38 lines
1.4 KiB
Haskell
38 lines
1.4 KiB
Haskell
{-# LANGUAGE NamedFieldPuns #-}
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import Codec.Compression.Zlib (decompress)
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import Data.ByteString.Lazy.Char8 (ByteString)
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import qualified Data.ByteString.Char8 as BS (readFile)
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import qualified Data.ByteString.Lazy.Char8 as Lazy (concat, fromStrict, putStr, toStrict)
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import Data.Map ((!))
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import qualified Data.Map as Map (lookup)
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import PDF (Document(..), parseDocument)
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import qualified PDF.EOL as EOL (Style)
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import PDF.Object (Content(..), DirectObject(..), Object(..), Name(..))
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import PDF.Output (ObjectId(..))
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import qualified PDF.Output as Output (render)
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import System.Environment (getArgs)
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import System.IO (hPutStrLn, stderr)
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display :: EOL.Style -> Object -> ByteString
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display eolStyle d@(Direct _) = Output.render eolStyle d
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display eolStyle s@(Stream {header, streamContent}) = Output.render eolStyle $
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case Map.lookup (Name "Filter") header of
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Just (NameObject (Name "FlateDecode")) -> Stream {
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header
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, streamContent = Lazy.toStrict . decompress $ Lazy.fromStrict streamContent
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}
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_ -> s
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extractObject :: ObjectId -> Document -> ByteString
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extractObject objectId (Document {eolStyle, updates}) =
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Lazy.concat $ display eolStyle . (!objectId) . objects <$> updates
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main :: IO ()
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main = do
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[inputFile, objectId] <- getArgs
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result <- parseDocument <$> BS.readFile inputFile
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case result of
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Left parseError -> hPutStrLn stderr $ show parseError
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Right doc -> Lazy.putStr $ extractObject (ObjectId (read objectId)) doc
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