diff options
Diffstat (limited to 'src/GF/Text/UTF8.hs')
| -rw-r--r-- | src/GF/Text/UTF8.hs | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/src/GF/Text/UTF8.hs b/src/GF/Text/UTF8.hs new file mode 100644 index 000000000..57b711b4b --- /dev/null +++ b/src/GF/Text/UTF8.hs @@ -0,0 +1,35 @@ +module UTF8 where + +-- From the Char module supplied with HBC. +-- code by Thomas Hallgren (Jul 10 1999) + +-- 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 |