blob: e27773aadfd251935b548b3a22742246f3cd26a5 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
----------------------------------------------------------------------
-- |
-- Module : UTF8
-- Maintainer : AR
-- Stability : (stable)
-- Portability : (portable)
--
-- > CVS $Date: 2005/04/21 16:23:42 $
-- > CVS $Author: bringert $
-- > CVS $Revision: 1.5 $
--
-- From the Char module supplied with HBC.
-- code by Thomas Hallgren (Jul 10 1999)
-----------------------------------------------------------------------------
module GF.Text.UTF8 (decodeUTF8, encodeUTF8) where
-- | Take a Unicode string and encode it as a string
-- with the UTF8 method.
decodeUTF8 :: String -> String
decodeUTF8 "" = ""
decodeUTF8 (c:cs) | c < '\x80' = c : decodeUTF8 cs
decodeUTF8 (c:c':cs) | '\xc0' <= c && c <= '\xdf' &&
'\x80' <= c' && c' <= '\xbf' =
toEnum ((fromEnum c `mod` 0x20) * 0x40 + fromEnum c' `mod` 0x40) : decodeUTF8 cs
decodeUTF8 (c:c':c'':cs) | '\xe0' <= c && c <= '\xef' &&
'\x80' <= c' && c' <= '\xbf' &&
'\x80' <= c'' && c'' <= '\xbf' =
toEnum ((fromEnum c `mod` 0x10 * 0x1000) + (fromEnum c' `mod` 0x40) * 0x40 + fromEnum c'' `mod` 0x40) : decodeUTF8 cs
decodeUTF8 _ = error "UniChar.decodeUTF8: bad data"
encodeUTF8 :: String -> String
encodeUTF8 "" = ""
encodeUTF8 (c:cs) =
if c > '\x0000' && c < '\x0080' then
c : encodeUTF8 cs
else if c < toEnum 0x0800 then
let i = fromEnum c
in toEnum (0xc0 + i `div` 0x40) :
toEnum (0x80 + i `mod` 0x40) :
encodeUTF8 cs
else
let i = fromEnum c
in toEnum (0xe0 + i `div` 0x1000) :
toEnum (0x80 + (i `mod` 0x1000) `div` 0x40) :
toEnum (0x80 + i `mod` 0x40) :
encodeUTF8 cs
|
