Add zs generate command for generating partial fragments

main.go

@@ -199,6 +199,22 @@ var BuildCmd = &cobra.Command{
 	},
 }
 
+// GenerateCmd is the generate sub-command that builds partial fragments
+var GenerateCmd = &cobra.Command{
+	Use:     "generate",
+	Aliases: []string{"gen"},
+	Short:   "Generates partial fragments",
+	Long:    `The generate command parses and renders partial fragments from stdin and writes to stdout`,
+	Args:    cobra.RangeArgs(0, 1),
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := generate(os.Stdin, os.Stdout, globals()); err != nil {
+			return fmt.Errorf("error generating fragment: %w", err)
+		}
+
+		return nil
+	},
+}
+
 // ServeCmd is the serve sub-command that performs whole builds or single builds
 var ServeCmd = &cobra.Command{
 	Use:   "serve [flags]",
@@ -632,6 +648,26 @@ func buildAll(ctx context.Context, watch bool) error {
 	}
 }
 
+// gen generates partial fragments
+func generate(r io.Reader, w io.Writer, v Vars) error {
+	data, err := io.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	body := string(data)
+
+	source, err := render(body, v)
+	if err != nil {
+		return err
+	}
+
+	if err := Parser.Convert([]byte(source), w); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 // serve runs a static web server and builds and continuously watches for changes to rebuild
 func serve(ctx context.Context, bind, root string) error {
 	os.Mkdir(root, 0755)
@@ -700,6 +736,7 @@ func init() {
 	ServeCmd.Flags().StringP("root", "r", PUBDIR, "set the root directory to serve")
 
 	RootCmd.AddCommand(BuildCmd)
+	RootCmd.AddCommand(GenerateCmd)
 	RootCmd.AddCommand(ServeCmd)
 	RootCmd.AddCommand(VarCmd)
 	RootCmd.AddCommand(WatchCmd)