Reorganisation of the source tree

Most of the other users of the fptools build system have migrated to
Cabal, and with the move to darcs we can now flatten the source tree
without losing history, so here goes.

The main change is that the ghc/ subdir is gone, and most of what it
contained is now at the top level.  The build system now makes no
pretense at being multi-project, it is just the GHC build system.

No doubt this will break many things, and there will be a period of
instability while we fix the dependencies.  A straightforward build
should work, but I haven't yet fixed binary/source distributions.
Changes to the Building Guide will follow, too.

1 files changed, 373 insertions, 0 deletions

diff --git a/compiler/utils/Encoding.hs b/compiler/utils/Encoding.hs
new file mode 100644
index 0000000000..152bf3c60e
--- /dev/null
+++ b/compiler/utils/Encoding.hs
@@ -0,0 +1,373 @@
+-- -----------------------------------------------------------------------------
+--
+-- (c) The University of Glasgow, 1997-2006
+--
+-- Character encodings 
+--
+-- -----------------------------------------------------------------------------
+
+module Encoding ( 
+	-- * UTF-8
+	utf8DecodeChar#,
+	utf8PrevChar,
+	utf8CharStart,
+	utf8DecodeChar,
+	utf8DecodeString,
+	utf8EncodeChar,
+	utf8EncodeString,
+	utf8EncodedLength,
+	countUTF8Chars,
+
+	-- * Z-encoding
+	zEncodeString,
+	zDecodeString
+  ) where
+
+#define COMPILING_FAST_STRING
+#include "HsVersions.h"
+import Foreign
+import Data.Char	( ord, chr, isDigit, digitToInt, isHexDigit )
+import Numeric		( showHex )
+
+import Data.Bits
+import GHC.Ptr		( Ptr(..) )
+import GHC.Base
+
+-- -----------------------------------------------------------------------------
+-- UTF-8
+
+-- We can't write the decoder as efficiently as we'd like without
+-- resorting to unboxed extensions, unfortunately.  I tried to write
+-- an IO version of this function, but GHC can't eliminate boxed
+-- results from an IO-returning function.
+--
+-- We assume we can ignore overflow when parsing a multibyte character here.
+-- To make this safe, we add extra sentinel bytes to unparsed UTF-8 sequences
+-- before decoding them (see StringBuffer.hs).
+
+{-# INLINE utf8DecodeChar# #-}
+utf8DecodeChar# :: Addr# -> (# Char#, Addr# #)
+utf8DecodeChar# a# =
+  let ch0 = word2Int# (indexWord8OffAddr# a# 0#) in
+  case () of 
+    _ | ch0 <=# 0x7F# -> (# chr# ch0, a# `plusAddr#` 1# #)
+
+      | ch0 >=# 0xC0# && ch0 <=# 0xDF# ->
+	let ch1 = word2Int# (indexWord8OffAddr# a# 1#) in
+	if ch1 <# 0x80# || ch1 >=# 0xC0# then fail 1# else
+	(# chr# (((ch0 -# 0xC0#) `uncheckedIShiftL#` 6#) +#
+	   	  (ch1 -# 0x80#)),
+	   a# `plusAddr#` 2# #)
+
+      | ch0 >=# 0xE0# && ch0 <=# 0xEF# ->
+	let ch1 = word2Int# (indexWord8OffAddr# a# 1#) in
+	if ch1 <# 0x80# || ch1 >=# 0xC0# then fail 1# else
+	let ch2 = word2Int# (indexWord8OffAddr# a# 2#) in
+	if ch2 <# 0x80# || ch2 >=# 0xC0# then fail 2# else
+	(# chr# (((ch0 -# 0xE0#) `uncheckedIShiftL#` 12#) +#
+	   	 ((ch1 -# 0x80#) `uncheckedIShiftL#` 6#)  +#
+	    	  (ch2 -# 0x80#)),
+	   a# `plusAddr#` 3# #)
+
+     | ch0 >=# 0xF0# && ch0 <=# 0xF8# ->
+	let ch1 = word2Int# (indexWord8OffAddr# a# 1#) in
+	if ch1 <# 0x80# || ch1 >=# 0xC0# then fail 1# else
+	let ch2 = word2Int# (indexWord8OffAddr# a# 2#) in
+	if ch2 <# 0x80# || ch2 >=# 0xC0# then fail 2# else
+	let ch3 = word2Int# (indexWord8OffAddr# a# 3#) in
+	if ch3 <# 0x80# || ch3 >=# 0xC0# then fail 3# else
+	(# chr# (((ch0 -# 0xF0#) `uncheckedIShiftL#` 18#) +#
+		 ((ch1 -# 0x80#) `uncheckedIShiftL#` 12#) +#
+		 ((ch2 -# 0x80#) `uncheckedIShiftL#` 6#)  +#
+		  (ch3 -# 0x80#)),
+	   a# `plusAddr#` 4# #)
+
+      | otherwise -> fail 1#
+  where
+	-- all invalid sequences end up here:
+	fail n = (# '\0'#, a# `plusAddr#` n #)
+	-- '\xFFFD' would be the usual replacement character, but
+	-- that's a valid symbol in Haskell, so will result in a
+	-- confusing parse error later on.  Instead we use '\0' which
+	-- will signal a lexer error immediately.
+
+utf8DecodeChar :: Ptr Word8 -> (Char, Ptr Word8)
+utf8DecodeChar (Ptr a#) = 
+  case utf8DecodeChar# a# of (# c#, b# #) -> ( C# c#, Ptr b# )
+
+-- UTF-8 is cleverly designed so that we can always figure out where
+-- the start of the current character is, given any position in a
+-- stream.  This function finds the start of the previous character,
+-- assuming there *is* a previous character.
+utf8PrevChar :: Ptr Word8 -> IO (Ptr Word8)
+utf8PrevChar p = utf8CharStart (p `plusPtr` (-1))
+
+utf8CharStart :: Ptr Word8 -> IO (Ptr Word8)
+utf8CharStart p = go p
+ where go p = do w <- peek p
+		 if w >= 0x80 && w < 0xC0
+			then go (p `plusPtr` (-1))
+			else return p
+
+utf8DecodeString :: Ptr Word8 -> Int -> IO [Char]
+STRICT2(utf8DecodeString)
+utf8DecodeString (Ptr a#) (I# len#)
+  = unpack a#
+  where
+    end# = addr2Int# (a# `plusAddr#` len#)
+
+    unpack p#
+	| addr2Int# p# >=# end# = return []
+	| otherwise  =
+	case utf8DecodeChar# p# of
+	   (# c#, q# #) -> do
+		chs <- unpack q#
+		return (C# c# : chs)
+
+countUTF8Chars :: Ptr Word8 -> Int -> IO Int
+countUTF8Chars ptr bytes = go ptr 0
+  where
+	end = ptr `plusPtr` bytes
+
+	STRICT2(go)
+	go ptr n 
+	   | ptr >= end = return n
+	   | otherwise  = do
+		case utf8DecodeChar# (unPtr ptr) of
+		  (# c, a #) -> go (Ptr a) (n+1)
+
+unPtr (Ptr a) = a
+
+utf8EncodeChar c ptr =
+  let x = ord c in
+  case () of
+    _ | x > 0 && x <= 0x007f -> do
+	  poke ptr (fromIntegral x)
+	  return (ptr `plusPtr` 1)
+	-- NB. '\0' is encoded as '\xC0\x80', not '\0'.  This is so that we
+	-- can have 0-terminated UTF-8 strings (see GHC.Base.unpackCStringUtf8).
+      | x <= 0x07ff -> do
+	  poke ptr (fromIntegral (0xC0 .|. ((x `shiftR` 6) .&. 0x1F)))
+	  pokeElemOff ptr 1 (fromIntegral (0x80 .|. (x .&. 0x3F)))
+	  return (ptr `plusPtr` 2)
+      | x <= 0xffff -> do
+	  poke ptr (fromIntegral (0xE0 .|. (x `shiftR` 12) .&. 0x0F))
+	  pokeElemOff ptr 1 (fromIntegral (0x80 .|. (x `shiftR` 6) .&. 0x3F))
+	  pokeElemOff ptr 2 (fromIntegral (0x80 .|. (x .&. 0x3F)))
+	  return (ptr `plusPtr` 3)
+      | otherwise -> do
+	  poke ptr (fromIntegral (0xF0 .|. (x `shiftR` 18)))
+	  pokeElemOff ptr 1 (fromIntegral (0x80 .|. ((x `shiftR` 12) .&. 0x3F)))
+	  pokeElemOff ptr 2 (fromIntegral (0x80 .|. ((x `shiftR` 6) .&. 0x3F)))
+	  pokeElemOff ptr 3 (fromIntegral (0x80 .|. (x .&. 0x3F)))
+	  return (ptr `plusPtr` 4)
+
+utf8EncodeString :: Ptr Word8 -> String -> IO ()
+utf8EncodeString ptr str = go ptr str
+  where STRICT2(go)
+	go ptr [] = return ()
+	go ptr (c:cs) = do
+	  ptr' <- utf8EncodeChar c ptr
+	  go ptr' cs
+
+utf8EncodedLength :: String -> Int
+utf8EncodedLength str = go 0 str
+  where STRICT2(go)
+	go n [] = n
+        go n (c:cs)
+	  | ord c > 0 && ord c <= 0x007f = go (n+1) cs
+	  | ord c <= 0x07ff = go (n+2) cs
+	  | ord c <= 0xffff = go (n+3) cs	
+	  | otherwise       = go (n+4) cs	
+
+-- -----------------------------------------------------------------------------
+-- The Z-encoding
+
+{-
+This is the main name-encoding and decoding function.  It encodes any
+string into a string that is acceptable as a C name.  This is done
+right before we emit a symbol name into the compiled C or asm code.
+Z-encoding of strings is cached in the FastString interface, so we
+never encode the same string more than once.
+
+The basic encoding scheme is this.  
+
+* Tuples (,,,) are coded as Z3T
+
+* Alphabetic characters (upper and lower) and digits
+	all translate to themselves; 
+	except 'Z', which translates to 'ZZ'
+	and    'z', which translates to 'zz'
+  We need both so that we can preserve the variable/tycon distinction
+
+* Most other printable characters translate to 'zx' or 'Zx' for some
+	alphabetic character x
+
+* The others translate as 'znnnU' where 'nnn' is the decimal number
+        of the character
+
+	Before		After
+	--------------------------
+	Trak		Trak
+	foo_wib		foozuwib
+	>		zg
+	>1		zg1
+	foo#		foozh
+	foo##		foozhzh
+	foo##1		foozhzh1
+	fooZ		fooZZ	
+	:+		ZCzp
+	()		Z0T	0-tuple
+	(,,,,)		Z5T	5-tuple  
+	(# #)           Z1H     unboxed 1-tuple	(note the space)
+	(#,,,,#)	Z5H	unboxed 5-tuple
+		(NB: There is no Z1T nor Z0H.)
+-}
+
+type UserString = String	-- As the user typed it
+type EncodedString = String	-- Encoded form
+
+
+zEncodeString :: UserString -> EncodedString
+zEncodeString cs = case maybe_tuple cs of
+		Just n  -> n		-- Tuples go to Z2T etc
+		Nothing -> go cs
+	  where
+		go []     = []
+		go (c:cs) = encode_ch c ++ go cs
+
+unencodedChar :: Char -> Bool	-- True for chars that don't need encoding
+unencodedChar 'Z' = False
+unencodedChar 'z' = False
+unencodedChar c   =  c >= 'a' && c <= 'z'
+	          || c >= 'A' && c <= 'Z'
+		  || c >= '0' && c <= '9'
+
+encode_ch :: Char -> EncodedString
+encode_ch c | unencodedChar c = [c]	-- Common case first
+
+-- Constructors
+encode_ch '('  = "ZL"	-- Needed for things like (,), and (->)
+encode_ch ')'  = "ZR"	-- For symmetry with (
+encode_ch '['  = "ZM"
+encode_ch ']'  = "ZN"
+encode_ch ':'  = "ZC"
+encode_ch 'Z'  = "ZZ"
+
+-- Variables
+encode_ch 'z'  = "zz"
+encode_ch '&'  = "za"
+encode_ch '|'  = "zb"
+encode_ch '^'  = "zc"
+encode_ch '$'  = "zd"
+encode_ch '='  = "ze"
+encode_ch '>'  = "zg"
+encode_ch '#'  = "zh"
+encode_ch '.'  = "zi"
+encode_ch '<'  = "zl"
+encode_ch '-'  = "zm"
+encode_ch '!'  = "zn"
+encode_ch '+'  = "zp"
+encode_ch '\'' = "zq"
+encode_ch '\\' = "zr"
+encode_ch '/'  = "zs"
+encode_ch '*'  = "zt"
+encode_ch '_'  = "zu"
+encode_ch '%'  = "zv"
+encode_ch c    = 'z' : if isDigit (head hex_str) then hex_str
+					         else '0':hex_str
+  where hex_str = showHex (ord c) "U"
+  -- ToDo: we could improve the encoding here in various ways.
+  -- eg. strings of unicode characters come out as 'z1234Uz5678U', we
+  -- could remove the 'U' in the middle (the 'z' works as a separator).
+
+zDecodeString :: EncodedString -> UserString
+zDecodeString [] = []
+zDecodeString ('Z' : d : rest) 
+  | isDigit d = decode_tuple   d rest
+  | otherwise = decode_upper   d : zDecodeString rest
+zDecodeString ('z' : d : rest)
+  | isDigit d = decode_num_esc d rest
+  | otherwise = decode_lower   d : zDecodeString rest
+zDecodeString (c   : rest) = c : zDecodeString rest
+
+decode_upper, decode_lower :: Char -> Char
+
+decode_upper 'L' = '('
+decode_upper 'R' = ')'
+decode_upper 'M' = '['
+decode_upper 'N' = ']'
+decode_upper 'C' = ':'
+decode_upper 'Z' = 'Z'
+decode_upper ch  = {-pprTrace "decode_upper" (char ch)-} ch
+	     	
+decode_lower 'z' = 'z'
+decode_lower 'a' = '&'
+decode_lower 'b' = '|'
+decode_lower 'c' = '^'
+decode_lower 'd' = '$'
+decode_lower 'e' = '='
+decode_lower 'g' = '>'
+decode_lower 'h' = '#'
+decode_lower 'i' = '.'
+decode_lower 'l' = '<'
+decode_lower 'm' = '-'
+decode_lower 'n' = '!'
+decode_lower 'p' = '+'
+decode_lower 'q' = '\''
+decode_lower 'r' = '\\'
+decode_lower 's' = '/'
+decode_lower 't' = '*'
+decode_lower 'u' = '_'
+decode_lower 'v' = '%'
+decode_lower ch  = {-pprTrace "decode_lower" (char ch)-} ch
+
+-- Characters not having a specific code are coded as z224U (in hex)
+decode_num_esc d rest
+  = go (digitToInt d) rest
+  where
+    go n (c : rest) | isHexDigit c = go (16*n + digitToInt c) rest
+    go n ('U' : rest)           = chr n : zDecodeString rest
+    go n other = error ("decode_num_esc: " ++ show n ++  ' ':other)
+
+decode_tuple :: Char -> EncodedString -> UserString
+decode_tuple d rest
+  = go (digitToInt d) rest
+  where
+	-- NB. recurse back to zDecodeString after decoding the tuple, because
+	-- the tuple might be embedded in a longer name.
+    go n (c : rest) | isDigit c = go (10*n + digitToInt c) rest
+    go 0 ('T':rest)	= "()" ++ zDecodeString rest
+    go n ('T':rest)	= '(' : replicate (n-1) ',' ++ ")" ++ zDecodeString rest
+    go 1 ('H':rest)	= "(# #)" ++ zDecodeString rest
+    go n ('H':rest)	= '(' : '#' : replicate (n-1) ',' ++ "#)" ++ zDecodeString rest
+    go n other = error ("decode_tuple: " ++ show n ++ ' ':other)
+
+{-
+Tuples are encoded as
+	Z3T or Z3H
+for 3-tuples or unboxed 3-tuples respectively.  No other encoding starts 
+	Z<digit>
+
+* "(# #)" is the tycon for an unboxed 1-tuple (not 0-tuple)
+  There are no unboxed 0-tuples.  
+
+* "()" is the tycon for a boxed 0-tuple.
+  There are no boxed 1-tuples.
+-}
+
+maybe_tuple :: UserString -> Maybe EncodedString
+
+maybe_tuple "(# #)" = Just("Z1H")
+maybe_tuple ('(' : '#' : cs) = case count_commas (0::Int) cs of
+				 (n, '#' : ')' : cs) -> Just ('Z' : shows (n+1) "H")
+				 other		     -> Nothing
+maybe_tuple "()" = Just("Z0T")
+maybe_tuple ('(' : cs)       = case count_commas (0::Int) cs of
+				 (n, ')' : cs) -> Just ('Z' : shows (n+1) "T")
+				 other	       -> Nothing
+maybe_tuple other    	     = Nothing
+
+count_commas :: Int -> String -> (Int, String)
+count_commas n (',' : cs) = count_commas (n+1) cs
+count_commas n cs	  = (n,cs)