Copyright	(c) 2019-2021 Edward Kmett
License	BSD-2-Clause OR Apache-2.0
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	None
Language	Haskell2010

Foreign.Ptr.Diff

Description

Synopsis

newtype Diff a b = Diff {
- getDiff :: Int
}
inv :: Diff a b -> Diff b a
next :: forall a. Storable a => Diff a a
prev :: Storable a => Diff a a
(.*) :: Int -> Diff a a -> Diff a a
advance :: Storable a => Int -> Diff a a
class DiffTorsor t where
- act :: Diff a b -> t a -> t b
- diff :: t b -> t a -> Diff a b
peekDiffOff :: (MonadIO m, Storable b) => Ptr a -> Diff a b -> m b
pokeDiffOff :: (MonadIO m, Storable b) => Ptr a -> Diff a b -> b -> m ()

Documentation

newtype Diff a b Source #

So long as minusPtr returns an Int, we're stuck with size of Int = size of ptrdiff_t

Constructors

Diff
Fields getDiff :: Int

Instances

Category Diff Source #
Instance details Defined in Foreign.Ptr.Diff Methods id :: Diff a a # (.) :: Diff b c -> Diff a b -> Diff a c #
Eq (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Methods (==) :: Diff a b -> Diff a b -> Bool # (/=) :: Diff a b -> Diff a b -> Bool #
(Data a, Data b) => Data (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Methods gfoldl :: (forall d b0. Data d => c (d -> b0) -> d -> c b0) -> (forall g. g -> c g) -> Diff a b -> c (Diff a b) # gunfold :: (forall b0 r. Data b0 => c (b0 -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (Diff a b) # toConstr :: Diff a b -> Constr # dataTypeOf :: Diff a b -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (Diff a b)) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (Diff a b)) # gmapT :: (forall b0. Data b0 => b0 -> b0) -> Diff a b -> Diff a b # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Diff a b -> r # gmapQr :: (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Diff a b -> r # gmapQ :: (forall d. Data d => d -> u) -> Diff a b -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> Diff a b -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Diff a b -> m (Diff a b) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Diff a b -> m (Diff a b) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Diff a b -> m (Diff a b) #
Ord (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Methods compare :: Diff a b -> Diff a b -> Ordering # (<) :: Diff a b -> Diff a b -> Bool # (<=) :: Diff a b -> Diff a b -> Bool # (>) :: Diff a b -> Diff a b -> Bool # (>=) :: Diff a b -> Diff a b -> Bool # max :: Diff a b -> Diff a b -> Diff a b # min :: Diff a b -> Diff a b -> Diff a b #
Read (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Methods readsPrec :: Int -> ReadS (Diff a b) # readList :: ReadS [Diff a b] # readPrec :: ReadPrec (Diff a b) # readListPrec :: ReadPrec [Diff a b] #
Show (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Methods showsPrec :: Int -> Diff a b -> ShowS # show :: Diff a b -> String # showList :: [Diff a b] -> ShowS #
Generic (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff Associated Types type Rep (Diff a b) :: Type -> Type # Methods from :: Diff a b -> Rep (Diff a b) x # to :: Rep (Diff a b) x -> Diff a b #
type Rep (Diff a b) Source #
Instance details Defined in Foreign.Ptr.Diff type Rep (Diff a b) = D1 (MetaData "Diff" "Foreign.Ptr.Diff" "ptrdiff-0-inplace" True) (C1 (MetaCons "Diff" PrefixI True) (S1 (MetaSel (Just "getDiff") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Int)))

inv :: Diff a b -> Diff b a Source #

Invert a pointer Diff, e.g. convert a pointer to a field member to one that computes the location of the parent, or one that computes the offset of the next item into one that computes the offset of the previous element.

next :: forall a. Storable a => Diff a a Source #

Calculate the position of the next elment of a given type when they are packed in densely.

prev :: Storable a => Diff a a Source #

Calculate the position of the previous element of a given type when they are packed in densely.

(.*) :: Int -> Diff a a -> Diff a a infixr 6 Source #

Diff is a groupoid, so Diff a a is a group, and as such it forms a module over the integers

advance :: Storable a => Int -> Diff a a Source #

Advance n (possibly negative) items in a dense packing.

class DiffTorsor t where Source #

Methods

act :: Diff a b -> t a -> t b Source #

diff :: t b -> t a -> Diff a b Source #

Instances

DiffTorsor Ptr Source #
Instance details Defined in Foreign.Ptr.Diff Methods act :: Diff a b -> Ptr a -> Ptr b Source # diff :: Ptr b -> Ptr a -> Diff a b Source #
DiffTorsor FunPtr Source #
Instance details Defined in Foreign.Ptr.Diff Methods act :: Diff a b -> FunPtr a -> FunPtr b Source # diff :: FunPtr b -> FunPtr a -> Diff a b Source #
DiffTorsor ForeignPtr Source #	due to finalizers this doesn't _quite_ satisfy ForeignPtr a * Diff a b - ForeignPtr a * ForeignPtr b
Instance details Defined in Foreign.Ptr.Diff Methods act :: Diff a b -> ForeignPtr a -> ForeignPtr b Source # diff :: ForeignPtr b -> ForeignPtr a -> Diff a b Source #

peekDiffOff :: (MonadIO m, Storable b) => Ptr a -> Diff a b -> m b Source #

peek using a Diff between pointers to calculate the offset.

pokeDiffOff :: (MonadIO m, Storable b) => Ptr a -> Diff a b -> b -> m () Source #

poke using a Diff between pointers to calculate the offset.