,
+	})
+
+	if err := r.Run(); err != nil {
+		panic(err)
+	}
+
+	// Output: foo
+}
+
 func ExampleAutosuggestion() {
 	testOut := os.Stdout
 	testArgs := []string{"baz"}