112 lines
3.4 KiB
Haskell
112 lines
3.4 KiB
Haskell
{- misc utility functions
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-
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- Copyright 2010-2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility.Misc where
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import System.IO
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import Control.Monad
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import Foreign
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import Data.Char
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import Control.Applicative
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import System.Posix.Process (getAnyProcessStatus)
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import Utility.Exception
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{- A version of hgetContents that is not lazy. Ensures file is
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- all read before it gets closed. -}
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hGetContentsStrict :: Handle -> IO String
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hGetContentsStrict = hGetContents >=> \s -> length s `seq` return s
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{- A version of readFile that is not lazy. -}
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readFileStrict :: FilePath -> IO String
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readFileStrict = readFile >=> \s -> length s `seq` return s
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{- Like break, but the character matching the condition is not included
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- in the second result list.
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-
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- separate (== ':') "foo:bar" = ("foo", "bar")
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- separate (== ':') "foobar" = ("foobar", "")
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-}
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separate :: (a -> Bool) -> [a] -> ([a], [a])
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separate c l = unbreak $ break c l
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where
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unbreak r@(a, b)
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| null b = r
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| otherwise = (a, tail b)
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{- Breaks out the first line. -}
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firstLine :: String -> String
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firstLine = takeWhile (/= '\n')
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{- Splits a list into segments that are delimited by items matching
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- a predicate. (The delimiters are not included in the segments.)
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- Segments may be empty. -}
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segment :: (a -> Bool) -> [a] -> [[a]]
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segment p l = map reverse $ go [] [] l
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where
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go c r [] = reverse $ c:r
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go c r (i:is)
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| p i = go [] (c:r) is
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| otherwise = go (i:c) r is
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prop_segment_regressionTest :: Bool
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prop_segment_regressionTest = all id
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-- Even an empty list is a segment.
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[ segment (== "--") [] == [[]]
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-- There are two segements in this list, even though the first is empty.
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, segment (== "--") ["--", "foo", "bar"] == [[],["foo","bar"]]
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]
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{- Includes the delimiters as segments of their own. -}
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segmentDelim :: (a -> Bool) -> [a] -> [[a]]
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segmentDelim p l = map reverse $ go [] [] l
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where
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go c r [] = reverse $ c:r
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go c r (i:is)
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| p i = go [] ([i]:c:r) is
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| otherwise = go (i:c) r is
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{- Given two orderings, returns the second if the first is EQ and returns
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- the first otherwise.
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-
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- Example use:
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-
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- compare lname1 lname2 `thenOrd` compare fname1 fname2
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-}
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thenOrd :: Ordering -> Ordering -> Ordering
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thenOrd EQ x = x
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thenOrd x _ = x
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{-# INLINE thenOrd #-}
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{- Wrapper around hGetBufSome that returns a String.
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-
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- The null string is returned on eof, otherwise returns whatever
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- data is currently available to read from the handle, or waits for
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- data to be written to it if none is currently available.
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-
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- Note on encodings: The normal encoding of the Handle is ignored;
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- each byte is converted to a Char. Not unicode clean!
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-}
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hGetSomeString :: Handle -> Int -> IO String
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hGetSomeString h sz = do
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fp <- mallocForeignPtrBytes sz
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len <- withForeignPtr fp $ \buf -> hGetBufSome h buf sz
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map (chr . fromIntegral) <$> withForeignPtr fp (peekbytes len)
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where
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peekbytes :: Int -> Ptr Word8 -> IO [Word8]
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peekbytes len buf = mapM (peekElemOff buf) [0..pred len]
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{- Reaps any zombie git processes.
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-
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- Warning: Not thread safe. Anything that was expecting to wait
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- on a process and get back an exit status is going to be confused
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- if this reap gets there first. -}
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reapZombies :: IO ()
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reapZombies = do
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-- throws an exception when there are no child processes
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catchDefaultIO Nothing (getAnyProcessStatus False True)
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>>= maybe (return ()) (const reapZombies)
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