[unicode] Address comments in PR#314.

1 files changed, 4 insertions, 23 deletions

diff --git a/lib/unicode.ml b/lib/unicode.ml
index 3ac4e8ca7c..959ccaf73c 100644
--- a/lib/unicode.ml
+++ b/lib/unicode.ml
@@ -124,30 +124,11 @@ exception End_of_input
 let utf8_of_unicode n =
   if n < 128 then
     String.make 1 (Char.chr n)
-  else if n < 2048 then
-    String.init 2 (fun idx ->
-        match idx with
-        | 0 -> Char.chr (192 + n / 64)
-        | 1 -> Char.chr (128 + n mod 64)
-        | _ -> 'x'
-      )
-  else if n < 65536 then
-    String.init 3 (fun idx ->
-        match idx with
-        | 0 -> Char.chr (224 + n / 4096)
-        | 1 -> Char.chr (128 + (n / 64) mod 64)
-        | 2 -> Char.chr (128 + n mod 64)
-        | _ -> 'x'
-      )
   else
-    String.init 4 (fun idx ->
-        match idx with
-        | 0 -> Char.chr (240 + n / 262144)
-        | 1 -> Char.chr (128 + (n / 4096) mod 64)
-        | 2 -> Char.chr (128 + (n / 64) mod 64)
-        | 4 -> Char.chr (128 + n mod 64)
-        | _ -> 'x'
-      )
+    let (m,s) = if n < 2048 then (2,192) else if n < 65536 then (3,224) else (4,240) in
+    String.init m (fun i ->
+        let j = (n lsr ((m - 1 - i) * 6)) land 63 in
+        Char.chr (j + if i = 0 then s else 128))
 
 (* If [s] is some UTF-8 encoded string
    and [i] is a position of some UTF-8 character within [s]