diff options
Diffstat (limited to 'compiler/utils/StringBuffer.hs')
| -rw-r--r-- | compiler/utils/StringBuffer.hs | 42 |
1 files changed, 38 insertions, 4 deletions
diff --git a/compiler/utils/StringBuffer.hs b/compiler/utils/StringBuffer.hs index 7da9f6c22d..bac752ac28 100644 --- a/compiler/utils/StringBuffer.hs +++ b/compiler/utils/StringBuffer.hs @@ -89,6 +89,8 @@ instance Show StringBuffer where -- ----------------------------------------------------------------------------- -- Creation / Destruction +-- | Read a file into a 'StringBuffer'. The resulting buffer is automatically +-- managed by the garbage collector. hGetStringBuffer :: FilePath -> IO StringBuffer hGetStringBuffer fname = do h <- openBinaryFile fname ReadMode @@ -161,6 +163,8 @@ appendStringBuffers sb1 sb2 calcLen sb = len sb - cur sb size = sb1_len + sb2_len +-- | Encode a 'String' into a 'StringBuffer' as UTF-8. The resulting buffer +-- is automatically managed by the garbage collector. stringToStringBuffer :: String -> StringBuffer stringToStringBuffer str = unsafePerformIO $ do @@ -175,10 +179,15 @@ stringToStringBuffer str = -- ----------------------------------------------------------------------------- -- Grab a character --- Getting our fingers dirty a little here, but this is performance-critical +-- | Return the first UTF-8 character of a nonempty 'StringBuffer' and as well +-- the remaining portion (analogous to 'Data.List.uncons'). __Warning:__ The +-- behavior is undefined if the 'StringBuffer' is empty. The result shares +-- the same buffer as the original. Similar to 'utf8DecodeChar', if the +-- character cannot be decoded as UTF-8, '\0' is returned. {-# INLINE nextChar #-} nextChar :: StringBuffer -> (Char,StringBuffer) nextChar (StringBuffer buf len (I# cur#)) = + -- Getting our fingers dirty a little here, but this is performance-critical inlinePerformIO $ do withForeignPtr buf $ \(Ptr a#) -> do case utf8DecodeChar# (a# `plusAddr#` cur#) of @@ -186,6 +195,10 @@ nextChar (StringBuffer buf len (I# cur#)) = let cur' = I# (cur# +# nBytes#) in return (C# c#, StringBuffer buf len cur') +-- | Return the first UTF-8 character of a nonempty 'StringBuffer' (analogous +-- to 'Data.List.head'). __Warning:__ The behavior is undefined if the +-- 'StringBuffer' is empty. Similar to 'utf8DecodeChar', if the character +-- cannot be decoded as UTF-8, '\0' is returned. currentChar :: StringBuffer -> Char currentChar = fst . nextChar @@ -200,29 +213,50 @@ prevChar (StringBuffer buf _ cur) _ = -- ----------------------------------------------------------------------------- -- Moving +-- | Return a 'StringBuffer' with the first UTF-8 character removed (analogous +-- to 'Data.List.tail'). __Warning:__ The behavior is undefined if the +-- 'StringBuffer' is empty. The result shares the same buffer as the +-- original. stepOn :: StringBuffer -> StringBuffer stepOn s = snd (nextChar s) -offsetBytes :: Int -> StringBuffer -> StringBuffer +-- | Return a 'StringBuffer' with the first @n@ bytes removed. __Warning:__ +-- If there aren't enough characters, the returned 'StringBuffer' will be +-- invalid and any use of it may lead to undefined behavior. The result +-- shares the same buffer as the original. +offsetBytes :: Int -- ^ @n@, the number of bytes + -> StringBuffer + -> StringBuffer offsetBytes i s = s { cur = cur s + i } +-- | Compute the difference in offset between two 'StringBuffer's that share +-- the same buffer. __Warning:__ The behavior is undefined if the +-- 'StringBuffer's use separate buffers. byteDiff :: StringBuffer -> StringBuffer -> Int byteDiff s1 s2 = cur s2 - cur s1 +-- | Check whether a 'StringBuffer' is empty (analogous to 'Data.List.null'). atEnd :: StringBuffer -> Bool atEnd (StringBuffer _ l c) = l == c -- ----------------------------------------------------------------------------- -- Conversion -lexemeToString :: StringBuffer -> Int {-bytes-} -> String +-- | Decode the first @n@ bytes of a 'StringBuffer' as UTF-8 into a 'String'. +-- Similar to 'utf8DecodeChar', if the character cannot be decoded as UTF-8, +-- they will be replaced with '\0'. +lexemeToString :: StringBuffer + -> Int -- ^ @n@, the number of bytes + -> String lexemeToString _ 0 = "" lexemeToString (StringBuffer buf _ cur) bytes = inlinePerformIO $ withForeignPtr buf $ \ptr -> utf8DecodeString (ptr `plusPtr` cur) bytes -lexemeToFastString :: StringBuffer -> Int {-bytes-} -> FastString +lexemeToFastString :: StringBuffer + -> Int -- ^ @n@, the number of bytes + -> FastString lexemeToFastString _ 0 = nilFS lexemeToFastString (StringBuffer buf _ cur) len = inlinePerformIO $ |