Autocomplete a command's args

app.go

@@ -670,10 +670,10 @@ func (a *Application) completionOptions(context *ParseContext) []string {
 			}
 		}
 		return options
-	} else {
-		// Perform completion for sub commands.
-		return target.CmdCompletion()
 	}
+
+	// Perform completion for sub commands and arguments.
+	return target.CmdCompletion()
 }
 
 func (a *Application) generateBashCompletion(context *ParseContext) {

app_test.go

@@ -244,13 +244,21 @@ func TestBashCompletionOptions(t *testing.T) {
 	two.Flag("flag-2", "").String()
 	two.Flag("flag-3", "").HintOptions("opt4", "opt5", "opt6").String()
 
+	three := a.Command("three", "")
+	three.Flag("flag-4", "").String()
+	three.Arg("arg-1", "").String()
+	three.Arg("arg-2", "").HintOptions("arg-2-opt-1", "arg-2-opt-2").String()
+	three.Arg("arg-3", "").HintAction(func() []string {
+		return []string{"arg-3-opt-1", "arg-3-opt-2"}
+	}).String()
+
 	cases := []struct {
 		Args            string
 		ExpectedOptions []string
 	}{
 		{
 			Args:            "--completion-bash",
-			ExpectedOptions: []string{"help", "one", "two"},
+			ExpectedOptions: []string{"help", "one", "three", "two"},
 		},
 		{
 			Args:            "--completion-bash --",
@@ -263,7 +271,7 @@ func TestBashCompletionOptions(t *testing.T) {
 		{
 			// No options available for flag-0, return to cmd completion
 			Args:            "--completion-bash --flag-0",
-			ExpectedOptions: []string{"help", "one", "two"},
+			ExpectedOptions: []string{"help", "one", "three", "two"},
 		},
 		{
 			Args:            "--completion-bash --flag-0 --",
@@ -279,7 +287,7 @@ func TestBashCompletionOptions(t *testing.T) {
 		},
 		{
 			Args:            "--completion-bash --flag-1 opt1",
-			ExpectedOptions: []string{"help", "one", "two"},
+			ExpectedOptions: []string{"help", "one", "three", "two"},
 		},
 		{
 			Args:            "--completion-bash --flag-1 opt1 --",
@@ -334,6 +342,28 @@ func TestBashCompletionOptions(t *testing.T) {
 			Args:            "--completion-bash two --flag-3 opt4 --",
 			ExpectedOptions: []string{"--help", "--flag-2", "--flag-3", "--flag-0", "--flag-1"},
 		},
+
+		// Args complete
+		{
+			// After a command with arg options
+			Args:            "--completion-bash three ",
+			ExpectedOptions: []string{"arg-2-opt-1", "arg-2-opt-2", "arg-3-opt-1", "arg-3-opt-2"},
+		},
+		{
+			// But not after flag start
+			Args:            "--completion-bash three --",
+			ExpectedOptions: []string{"--flag-0", "--flag-1", "--flag-4", "--help"},
+		},
+		{
+			// Completes args after one already listed
+			Args:            "--completion-bash three firstArg ",
+			ExpectedOptions: []string{"arg-2-opt-1", "arg-2-opt-2", "arg-3-opt-1", "arg-3-opt-2"},
+		},
+		{
+			// Completes args after a flag
+			Args:            "--completion-bash three firstArg --flag-4 ",
+			ExpectedOptions: []string{"arg-2-opt-1", "arg-2-opt-2", "arg-3-opt-1", "arg-3-opt-2"},
+		},
 	}
 
 	for _, c := range cases {

args.go

@@ -64,6 +64,7 @@ func (a *argGroup) init() error {
 type ArgClause struct {
 	actionMixin
 	parserMixin
+	completionsMixin
 	name          string
 	help          string
 	defaultValues []string
@@ -107,6 +108,20 @@ func (a *ArgClause) PreAction(action Action) *ArgClause {
 	return a
 }
 
+// HintAction registers a HintAction (function) for the arg to provide completions
+func (a *ArgClause) HintAction(action HintAction) *ArgClause {
+	a.addHintAction(action)
+	return a
+}
+
+// HintOptions registers any number of options for the flag to provide completions
+func (a *ArgClause) HintOptions(options ...string) *ArgClause {
+	a.addHintAction(func() []string {
+		return options
+	})
+	return a
+}
+
 func (a *ArgClause) init() error {
 	if a.required && len(a.defaultValues) > 0 {
 		return fmt.Errorf("required argument '%s' with unusable default value", a.name)

cmd.go

@@ -13,17 +13,18 @@ type cmdMixin struct {
 }
 
 func (c *cmdMixin) CmdCompletion() []string {
-	rv := []string{}
-	if len(c.cmdGroup.commandOrder) > 0 {
-		// This command has subcommands. We should
-		// show these to the user.
-		for _, option := range c.cmdGroup.commandOrder {
-			rv = append(rv, option.name)
-		}
-	} else {
-		// No subcommands
-		rv = nil
+	var rv []string
+
+	// If this command has subcommands, we should show these to the user.
+	for _, option := range c.cmdGroup.commandOrder {
+		rv = append(rv, option.name)
 	}
+
+	// Add any completions from args as well
+	for _, arg := range c.argGroup.args {
+		rv = append(rv, arg.resolveCompletions()...)
+	}
+
 	return rv
 }