d5d8259937
Attoparsec parser for diff-tree. Changed fromRef back to producing a String, to avoid needing to convert every use of it. However, this does mean I'm going to miss some opportunities where fromRef is used and the result converted back to a ByteString. Would be worth revisiting that at some point maybe.
139 lines
3.8 KiB
Haskell
139 lines
3.8 KiB
Haskell
{- misc utility functions
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-
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- Copyright 2010-2011 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# OPTIONS_GHC -fno-warn-tabs #-}
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module Utility.Misc (
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hGetContentsStrict,
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readFileStrict,
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separate,
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separate',
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firstLine,
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firstLine',
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segment,
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segmentDelim,
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massReplace,
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hGetSomeString,
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exitBool,
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prop_segment_regressionTest,
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) 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 Data.List
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import System.Exit
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import Control.Applicative
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import qualified Data.ByteString as S
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import Prelude
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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 item 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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separate' :: (Word8 -> Bool) -> S.ByteString -> (S.ByteString, S.ByteString)
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separate' c l = unbreak $ S.break c l
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where
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unbreak r@(a, b)
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| S.null b = r
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| otherwise = (a, S.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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firstLine' :: S.ByteString -> S.ByteString
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firstLine' = S.takeWhile (/= nl)
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where
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nl = fromIntegral (ord '\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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{- Replaces multiple values in a string.
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-
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- Takes care to skip over just-replaced values, so that they are not
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- mangled. For example, massReplace [("foo", "new foo")] does not
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- replace the "new foo" with "new new foo".
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-}
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massReplace :: [(String, String)] -> String -> String
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massReplace vs = go [] vs
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where
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go acc _ [] = concat $ reverse acc
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go acc [] (c:cs) = go ([c]:acc) vs cs
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go acc ((val, replacement):rest) s
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| val `isPrefixOf` s =
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go (replacement:acc) vs (drop (length val) s)
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| otherwise = go acc rest s
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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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exitBool :: Bool -> IO a
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exitBool False = exitFailure
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exitBool True = exitSuccess
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