{- Copyright 2009-2010 Mario Blazevic This file is part of the Streaming Component Combinators (SCC) project. The SCC project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. SCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with SCC. If not, see <http://www.gnu.org/licenses/>. -} -- | This module defines various 'Control.Concurrent.SCC.Coroutine' types that operate on -- 'Control.Concurrent.SCC.Streams.Sink' and 'Control.Concurrent.SCC.Streams.Source' values. The simplest of the bunch -- are 'Consumer' and 'Producer' types, which respectively operate on a single source or sink. A 'Transducer' has access -- both to a 'Control.Concurrent.SCC.Streams.Source' to read from and a 'Control.Concurrent.SCC.Streams.Sink' to write -- into. Finally, a 'Splitter' reads from a single source and writes all input into two sinks of the same type, -- signalling interesting input boundaries by writing into the third sink. -- {-# LANGUAGE ScopedTypeVariables, KindSignatures, RankNTypes, MultiParamTypeClasses, FlexibleContexts, FlexibleInstances, FunctionalDependencies, TypeFamilies #-} {-# OPTIONS_HADDOCK hide #-} module Control.Concurrent.SCC.Types ( -- * Component types Performer(..), OpenConsumer, Consumer(..), OpenProducer, Producer(..), OpenTransducer, Transducer(..), OpenSplitter, Splitter(..), Boundary(..), Markup(..), Parser, Branching (combineBranches), -- * Component constructors isolateConsumer, isolateProducer, isolateTransducer, isolateSplitter, oneToOneTransducer, statelessTransducer, statefulTransducer, statelessSplitter, statefulSplitter, ) where import Control.Category (Category(..)) import qualified Control.Category as Category import Control.Monad.Coroutine import Control.Concurrent.SCC.Streams type OpenConsumer m a d x r = AncestorFunctor a d => Source m a x -> Coroutine d m r type OpenProducer m a d x r = AncestorFunctor a d => Sink m a x -> Coroutine d m r type OpenTransducer m a1 a2 d x y r = (AncestorFunctor a1 d, AncestorFunctor a2 d) => Source m a1 x -> Sink m a2 y -> Coroutine d m r type OpenSplitter m a1 a2 a3 a4 d x b r = (AncestorFunctor a1 d, AncestorFunctor a2 d, AncestorFunctor a3 d, AncestorFunctor a4 d) => Source m a1 x -> Sink m a2 x -> Sink m a3 x -> Sink m a4 b -> Coroutine d m r -- | A coroutine that has no inputs nor outputs - and therefore may not suspend at all, which means it's not really a -- /co/routine. newtype Performer m r = Performer {perform :: m r} -- | A coroutine that consumes values from a 'Control.Concurrent.SCC.Streams.Source'. newtype Consumer m x r = Consumer {consume :: forall a d. OpenConsumer m a d x r} -- | A coroutine that produces values and puts them into a 'Control.Concurrent.SCC.Streams.Sink'. newtype Producer m x r = Producer {produce :: forall a d. OpenProducer m a d x r} -- | The 'Transducer' type represents coroutines that transform a data stream. Execution of 'transduce' must continue -- consuming the given 'Control.Concurrent.SCC.Streams.Source' and feeding the 'Control.Concurrent.SCC.Streams.Sink' as -- long as there is any data in the source. newtype Transducer m x y = Transducer {transduce :: forall a1 a2 d. OpenTransducer m a1 a2 d x y ()} -- | The 'Splitter' type represents coroutines that distribute the input stream acording to some criteria. A splitter -- should distribute only the original input data, and feed it into the sinks in the same order it has been read from -- the source. Furthermore, the input source should be entirely consumed and fed into the first two sinks. The third -- sink can be used to supply extra information at arbitrary points in the input. -- -- A splitter can be used in two ways: as a predicate to determine which portions of its input stream satisfy a certain -- property, or as a chunker to divide the input stream into chunks. In the former case, the predicate is considered -- true for exactly those parts of the input that are written to its /true/ sink. In the latter case, a chunk is a -- contiguous section of the input stream that is written exclusively to one sink, either true or false. Anything -- written to the third sink also terminates the chunk. newtype Splitter m x b = Splitter {split :: forall a1 a2 a3 a4 d. OpenSplitter m a1 a2 a3 a4 d x b ()} -- | A 'Boundary' value is produced to mark either a 'Start' and 'End' of a region of data, or an arbitrary 'Point' in -- data. A 'Point' is semantically equivalent to a 'Start' immediately followed by 'End'. data Boundary y = Start y | End y | Point y deriving (Eq, Show) -- | Type of values in a markup-up stream. The 'Content' constructor wraps the actual data. data Markup y x = Content x | Markup (Boundary y) deriving (Eq) -- | A parser is a transducer that marks up its input. type Parser m x b = Transducer m x (Markup b x) instance Functor Boundary where fmap f (Start b) = Start (f b) fmap f (End b) = End (f b) fmap f (Point b) = Point (f b) instance Functor (Markup y) where fmap f (Content x) = Content (f x) fmap _ (Markup b) = Markup b instance (Show x , Show y) => Show (Markup y x) where showsPrec _ (Content x) s = shows x s showsPrec _ (Markup b) s = '[' : shows b (']' : s) instance Monad m => Category (Transducer m) where id = Transducer pour t1 . t2 = isolateTransducer $ \source sink-> pipe (transduce t2 source) (\source'-> transduce t1 source' sink) >> return () -- | Creates a proper 'Consumer' from a function that is, but can't be proven to be, an 'OpenConsumer'. isolateConsumer :: forall m x r. Monad m => (forall d. Functor d => Source m d x -> Coroutine d m r) -> Consumer m x r isolateConsumer c = Consumer consume' where consume' :: forall a d. OpenConsumer m a d x r consume' source = let source' :: Source m d x source' = liftSource source in c source' -- | Creates a proper 'Producer' from a function that is, but can't be proven to be, an 'OpenProducer'. isolateProducer :: forall m x r. Monad m => (forall d. Functor d => Sink m d x -> Coroutine d m r) -> Producer m x r isolateProducer p = Producer produce' where produce' :: forall a d. OpenProducer m a d x r produce' sink = let sink' :: Sink m d x sink' = liftSink sink in p sink' -- | Creates a proper 'Transducer' from a function that is, but can't be proven to be, an 'OpenTransducer'. isolateTransducer :: forall m x y. Monad m => (forall d. Functor d => Source m d x -> Sink m d y -> Coroutine d m ()) -> Transducer m x y isolateTransducer t = Transducer transduce' where transduce' :: forall a1 a2 d. OpenTransducer m a1 a2 d x y () transduce' source sink = let source' :: Source m d x source' = liftSource source sink' :: Sink m d y sink' = liftSink sink in t source' sink' -- | Creates a proper 'Splitter' from a function that is, but can't be proven to be, an 'OpenSplitter'. isolateSplitter :: forall m x b. Monad m => (forall d. Functor d => Source m d x -> Sink m d x -> Sink m d x -> Sink m d b -> Coroutine d m ()) -> Splitter m x b isolateSplitter s = Splitter split' where split' :: forall a1 a2 a3 a4 d. OpenSplitter m a1 a2 a3 a4 d x b () split' source true false edge = let source' :: Source m d x source' = liftSource source true' :: Sink m d x true' = liftSink true false' :: Sink m d x false' = liftSink false edge' :: Sink m d b edge' = liftSink edge in s source' true' false' edge' -- | 'Branching' is a type class representing all types that can act as consumers, namely 'Consumer', -- 'Transducer', and 'Splitter'. class Branching c (m :: * -> *) x r | c -> m x where -- | 'combineBranches' is used to combine two values of 'Branch' class into one, using the given 'Consumer' binary -- combinator. combineBranches :: (forall d. (PairBinder m -> (forall a d'. AncestorFunctor d d' => OpenConsumer m a d' x r) -> (forall a d'. AncestorFunctor d d' => OpenConsumer m a d' x r) -> (forall a. OpenConsumer m a d x r))) -> PairBinder m -> c -> c -> c instance forall m x r. Monad m => Branching (Consumer m x r) m x r where combineBranches combinator binder c1 c2 = Consumer $ combinator binder (consume c1) (consume c2) instance forall m x y. Monad m => Branching (Transducer m x y) m x () where combineBranches combinator binder t1 t2 = let transduce' :: forall a1 a2 d. OpenTransducer m a1 a2 d x y () transduce' source sink = combinator binder (\source'-> transduce t1 source' sink') (\source'-> transduce t2 source' sink') source where sink' :: Sink m d y sink' = liftSink sink in Transducer transduce' instance forall m x b. Monad m => Branching (Splitter m x b) m x () where combineBranches combinator binder s1 s2 = let split' :: forall a1 a2 a3 a4 d. OpenSplitter m a1 a2 a3 a4 d x b () split' source true false edge = combinator binder (\source'-> split s1 source' true' false' edge') (\source'-> split s2 source' true' false' edge') source where true' :: Sink m d x true' = liftSink true false' :: Sink m d x false' = liftSink false edge' :: Sink m d b edge' = liftSink edge in Splitter split' -- | Function 'oneToOneTransducer' takes a function that maps one input value to one output value each, and lifts it -- into a 'Transducer'. oneToOneTransducer :: Monad m => (x -> y) -> Transducer m x y oneToOneTransducer f = Transducer (mapStream f) -- | Function 'statelessTransducer' takes a function that maps one input value into a list of output values, and -- lifts it into a 'Transducer'. statelessTransducer :: Monad m => (x -> [y]) -> Transducer m x y statelessTransducer f = Transducer (concatMapStream f) -- | Function 'statefulTransducer' constructs a 'Transducer' from a state-transition function and the initial -- state. The transition function may produce arbitrary output at any transition step. statefulTransducer :: Monad m => (state -> x -> (state, [y])) -> state -> Transducer m x y statefulTransducer f s0 = Transducer (\source sink-> foldMStream_ (\ s x -> let (s', ys) = f s x in putList ys sink >> return s') s0 source) -- | Function 'statelessSplitter' takes a function that assigns a Boolean value to each input item and lifts it into -- a 'Splitter'. statelessSplitter :: Monad m => (x -> Bool) -> Splitter m x b statelessSplitter f = Splitter (\source true false _edge-> partitionStream f source true false) -- | Function 'statefulSplitter' takes a state-converting function that also assigns a Boolean value to each input -- item and lifts it into a 'Splitter'. statefulSplitter :: Monad m => (state -> x -> (state, Bool)) -> state -> Splitter m x () statefulSplitter f s0 = Splitter (\source true false _edge-> foldMStream_ (\ s x -> let (s', truth) = f s x in (if truth then put true x else put false x) >> return s') s0 source)