Copyright | © 2021 Julian Ospald |
---|---|
License | MIT |
Maintainer | Julian Ospald <hasufell@posteo.de> |
Stability | experimental |
Portability | portable |
Safe Haskell | None |
Language | Haskell2010 |
Data.ByteString.Short.Word16
Description
ShortByteStrings encoded as UTF16-LE, suitable for windows FFI calls.
Word16s are *always* in BE encoding (both input and output), so e.g. pack
takes a list of BE encoded [Word16]
and produces a UTF16-LE encoded ShortByteString.
Likewise, unpack
takes a UTF16-LE encoded ShortByteString and produces a list of BE encoded [Word16]
.
Indices and lengths are always in respect to Word16, not Word8.
All functions will error out if the input string is not a valid UTF16 stream (uneven number of bytes). So use this module with caution.
Synopsis
- data ShortByteString
- empty :: ShortByteString
- singleton :: Word16 -> ShortByteString
- pack :: [Word16] -> ShortByteString
- unpack :: ShortByteString -> [Word16]
- fromShort :: ShortByteString -> ByteString
- toShort :: ByteString -> ShortByteString
- snoc :: ShortByteString -> Word16 -> ShortByteString
- cons :: Word16 -> ShortByteString -> ShortByteString
- append :: ShortByteString -> ShortByteString -> ShortByteString
- last :: ShortByteString -> Word16
- tail :: ShortByteString -> ShortByteString
- head :: ShortByteString -> Word16
- init :: ShortByteString -> ShortByteString
- null :: ShortByteString -> Bool
- length :: ShortByteString -> Int
- map :: (Word16 -> Word16) -> ShortByteString -> ShortByteString
- reverse :: ShortByteString -> ShortByteString
- intercalate :: ShortByteString -> [ShortByteString] -> ShortByteString
- foldl :: (a -> Word16 -> a) -> a -> ShortByteString -> a
- foldl' :: (a -> Word16 -> a) -> a -> ShortByteString -> a
- foldl1 :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16
- foldl1' :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16
- foldr :: (Word16 -> a -> a) -> a -> ShortByteString -> a
- foldr' :: (Word16 -> a -> a) -> a -> ShortByteString -> a
- foldr1 :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16
- foldr1' :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16
- all :: (Word16 -> Bool) -> ShortByteString -> Bool
- any :: (Word16 -> Bool) -> ShortByteString -> Bool
- concat :: [ShortByteString] -> ShortByteString
- replicate :: Int -> Word16 -> ShortByteString
- unfoldr :: (a -> Maybe (Word16, a)) -> a -> ShortByteString
- unfoldrN :: Int -> (a -> Maybe (Word16, a)) -> a -> (ShortByteString, Maybe a)
- take :: Int -> ShortByteString -> ShortByteString
- takeEnd :: Int -> ShortByteString -> ShortByteString
- takeWhile :: (Word16 -> Bool) -> ShortByteString -> ShortByteString
- takeWhileEnd :: (Word16 -> Bool) -> ShortByteString -> ShortByteString
- drop :: Int -> ShortByteString -> ShortByteString
- dropEnd :: Int -> ShortByteString -> ShortByteString
- dropWhile :: (Word16 -> Bool) -> ShortByteString -> ShortByteString
- dropWhileEnd :: (Word16 -> Bool) -> ShortByteString -> ShortByteString
- breakEnd :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- break :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- span :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- spanEnd :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- splitAt :: Int -> ShortByteString -> (ShortByteString, ShortByteString)
- split :: Word16 -> ShortByteString -> [ShortByteString]
- splitWith :: (Word16 -> 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
- elem :: Word16 -> ShortByteString -> Bool
- find :: (Word16 -> Bool) -> ShortByteString -> Maybe Word16
- filter :: (Word16 -> Bool) -> ShortByteString -> ShortByteString
- partition :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString)
- index :: ShortByteString -> Int -> Word16
- indexMaybe :: ShortByteString -> Int -> Maybe Word16
- (!?) :: ShortByteString -> Int -> Maybe Word16
- elemIndex :: Word16 -> ShortByteString -> Maybe Int
- elemIndices :: Word16 -> ShortByteString -> [Int]
- count :: Word16 -> ShortByteString -> Int
- findIndex :: (Word16 -> Bool) -> ShortByteString -> Maybe Int
- findIndices :: (Word16 -> Bool) -> ShortByteString -> [Int]
- packCWString :: Ptr Word16 -> IO ShortByteString
- packCWStringLen :: (Ptr Word16, Int) -> IO ShortByteString
- newCWString :: ShortByteString -> IO (Ptr Word16)
- useAsCWString :: ShortByteString -> (Ptr Word16 -> IO a) -> IO a
- useAsCWStringLen :: ShortByteString -> ((Ptr Word16, Int) -> IO a) -> IO a
Types
data ShortByteString #
A compact representation of a Word8
vector.
It has a lower memory overhead than a ByteString
and and does not
contribute to heap fragmentation. It can be converted to or from a
ByteString
(at the cost of copying the string data). It supports very few
other operations.
It is suitable for use as an internal representation for code that needs
to keep many short strings in memory, but it should not be used as an
interchange type. That is, it should not generally be used in public APIs.
The ByteString
type is usually more suitable for use in interfaces; it is
more flexible and it supports a wide range of operations.
Instances
Introducing and eliminating ShortByteString
s
O(1). The empty ShortByteString
.
singleton :: Word16 -> ShortByteString Source #
O(1) Convert a Word16
into a ShortByteString
pack :: [Word16] -> ShortByteString Source #
O(n). Convert a list into a ShortByteString
unpack :: ShortByteString -> [Word16] Source #
O(n). Convert a ShortByteString
into a list.
fromShort :: ShortByteString -> ByteString #
O(n). Convert a ShortByteString
into a ByteString
.
toShort :: ByteString -> ShortByteString #
O(n). Convert a ByteString
into a ShortByteString
.
This makes a copy, so does not retain the input string.
Basic interface
snoc :: ShortByteString -> Word16 -> ShortByteString infixl 5 Source #
O(n) Append a Word16 to the end of a ShortByteString
Note: copies the entire byte array
cons :: Word16 -> ShortByteString -> ShortByteString infixr 5 Source #
O(n) cons
is analogous to (:) for lists.
Note: copies the entire byte array
append :: ShortByteString -> ShortByteString -> ShortByteString Source #
O(n) Append two ShortByteStrings
last :: ShortByteString -> Word16 Source #
O(1) Extract the last element of a ShortByteString, which must be finite and at least one Word16. An exception will be thrown in the case of an empty ShortByteString.
tail :: ShortByteString -> ShortByteString Source #
O(n) Extract the elements after the head of a ShortByteString, which must at least one Word16. An exception will be thrown in the case of an empty ShortByteString.
Note: copies the entire byte array
head :: ShortByteString -> Word16 Source #
O(1) Extract the first element of a ShortByteString, which must be at least one Word16. An exception will be thrown in the case of an empty ShortByteString.
init :: ShortByteString -> ShortByteString Source #
O(n) Return all the elements of a ShortByteString
except the last one.
An exception will be thrown in the case of an empty ShortByteString.
Note: copies the entire byte array
null :: ShortByteString -> Bool #
O(1) Test whether a ShortByteString
is empty.
Transforming ShortByteStrings
map :: (Word16 -> Word16) -> ShortByteString -> ShortByteString Source #
O(n) map
f xs
is the ShortByteString obtained by applying f
to each
element of xs
.
reverse :: ShortByteString -> ShortByteString Source #
O(n) reverse
xs
efficiently returns the elements of xs
in reverse order.
intercalate :: ShortByteString -> [ShortByteString] -> ShortByteString Source #
O(n) The intercalate
function takes a ShortByteString
and a list of
ShortByteString
s and concatenates the list after interspersing the first
argument between each element of the list.
Reducing ShortByteString
s (folds)
foldl :: (a -> Word16 -> a) -> a -> ShortByteString -> a Source #
foldl
, applied to a binary operator, a starting value (typically
the left-identity of the operator), and a ShortByteString, reduces the
ShortByteString using the binary operator, from left to right.
foldl' :: (a -> Word16 -> a) -> a -> ShortByteString -> a Source #
foldl1 :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16 Source #
foldl1
is a variant of foldl
that has no starting value
argument, and thus must be applied to non-empty ShortByteString
s.
An exception will be thrown in the case of an empty ShortByteString.
foldr :: (Word16 -> a -> a) -> a -> ShortByteString -> a Source #
foldr
, applied to a binary operator, a starting value
(typically the right-identity of the operator), and a ShortByteString,
reduces the ShortByteString using the binary operator, from right to left.
foldr' :: (Word16 -> a -> a) -> a -> ShortByteString -> a Source #
foldr1 :: (Word16 -> Word16 -> Word16) -> ShortByteString -> Word16 Source #
foldr1
is a variant of foldr
that has no starting value argument,
and thus must be applied to non-empty ShortByteString
s
An exception will be thrown in the case of an empty ShortByteString.
Special folds
all :: (Word16 -> Bool) -> ShortByteString -> Bool Source #
O(n) Applied to a predicate and a ShortByteString
, all
determines
if all elements of the ShortByteString
satisfy the predicate.
any :: (Word16 -> Bool) -> ShortByteString -> Bool Source #
O(n) Applied to a predicate and a ByteString, any
determines if
any element of the ByteString
satisfies the predicate.
concat :: [ShortByteString] -> ShortByteString Source #
O(n) Concatenate a list of ShortByteStrings.
Generating and unfolding ByteStrings
replicate :: Int -> Word16 -> ShortByteString Source #
O(n) replicate
n x
is a ByteString of length n
with x
the value of every element. The following holds:
replicate w c = unfoldr w (\u -> Just (u,u)) c
unfoldr :: (a -> Maybe (Word16, a)) -> a -> ShortByteString Source #
O(n), where n is the length of the result. The unfoldr
function is analogous to the List 'unfoldr'. unfoldr
builds a
ShortByteString from a seed value. The function takes the element and
returns Nothing
if it is done producing the ShortByteString or returns
Just
(a,b)
, in which case, a
is the next byte in the string,
and b
is the seed value for further production.
This function is not efficient/safe. It will build a list of [Word16]
and run the generator until it returns Nothing
, otherwise recurse infinitely,
then finally create a ShortByteString
.
Examples:
unfoldr (\x -> if x <= 5 then Just (x, x + 1) else Nothing) 0 == pack [0, 1, 2, 3, 4, 5]
unfoldrN :: Int -> (a -> Maybe (Word16, a)) -> a -> (ShortByteString, Maybe a) Source #
O(n) Like unfoldr
, unfoldrN
builds a ShortByteString from a seed
value. However, the length of the result is limited by the first
argument to unfoldrN
. This function is more efficient than unfoldr
when the maximum length of the result is known.
This function is not efficient. It will build a full list of [Word8]
before creating a ShortByteString
.
The following equation relates unfoldrN
and unfoldr
:
fst (unfoldrN n f s) == take n (unfoldr f s)
Substrings
Breaking strings
Arguments
:: Int | number of Word16 |
-> ShortByteString | |
-> ShortByteString |
takeEnd :: Int -> ShortByteString -> ShortByteString Source #
takeWhile :: (Word16 -> Bool) -> ShortByteString -> ShortByteString Source #
Similar to takeWhile
,
returns the longest (possibly empty) prefix of elements
satisfying the predicate.
takeWhileEnd :: (Word16 -> Bool) -> ShortByteString -> ShortByteString Source #
Returns the longest (possibly empty) suffix of elements satisfying the predicate.
is equivalent to takeWhileEnd
p
.reverse
. takeWhile
p . reverse
drop :: Int -> ShortByteString -> ShortByteString Source #
dropEnd :: Int -> ShortByteString -> ShortByteString Source #
dropWhile :: (Word16 -> Bool) -> ShortByteString -> ShortByteString Source #
Similar to dropWhile
,
drops the longest (possibly empty) prefix of elements
satisfying the predicate and returns the remainder.
Note: copies the entire byte array
dropWhileEnd :: (Word16 -> Bool) -> ShortByteString -> ShortByteString Source #
Similar to dropWhileEnd
,
drops the longest (possibly empty) suffix of elements
satisfying the predicate and returns the remainder.
is equivalent to dropWhileEnd
p
.reverse
. dropWhile
p . reverse
Since: 0.10.12.0
breakEnd :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) Source #
Returns the longest (possibly empty) suffix of elements which do not satisfy the predicate and the remainder of the string.
breakEnd
p
is equivalent to
and to spanEnd
(not . p)(
.takeWhileEnd
(not . p) &&& dropWhileEnd
(not . p))
break :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) Source #
span :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) Source #
spanEnd :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) Source #
Returns the longest (possibly empty) suffix of elements satisfying the predicate and the remainder of the string.
spanEnd
p
is equivalent to
and to breakEnd
(not . p)(
.takeWhileEnd
p &&& dropWhileEnd
p)
We have
spanEnd (not . isSpace) "x y z" == ("x y ", "z")
and
spanEnd (not . isSpace) ps == let (x, y) = span (not . isSpace) (reverse ps) in (reverse y, reverse x)
Arguments
:: Int | number of Word16 |
-> ShortByteString | |
-> (ShortByteString, ShortByteString) |
split :: Word16 -> ShortByteString -> [ShortByteString] Source #
O(n) Break a ShortByteString
into pieces separated by the byte
argument, consuming the delimiter. I.e.
split 10 "a\nb\nd\ne" == ["a","b","d","e"] -- fromEnum '\n' == 10 split 97 "aXaXaXa" == ["","X","X","X",""] -- fromEnum 'a' == 97 split 120 "x" == ["",""] -- fromEnum 'x' == 120 split undefined "" == [] -- and not [""]
and
intercalate [c] . split c == id split == splitWith . (==)
Note: copies the substrings
splitWith :: (Word16 -> Bool) -> ShortByteString -> [ShortByteString] Source #
O(n) Splits a ShortByteString
into components delimited by
separators, where the predicate returns True for a separator element.
The resulting components do not contain the separators. Two adjacent
separators result in an empty component in the output. eg.
splitWith (==97) "aabbaca" == ["","","bb","c",""] -- fromEnum 'a' == 97 splitWith undefined "" == [] -- and not [""]
stripSuffix :: ShortByteString -> ShortByteString -> Maybe ShortByteString Source #
O(n) The stripSuffix
function takes two ShortByteStrings and returns Just
the remainder of the second iff the first is its suffix, and otherwise
Nothing
.
stripPrefix :: ShortByteString -> ShortByteString -> Maybe ShortByteString Source #
O(n) The stripPrefix
function takes two ShortByteStrings and returns Just
the remainder of the second iff the first is its prefix, and otherwise
Nothing
.
Predicates
isInfixOf :: ShortByteString -> ShortByteString -> Bool Source #
Check whether one string is a substring of another.
isPrefixOf :: ShortByteString -> ShortByteString -> Bool Source #
O(n) The isPrefixOf
function takes two ShortByteStrings and returns True
isSuffixOf :: ShortByteString -> ShortByteString -> Bool Source #
O(n) The isSuffixOf
function takes two ShortByteStrings and returns True
iff the first is a suffix of the second.
The following holds:
isSuffixOf x y == reverse x `isPrefixOf` reverse y
Searching ShortByteStrings
Searching by equality
elem :: Word16 -> ShortByteString -> Bool Source #
O(n) elem
is the ShortByteString
membership predicate.
Searching with a predicate
filter :: (Word16 -> Bool) -> ShortByteString -> ShortByteString Source #
O(n) filter
, applied to a predicate and a ByteString,
returns a ByteString containing those characters that satisfy the
predicate.
partition :: (Word16 -> Bool) -> ShortByteString -> (ShortByteString, ShortByteString) Source #
O(n) The partition
function takes a predicate a ByteString and returns
the pair of ByteStrings with elements which do and do not satisfy the
predicate, respectively; i.e.,
partition p bs == (filter p xs, filter (not . p) xs)
Indexing ShortByteStrings
index :: ShortByteString -> Int -> Word16 Source #
O(1) ShortByteString
index (subscript) operator, starting from 0.
indexMaybe :: ShortByteString -> Int -> Maybe Word16 Source #
elemIndex :: Word16 -> ShortByteString -> Maybe Int Source #
O(n) The elemIndex
function returns the index of the first
element in the given ShortByteString
which is equal to the query
element, or Nothing
if there is no such element.
elemIndices :: Word16 -> ShortByteString -> [Int] Source #
O(n) The elemIndices
function extends elemIndex
, by returning
the indices of all elements equal to the query element, in ascending order.
count :: Word16 -> ShortByteString -> Int Source #
count returns the number of times its argument appears in the ShortByteString
findIndex :: (Word16 -> Bool) -> ShortByteString -> Maybe Int Source #
O(n) The findIndex
function takes a predicate and a ShortByteString
and
returns the index of the first element in the ByteString
satisfying the predicate.
findIndices :: (Word16 -> Bool) -> ShortByteString -> [Int] Source #
O(n) The findIndices
function extends findIndex
, by returning the
indices of all elements satisfying the predicate, in ascending order.
Low level conversions
Packing CString
s and pointers
packCWString :: Ptr Word16 -> IO ShortByteString Source #
O(n). Construct a new ShortByteString
from a CWString
. The
resulting ShortByteString
is an immutable copy of the original
CWString
, and is managed on the Haskell heap. The original
CWString
must be null terminated.
Since: 0.10.10.0
packCWStringLen :: (Ptr Word16, Int) -> IO ShortByteString Source #
O(n). Construct a new ShortByteString
from a CWStringLen
. The
resulting ShortByteString
is an immutable copy of the original CWStringLen
.
The ShortByteString
is a normal Haskell value and will be managed on the
Haskell heap.
Since: 0.10.10.0
newCWString :: ShortByteString -> IO (Ptr Word16) Source #
O(n) construction. Use a ShortByteString
with a function requiring a CWStringLen
.
As for useAsCWString
this function makes a copy of the original ShortByteString
.
It must not be stored or used after the subcomputation finishes.
Since: 0.10.10.0
Using ShortByteStrings as CString
s
useAsCWString :: ShortByteString -> (Ptr Word16 -> IO a) -> IO a Source #
O(n) construction. Use a ShortByteString
with a function requiring a
null-terminated CWString
. The CWString
is a copy and will be freed
automatically; it must not be stored or used after the
subcomputation finishes.
Since: 0.10.10.0
useAsCWStringLen :: ShortByteString -> ((Ptr Word16, Int) -> IO a) -> IO a Source #
O(n) construction. Use a ShortByteString
with a function requiring a CWStringLen
.
As for useAsCWString
this function makes a copy of the original ShortByteString
.
It must not be stored or used after the subcomputation finishes.
Since: 0.10.10.0