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Improve getObj example to catch no-existing ObjectId and default to listing existing ObjectIds when none is provided

This commit is contained in:
Tissevert 2019-11-29 11:53:08 +01:00
parent 380c1e439b
commit 7eca875900
1 changed files with 24 additions and 11 deletions
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35
examples/getObj.hs
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@ -4,16 +4,17 @@ import Codec.Compression.Zlib (decompress)
import Data.ByteString.Lazy.Char8 (ByteString)
import qualified Data.ByteString.Char8 as BS (readFile)
import qualified Data.ByteString.Lazy.Char8 as Lazy (fromStrict, putStr, toStrict)
import Data.Map ((!))
import qualified Data.Map as Map (lookup)
import Data.Map ((!?))
import qualified Data.Map as Map (keys, lookup)
import PDF (Document(..), parseDocument)
import qualified PDF.EOL as EOL (Style)
import PDF.Object (Content(..), DirectObject(..), Object(..), Name(..))
import PDF.Output (ObjectId(..))
import qualified PDF.Output as Output (render)
import PDF.Update (unify)
import System.Environment (getArgs)
import System.IO (hPutStrLn, stderr)
import System.Environment (getArgs, getProgName)
import System.Exit (die)
import Text.Printf (printf)
display :: EOL.Style -> Object -> ByteString
display eolStyle d@(Direct _) = Output.render eolStyle d
@ -25,16 +26,28 @@ display eolStyle s@(Stream {header, streamContent}) = Output.render eolStyle $
}
_ -> s
extractObject :: ObjectId -> Document -> ByteString
extractObject :: ObjectId -> Document -> Either String ByteString
extractObject objectId (Document {eolStyle, updates}) =
display eolStyle . (!objectId) $ objects content
case objects content !? objectId of
Nothing -> Left $ "No object has ID " ++ show (getObjectId objectId)
Just o -> Right $ display eolStyle o
where
content = unify updates
listObjectIds :: Document -> Either String [String]
listObjectIds =
Right . prependTitle . toString . Map.keys . objects . unify . updates
where
toString = fmap (show . getObjectId)
prependTitle = ("ObjectIds defined in this PDF:":)
main :: IO ()
main = do
[inputFile, objectId] <- getArgs
result <- parseDocument <$> BS.readFile inputFile
case result of
Left parseError -> hPutStrLn stderr parseError
Right doc -> Lazy.putStr $ extractObject (ObjectId (read objectId)) doc
(inputFile, getData) <- parse =<< getArgs
input <- BS.readFile inputFile
either die id $ (parseDocument input >>= getData)
where
parse [inputFile] = return (inputFile, fmap (mapM_ putStrLn) . listObjectIds)
parse [inputFile, objectId] = return
(inputFile, fmap Lazy.putStr . extractObject (ObjectId (read objectId)))
parse _ = die . printf "Syntax: %s inputFile [OBJECT_ID]\n" =<< getProgName