cli: add Command.setup() (#7850)

vlib/cli/README.md

@@ -0,0 +1,30 @@
+Usage example:
+
+```v
+module main
+
+import os
+import cli
+
+fn main() {
+	mut app := cli.Command{
+		name: 'example-app'
+		description: 'example-app'
+		execute: fn (cmd cli.Command) ? {
+			println('hello app')
+			return
+		}
+		commands: [
+			cli.Command{
+				name: 'sub'
+				execute: fn (cmd cli.Command) ? {
+					println('hello subcommand')
+					return
+				}
+			},
+		]
+	}
+	app.setup()
+	app.parse(os.args)
+}
+```

vlib/cli/command.v

@@ -89,6 +89,13 @@ pub fn (mut cmd Command) add_command(command Command) {
 	cmd.commands << subcmd
 }
 
+pub fn (mut cmd Command) setup() {
+	for mut subcmd in cmd.commands {
+		subcmd.parent = cmd
+		subcmd.setup()
+	}
+}
+
 pub fn (mut cmd Command) add_flags(flags []Flag) {
 	for flag in flags {
 		cmd.add_flag(flag)

vlib/cli/command_test.v

@@ -145,6 +145,27 @@ fn test_if_global_flag_gets_set_in_subcommand() {
 	cmd.parse(['command', '-flag', 'value', 'subcommand'])
 }
 
+fn test_command_setup() {
+	mut cmd := cli.Command{
+		name: 'root'
+		commands: [
+			cli.Command{
+				name: 'child'
+				commands: [
+					cli.Command{
+						name: 'child-child'
+					},
+				]
+			},
+		]
+	}
+	assert isnil(cmd.commands[0].parent)
+	assert isnil(cmd.commands[0].commands[0].parent)
+	cmd.setup()
+	assert cmd.commands[0].parent.name == 'root'
+	assert cmd.commands[0].commands[0].parent.name == 'child'
+}
+
 // helper functions
 fn empty_func(cmd cli.Command) ? {
 }