1 files changed, 16 insertions, 0 deletions
diff --git a/tex/context/base/mkiv/font-prv.lua b/tex/context/base/mkiv/font-prv.lua
index e613eb7d3..59b793444 100644
--- a/tex/context/base/mkiv/font-prv.lua
+++ b/tex/context/base/mkiv/font-prv.lua
@@ -83,6 +83,22 @@ function helpers.newprivateslot(name)
     return sharedprivates[name]
 end
 
+function helpers.isprivate(unicode)
+    if unicode < 0xD7FF or (unicode > 0xDFFF and unicode <= 0xFFFF) then
+        return false
+    elseif unicode >= 0x00E000 and unicode <= 0x00F8FF then
+        return true
+    elseif unicode >= 0x0F0000 and unicode <= 0x0FFFFF then
+        return true
+    elseif unicode >= 0x100000 and unicode <= 0x10FFFF then
+        return true
+    elseif unicode >= 0x00D800 and unicode <= 0x00DFFF then
+        return true
+    else
+        return false
+    end
+end
+
 do
 
     local context = context