darcs-2.4.1: a distributed, interactive, smart revision control system




GZIp and MMap IO for ByteStrings, and miscellaneous functions for Data.ByteString



unsafeWithInternals :: ByteString -> (Ptr Word8 -> Int -> IO a) -> IO aSource

Do something with the internals of a PackedString. Beware of altering the contents!

gzReadFilePS :: FilePath -> IO ByteStringSource

Read an entire file, which may or may not be gzip compressed, directly into a ByteString.

mmapFilePS :: FilePath -> IO ByteStringSource

Like readFilePS, this reads an entire file directly into a ByteString, but it is even more efficient. It involves directly mapping the file to memory. This has the advantage that the contents of the file never need to be copied. Also, under memory pressure the page may simply be discarded, wile in the case of readFilePS it would need to be written to swap. If you read many small files, mmapFilePS will be less memory-efficient than readFilePS, since each mmapFilePS takes up a separate page of memory. Also, you can run into bus errors if the file is modified. NOTE: as with readFilePS, the string representation in the file is assumed to be ISO-8859-1.

gzDecompress :: Maybe Int -> ByteString -> ([ByteString], Bool)Source

Decompress the given bytestring into a lazy list of chunks, along with a boolean flag indicating (if True) that the CRC was corrupted. Inspecting the flag will cause the entire list of chunks to be evaluated (but if you throw away the list immediately this should run in constant space).

dropSpace :: ByteString -> ByteStringSource

dropSpace efficiently returns the ByteString argument with white space Chars removed from the front. It is more efficient than calling dropWhile for removing whitespace. I.e.

 dropWhile isSpace == dropSpace

breakSpace :: ByteString -> (ByteString, ByteString)Source

breakSpace returns the pair of ByteStrings when the argument is broken at the first whitespace byte. I.e.

 break isSpace == breakSpace

unlinesPS :: [ByteString] -> ByteStringSource

This function acts exactly like the Prelude unlines function, or like Data.ByteString.Char8 unlines, but with one important difference: it will produce a string which may not end with a newline! That is:

 unlinesPS ["foo", "bar"]

evaluates to "foo\nbar", not "foo\nbar\n"! This point should hold true for linesPS as well.

TODO: rename this function.

readIntPS :: ByteString -> Maybe (Int, ByteString)Source

readIntPS skips any whitespace at the beginning of its argument, and reads an Int from the beginning of the PackedString. If there is no integer at the beginning of the string, it returns Nothing, otherwise it just returns the int read, along with a B.ByteString containing the remainder of its input.

betweenLinesPS :: ByteString -> ByteString -> ByteString -> Maybe ByteStringSource

betweenLinesPS returns the B.ByteString between the two lines given, or Nothing if they do not appear.

intercalate :: ByteString -> [ByteString] -> ByteString

O(n) The intercalate function takes a ByteString and a list of ByteStrings and concatenates the list after interspersing the first argument between each element of the list.