public static boolean checkCyclicInheritance(Language lang) {
List<Language> frontier = ModuleUtil.refsToLanguages(lang.getExtendedLanguageRefs());
ArrayList<Language> passed = new ArrayList<Language>();
while (!frontier.isEmpty()) {
List<Language> newFrontier = new ArrayList<Language>();
for (Language extendedLang : frontier) {
if (extendedLang == lang && lang != BootstrapLanguages.coreLanguage()) {
return false;
}
if (!passed.contains(extendedLang)) {
newFrontier.addAll(ModuleUtil.refsToLanguages(extendedLang.getExtendedLanguageRefs()));
}
passed.add(extendedLang);
}
frontier = newFrontier;
}
return true;
}
