godot get custom classes

main.gd

func get_custom_classes():
	#gets list of "custom" classes (defined using class_name keyword)
	var find_this = "_global_script_classes="
	
	var custom_classes_lines = PoolStringArray()
	var f = File.new()
	f.open("res://project.godot", File.READ)

	var add_lines = false

	while not f.eof_reached():

		var line = f.get_line()

		if line.begins_with(find_this):
			if "]" in line:
				f.close()
				return []

			add_lines = true


		if add_lines:
			custom_classes_lines.append(line)
			if "]" in line:
				break

	f.close()

	var strip_var_name_len = find_this.length()
	custom_classes_lines[0] = custom_classes_lines[0].substr(strip_var_name_len)
	
	return str2var(custom_classes_lines.join(''))