181 lines
6.4 KiB
Haskell
181 lines
6.4 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module PDF.Text (
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CMap
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, CMappers
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, PageContents(..)
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, cMap
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, emptyCMap
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, pageContents
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) where
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import Control.Applicative ((<|>), many)
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import Control.Monad (foldM, join)
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import Control.Monad.Reader (ReaderT, runReaderT, asks)
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import Control.Monad.State (put)
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import Data.Attoparsec.ByteString.Char8 (choice, count, parseOnly, sepBy)
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import qualified Data.Attoparsec.ByteString.Char8 as Atto (Parser)
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import Data.ByteString.Char8 (ByteString, pack)
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import qualified Data.ByteString.UTF8 as UTF8 (toString)
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import Data.Map (Map, (!))
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import qualified Data.Map as Map (empty, fromList)
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import PDF.Object (
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DirectObject(..), Name, StringObject(..)
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, array, blank, directObject, integer, line, name, regular, stringObject
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)
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import qualified PDF.EOL as EOL (charset, parser)
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import PDF.Parser (Parser, evalParser, string, takeAll)
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type CMappers = Map Name CMap
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type CMap = Map Int ByteString
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emptyCMap :: CMap
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emptyCMap = Map.empty
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cMap :: ByteString -> Either String CMap
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cMap = parseOnly $ mconcat <$> many (cMapRange <|> cMapChar <|> ignoredLine)
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where
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ignoredLine =
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takeAll (not . (`elem` EOL.charset)) *> EOL.parser *> return Map.empty
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cMapRange :: Atto.Parser CMap
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cMapRange = do
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size <- integer <* line "beginbfrange"
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mconcat <$> count size rangeMapping <* line "endbfrange"
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where
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rangeMapping = mapFromTo
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<$> (stringObject <* blank)
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<*> (stringObject <* blank)
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<*> directObject <* EOL.parser
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cMapChar :: Atto.Parser CMap
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cMapChar = do
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size <- integer <* line "beginbfchar"
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Map.fromList <$> count size charMapping <* line "endbfchar"
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where
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charMapping = pairMapping
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<$> (stringObject <* blank) <*> (stringObject <* blank) <* EOL.parser
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mapFromTo (Hexadecimal from) (Hexadecimal to) (StringObject (Hexadecimal dstFrom)) =
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let dstFrom
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mapFromTo (Hexadecimal from) (Hexadecimal to) (Array dstPoints) = undefined
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mapFromTo _ _ _ = fail "invalid range mapping found"
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pairMapping :: StringObject -> StringObject -> (Int, ByteString)
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pairMapping (Hexadecimal from) (Hexadecimal to) =
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(hexString from, toByteString to)
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pairMapping = fail "invalid pair mapping found"
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hexString :: Num a => String -> a
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hexString s = read $ "0x" ++ s
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toByteString :: String -> [Word8]
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toByteString = pack . toBaseWord8 [] . hexString
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where
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toBaseWord8 digits n
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| n < 0xff = (fromIntegral n):digits
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| otherwise =
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let newDigits = (fromIntegral (n `mod` 0xff)):digits in
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case n `div` 0xff of
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0 -> newDigits
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k -> toBaseWord8 newDigits k
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data StateOperator =
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Cm | W | J | J_ | M | D | Ri | I | Gs -- general graphic state
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deriving (Bounded, Enum)
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data TextOperator =
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Td | TD | Tm | Tstar -- text positioning
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| TJ | Tj | Quote | DQuote -- text showing
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| Tc | Tw | Tz | TL | Tf | Tr | Ts -- text state
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deriving (Bounded, Enum)
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data Argument = Raw ByteString | Typed DirectObject
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type Call a = (a, [Argument])
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stateOperator :: StateOperator -> ParserWithFont (Call StateOperator)
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stateOperator Cm = (,) Cm <$> count 6 argument <* string "cm"
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stateOperator W = (,) W <$> count 1 argument <* string "w"
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stateOperator J = (,) J <$> count 1 argument <* string "J"
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stateOperator J_ = (,) J_ <$> count 1 argument <* string "j"
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stateOperator M = (,) M <$> count 1 argument <* string "M"
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stateOperator D = (,) D <$> count 2 argument <* string "d"
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stateOperator Ri = (,) Ri <$> count 1 argument <* string "ri"
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stateOperator I = (,) I <$> count 1 argument <* string "i"
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stateOperator Gs = (,) Gs <$> count 1 argument <* string "gs"
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textOperator :: TextOperator -> ParserWithFont (Call TextOperator)
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textOperator Td = (,) Td <$> count 2 argument <* string "Td"
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textOperator TD = (,) TD <$> count 2 argument <* string "TD"
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textOperator Tm = (,) Tm <$> count 6 argument <* string "Tm"
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textOperator Tstar = (,) Td <$> return [] <* string "T*"
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textOperator TJ =
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(,) TJ <$> sequence [Typed . Array <$> array] <* string "TJ"
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textOperator Tj =
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(,) Tj <$> sequence [Typed . StringObject <$> stringObject] <* string "Tj"
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textOperator Quote = (,) Quote <$> count 1 argument <* string "'"
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textOperator DQuote = (,) DQuote <$> count 1 argument <* string "\""
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textOperator Tc = (,) Tc <$> count 1 argument <* string "Tc"
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textOperator Tw = (,) Tw <$> count 1 argument <* string "Tw"
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textOperator Tz = (,) Tz <$> count 1 argument <* string "Tz"
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textOperator TL = (,) TL <$> count 1 argument <* string "TL"
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textOperator Tf = (,) Tf <$> sequence [Typed . NameObject <$> name, argument] <* string "Tf"
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textOperator Tr = (,) Tr <$> count 1 argument <* string "Tr"
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textOperator Ts = (,) Ts <$> count 1 argument <* string "Ts"
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a :: (Bounded o, Enum o) => (o -> ParserWithFont (Call o)) -> ParserWithFont (Call o)
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a parserGenerator = choice $ parserGenerator <$> [minBound .. maxBound]
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argument :: ParserWithFont Argument
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argument = Raw <$> takeAll regular <* blank
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data PageContents = PageContents {
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chunks :: [ByteString]
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}
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type ParserWithFont = ReaderT CMappers (Parser CMap)
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pageContents :: CMappers -> ByteString -> Either String PageContents
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pageContents font input =
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evalParser (runReaderT (PageContents <$> page) font) emptyCMap input
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page :: ParserWithFont [ByteString]
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page = graphicState <|> text
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graphicState :: ParserWithFont [ByteString]
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graphicState =
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string "q" *> blank *> insideQ <* string "Q"
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where
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insideQ = join <$> (command <|> page `sepBy` blank )
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command = a stateOperator *> return []
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text :: ParserWithFont [ByteString]
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text =
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string "BT" *> blank *> commands <* blank <* string "ET"
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where
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commands = join <$> (a textOperator >>= runOperator) `sepBy` blank
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runOperator :: Call TextOperator -> ParserWithFont [ByteString]
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runOperator (Tf, [Typed (NameObject fontName), _]) =
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asks (! fontName) >>= put >> return []
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runOperator (Tstar, []) = return ["\n"]
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runOperator (TJ, [Typed (Array arrayObject)]) =
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replicate 1 <$> foldM appendText "" arrayObject
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where
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appendText bs (StringObject outputString) =
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mappend bs <$> decodeString outputString
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appendText bs _ = return bs
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runOperator (Tj, [Typed (StringObject outputString)]) =
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replicate 1 <$> decodeString outputString
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runOperator (Quote, [Typed (StringObject outputString)]) =
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(\bs -> ["\n", bs]) <$> decodeString outputString
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runOperator (DQuote, [Typed (StringObject outputString)]) =
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(\bs -> ["\n", bs]) <$> decodeString outputString
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runOperator _ = return []
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decodeString :: StringObject -> ParserWithFont ByteString
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decodeString = undefined
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