Copyright | (c) Duncan Coutts 2012-2013 Julian Ospald 2022 |
---|---|
License | BSD-style |
Maintainer | hasufell@posteo.de |
Stability | stable |
Portability | ghc only |
Safe Haskell | None |
Language | Haskell2010 |
System.OsString.Data.ByteString.Short
Description
A compact representation suitable for storing short byte strings in memory.
In typical use cases it can be imported alongside Data.ByteString, e.g.
import qualified Data.ByteString as B import qualified Data.ByteString.Short as B (ShortByteString, toShort, fromShort)
Other ShortByteString
operations clash with Data.ByteString or Prelude
functions however, so they should be imported qualified
with a different
alias e.g.
import qualified Data.ByteString.Short as B.Short
Synopsis
- newtype ShortByteString where
- ShortByteString {
- unShortByteString :: ByteArray
- pattern SBS :: ByteArray# -> ShortByteString
- ShortByteString {
- empty :: ShortByteString
- singleton :: Word8 -> ShortByteString
- pack :: [Word8] -> ShortByteString
- unpack :: ShortByteString -> [Word8]
- fromShort :: ShortByteString -> ByteString
- toShort :: ByteString -> ShortByteString
- snoc :: ShortByteString -> Word8 -> ShortByteString
- cons :: Word8 -> ShortByteString -> ShortByteString
- append :: ShortByteString -> ShortByteString -> ShortByteString
- last :: HasCallStack => ShortByteString -> Word8
- tail :: HasCallStack => ShortByteString -> ShortByteString
- uncons :: ShortByteString -> Maybe (Word8, ShortByteString)
- uncons2 :: ShortByteString -> Maybe (Word8, Word8, ShortByteString)
- head :: HasCallStack => ShortByteString -> Word8
- init :: HasCallStack => ShortByteString -> ShortByteString
- unsnoc :: ShortByteString -> Maybe (ShortByteString, Word8)
- null :: ShortByteString -> Bool
- length :: ShortByteString -> Int
- map :: (Word8 -> Word8) -> ShortByteString -> ShortByteString
- reverse :: ShortByteString -> ShortByteString
- intercalate :: ShortByteString -> [ShortByteString] -> ShortByteString
- foldl :: (a -> Word8 -> a) -> a -> ShortByteString -> a
- foldl' :: (a -> Word8 -> a) -> a -> ShortByteString -> a
- foldl1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8
- foldl1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8
- foldr :: (Word8 -> a -> a) -> a -> ShortByteString -> a
- foldr' :: (Word8 -> a -> a) -> a -> ShortByteString -> a
- foldr1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8
- foldr1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8
- all :: (Word8 -> Bool) -> ShortByteString -> Bool
- any :: (Word8 -> Bool) -> ShortByteString -> Bool
- concat :: [ShortByteString] -> ShortByteString
- replicate :: Int -> Word8 -> ShortByteString
- unfoldr :: (a -> Maybe (Word8, a)) -> a -> ShortByteString
- unfoldrN :: Int -> (a -> Maybe (Word8, a)) -> a -> (ShortByteString, Maybe a)
- take :: Int -> ShortByteString -> ShortByteString
- takeEnd :: Int -> ShortByteString -> ShortByteString
- takeWhileEnd :: (Word8 -> Bool) -> ShortByteString -> ShortByteString
- takeWhile :: (Word8 -> Bool) -> ShortByteString -> ShortByteString
- drop :: Int -> ShortByteString -> ShortByteString
- dropEnd :: Int -> ShortByteString -> ShortByteString
- dropWhile :: (Word8 -> Bool) -> ShortByteString -> ShortByteString
- dropWhileEnd :: (Word8 -> Bool) -> ShortByteString -> ShortByteString
- breakEnd :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- break :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- span :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- spanEnd :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- splitAt :: Int -> ShortByteString -> (ShortByteString, ShortByteString)
- split :: Word8 -> ShortByteString -> [ShortByteString]
- splitWith :: (Word8 -> Bool) -> ShortByteString -> [ShortByteString]
- stripSuffix :: ShortByteString -> ShortByteString -> Maybe ShortByteString
- stripPrefix :: ShortByteString -> ShortByteString -> Maybe ShortByteString
- isInfixOf :: ShortByteString -> ShortByteString -> Bool
- isPrefixOf :: ShortByteString -> ShortByteString -> Bool
- isSuffixOf :: ShortByteString -> ShortByteString -> Bool
- breakSubstring :: ShortByteString -> ShortByteString -> (ShortByteString, ShortByteString)
- elem :: Word8 -> ShortByteString -> Bool
- find :: (Word8 -> Bool) -> ShortByteString -> Maybe Word8
- filter :: (Word8 -> Bool) -> ShortByteString -> ShortByteString
- partition :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- index :: HasCallStack => ShortByteString -> Int -> Word8
- indexMaybe :: ShortByteString -> Int -> Maybe Word8
- (!?) :: ShortByteString -> Int -> Maybe Word8
- elemIndex :: Word8 -> ShortByteString -> Maybe Int
- elemIndices :: Word8 -> ShortByteString -> [Int]
- count :: Word8 -> ShortByteString -> Int
- findIndex :: (Word8 -> Bool) -> ShortByteString -> Maybe Int
- findIndices :: (Word8 -> Bool) -> ShortByteString -> [Int]
- packCString :: CString -> IO ShortByteString
- packCStringLen :: CStringLen -> IO ShortByteString
- useAsCString :: ShortByteString -> (CString -> IO a) -> IO a
- useAsCStringLen :: ShortByteString -> (CStringLen -> IO a) -> IO a
The ShortByteString
type
newtype ShortByteString #
Constructors
ShortByteString | |
Fields
|
Bundled Patterns
pattern SBS :: ByteArray# -> ShortByteString |
Instances
Data ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> ShortByteString -> c ShortByteString gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c ShortByteString toConstr :: ShortByteString -> Constr dataTypeOf :: ShortByteString -> DataType dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c ShortByteString) dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c ShortByteString) gmapT :: (forall b. Data b => b -> b) -> ShortByteString -> ShortByteString gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> ShortByteString -> r gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> ShortByteString -> r gmapQ :: (forall d. Data d => d -> u) -> ShortByteString -> [u] gmapQi :: Int -> (forall d. Data d => d -> u) -> ShortByteString -> u gmapM :: Monad m => (forall d. Data d => d -> m d) -> ShortByteString -> m ShortByteString gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> ShortByteString -> m ShortByteString gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> ShortByteString -> m ShortByteString | |||||
IsString ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods fromString :: String -> ShortByteString | |||||
Monoid ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods mappend :: ShortByteString -> ShortByteString -> ShortByteString mconcat :: [ShortByteString] -> ShortByteString | |||||
Semigroup ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods (<>) :: ShortByteString -> ShortByteString -> ShortByteString sconcat :: NonEmpty ShortByteString -> ShortByteString stimes :: Integral b => b -> ShortByteString -> ShortByteString | |||||
Generic ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Associated Types
Methods from :: ShortByteString -> Rep ShortByteString x to :: Rep ShortByteString x -> ShortByteString | |||||
IsList ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Associated Types
Methods fromList :: [Item ShortByteString] -> ShortByteString fromListN :: Int -> [Item ShortByteString] -> ShortByteString toList :: ShortByteString -> [Item ShortByteString] | |||||
Read ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods readsPrec :: Int -> ReadS ShortByteString readList :: ReadS [ShortByteString] readPrec :: ReadPrec ShortByteString readListPrec :: ReadPrec [ShortByteString] | |||||
Show ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods showsPrec :: Int -> ShortByteString -> ShowS show :: ShortByteString -> String showList :: [ShortByteString] -> ShowS | |||||
NFData ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods rnf :: ShortByteString -> () | |||||
Eq ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods (==) :: ShortByteString -> ShortByteString -> Bool (/=) :: ShortByteString -> ShortByteString -> Bool | |||||
Ord ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods compare :: ShortByteString -> ShortByteString -> Ordering (<) :: ShortByteString -> ShortByteString -> Bool (<=) :: ShortByteString -> ShortByteString -> Bool (>) :: ShortByteString -> ShortByteString -> Bool (>=) :: ShortByteString -> ShortByteString -> Bool max :: ShortByteString -> ShortByteString -> ShortByteString min :: ShortByteString -> ShortByteString -> ShortByteString | |||||
Lift ShortByteString | |||||
Defined in Data.ByteString.Short.Internal Methods lift :: Quote m => ShortByteString -> m Exp liftTyped :: forall (m :: Type -> Type). Quote m => ShortByteString -> Code m ShortByteString | |||||
type Rep ShortByteString | |||||
Defined in Data.ByteString.Short.Internal type Rep ShortByteString = D1 ('MetaData "ShortByteString" "Data.ByteString.Short.Internal" "bytestring-0.12.1.0-a393" 'True) (C1 ('MetaCons "ShortByteString" 'PrefixI 'True) (S1 ('MetaSel ('Just "unShortByteString") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 ByteArray))) | |||||
type Item ShortByteString | |||||
Defined in Data.ByteString.Short.Internal type Item ShortByteString = Word8 |
Memory overhead
With GHC, the memory overheads are as follows, expressed in words and in bytes (words are 4 and 8 bytes on 32 or 64bit machines respectively).
ByteString
unshared: 8 words; 32 or 64 bytes.ByteString
shared substring: 4 words; 16 or 32 bytes.ShortByteString
: 4 words; 16 or 32 bytes.
For the string data itself, both ShortByteString
and ByteString
use
one byte per element, rounded up to the nearest word. For example,
including the overheads, a length 10 ShortByteString
would take
16 + 12 = 28
bytes on a 32bit platform and 32 + 16 = 48
bytes on a
64bit platform.
These overheads can all be reduced by 1 word (4 or 8 bytes) when the
ShortByteString
or ByteString
is unpacked into another constructor.
For example:
data ThingId = ThingId {-# UNPACK #-} !Int {-# UNPACK #-} !ShortByteString
This will take 1 + 1 + 3
words (the ThingId
constructor +
unpacked Int
+ unpacked ShortByteString
), plus the words for the
string data.
Heap fragmentation
With GHC, the ByteString
representation uses pinned memory,
meaning it cannot be moved by the GC. This is usually the right thing to
do for larger strings, but for small strings using pinned memory can
lead to heap fragmentation which wastes space. The ShortByteString
type (and the Text
type from the text
package) use unpinned memory
so they do not contribute to heap fragmentation. In addition, with GHC,
small unpinned strings are allocated in the same way as normal heap
allocations, rather than in a separate pinned area.
Introducing and eliminating ShortByteString
s
singleton :: Word8 -> ShortByteString #
pack :: [Word8] -> ShortByteString #
unpack :: ShortByteString -> [Word8] #
fromShort :: ShortByteString -> ByteString #
toShort :: ByteString -> ShortByteString #
Basic interface
snoc :: ShortByteString -> Word8 -> ShortByteString #
cons :: Word8 -> ShortByteString -> ShortByteString #
append :: ShortByteString -> ShortByteString -> ShortByteString #
last :: HasCallStack => ShortByteString -> Word8 #
tail :: HasCallStack => ShortByteString -> ShortByteString #
uncons :: ShortByteString -> Maybe (Word8, ShortByteString) #
uncons2 :: ShortByteString -> Maybe (Word8, Word8, ShortByteString) Source #
head :: HasCallStack => ShortByteString -> Word8 #
init :: HasCallStack => ShortByteString -> ShortByteString #
unsnoc :: ShortByteString -> Maybe (ShortByteString, Word8) #
null :: ShortByteString -> Bool #
length :: ShortByteString -> Int #
Transforming ShortByteStrings
map :: (Word8 -> Word8) -> ShortByteString -> ShortByteString #
intercalate :: ShortByteString -> [ShortByteString] -> ShortByteString #
Reducing ShortByteString
s (folds)
foldl :: (a -> Word8 -> a) -> a -> ShortByteString -> a #
foldl' :: (a -> Word8 -> a) -> a -> ShortByteString -> a #
foldl1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8 #
foldl1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8 #
foldr :: (Word8 -> a -> a) -> a -> ShortByteString -> a #
foldr' :: (Word8 -> a -> a) -> a -> ShortByteString -> a #
foldr1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8 #
foldr1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ShortByteString -> Word8 #
Special folds
all :: (Word8 -> Bool) -> ShortByteString -> Bool #
any :: (Word8 -> Bool) -> ShortByteString -> Bool #
concat :: [ShortByteString] -> ShortByteString #
Generating and unfolding ByteStrings
replicate :: Int -> Word8 -> ShortByteString #
unfoldr :: (a -> Maybe (Word8, a)) -> a -> ShortByteString #
unfoldrN :: Int -> (a -> Maybe (Word8, a)) -> a -> (ShortByteString, Maybe a) #
Substrings
Breaking strings
take :: Int -> ShortByteString -> ShortByteString #
takeEnd :: Int -> ShortByteString -> ShortByteString #
takeWhileEnd :: (Word8 -> Bool) -> ShortByteString -> ShortByteString #
takeWhile :: (Word8 -> Bool) -> ShortByteString -> ShortByteString #
drop :: Int -> ShortByteString -> ShortByteString #
dropEnd :: Int -> ShortByteString -> ShortByteString #
dropWhile :: (Word8 -> Bool) -> ShortByteString -> ShortByteString #
dropWhileEnd :: (Word8 -> Bool) -> ShortByteString -> ShortByteString #
breakEnd :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) #
break :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) #
span :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) #
spanEnd :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) #
splitAt :: Int -> ShortByteString -> (ShortByteString, ShortByteString) #
split :: Word8 -> ShortByteString -> [ShortByteString] #
splitWith :: (Word8 -> Bool) -> ShortByteString -> [ShortByteString] #
stripSuffix :: ShortByteString -> ShortByteString -> Maybe ShortByteString #
stripPrefix :: ShortByteString -> ShortByteString -> Maybe ShortByteString #
Predicates
isInfixOf :: ShortByteString -> ShortByteString -> Bool #
isPrefixOf :: ShortByteString -> ShortByteString -> Bool #
isSuffixOf :: ShortByteString -> ShortByteString -> Bool #
Search for arbitrary substrings
Searching ShortByteStrings
Searching by equality
elem :: Word8 -> ShortByteString -> Bool #
Searching with a predicate
find :: (Word8 -> Bool) -> ShortByteString -> Maybe Word8 #
filter :: (Word8 -> Bool) -> ShortByteString -> ShortByteString #
partition :: (Word8 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) #
Indexing ShortByteStrings
index :: HasCallStack => ShortByteString -> Int -> Word8 #
indexMaybe :: ShortByteString -> Int -> Maybe Word8 #
(!?) :: ShortByteString -> Int -> Maybe Word8 #
elemIndex :: Word8 -> ShortByteString -> Maybe Int #
elemIndices :: Word8 -> ShortByteString -> [Int] #
count :: Word8 -> ShortByteString -> Int #
findIndex :: (Word8 -> Bool) -> ShortByteString -> Maybe Int #
findIndices :: (Word8 -> Bool) -> ShortByteString -> [Int] #
Low level conversions
Packing CString
s and pointers
packCString :: CString -> IO ShortByteString #
packCStringLen :: CStringLen -> IO ShortByteString #
Using ShortByteStrings as CString
s
useAsCString :: ShortByteString -> (CString -> IO a) -> IO a #
useAsCStringLen :: ShortByteString -> (CStringLen -> IO a) -> IO a #