language/Language.php
public static function GetReverseGroupMap () {
		static $reverse_group_map;
		if (!isset($reverse_group_map)) {
			foreach (static::GetGroupMap() as $group_lang => $group_map) {
				foreach ($group_map as $lang) {
					$reverse_group_map[$lang] = $group_lang;
				}
			}
		}
		return $reverse_group_map;
	}
public static function GetReverseGroupMap () {
		static $reverse_group_map;
		if (!isset($reverse_group_map)) {
			foreach (static::GetGroupMap() as $group_lang => $group_map) {
				foreach ($group_map as $lang) {
					$reverse_group_map[$lang] = $group_lang;
				}
			}
		}
		return $reverse_group_map;
	}
言語グループの逆引きマップを返します。