Level flg of xtree (#358)

* Add level flg for xtree

* fix test

Author: ddddddO

README.md

@@ -731,7 +731,7 @@ $ go install github.com/ddddddO/gtree/cmd/xtree@latest
 ```console
 $ xtree --help
 NAME:
-   xtree - This CLI uses {JSON|YAML|TOML} to generate directory tree
+   xtree - This CLI uses {JSON|YAML|TOML} to generate ASCII tree
 
 USAGE:
    xtree [global options] [command [command options]]
@@ -758,9 +758,10 @@ USAGE:
    xtree output [options]
 
 OPTIONS:
-   --omit-index, --omit, -o   set this option when you do not want to display array indices.
-   --allow-duplicate, -a      set this option when you want to allow duplicate node names at the same level.
-   --help, -h                 show help
+   --omit-index, --omit, -o  set this option when you do not want to display array indices.
+   --allow-duplicate, -a     set this option when you want to allow duplicate node names at the same level.
+   --level int, -l int       set this option when you want to specify the depth of the tree.
+   --help, -h                show help
 ```
 
 #### JSON to tree
@@ -927,6 +928,73 @@ $ cat a.yaml | xtree output
         └── dark
 ```
 
+### Omit index flg
+```console
+$ cat a.json | xtree output --omit-index
+.
+├── age
+│   └── 30
+├── devices
+│   ├── os
+│   │   ├── ios
+│   │   └── windows
+│   └── type
+│       ├── mobile
+│       └── desktop
+├── height
+│   └── 175.5
+├── is_active
+│   └── true
+├── metadata
+│   └── <nil>
+├── name
+│   └── Alice
+├── roles
+│   ├── admin
+│   └── editor
+└── settings
+    ├── notifications
+    │   └── true
+    └── theme
+        └── dark
+```
+
+### Level flg
+```console
+$ cat a.json | xtree output --level 1
+.
+├── age
+├── devices
+├── height
+├── is_active
+├── metadata
+├── name
+├── roles
+└── settings
+
+$ cat a.json | xtree output --level 2 --omit-index
+.
+├── age
+│   └── 30
+├── devices
+│   ├── os
+│   └── type
+├── height
+│   └── 175.5
+├── is_active
+│   └── true
+├── metadata
+│   └── <nil>
+├── name
+│   └── Alice
+├── roles
+│   ├── admin
+│   └── editor
+└── settings
+    ├── notifications
+    └── theme
+```
+
 # Process
 
 > [!NOTE]

cmd/xtree/main.go

@@ -25,7 +25,7 @@ var (
 func main() {
 	app := &cli.Command{
 		Name:    "xtree",
-		Usage:   "This CLI uses {JSON|YAML|TOML} to generate directory tree",
+		Usage:   "This CLI uses {JSON|YAML|TOML} to generate ASCII tree",
 		Version: fmt.Sprintf("%s / revision %s", Version, Revision),
 		Commands: []*cli.Command{
 			{
@@ -44,6 +44,12 @@ func main() {
 						Aliases: []string{"a"},
 						Usage:   "set this option when you want to allow duplicate node names at the same level.",
 					},
+					&cli.IntFlag{
+						Name:        "level",
+						Aliases:     []string{"l"},
+						Usage:       "set this option when you want to specify the depth of the tree.",
+						HideDefault: true,
+					},
 				},
 				Before: notExistArgs,
 				Action: actionOutput,
@@ -72,11 +78,15 @@ func actionOutput(ctx context.Context, c *cli.Command) error {
 		root = gtree.NewRoot(".", gtree.WithDuplicationAllowed())
 	}
 	omitIndex := c.Bool("omit-index")
+	level := c.Int("level")
+	if c.IsSet("level") && level <= 0 {
+		return errors.New("invalid level, must be greater than 0.")
+	}
 
-	return output(os.Stdout, os.Stdin, root, omitIndex)
+	return output(os.Stdout, os.Stdin, root, omitIndex, level)
 }
 
-func output(w io.Writer, r io.Reader, root *gtree.Node, omitIndex bool) error {
+func output(w io.Writer, r io.Reader, root *gtree.Node, omitIndex bool, level int) error {
 	input, err := io.ReadAll(r)
 	if err != nil {
 		return err
@@ -87,12 +97,20 @@ func output(w io.Writer, r io.Reader, root *gtree.Node, omitIndex bool) error {
 	}
 	walk(root, "", data, omitIndex)
 
+	limit := level + 1
 	for wn, err := range gtree.WalkIterFromRoot(root) {
 		if err != nil {
 			return err
 		}
 
-		fmt.Fprintln(w, wn.Row())
+		if level == 0 {
+			fmt.Fprintln(w, wn.Row())
+			continue
+		}
+		if wn.Level() <= uint(limit) {
+			fmt.Fprintln(w, wn.Row())
+			continue
+		}
 	}
 
 	return nil

cmd/xtree/main_test.go

@@ -73,6 +73,7 @@ func TestOutput(t *testing.T) {
 		inputData      io.Reader
 		inputRoot      *gtree.Node
 		inputOmitIndex bool
+		inputLevel     int
 		want           string
 		wantErr        error
 	}{
@@ -537,7 +538,7 @@ func TestOutput(t *testing.T) {
 			t.Parallel()
 
 			ret := &bytes.Buffer{}
-			gotErr := output(ret, tt.inputData, tt.inputRoot, tt.inputOmitIndex)
+			gotErr := output(ret, tt.inputData, tt.inputRoot, tt.inputOmitIndex, tt.inputLevel)
 			gotOutput := ret.String()
 
 			if gotErr != nil {
@@ -559,6 +560,7 @@ func TestOutput_multiRow(t *testing.T) {
 		inputData      io.Reader
 		inputRoot      *gtree.Node
 		inputOmitIndex bool
+		inputLevel     int
 		want           string
 		wantErr        error
 	}{
@@ -633,7 +635,7 @@ config:
 			t.Parallel()
 
 			ret := &bytes.Buffer{}
-			gotErr := output(ret, tt.inputData, tt.inputRoot, tt.inputOmitIndex)
+			gotErr := output(ret, tt.inputData, tt.inputRoot, tt.inputOmitIndex, tt.inputLevel)
 			gotOutput := ret.String()
 
 			if gotErr != nil {