380 lines
11 KiB
Haskell
380 lines
11 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE NamedFieldPuns #-}
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{-# LANGUAGE FlexibleInstances #-}
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module PDF.Object (
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Dictionary
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, DirectObject(..)
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, Flow(..)
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, IndirectObjCoordinates(..)
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, InputStructure(..)
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, Name(..)
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, Number(..)
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, Object(..)
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, Occurrence(..)
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, StringObject(..)
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, Structure(..)
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, XRefEntry(..)
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, XRefSection
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, array
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, blank
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, dictionary
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, directObject
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, eofMarker
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, integer
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, line
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, magicNumber
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, name
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, number
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, outputBody
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, regular
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, stringObject
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, structure
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, toByteString
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) where
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import Control.Applicative ((<|>), many)
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import Data.Attoparsec.ByteString.Char8 (choice, count, option, sepBy)
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import Data.ByteString (ByteString)
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import qualified Data.ByteString as BS (concat)
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import qualified Data.ByteString.Char8 as Char8 (
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cons, length, pack, singleton, snoc, unpack
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)
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import Data.ByteString.Char8.Util (B16Int(..), b16ToBytes, unescape)
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import Data.Id (Id(..), Indexed)
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import Data.Map (Map, (!))
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import qualified Data.Map as Map (
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delete, empty, fromList, lookup, minViewWithKey, toList, union
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)
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import qualified Data.Set as Set (fromList, member)
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import qualified PDF.EOL as EOL (charset, parser)
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import qualified PDF.Output as Output (line, string)
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import PDF.Output (
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OBuilder, Offset(..), Output(..), Resource(..)
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, byteString, getOffset, join, newLine, saveOffset
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)
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import PDF.Parser (MonadParser(..), Parser, (<?>), octDigit, oneOf)
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import Text.Printf (printf)
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line :: MonadParser m => String -> m ()
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line l = (string (Char8.pack l) *> blank *> return ()) <?> printf "line «%s»" l
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magicNumber :: ByteString
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magicNumber = "%PDF-"
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eofMarker :: ByteString
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eofMarker = "%%EOF"
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whiteSpaceCharset :: String
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whiteSpaceCharset = "\0\t\12 "
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blank :: MonadParser m => m ()
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blank = takeAll (`elem` (EOL.charset ++ whiteSpaceCharset)) *> pure ()
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delimiterCharset :: String
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delimiterCharset = "()<>[]{}/%"
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regular :: Char -> Bool
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regular = not . (`elem` (EOL.charset ++ whiteSpaceCharset ++ delimiterCharset))
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integer :: MonadParser m => m Int
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integer = decNumber <* blank <?> "decimal integer"
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-------------------------------------
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-- OBJECTS
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-------------------------------------
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--
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-- Boolean
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--
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boolean :: MonadParser m => m Bool
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boolean =
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(string "true" *> return True) <|> (string "false" *> return False) <?> "boolean"
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--
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-- Number
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--
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newtype Number = Number Double deriving (Eq, Show)
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instance Output Number where
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output (Number f) = Output.string $
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case properFraction f of
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(n, 0) -> printf "%d" (n :: Int)
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_ -> printf "%f" f
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number :: MonadParser m => m Number
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number = Number <$> (sign <*> value) <?> "number"
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where
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sign = (string "-" *> return negate) <|> option id (char '+' >> return id)
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value = floatNumber <|> (char '.' *> afterPoint)
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afterPoint = read . ("0." ++) . Char8.unpack <$> takeAll (`Set.member` digits)
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digits = Set.fromList ['0' .. '9']
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--
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-- StringObject
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--
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data StringObject = Literal ByteString | Hexadecimal B16Int deriving (Eq, Show)
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instance Output StringObject where
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output (Literal s) = Output.string (printf "(%s)" (Char8.unpack s))
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output (Hexadecimal (B16Int n)) = Output.string (printf "<%s>" (Char8.unpack n))
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stringObject :: MonadParser m => m StringObject
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stringObject =
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Literal <$> (char '(' *> (BS.concat <$> literalString) <* char ')')
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<|> Hexadecimal . roundBytes <$> (char '<' *> hexNumber <* char '>')
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<?> "string object (literal or hexadecimal)"
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where
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literalString = many literalStringBlock
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literalStringBlock = takeAll1 normalChar <|> matchingParenthesis <|> escapedChar
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normalChar = not . (`elem` ("\\()" :: String))
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matchingParenthesis =
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mappend <$> (Char8.cons <$> char '(' <*> literalStringBlock) <*> string ")"
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escapedChar =
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Char8.cons <$> char '\\' <*> (Char8.singleton <$> oneOf "nrtbf()\\\n" <|> octalCode)
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octalCode = choice $ (\n -> Char8.pack <$> count n octDigit) <$> [1..3]
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roundBytes (B16Int bs)
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| Char8.length bs `mod` 2 == 1 = B16Int (bs `Char8.snoc` '0')
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| otherwise = B16Int bs
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toByteString :: StringObject -> ByteString
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toByteString (Hexadecimal h) = b16ToBytes h
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toByteString (Literal s) = unescape s
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--
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-- Name
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--
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newtype Name = Name String deriving (Eq, Ord, Show)
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instance Output Name where
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output (Name n) = Output.string ('/':n)
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name :: MonadParser m => m Name
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name = Name . Char8.unpack <$> (char '/' *> takeAll regular) <?> "name"
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--
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-- Array
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--
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array :: MonadParser m => m [DirectObject]
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array =
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char '[' *> blank *> directObject `sepBy` blank <* blank <* char ']' <?> "array"
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--
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-- Dictionary
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--
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type Dictionary = Map Name DirectObject
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instance Output Dictionary where
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output aDictionary =
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"<<" `mappend` keyValues `mappend` ">>"
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where
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keyValues = join " " $ outputKeyVal <$> Map.toList aDictionary
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outputKeyVal :: (Name, DirectObject) -> OBuilder
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outputKeyVal (key, val) = mconcat [output key, " ", output val]
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dictionary :: MonadParser m => m Dictionary
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dictionary =
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string "<<" *> blank *> keyValPairs <* string ">>" <?> "dictionary"
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where
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keyVal = (,) <$> name <* blank <*> directObject
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keyValPairs = Map.fromList <$> keyVal `sepBy` blank <* blank
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--
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-- Null
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--
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nullObject :: MonadParser m => m ()
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nullObject = string "null" *> return () <?> "null object"
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--
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-- Reference
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--
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data IndirectObjCoordinates = IndirectObjCoordinates {
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objectId :: (Id Object)
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, versionNumber :: Int
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} deriving Show
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reference :: MonadParser m => m IndirectObjCoordinates
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reference = IndirectObjCoordinates
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<$> (fmap Id integer) <*> integer <* char 'R' <?> "reference to an object"
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--
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-- DirectObject
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--
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data DirectObject =
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Boolean Bool
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| NumberObject Number
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| StringObject StringObject
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| NameObject Name
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| Array [DirectObject]
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| Dictionary Dictionary
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| Null
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| Reference IndirectObjCoordinates
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deriving Show
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instance Output DirectObject where
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output (Boolean b) = output b
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output (NumberObject n) = output n
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output (StringObject s) = output s
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output (NameObject n) = output n
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output (Array a) = mconcat ["[", join " " a, "]"]
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output (Dictionary d) = output d
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output (Null) = "null"
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output (Reference (IndirectObjCoordinates {objectId, versionNumber})) =
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Output.string (printf "%d %d R" (getId objectId) versionNumber)
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directObject :: MonadParser m => m DirectObject
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directObject = (peek >>= dispatch) <?> "direct object"
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where
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dispatch 't' = Boolean <$> boolean
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dispatch 'f' = Boolean <$> boolean
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dispatch '(' = StringObject <$> stringObject
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dispatch '<' = StringObject <$> stringObject <|> Dictionary <$> dictionary
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dispatch '/' = NameObject <$> name
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dispatch '[' = Array <$> array
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dispatch 'n' = nullObject *> return Null
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dispatch _ =
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Reference <$> reference {- defined before Number because Number is a prefix of it -}
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<|> NumberObject <$> number
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--
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-- Object
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--
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data Object =
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Direct DirectObject
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| Stream {
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header :: Dictionary
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, streamContent :: ByteString
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}
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deriving Show
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instance Output Object where
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output (Direct d) = output d
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output (Stream {header, streamContent}) = mconcat [
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output header, newLine
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, Output.line "stream"
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, byteString streamContent
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, "endstream"
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]
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--
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-- Occurrence
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--
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data Occurrence = Comment String | Indirect IndirectObjCoordinates deriving Show
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outputOccurrence :: (Indexed Object) -> Occurrence -> OBuilder
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outputOccurrence _ (Comment c) = Output.line c
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outputOccurrence objects (Indirect (IndirectObjCoordinates {objectId, versionNumber})) =
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saveOffset (ObjectId $ getId objectId) >> mconcat [
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Output.line (printf "%d %d obj" (getId objectId) versionNumber)
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, output (objects ! objectId), newLine
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, Output.line "endobj"
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]
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outputBody :: ([Occurrence], (Indexed Object)) -> OBuilder
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outputBody (occurrences, objects) =
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output (outputOccurrence objects <$> occurrences) <* saveOffset StartXRef
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-------------------------------------
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-- XREF TABLE
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-------------------------------------
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--
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-- XRefEntry
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--
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data XRefEntry = InUse {
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offset :: Offset
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, generation :: Int
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} | Free {
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nextFree :: (Id Object)
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, generation :: Int
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} deriving Show
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instance Output XRefEntry where
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output (InUse {offset, generation}) =
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Output.line (printf "%010d %05d n " (getOffset offset) generation)
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output (Free {nextFree, generation}) =
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Output.line (printf "%010d %05d f " (getId nextFree) generation)
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entry :: Parser u XRefEntry
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entry = do
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(big, small) <- (,) <$> integer <*> integer
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(inUse big small <|> free big small <?> "XRef entry") <* blank
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where
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inUse :: Int -> Int -> Parser u XRefEntry
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inUse big generation =
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char 'n' *> return (InUse {offset = Offset big, generation})
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free :: Int -> Int -> Parser u XRefEntry
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free big generation =
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char 'f' *> return (Free {nextFree = Id big, generation})
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--
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-- XRefSubSection
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--
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data XRefSubSection = XRefSubSection {
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firstObjectId :: (Id Object)
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, entries :: [XRefEntry]
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} deriving Show
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instance Output XRefSubSection where
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output (XRefSubSection {firstObjectId, entries}) =
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Output.line (printf "%d %d" (getId firstObjectId) (length entries))
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`mappend` output entries
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xRefSubSection :: Parser u XRefSubSection
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xRefSubSection = do
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(firstId, entriesNumber) <- (,) <$> integer <*> integer <?> "XRef subsection"
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entries <- count entriesNumber entry
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return $ XRefSubSection {firstObjectId = Id firstId, entries}
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type XRefSection = Map (Id Object) XRefEntry
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instance Output XRefSection where
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output = output . sections
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where
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sections tmp =
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case Map.minViewWithKey tmp of
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Nothing -> []
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Just ((objectId@(Id value), firstEntry), rest) ->
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let (subSection, sndRest) = section objectId [firstEntry] (value + 1) rest in
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subSection : sections sndRest
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section firstObjectId stack nextValue tmp =
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let nextId = Id nextValue in
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case Map.lookup nextId tmp of
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Nothing -> (XRefSubSection {firstObjectId, entries = reverse stack}, tmp)
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Just nextEntry ->
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section firstObjectId (nextEntry:stack) (nextValue + 1) (Map.delete nextId tmp)
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xRefSection :: Parser u XRefSection
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xRefSection = foldr addSubsection Map.empty <$>
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(line "xref" *> xRefSubSection `sepBy` many EOL.parser)
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where
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addSubsection (XRefSubSection {firstObjectId, entries}) =
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Map.union . Map.fromList $ zip ([firstObjectId..]) entries
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--
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-- Structure
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--
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data InputStructure = InputStructure {
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startOffset :: Int
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, inputStructure :: Structure
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}
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data Structure = Structure {
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xRef :: XRefSection
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, trailer :: Dictionary
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} deriving Show
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structure :: Parser u Structure
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structure =
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Structure
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<$> xRefSection
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<*> (string "trailer" *> blank *> dictionary <* EOL.parser)
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--
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-- Flow
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--
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data Flow = Flow {
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occurrencesStack :: [Occurrence]
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, tmpObjects :: (Indexed Object)
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} deriving Show
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