+static FcLangSet *
+FcLangSetOperate(const FcLangSet *a,
+ const FcLangSet *b,
+ FcBool (*func) (FcLangSet *ls,
+ const FcChar8 *s))
+{
+ FcLangSet *langset = FcLangSetCopy (a);
+ FcStrList *sl = FcStrListCreate (FcLangSetGetLangs (b));
+ FcChar8 *str;
+
+ while ((str = FcStrListNext (sl)))
+ {
+ func (langset, str);
+ }
+ FcStrListDone (sl);
+
+ return langset;
+}
+
+FcLangSet *
+FcLangSetUnion (const FcLangSet *a, const FcLangSet *b)
+{
+ return FcLangSetOperate(a, b, FcLangSetAdd);
+}
+
+FcLangSet *
+FcLangSetSubtract (const FcLangSet *a, const FcLangSet *b)
+{
+ return FcLangSetOperate(a, b, FcLangSetDel);
+}
+