diff --git a/Data/Attoparsec/Split.hs b/Data/Attoparsec/Split.hs new file mode 100644 --- /dev/null +++ b/Data/Attoparsec/Split.hs @@ -0,0 +1,83 @@ +----------------------------------------------------------------------------- +-- | +-- Module : Data.Attoparsec.Split +-- Copyright : 2010 Suite Solutions Ltd., Israel +-- +-- Maintainer : Yitz Gale +-- Portability : portable +-- +-- Split a lazy bytestring into a lazy list of lazy bytestrings at +-- boundaries defined by an attoparsec parser. The result of +-- a matching parse is included at the beginning of the +-- lazy bytestring which begins at that point. + +{- Copyright (c) 2010 Suite Solutions Ltd., Israel. All rights reserved. +For licensing information, see the BSD3-style license in the file +LICENSE that was originally distributed by the author together with +this file. -} + +module Data.Attoparsec.Split (split) where + +import Data.Attoparsec (Parser, Result(..), parse) +import Data.ByteString.Lazy.Internal (ByteString(..), chunk) +import qualified Data.ByteString.Lazy as Lazy +import qualified Data.ByteString as B +import qualified Data.ByteString as Strict +import Data.Maybe (fromMaybe, isJust) + +-- The result of examining the next group of bytes in the input stream +data SplitResult = + -- A match of the parser, ending the current lazy bytestring + Match !B.ByteString -- The result of the match, to be used as + -- the prefix for the next component + !ByteString -- The rest of the input after the match + !Bool -- Did the match consume any input? + | SplitChunk !B.ByteString -- A chunk of the current lazy bytestring + deriving Show + +isChunk :: SplitResult -> Bool +isChunk (SplitChunk _) = True +isChunk _ = False + +asChunk :: SplitResult -> B.ByteString +asChunk (SplitChunk c) = c +asChunk _ = B.empty + +-- | Split a lazy bytestring at boundaries defined by an attoparsec parser. +split :: Parser Strict.ByteString -> Lazy.ByteString -> [Lazy.ByteString] +split bdry = firstSplit . splitOne True bdry + where + firstSplit [] = [] + firstSplit result@(Match _ _ _ : _) = continue result + firstSplit result = nextSplit B.empty result + + nextSplit pfx result = + chunk pfx (foldr (chunk . asChunk) Empty result) : + continue (dropWhile isChunk result) + + continue (Match pfx xs bump : _) = nextSplit pfx (splitOne bump bdry xs) + continue _ = [] + +-- Split off the chunks of the first lazy bytestring from the input. +-- If the previous parser match did not consume any input, pass the +-- first byte through and only start looking for further parser matches +-- at the second byte. +-- A Match element will only occur as the last element of the result list. +-- If the last element is not a Match, end of input was reached. +splitOne :: Bool -> (Parser B.ByteString) -> ByteString -> [SplitResult] +splitOne _ _ Empty = [] +splitOne bump bdry (Chunk x xs) + | bump = go 0 Nothing . parse bdry $ x + | otherwise = go 1 Nothing . parse bdry $ B.tail x + where + go n _ (Fail _ _ _) + | n < B.length x = let n' = n + 1 + in go n' Nothing . parse bdry $ B.drop n' x + | otherwise = SplitChunk x : splitOne True bdry xs + go n ys (Done x' pfx) = [SplitChunk $ B.take n x, + Match pfx (chunk x' $ fromMaybe xs ys) $ + isJust ys || B.length x' < B.length x - n] + go n ys (Partial k) = goPartial n (fromMaybe xs ys) k + + goPartial n (Chunk y ys) k = go n (Just ys) $ k y + goPartial n _ _ = go n Nothing $ Fail B.empty [] "" diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,29 @@ +Copyright (c) 2010 Suite Solutions Ltd., Israel. All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + * Redistributions in binary form must reproduce the above + copyright notice, this list of conditions and the following + disclaimer in the documentation and/or other materials provided + with the distribution. + + * Neither the name of Yitzchak Gale nor the name Suite Solutions + nor the names of other contributors may be used to endorse or + promote products derived from this software without specific + prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/attosplit.cabal b/attosplit.cabal new file mode 100644 --- /dev/null +++ b/attosplit.cabal @@ -0,0 +1,76 @@ +-- attosplit.cabal auto-generated by cabal init. For additional +-- options, see +-- http://www.haskell.org/cabal/release/cabal-latest/doc/users-guide/authors.html#pkg-descr. +-- The name of the package. +Name: attosplit + +-- The package version. See the Haskell package versioning policy +-- (http://www.haskell.org/haskellwiki/Package_versioning_policy) for +-- standards guiding when and how versions should be incremented. +Version: 0.0.1 + +-- A short (one-line) description of the package. +Synopsis: + Split a lazy bytestring at boundaries defined by an attoparsec parser + +-- A longer description of the package. +Description: + Split a lazy bytestring into a lazy list of lazy bytestrings at + boundaries defined by an attoparsec parser. The result of + a matching parse is included at the beginning of the + lazy bytestring which begins at that point. + +-- URL for the project homepage or repository. +Homepage: http://projects.haskell.org/attosplit + +-- The license under which the package is released. +License: BSD3 + +-- The file containing the license text. +License-file: LICENSE + +-- The package author(s). +Author: Yitzchak Gale + +-- An email address to which users can send suggestions, bug reports, +-- and patches. +Maintainer: yitz@community.haskell.org + +-- A copyright notice. +Copyright: + Copyright (c) 2010 Suite Solutions Ltd., Israel. All rights reserved. + +Category: Data + +Build-type: Simple + +-- Extra files to be distributed with the package, such as examples or +-- a README. +-- Extra-source-files: + +-- Constraint on the version of Cabal needed to build this package. +Cabal-version: >=1.6 + + +Library + -- Modules exported by the library. + Exposed-modules: Data.Attoparsec.Split + + -- Packages needed in order to build this package. + Build-depends: + base >= 3 && < 5, + attoparsec == 0.8.*, + bytestring == 0.9.* + + -- Modules not exported by this package. + -- Other-modules: + + -- Extra tools (e.g. alex, hsc2hs, ...) needed to build the source. + -- Build-tools: + + GHC-options: -O2 -Wall + GHC-prof-options: -auto-all + +Source-repository HEAD + Type: darcs + Location: http://code.haskell.org/attosplit