107 lines
3.6 KiB
Haskell
107 lines
3.6 KiB
Haskell
{-# LANGUAGE NamedFieldPuns #-}
|
|
{-# LANGUAGE ConstraintKinds #-}
|
|
{-# LANGUAGE FlexibleContexts #-}
|
|
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
|
|
{-# LANGUAGE MultiParamTypeClasses #-}
|
|
{-# LANGUAGE FlexibleInstances #-}
|
|
module PDF.Object.Navigation (
|
|
Error(..)
|
|
, PDFContent
|
|
, StreamContent(..)
|
|
, (./)
|
|
, (//)
|
|
, (>./)
|
|
, (>//)
|
|
, getDictionary
|
|
, objectById
|
|
, origin
|
|
) where
|
|
|
|
import Codec.Compression.Zlib (compress, decompress)
|
|
import Control.Applicative (Alternative(..))
|
|
import Control.Monad (MonadPlus(..))
|
|
import Control.Monad.Reader (MonadReader(..))
|
|
import Control.Monad.Fail (MonadFail(..))
|
|
import Data.ByteString (ByteString)
|
|
import qualified Data.ByteString.Lazy as Lazy (ByteString, fromStrict, toStrict)
|
|
import Data.Map ((!))
|
|
import qualified Data.Map as Map (lookup)
|
|
import PDF.Box (Box(..))
|
|
import PDF.Layer (Layer(..))
|
|
import PDF.Object (
|
|
Dictionary, DirectObject(..), IndirectObjCoordinates(..)
|
|
, Name(..), Object(..), Structure(..)
|
|
)
|
|
import PDF.Output (ObjectId)
|
|
import Prelude hiding (fail)
|
|
import Text.Printf (printf)
|
|
|
|
type PDFContent m = (Alternative m, MonadReader Layer m, MonadFail m)
|
|
newtype Error a = Error {
|
|
runError :: Either String a
|
|
} deriving (Alternative, Functor, Applicative, Monad, MonadPlus)
|
|
instance MonadFail Error where
|
|
fail = Error . Left
|
|
type Component = String
|
|
|
|
getDictionary :: PDFContent m => Object -> m Dictionary
|
|
getDictionary (Direct (Dictionary aDict)) = return aDict
|
|
getDictionary (Direct (Reference (IndirectObjCoordinates {objectId}))) =
|
|
objectById objectId >>= getDictionary
|
|
getDictionary (Stream {header}) = return header
|
|
getDictionary obj = expected "dictionary : " obj
|
|
|
|
expected :: (MonadFail m, Show a) => String -> a -> m b
|
|
expected name = fail . printf "Not a %s: %s" name . show
|
|
|
|
getField :: MonadFail m => String -> Dictionary -> m DirectObject
|
|
getField key aDictionary =
|
|
maybe (fail errorMessage) return (Map.lookup (Name key) aDictionary)
|
|
where
|
|
errorMessage =
|
|
printf "Key %s not found in dictionary %s" key (show aDictionary)
|
|
|
|
objectById :: PDFContent m => ObjectId -> m Object
|
|
objectById objectId = do
|
|
layer <- ask
|
|
return (objects layer ! objectId)
|
|
|
|
(./) :: PDFContent m => m Object -> Component -> m Object
|
|
(./) object key = (object >>= getDictionary >>= getField key >>= castObject)
|
|
where
|
|
castObject (Reference (IndirectObjCoordinates {objectId})) =
|
|
objectById objectId
|
|
castObject directObject = return $ Direct directObject
|
|
|
|
(//) :: PDFContent m => m Object -> [Component] -> m Object
|
|
(//) object [] = object
|
|
(//) object (key:keys) = object ./ key // keys
|
|
|
|
(>./) :: PDFContent m => Object -> Component -> m Object
|
|
(>./) object = (return object ./)
|
|
|
|
(>//) :: PDFContent m => Object -> [Component] -> m Object
|
|
(>//) object = (return object //)
|
|
|
|
origin :: PDFContent m => m Object
|
|
origin = Direct . Dictionary . trailer . docStructure <$> ask
|
|
|
|
data StreamContent = StreamContent
|
|
|
|
onLazy :: (Lazy.ByteString -> Lazy.ByteString) -> ByteString -> ByteString
|
|
onLazy f = Lazy.toStrict . f . Lazy.fromStrict
|
|
|
|
instance MonadFail m => Box m StreamContent Object ByteString where
|
|
r StreamContent (Stream {header, streamContent}) = return $
|
|
case Map.lookup (Name "Filter") header of
|
|
Just (NameObject (Name "FlateDecode")) -> onLazy decompress streamContent
|
|
_ -> streamContent
|
|
r StreamContent obj = expected "stream" obj
|
|
|
|
w StreamContent streamContent obj@(Stream {header}) = return $
|
|
case Map.lookup (Name "Filter") header of
|
|
Just (NameObject (Name "FlateDecode")) ->
|
|
obj {streamContent = onLazy compress streamContent}
|
|
_ -> obj {streamContent}
|
|
w _ _ obj = expected "stream" obj
|