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<h2>Comments</h2>
<pre><code>-- Single line comment
{- Multi-line
comment -}</code></pre>
<h2>Strings and characters</h2>
<pre><code>'a'
'\n'
'\^A'
'\^]'
'\NUL'
'\23'
'\o75'
'\xFE'
"Here is a backslant \\ as well as \137, \
\a numeric escape character, and \^X, a control character."</code></pre>
<h2>Numbers</h2>
<pre><code>42
123.456
123.456e-789
1e+3
0o74
0XAF</code></pre>
<h2>Full example</h2>
<pre><code>hGetLine h =
wantReadableHandle_ "Data.ByteString.hGetLine" h $
\ h_@Handle__{haByteBuffer} -> do
flushCharReadBuffer h_
buf <- readIORef haByteBuffer
if isEmptyBuffer buf
then fill h_ buf 0 []
else haveBuf h_ buf 0 []
where
fill h_@Handle__{haByteBuffer,haDevice} buf len xss =
len `seq` do
(r,buf') <- Buffered.fillReadBuffer haDevice buf
if r == 0
then do writeIORef haByteBuffer buf{ bufR=0, bufL=0 }
if len > 0
then mkBigPS len xss
else ioe_EOF
else haveBuf h_ buf' len xss
haveBuf h_@Handle__{haByteBuffer}
buf@Buffer{ bufRaw=raw, bufR=w, bufL=r }
len xss =
do
off <- findEOL r w raw
let new_len = len + off - r
xs <- mkPS raw r off
-- if eol == True, then off is the offset of the '\n'
-- otherwise off == w and the buffer is now empty.
if off /= w
then do if (w == off + 1)
then writeIORef haByteBuffer buf{ bufL=0, bufR=0 }
else writeIORef haByteBuffer buf{ bufL = off + 1 }
mkBigPS new_len (xs:xss)
else do
fill h_ buf{ bufL=0, bufR=0 } new_len (xs:xss)
-- find the end-of-line character, if there is one
findEOL r w raw
| r == w = return w
| otherwise = do
c <- readWord8Buf raw r
if c == fromIntegral (ord '\n')
then return r -- NB. not r+1: don't include the '\n'
else findEOL (r+1) w raw
mkPS :: RawBuffer Word8 -> Int -> Int -> IO ByteString
mkPS buf start end =
create len $ \p ->
withRawBuffer buf $ \pbuf -> do
copyBytes p (pbuf `plusPtr` start) len
where
len = end - start</code></pre>
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