GHC.Data.FastString

There are two principal string types used internally by GHC:

FastString

• A compact, hash-consed, representation of character strings.
• Generated by fsLit.
• You can get a Unique from them.
• Equality test is O(1) (it uses the Unique).
• Comparison is O(1) or O(n):
• O(n) but deterministic with lexical comparison (lexicalCompareFS)
• O(1) but non-deterministic with Unique comparison (uniqCompareFS)
• Turn into SDoc with ftext.

PtrString

• Pointer and size of a Latin-1 encoded string.
• Practically no operations.
• Outputting them is fast.
• Generated by mkPtrString.
• Length of string literals (mkPtrString "abc") is computed statically
• Turn into SDoc with ptext
• Requires manual memory management. Improper use may lead to memory leaks or dangling pointers.
• It assumes Latin-1 as the encoding, therefore it cannot represent arbitrary Unicode strings.

Use PtrString unless you want the facilities of FastString.

ByteString

bytesFS :: FastString -> ByteString

Gives the Modified UTF-8 encoded bytes corresponding to a FastString

fastStringToByteString :: FastString -> ByteString

Deprecated: Use bytesFS instead

Gives the Modified UTF-8 encoded bytes corresponding to a FastString

mkFastStringByteString :: ByteString -> FastString

Create a FastString by copying an existing ByteString

fastZStringToByteString :: FastZString -> ByteString

unsafeMkByteString :: String -> ByteString

ShortByteString

fastStringToShortByteString :: FastString -> ShortByteString

mkFastStringShortByteString :: ShortByteString -> FastString

Create a FastString from an existing ShortByteString without copying.

FastZString

data FastZString

Instances

NFData FastZString

Defined in GHC.Data.FastString

Methods

rnf :: FastZString -> ()

hPutFZS :: Handle -> FastZString -> IO ()

zString :: FastZString -> String

lengthFZS :: FastZString -> Int

FastStrings

data FastString

A FastString is a UTF-8 encoded string together with a unique ID. All FastStrings are stored in a global hashtable to support fast O(1) comparison.

It is also associated with a lazy reference to the Z-encoding of this string which is used by the compiler internally.

Constructors

FastString

Fields

• uniq :: !Int
• n_chars :: !Int
• fs_sbs :: !ShortByteString
• fs_zenc :: FastZString

  Lazily computed Z-encoding of this string. See Note [Z-Encoding] in GHC.Utils.Encoding.

  Since FastStrings are globally memoized this is computed at most once for any given string.

Instances

Data FastString

Defined in GHC.Data.FastString

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> FastString -> c FastString

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c FastString

toConstr :: FastString -> Constr

dataTypeOf :: FastString -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c FastString)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c FastString)

gmapT :: (forall b. Data b => b -> b) -> FastString -> FastString

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> FastString -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> FastString -> r

gmapQ :: (forall d. Data d => d -> u) -> FastString -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> FastString -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> FastString -> m FastString

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> FastString -> m FastString

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> FastString -> m FastString

IsString FastString

Defined in GHC.Data.FastString

Methods

fromString :: String -> FastString

Monoid FastString

Defined in GHC.Data.FastString

Methods

mempty :: FastString

mappend :: FastString -> FastString -> FastString

mconcat :: [FastString] -> FastString

Semigroup FastString

Defined in GHC.Data.FastString

Methods

(<>) :: FastString -> FastString -> FastString

sconcat :: NonEmpty FastString -> FastString

stimes :: Integral b => b -> FastString -> FastString

Show FastString

Defined in GHC.Data.FastString

Methods

showsPrec :: Int -> FastString -> ShowS

show :: FastString -> String

showList :: [FastString] -> ShowS

NFData FastString

Defined in GHC.Data.FastString

Methods

rnf :: FastString -> ()

Uniquable FastString

Defined in GHC.Types.Unique

Methods

getUnique :: FastString -> Unique

Binary FastString

Defined in GHC.Utils.Binary

Methods

put_ :: BinHandle -> FastString -> IO ()

put :: BinHandle -> FastString -> IO (Bin FastString)

get :: BinHandle -> IO FastString

Outputable FastString

Defined in GHC.Utils.Outputable

Methods

ppr :: FastString -> SDoc

Eq FastString

Defined in GHC.Data.FastString

Methods

(==) :: FastString -> FastString -> Bool

(/=) :: FastString -> FastString -> Bool

type Anno FieldLabelString

Defined in GHC.Hs.Expr

type Anno FieldLabelString = SrcSpanAnnN

type Anno (SourceText, RuleName)

Defined in GHC.Hs.Decls

type Anno (SourceText, RuleName) = SrcAnn NoEpAnns

type Anno (SourceText, RuleName)

Defined in GHC.Hs.Decls

type Anno (SourceText, RuleName) = SrcAnn NoEpAnns

newtype NonDetFastString

Non-deterministic FastString

This is a simple FastString wrapper with an Ord instance using uniqCompareFS (i.e. which compares FastStrings on their Uniques). Hence it is not deterministic from one run to the other.

Constructors

NonDetFastString FastString

Instances

Data NonDetFastString

Defined in GHC.Data.FastString

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> NonDetFastString -> c NonDetFastString

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c NonDetFastString

toConstr :: NonDetFastString -> Constr

dataTypeOf :: NonDetFastString -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c NonDetFastString)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c NonDetFastString)

gmapT :: (forall b. Data b => b -> b) -> NonDetFastString -> NonDetFastString

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> NonDetFastString -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> NonDetFastString -> r

gmapQ :: (forall d. Data d => d -> u) -> NonDetFastString -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> NonDetFastString -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> NonDetFastString -> m NonDetFastString

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> NonDetFastString -> m NonDetFastString

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> NonDetFastString -> m NonDetFastString

Show NonDetFastString

Defined in GHC.Data.FastString

Methods

showsPrec :: Int -> NonDetFastString -> ShowS

show :: NonDetFastString -> String

showList :: [NonDetFastString] -> ShowS

Binary NonDetFastString

Defined in GHC.Utils.Binary

Methods

put_ :: BinHandle -> NonDetFastString -> IO ()

put :: BinHandle -> NonDetFastString -> IO (Bin NonDetFastString)

get :: BinHandle -> IO NonDetFastString

Outputable NonDetFastString

Defined in GHC.Utils.Outputable

Methods

ppr :: NonDetFastString -> SDoc

Eq NonDetFastString

Defined in GHC.Data.FastString

Methods

(==) :: NonDetFastString -> NonDetFastString -> Bool

(/=) :: NonDetFastString -> NonDetFastString -> Bool

Ord NonDetFastString

Defined in GHC.Data.FastString

Methods

compare :: NonDetFastString -> NonDetFastString -> Ordering

(<) :: NonDetFastString -> NonDetFastString -> Bool

(<=) :: NonDetFastString -> NonDetFastString -> Bool

(>) :: NonDetFastString -> NonDetFastString -> Bool

(>=) :: NonDetFastString -> NonDetFastString -> Bool

max :: NonDetFastString -> NonDetFastString -> NonDetFastString

min :: NonDetFastString -> NonDetFastString -> NonDetFastString

newtype LexicalFastString

Lexical FastString

This is a simple FastString wrapper with an Ord instance using lexicalCompareFS (i.e. which compares FastStrings on their String representation). Hence it is deterministic from one run to the other.

Constructors

LexicalFastString FastString

Instances

Data LexicalFastString

Defined in GHC.Data.FastString

Methods

gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> LexicalFastString -> c LexicalFastString

gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c LexicalFastString

toConstr :: LexicalFastString -> Constr

dataTypeOf :: LexicalFastString -> DataType

dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c LexicalFastString)

dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c LexicalFastString)

gmapT :: (forall b. Data b => b -> b) -> LexicalFastString -> LexicalFastString

gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> LexicalFastString -> r

gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> LexicalFastString -> r

gmapQ :: (forall d. Data d => d -> u) -> LexicalFastString -> [u]

gmapQi :: Int -> (forall d. Data d => d -> u) -> LexicalFastString -> u

gmapM :: Monad m => (forall d. Data d => d -> m d) -> LexicalFastString -> m LexicalFastString

gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> LexicalFastString -> m LexicalFastString

gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> LexicalFastString -> m LexicalFastString

Show LexicalFastString

Defined in GHC.Data.FastString

Methods

showsPrec :: Int -> LexicalFastString -> ShowS

show :: LexicalFastString -> String

showList :: [LexicalFastString] -> ShowS

Binary LexicalFastString

Defined in GHC.Utils.Binary

Methods

put_ :: BinHandle -> LexicalFastString -> IO ()

put :: BinHandle -> LexicalFastString -> IO (Bin LexicalFastString)

get :: BinHandle -> IO LexicalFastString

Outputable LexicalFastString

Defined in GHC.Utils.Outputable

Methods

ppr :: LexicalFastString -> SDoc

Eq LexicalFastString

Defined in GHC.Data.FastString

Methods

(==) :: LexicalFastString -> LexicalFastString -> Bool

(/=) :: LexicalFastString -> LexicalFastString -> Bool

Ord LexicalFastString

Defined in GHC.Data.FastString

Methods

compare :: LexicalFastString -> LexicalFastString -> Ordering

(<) :: LexicalFastString -> LexicalFastString -> Bool

(<=) :: LexicalFastString -> LexicalFastString -> Bool

(>) :: LexicalFastString -> LexicalFastString -> Bool

(>=) :: LexicalFastString -> LexicalFastString -> Bool

max :: LexicalFastString -> LexicalFastString -> LexicalFastString

min :: LexicalFastString -> LexicalFastString -> LexicalFastString

Construction

fsLit :: String -> FastString

mkFastString :: String -> FastString

Creates a UTF-8 encoded FastString from a String

mkFastStringBytes :: Ptr Word8 -> Int -> FastString

mkFastStringByteList :: [Word8] -> FastString

Creates a FastString from a UTF-8 encoded [Word8]

mkFastString# :: Addr# -> FastString

Deconstruction

unpackFS :: FastString -> String

Unpacks and decodes the FastString

unconsFS :: FastString -> Maybe (Char, FastString)

Encoding

zEncodeFS :: FastString -> FastZString

Returns a Z-encoded version of a FastString. This might be the original, if it was already Z-encoded. The first time this function is applied to a particular FastString, the results are memoized.

Operations

uniqueOfFS :: FastString -> Int

lengthFS :: FastString -> Int

Returns the length of the FastString in characters

nullFS :: FastString -> Bool

Returns True if the FastString is empty

appendFS :: FastString -> FastString -> FastString

headFS :: FastString -> Char

concatFS :: [FastString] -> FastString

consFS :: Char -> FastString -> FastString

nilFS :: FastString

isUnderscoreFS :: FastString -> Bool

lexicalCompareFS :: FastString -> FastString -> Ordering

Compare FastString lexically

If you don't care about the lexical ordering, use uniqCompareFS instead.

uniqCompareFS :: FastString -> FastString -> Ordering

Compare FastString by their Unique (not lexically).

Much cheaper than lexicalCompareFS but non-deterministic!

Outputting

hPutFS :: Handle -> FastString -> IO ()

Outputs a FastString with no decoding at all, that is, you get the actual bytes in the FastString written to the Handle.

Internal

getFastStringTable :: IO [[[FastString]]]

getFastStringZEncCounter :: IO Int

PtrStrings

data PtrString

A PtrString is a pointer to some array of Latin-1 encoded chars.

Constructors

PtrString !(Ptr Word8) !Int

Construction

mkPtrString# :: Addr# -> PtrString

Wrap an unboxed address into a PtrString.

mkPtrString :: String -> PtrString

Encode a String into a newly allocated PtrString using Latin-1 encoding. The original string must not contain non-Latin-1 characters (above codepoint 0xff).

Deconstruction

unpackPtrString :: PtrString -> String

Decode a PtrString back into a String using Latin-1 encoding. This does not free the memory associated with PtrString.

Operations

lengthPS :: PtrString -> Int

Return the length of a PtrString