Add hb_ot_tag_to_script()

src/hb-ot-tag.c

@@ -134,6 +134,20 @@ hb_ot_tags_from_script (hb_script_t script)
   return ot_scripts[script];
 }
 
+hb_script_t
+hb_ot_tag_to_script (hb_tag_t tag)
+{
+  int i;
+
+  for (i = 0; i < ARRAY_LENGTH (ot_scripts); i++) {
+    hb_tag_t *p = ot_scripts[i];
+    while (*p)
+      if (tag == *p)
+        return i;
+  }
+
+  return HB_SCRIPT_UNKNOWN;
+}
 
 typedef struct {
   char language[6];

src/hb-ot-tag.h

@@ -38,6 +38,9 @@ HB_BEGIN_DECLS
 const hb_tag_t *
 hb_ot_tags_from_script (hb_script_t script);
 
+hb_script_t
+hb_ot_tag_to_script (hb_tag_t tag);
+
 hb_tag_t
 hb_ot_tag_from_language (hb_language_t language);