{--
JVM-Bridge -- bridge from FP languages and others to the Java VM
Copyright (C) 2001 Ashley Yakeley <ashley@semantic.org>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
--}

module Platform.JavaVM.Types.Text where
	{
	import Platform.JavaVM.Types.Types;
	import Data.String;
	import Data.Bytes;
	import Data.Word;
	import Data.Bits;

	{--
	0000 0000-0000 007F   0xxxxxxx
	0000 0080-0000 07FF   110xxxxx 10xxxxxx
	0000 0800-0000 FFFF   1110xxxx 10xxxxxx 10xxxxxx
	0001 0000-001F FFFF   11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
	0020 0000-03FF FFFF   111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
	0400 0000-7FFF FFFF   1111110x 10xxxxxx ... 10xxxxxx
	--}
	
	type JavaString = [Jchar];

	type ClassName	= JavaString;
	type MemberName	= JavaString;
	
	toJChar :: Char -> Jchar;
	toJChar c = fromIntegral (fromEnum c);
	
	showJChar :: Jchar -> Char;
	showJChar c = toEnum (fromIntegral c);
	
	instance IsString JavaString where
		{
		fromString = fmap toJChar;
		};
	
	showJavaString :: JavaString -> String;
	showJavaString = fmap showJChar;
	
	showUTF8 :: [Word8] -> String;
	showUTF8 = fmap (\c -> showJChar (upWord16 c));
	
	shiftToByte :: Int -> Jchar -> Word8;
	shiftToByte i c = lo8 (shiftR c i);
	
	trailingByte :: Int -> Jchar -> Word8;
	trailingByte i c = 0x80 .|. (0x3F .&. (shiftToByte i c));
	
	encodeSingleUTF8 :: Jchar -> [Word8];
	encodeSingleUTF8 c = if (c < 0x0080) then [lo8 c]
		else if (c < 0x800) then
			[
			0xC0 .|. (shiftToByte 6 c),
			trailingByte 0 c
			]
		else
			[
			0xE0 .|. (shiftToByte 12 c),
			trailingByte 6 c,
			trailingByte 0 c
			];

	-- note: doesn't handle UTF-16 surrogates correctly
	encodeUTF8 :: JavaString -> [Word8];
	encodeUTF8 s = foldr prependOne [] s where
		{
		prependOne c bytes = (encodeSingleUTF8 c) ++ bytes;
		};
	}