{- Copyright 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/>. -} {-# LANGUAGE Rank2Types, FlexibleContexts #-} {-# OPTIONS_HADDOCK hide #-} -- | This module exports sequential versions of the combinators from the "Control.Concurrent.SCC.Combinators" module. module Control.Concurrent.SCC.Combinators.Sequential ( -- * Consumer, producer, and transducer combinators Combinators.consumeBy, Combinators.prepend, Combinators.append, Combinators.substitute, Combinators.PipeableComponentPair, (>->), Combinators.JoinableComponentPair (Combinators.sequence), join, -- * Splitter combinators Combinators.sNot, -- ** Pseudo-logic flow combinators -- | Combinators '>&' and '>|' are only /pseudo/-logic. While the laws of double negation and De Morgan's laws -- hold, 'sAnd' and 'sOr' are in general not commutative, associative, nor idempotent. In the special case when all -- argument splitters are stateless, such as those produced by 'Control.Concurrent.SCC.Types.statelessSplitter', -- these combinators do satisfy all laws of Boolean algebra. (>&), (>|), -- ** Zipping logic combinators -- | The '&&' and '||' combinators run the argument splitters in parallel and combine their logical outputs using -- the corresponding logical operation on each output pair, in a manner similar to 'Data.List.zipWith'. They fully -- satisfy the laws of Boolean algebra. (&&), (||), -- * Flow-control combinators -- | The following combinators resemble the common flow-control programming language constructs. Combinators -- 'wherever', 'unless', and 'select' are just the special cases of the combinator 'ifs'. -- -- * /transducer/ ``wherever`` /splitter/ = 'ifs' /splitter/ /transducer/ 'Control.Category.id' -- -- * /transducer/ ``unless`` /splitter/ = 'ifs' /splitter/ 'Control.Category.id' /transducer/ -- -- * 'select' /splitter/ = 'ifs' /splitter/ 'Control.Category.id' -- 'Control.Concurrent.SCC.Primitives.suppress' -- ifs, wherever, unless, Combinators.select, -- ** Recursive while, nestedIn, -- * Section-based combinators -- | All combinators in this section use their 'Control.Concurrent.SCC.Splitter' argument to determine the structure -- of the input. Every contiguous portion of the input that gets passed to one or the other sink of the splitter is -- treated as one section in the logical structure of the input stream. What is done with the section depends on the -- combinator, but the sections, and therefore the logical structure of the input stream, are determined by the -- argument splitter alone. foreach, having, havingOnly, followedBy, Combinators.even, -- ** first and its variants Combinators.first, Combinators.uptoFirst, Combinators.prefix, -- ** last and its variants Combinators.last, Combinators.lastAndAfter, Combinators.suffix, -- ** positional splitters Combinators.startOf, Combinators.endOf, (...), -- * Parser support Combinators.splitterToMarker, Combinators.parseRegions, Combinators.parseNestedRegions, parseEachNestedRegion, ) where import Prelude hiding ((&&), (||), even, last, sequence) import Data.Text (Text) import Control.Monad.Coroutine (sequentialBinder) import Control.Concurrent.SCC.Types import Control.Concurrent.SCC.Coercions (Coercible) import qualified Control.Concurrent.SCC.Combinators as Combinators import qualified Control.Concurrent.SCC.XML as XML -- | Class 'PipeableComponentPair' applies to any two components that can be combined into a third component with the -- following properties: -- -- * The input of the result, if any, becomes the input of the first component. -- -- * The output produced by the first child component is consumed by the second child component. -- -- * The result output, if any, is the output of the second component. (>->) :: (Monad m, Combinators.PipeableComponentPair m w c1 c2 c3) => c1 -> c2 -> c3 (>->) = Combinators.compose sequentialBinder -- | The 'join' combinator may apply the components in any order. join :: (Monad m, Combinators.JoinableComponentPair t1 t2 t3 m x y c1 c2 c3) => c1 -> c2 -> c3 join = Combinators.join sequentialBinder -- | The '>&' combinator sends the /true/ sink output of its left operand to the input of its right operand for further -- splitting. Both operands' /false/ sinks are connected to the /false/ sink of the combined splitter, but any input -- value to reach the /true/ sink of the combined component data must be deemed true by both splitters. (>&) :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x (b1, b2) (>&) = Combinators.sAnd sequentialBinder -- | A '>|' combinator's input value can reach its /false/ sink only by going through both argument splitters' /false/ -- sinks. (>|) :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x (Either b1 b2) (>|) = Combinators.sOr sequentialBinder -- | Combinator '&&' is a pairwise logical conjunction of two splitters run in parallel on the same input. (&&) :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x (b1, b2) (&&) = Combinators.pAnd sequentialBinder -- | Combinator '||' is a pairwise logical disjunction of two splitters run in parallel on the same input. (||) :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x (Either b1 b2) (||) = Combinators.pOr sequentialBinder ifs :: (Monad m, Branching c m x ()) => Splitter m x b -> c -> c -> c ifs = Combinators.ifs sequentialBinder wherever :: Monad m => Transducer m x x -> Splitter m x b -> Transducer m x x wherever = Combinators.wherever sequentialBinder unless :: Monad m => Transducer m x x -> Splitter m x b -> Transducer m x x unless = Combinators.unless sequentialBinder -- | Converts a boundary-marking splitter into a parser. parseEachNestedRegion :: Monad m => Splitter m x (Boundary b) -> Transducer m x y -> Transducer m x (Markup b y) parseEachNestedRegion = Combinators.parseEachNestedRegion sequentialBinder -- | The recursive combinator 'while' feeds the true sink of the argument splitter back to itself, modified by the -- argument transducer. Data fed to the splitter's false sink is passed on unmodified. while :: Monad m => Transducer m x x -> Splitter m x b -> Transducer m x x while t s = Combinators.while sequentialBinder t s (while t s) -- | The recursive combinator 'nestedIn' combines two splitters into a mutually recursive loop acting as a single -- splitter. The true sink of one of the argument splitters and false sink of the other become the true and false sinks -- of the loop. The other two sinks are bound to the other splitter's source. The use of 'nestedIn' makes sense only on -- hierarchically structured streams. If we gave it some input containing a flat sequence of values, and assuming both -- component splitters are deterministic and stateless, an input value would either not loop at all or it would loop -- forever. nestedIn :: Monad m => Splitter m x b -> Splitter m x b -> Splitter m x b nestedIn s1 s2 = Combinators.nestedIn sequentialBinder s1 s2 (nestedIn s1 s2) -- | The 'foreach' combinator is similar to the combinator 'ifs' in that it combines a splitter and two transducers into -- another transducer. However, in this case the transducers are re-instantiated for each consecutive portion of the -- input as the splitter chunks it up. Each contiguous portion of the input that the splitter sends to one of its two -- sinks gets transducered through the appropriate argument transducer as that transducer's whole input. As soon as the -- contiguous portion is finished, the transducer gets terminated. foreach :: (Monad m, Branching c m x ()) => Splitter m x b -> c -> c -> c foreach = Combinators.foreach sequentialBinder -- | The 'having' combinator combines two pure splitters into a pure splitter. One splitter is used to chunk the input -- into contiguous portions. Its /false/ sink is routed directly to the /false/ sink of the combined splitter. The -- second splitter is instantiated and run on each portion of the input that goes to first splitter's /true/ sink. If -- the second splitter sends any output at all to its /true/ sink, the whole input portion is passed on to the /true/ -- sink of the combined splitter, otherwise it goes to its /false/ sink. having :: (Monad m, Coercible x y) => Splitter m x b1 -> Splitter m y b2 -> Splitter m x b1 having = Combinators.having sequentialBinder -- | The 'havingOnly' combinator is analogous to the 'having' combinator, but it succeeds and passes each chunk of the -- input to its /true/ sink only if the second splitter sends no part of it to its /false/ sink. havingOnly :: (Monad m, Coercible x y) => Splitter m x b1 -> Splitter m y b2 -> Splitter m x b1 havingOnly = Combinators.havingOnly sequentialBinder -- | Combinator 'followedBy' treats its argument 'Splitter's as patterns components and returns a 'Splitter' that -- matches their concatenation. A section of input is considered /true/ by the result iff its prefix is considered -- /true/ by argument /s1/ and the rest of the section is considered /true/ by /s2/. The splitter /s2/ is started anew -- after every section split to /true/ sink by /s1/. followedBy :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x (b1, b2) followedBy = Combinators.followedBy sequentialBinder -- | Combinator '...' tracks the running balance of difference between the number of preceding starts of sections -- considered /true/ according to its first argument and the ones according to its second argument. The combinator -- passes to /true/ all input values for which the difference balance is positive. This combinator is typically used -- with 'startOf' and 'endOf' in order to count entire input sections and ignore their lengths. (...) :: Monad m => Splitter m x b1 -> Splitter m x b2 -> Splitter m x b1 (...) = Combinators.between sequentialBinder