+++ /dev/null
-%
-% (c) The University of Glasgow, 1997-2006
-%
-\begin{code}
-{-
-FastString: A compact, hash-consed, representation of character strings.
- Comparison is O(1), and you can get a Unique from them.
- Generated by the FSLIT macro
- Turn into SDoc with Outputable.ftext
-
-LitString: Just a wrapper for the Addr# of a C string (Ptr CChar).
- Practically no operations
- Outputing them is fast
- Generated by the SLIT macro
- Turn into SDoc with Outputable.ptext
-
-Use LitString unless you want the facilities of FastString
--}
-module FastString
- (
- -- * FastStrings
- FastString(..), -- not abstract, for now.
-
- -- ** Construction
- mkFastString,
- mkFastStringBytes,
- mkFastStringForeignPtr,
- mkFastString#,
- mkZFastString,
- mkZFastStringBytes,
-
- -- ** Deconstruction
- unpackFS, -- :: FastString -> String
- bytesFS, -- :: FastString -> [Word8]
-
- -- ** Encoding
- isZEncoded,
- zEncodeFS,
-
- -- ** Operations
- uniqueOfFS,
- lengthFS,
- nullFS,
- appendFS,
- headFS,
- tailFS,
- concatFS,
- consFS,
- nilFS,
-
- -- ** Outputing
- hPutFS,
-
- -- ** Internal
- getFastStringTable,
- hasZEncoding,
-
- -- * LitStrings
- LitString,
- mkLitString#,
- strLength
- ) where
-
--- This #define suppresses the "import FastString" that
--- HsVersions otherwise produces
-#define COMPILING_FAST_STRING
-#include "HsVersions.h"
-
-import Encoding
-
-import Foreign
-import Foreign.C
-import GHC.Exts
-import System.IO.Unsafe ( unsafePerformIO )
-import Control.Monad.ST ( stToIO )
-import Data.IORef ( IORef, newIORef, readIORef, writeIORef )
-import System.IO ( hPutBuf )
-import Data.Maybe ( isJust )
-
-import GHC.Arr ( STArray(..), newSTArray )
-import GHC.IOBase ( IO(..) )
-import GHC.Ptr ( Ptr(..) )
-
-#define hASH_TBL_SIZE 4091
-
-
-{-|
-A 'FastString' is an array of bytes, hashed to support fast O(1)
-comparison. It is also associated with a character encoding, so that
-we know how to convert a 'FastString' to the local encoding, or to the
-Z-encoding used by the compiler internally.
-
-'FastString's support a memoized conversion to the Z-encoding via zEncodeFS.
--}
-
-data FastString = FastString {
- uniq :: {-# UNPACK #-} !Int, -- unique id
- n_bytes :: {-# UNPACK #-} !Int, -- number of bytes
- n_chars :: {-# UNPACK #-} !Int, -- number of chars
- buf :: {-# UNPACK #-} !(ForeignPtr Word8),
- enc :: FSEncoding
- }
-
-data FSEncoding
- = ZEncoded
- -- including strings that don't need any encoding
- | UTF8Encoded {-# UNPACK #-} !(IORef (Maybe FastString))
- -- A UTF-8 string with a memoized Z-encoding
-
-instance Eq FastString where
- f1 == f2 = uniq f1 == uniq f2
-
-instance Ord FastString where
- -- Compares lexicographically, not by unique
- a <= b = case cmpFS a b of { LT -> True; EQ -> True; GT -> False }
- a < b = case cmpFS a b of { LT -> True; EQ -> False; GT -> False }
- a >= b = case cmpFS a b of { LT -> False; EQ -> True; GT -> True }
- a > b = case cmpFS a b of { LT -> False; EQ -> False; GT -> True }
- max x y | x >= y = x
- | otherwise = y
- min x y | x <= y = x
- | otherwise = y
- compare a b = cmpFS a b
-
-instance Show FastString where
- show fs = show (unpackFS fs)
-
-cmpFS :: FastString -> FastString -> Ordering
-cmpFS (FastString u1 l1 _ buf1 _) (FastString u2 l2 _ buf2 _) =
- if u1 == u2 then EQ else
- let l = if l1 <= l2 then l1 else l2 in
- inlinePerformIO $
- withForeignPtr buf1 $ \p1 ->
- withForeignPtr buf2 $ \p2 -> do
- res <- memcmp p1 p2 l
- case () of
- _ | res < 0 -> return LT
- | res == 0 -> if l1 == l2 then return EQ
- else if l1 < l2 then return LT
- else return GT
- | otherwise -> return GT
-
-#ifndef __HADDOCK__
-foreign import ccall unsafe "ghc_memcmp"
- memcmp :: Ptr a -> Ptr b -> Int -> IO Int
-#endif
-
--- -----------------------------------------------------------------------------
--- Construction
-
-{-
-Internally, the compiler will maintain a fast string symbol
-table, providing sharing and fast comparison. Creation of
-new @FastString@s then covertly does a lookup, re-using the
-@FastString@ if there was a hit.
--}
-
-data FastStringTable =
- FastStringTable
- {-# UNPACK #-} !Int
- (MutableArray# RealWorld [FastString])
-
-string_table :: IORef FastStringTable
-string_table =
- unsafePerformIO $ do
- (STArray _ _ arr#) <- stToIO (newSTArray (0::Int,hASH_TBL_SIZE) [])
- newIORef (FastStringTable 0 arr#)
-
-lookupTbl :: FastStringTable -> Int -> IO [FastString]
-lookupTbl (FastStringTable _ arr#) (I# i#) =
- IO $ \ s# -> readArray# arr# i# s#
-
-updTbl :: IORef FastStringTable -> FastStringTable -> Int -> [FastString] -> IO ()
-updTbl fs_table_var (FastStringTable uid arr#) (I# i#) ls = do
- (IO $ \ s# -> case writeArray# arr# i# ls s# of { s2# -> (# s2#, () #) })
- writeIORef fs_table_var (FastStringTable (uid+1) arr#)
-
-mkFastString# :: Addr# -> FastString
-mkFastString# a# = mkFastStringBytes ptr (strLength ptr)
- where ptr = Ptr a#
-
-mkFastStringBytes :: Ptr Word8 -> Int -> FastString
-mkFastStringBytes ptr len = unsafePerformIO $ do
- ft@(FastStringTable uid tbl#) <- readIORef string_table
- let
- h = hashStr ptr len
- add_it ls = do
- fs <- copyNewFastString uid ptr len
- updTbl string_table ft h (fs:ls)
- {- _trace ("new: " ++ show f_str) $ -}
- return fs
- --
- lookup_result <- lookupTbl ft h
- case lookup_result of
- [] -> add_it []
- ls -> do
- b <- bucket_match ls len ptr
- case b of
- Nothing -> add_it ls
- Just v -> {- _trace ("re-use: "++show v) $ -} return v
-
-mkZFastStringBytes :: Ptr Word8 -> Int -> FastString
-mkZFastStringBytes ptr len = unsafePerformIO $ do
- ft@(FastStringTable uid tbl#) <- readIORef string_table
- let
- h = hashStr ptr len
- add_it ls = do
- fs <- copyNewZFastString uid ptr len
- updTbl string_table ft h (fs:ls)
- {- _trace ("new: " ++ show f_str) $ -}
- return fs
- --
- lookup_result <- lookupTbl ft h
- case lookup_result of
- [] -> add_it []
- ls -> do
- b <- bucket_match ls len ptr
- case b of
- Nothing -> add_it ls
- Just v -> {- _trace ("re-use: "++show v) $ -} return v
-
--- | Create a 'FastString' from an existing 'ForeignPtr'; the difference
--- between this and 'mkFastStringBytes' is that we don't have to copy
--- the bytes if the string is new to the table.
-mkFastStringForeignPtr :: Ptr Word8 -> ForeignPtr Word8 -> Int -> IO FastString
-mkFastStringForeignPtr ptr fp len = do
- ft@(FastStringTable uid tbl#) <- readIORef string_table
--- _trace ("hashed: "++show (I# h)) $
- let
- h = hashStr ptr len
- add_it ls = do
- fs <- mkNewFastString uid ptr fp len
- updTbl string_table ft h (fs:ls)
- {- _trace ("new: " ++ show f_str) $ -}
- return fs
- --
- lookup_result <- lookupTbl ft h
- case lookup_result of
- [] -> add_it []
- ls -> do
- b <- bucket_match ls len ptr
- case b of
- Nothing -> add_it ls
- Just v -> {- _trace ("re-use: "++show v) $ -} return v
-
-mkZFastStringForeignPtr :: Ptr Word8 -> ForeignPtr Word8 -> Int -> IO FastString
-mkZFastStringForeignPtr ptr fp len = do
- ft@(FastStringTable uid tbl#) <- readIORef string_table
--- _trace ("hashed: "++show (I# h)) $
- let
- h = hashStr ptr len
- add_it ls = do
- fs <- mkNewZFastString uid ptr fp len
- updTbl string_table ft h (fs:ls)
- {- _trace ("new: " ++ show f_str) $ -}
- return fs
- --
- lookup_result <- lookupTbl ft h
- case lookup_result of
- [] -> add_it []
- ls -> do
- b <- bucket_match ls len ptr
- case b of
- Nothing -> add_it ls
- Just v -> {- _trace ("re-use: "++show v) $ -} return v
-
-
--- | Creates a UTF-8 encoded 'FastString' from a 'String'
-mkFastString :: String -> FastString
-mkFastString str =
- inlinePerformIO $ do
- let l = utf8EncodedLength str
- buf <- mallocForeignPtrBytes l
- withForeignPtr buf $ \ptr -> do
- utf8EncodeString ptr str
- mkFastStringForeignPtr ptr buf l
-
-
--- | Creates a Z-encoded 'FastString' from a 'String'
-mkZFastString :: String -> FastString
-mkZFastString str =
- inlinePerformIO $ do
- let l = Prelude.length str
- buf <- mallocForeignPtrBytes l
- withForeignPtr buf $ \ptr -> do
- pokeCAString (castPtr ptr) str
- mkZFastStringForeignPtr ptr buf l
-
-bucket_match [] _ _ = return Nothing
-bucket_match (v@(FastString _ l _ buf _):ls) len ptr
- | len == l = do
- b <- cmpStringPrefix ptr buf len
- if b then return (Just v)
- else bucket_match ls len ptr
- | otherwise =
- bucket_match ls len ptr
-
-mkNewFastString uid ptr fp len = do
- ref <- newIORef Nothing
- n_chars <- countUTF8Chars ptr len
- return (FastString uid len n_chars fp (UTF8Encoded ref))
-
-mkNewZFastString uid ptr fp len = do
- return (FastString uid len len fp ZEncoded)
-
-
-copyNewFastString uid ptr len = do
- fp <- copyBytesToForeignPtr ptr len
- ref <- newIORef Nothing
- n_chars <- countUTF8Chars ptr len
- return (FastString uid len n_chars fp (UTF8Encoded ref))
-
-copyNewZFastString uid ptr len = do
- fp <- copyBytesToForeignPtr ptr len
- return (FastString uid len len fp ZEncoded)
-
-
-copyBytesToForeignPtr ptr len = do
- fp <- mallocForeignPtrBytes len
- withForeignPtr fp $ \ptr' -> copyBytes ptr' ptr len
- return fp
-
-cmpStringPrefix :: Ptr Word8 -> ForeignPtr Word8 -> Int -> IO Bool
-cmpStringPrefix ptr fp len =
- withForeignPtr fp $ \ptr' -> do
- r <- memcmp ptr ptr' len
- return (r == 0)
-
-
-hashStr :: Ptr Word8 -> Int -> Int
- -- use the Addr to produce a hash value between 0 & m (inclusive)
-hashStr (Ptr a#) (I# len#) = loop 0# 0#
- where
- loop h n | n ==# len# = I# h
- | otherwise = loop h2 (n +# 1#)
- where c = ord# (indexCharOffAddr# a# n)
- h2 = (c +# (h *# 128#)) `remInt#` hASH_TBL_SIZE#
-
--- -----------------------------------------------------------------------------
--- Operations
-
--- | Returns the length of the 'FastString' in characters
-lengthFS :: FastString -> Int
-lengthFS f = n_chars f
-
--- | Returns 'True' if the 'FastString' is Z-encoded
-isZEncoded :: FastString -> Bool
-isZEncoded fs | ZEncoded <- enc fs = True
- | otherwise = False
-
--- | Returns 'True' if this 'FastString' is not Z-encoded but already has
--- a Z-encoding cached (used in producing stats).
-hasZEncoding :: FastString -> Bool
-hasZEncoding fs@(FastString uid n_bytes _ fp enc) =
- case enc of
- ZEncoded -> False
- UTF8Encoded ref ->
- inlinePerformIO $ do
- m <- readIORef ref
- return (isJust m)
-
--- | Returns 'True' if the 'FastString' is empty
-nullFS :: FastString -> Bool
-nullFS f = n_bytes f == 0
-
--- | unpacks and decodes the FastString
-unpackFS :: FastString -> String
-unpackFS (FastString _ n_bytes _ buf enc) =
- inlinePerformIO $ withForeignPtr buf $ \ptr ->
- case enc of
- ZEncoded -> peekCAStringLen (castPtr ptr,n_bytes)
- UTF8Encoded _ -> utf8DecodeString ptr n_bytes
-
-bytesFS :: FastString -> [Word8]
-bytesFS (FastString _ n_bytes _ buf enc) =
- inlinePerformIO $ withForeignPtr buf $ \ptr ->
- peekArray n_bytes ptr
-
--- | returns a Z-encoded version of a 'FastString'. This might be the
--- original, if it was already Z-encoded. The first time this
--- function is applied to a particular 'FastString', the results are
--- memoized.
---
-zEncodeFS :: FastString -> FastString
-zEncodeFS fs@(FastString uid n_bytes _ fp enc) =
- case enc of
- ZEncoded -> fs
- UTF8Encoded ref ->
- inlinePerformIO $ do
- m <- readIORef ref
- case m of
- Just fs -> return fs
- Nothing -> do
- let efs = mkZFastString (zEncodeString (unpackFS fs))
- writeIORef ref (Just efs)
- return efs
-
-appendFS :: FastString -> FastString -> FastString
-appendFS fs1 fs2 = mkFastString (unpackFS fs1 ++ unpackFS fs2)
-
-concatFS :: [FastString] -> FastString
-concatFS ls = mkFastString (Prelude.concat (map unpackFS ls)) -- ToDo: do better
-
-headFS :: FastString -> Char
-headFS (FastString _ n_bytes _ buf enc) =
- inlinePerformIO $ withForeignPtr buf $ \ptr -> do
- case enc of
- ZEncoded -> do
- w <- peek (castPtr ptr)
- return (castCCharToChar w)
- UTF8Encoded _ ->
- return (fst (utf8DecodeChar ptr))
-
-tailFS :: FastString -> FastString
-tailFS (FastString _ n_bytes _ buf enc) =
- inlinePerformIO $ withForeignPtr buf $ \ptr -> do
- case enc of
- ZEncoded -> do
- return $! mkZFastStringBytes (ptr `plusPtr` 1) (n_bytes - 1)
- UTF8Encoded _ -> do
- let (_,ptr') = utf8DecodeChar ptr
- let off = ptr' `minusPtr` ptr
- return $! mkFastStringBytes (ptr `plusPtr` off) (n_bytes - off)
-
-consFS :: Char -> FastString -> FastString
-consFS c fs = mkFastString (c : unpackFS fs)
-
-uniqueOfFS :: FastString -> Int#
-uniqueOfFS (FastString (I# u#) _ _ _ _) = u#
-
-nilFS = mkFastString ""
-
--- -----------------------------------------------------------------------------
--- Stats
-
-getFastStringTable :: IO [[FastString]]
-getFastStringTable = do
- tbl <- readIORef string_table
- buckets <- mapM (lookupTbl tbl) [0 .. hASH_TBL_SIZE]
- return buckets
-
--- -----------------------------------------------------------------------------
--- Outputting 'FastString's
-
--- |Outputs a 'FastString' with /no decoding at all/, that is, you
--- get the actual bytes in the 'FastString' written to the 'Handle'.
-hPutFS handle (FastString _ len _ fp _)
- | len == 0 = return ()
- | otherwise = do withForeignPtr fp $ \ptr -> hPutBuf handle ptr len
-
--- ToDo: we'll probably want an hPutFSLocal, or something, to output
--- in the current locale's encoding (for error messages and suchlike).
-
--- -----------------------------------------------------------------------------
--- LitStrings, here for convenience only.
-
-type LitString = Ptr ()
-
-mkLitString# :: Addr# -> LitString
-mkLitString# a# = Ptr a#
-
-foreign import ccall unsafe "ghc_strlen"
- strLength :: Ptr () -> Int
-
--- -----------------------------------------------------------------------------
--- under the carpet
-
--- Just like unsafePerformIO, but we inline it.
-{-# INLINE inlinePerformIO #-}
-inlinePerformIO :: IO a -> a
-inlinePerformIO (IO m) = case m realWorld# of (# _, r #) -> r
-
--- NB. does *not* add a '\0'-terminator.
-pokeCAString :: Ptr CChar -> String -> IO ()
-pokeCAString ptr str =
- let
- go [] n = return ()
- go (c:cs) n = do pokeElemOff ptr n (castCharToCChar c); go cs (n+1)
- in
- go str 0
-
-#if __GLASGOW_HASKELL__ < 600
-
-mallocForeignPtrBytes :: Int -> IO (ForeignPtr a)
-mallocForeignPtrBytes n = do
- r <- mallocBytes n
- newForeignPtr r (finalizerFree r)
-
-foreign import ccall unsafe "stdlib.h free"
- finalizerFree :: Ptr a -> IO ()
-
-peekCAStringLen = peekCStringLen
-
-#elif __GLASGOW_HASKELL__ <= 602
-
-peekCAStringLen = peekCStringLen
-
-#endif
-\end{code}
projects / ghc-hetmet.git / blobdiff