398 lines
11 KiB
Haskell
398 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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Content(..)
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, DirectObject(..)
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, Flow(..)
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, IndexedObjects
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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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, Structure(..)
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, XRefEntry(..)
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, XRefSection
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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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, structure
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) where
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import Control.Applicative ((<|>))
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import Data.ByteString.Char8 (ByteString)
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import qualified Data.ByteString.Char8 as BS (
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concat, cons, pack, singleton, unpack
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)
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import Data.Map (Map, (!), mapWithKey)
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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 PDF.EOL as EOL (charset, parser)
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import qualified PDF.Output as Output (concat, line, string)
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import PDF.Output (
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OBuilder, ObjectId(..), Offset(..), Output(..), Resource(..)
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, byteString, getObjectId, getOffset, getOffsets, join, newLine
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, saveOffset
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)
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import PDF.Parser (
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Parser, (<?>)
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, char, choice, count, decNumber, hexNumber, many, octDigit, oneOf, option
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, sepBy, string, takeAll, takeAll1
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)
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import Text.Printf (printf)
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line :: String -> Parser u ()
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line l = (string (BS.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 :: Parser u ()
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blank = takeAll (`elem` (EOL.charset ++ whiteSpaceCharset)) *> return ()
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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 :: (Read a, Num a) => Parser u a
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integer = read . BS.unpack <$> decNumber <* blank <?> "decimal integer"
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-------------------------------------
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-- OBJECTS
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-------------------------------------
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type IndexedObjects = Map ObjectId Object
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--
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-- Boolean
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--
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boolean :: Parser u 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 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 :: Parser u Number
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number = Number . read . BS.unpack <$>
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(mappend <$> sign <*> (integerPart <|> BS.cons '0' <$> floatPart))
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<?> "number"
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where
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sign = string "-" <|> option "" (char '+' >> return "")
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integerPart = mappend <$> decNumber <*> option "" floatPart
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floatPart = BS.cons <$> char '.' <*> (option "0" $ decNumber)
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--
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-- StringObject
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--
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data StringObject = Literal String | Hexadecimal String deriving Show
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instance Output StringObject where
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output (Literal s) = Output.string (printf "(%s)" s)
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output (Hexadecimal s) = Output.string (printf "<%s>" s)
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stringObject :: Parser u StringObject
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stringObject =
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Literal . BS.unpack <$> (char '(' *> (BS.concat <$> literalString) <* char ')')
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<|> Hexadecimal . BS.unpack <$> (char '<' *> hexNumber <* char '>')
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<?> "string object (literal or hexadecimal)"
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where
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literalString = many literalStringBlock
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literalStringBlock = takeAll1 normalChar <|> matchingParenthesis <|> escapedChar
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normalChar = not . (`elem` ("\\()" :: String))
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matchingParenthesis =
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mappend <$> (BS.cons <$> char '(' <*> literalStringBlock) <*> string ")"
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escapedChar =
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BS.cons <$> char '\\' <*> (BS.singleton <$> oneOf "nrtbf()\\" <|> octalCode)
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octalCode = choice $ (\n -> BS.pack <$> count n octDigit) <$> [1..3]
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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 :: Parser u Name
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name = Name . BS.unpack <$> (char '/' *> takeAll regular) <?> "name"
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--
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-- Array
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--
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array :: Parser u [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 dict =
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"<<" `mappend` keyValues `mappend` ">>"
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where
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keyValues = join " " $ outputKeyVal <$> Map.toList dict
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outputKeyVal :: (Name, DirectObject) -> OBuilder
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outputKeyVal (key, val) = Output.concat [output key, " ", output val]
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dictionary :: Parser u Dictionary
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dictionary =
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string "<<" *> blank *> keyValPairs <* string ">>" <?> "dictionary"
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where
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keyVal = (,) <$> name <* blank <*> directObject
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keyValPairs = Map.fromList <$> keyVal `sepBy` blank <* blank
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--
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-- Null
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--
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nullObject :: Parser u ()
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nullObject = string "null" *> return () <?> "null object"
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--
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-- Reference
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--
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data IndirectObjCoordinates = IndirectObjCoordinates {
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objectId :: ObjectId
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, versionNumber :: Int
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} deriving Show
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reference :: Parser u IndirectObjCoordinates
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reference = IndirectObjCoordinates
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<$> (fmap ObjectId 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) = Output.concat ["[", 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" (getObjectId objectId) versionNumber)
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directObject :: Parser u DirectObject
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directObject =
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Boolean <$> boolean
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<|> Reference <$> reference {- defined before Number because Number is a prefix of it -}
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<|> NumberObject <$> number
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<|> StringObject <$> stringObject
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<|> NameObject <$> name
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<|> Array <$> array
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<|> Dictionary <$> dictionary
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<|> const Null <$> nullObject
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<?> "direct object"
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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}) = Output.concat [
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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 :: IndexedObjects -> 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 (Object objectId) >> Output.concat [
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Output.line (printf "%d %d obj" (getObjectId 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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-------------------------------------
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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 :: ObjectId
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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 " (getObjectId nextFree) generation)
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entry :: Parser u XRefEntry
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entry = do
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(big, small) <- (,) <$> integer <*> integer
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(inUse big small <|> free big small <?> "XRef entry") <* blank
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where
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inUse :: Int -> Int -> Parser u XRefEntry
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inUse big generation =
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char 'n' *> return (InUse {offset = Offset big, generation})
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free :: Int -> Int -> Parser u XRefEntry
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free big generation =
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char 'f' *> return (Free {nextFree = ObjectId big, generation})
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--
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-- XRefSubSection
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--
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data XRefSubSection = XRefSubSection {
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firstObjectId :: ObjectId
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, entries :: [XRefEntry]
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} deriving Show
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instance Output XRefSubSection where
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output (XRefSubSection {firstObjectId, entries}) =
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Output.line (printf "%d %d" (getObjectId firstObjectId) (length entries))
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`mappend` output entries
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xRefSubSection :: Parser u XRefSubSection
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xRefSubSection = do
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(firstId, entriesNumber) <- (,) <$> integer <*> integer <?> "XRef subsection"
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entries <- count entriesNumber entry
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return $ XRefSubSection {firstObjectId = ObjectId firstId, entries}
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type XRefSection = Map ObjectId 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@(ObjectId 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 = ObjectId 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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<$> xRefSection
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<*> (string "trailer" *> blank *> dictionary <* EOL.parser)
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updateXrefs :: XRefSection -> Map Resource Offset -> (XRefSection, Offset)
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updateXrefs xRef offsets = (mapWithKey updateEntry xRef, offsets ! StartXRef)
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where
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updateEntry objectId e@(InUse {}) = e {offset = offsets ! (Object objectId)}
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updateEntry _ e = e
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--
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-- Flow
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--
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data Flow = Flow {
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occurrencesStack :: [Occurrence]
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, tmpObjects :: IndexedObjects
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} deriving Show
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--
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-- Content
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--
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data Content = Content {
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occurrences :: [Occurrence]
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, objects :: IndexedObjects
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, docStructure :: Structure
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} deriving Show
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outputBody :: ([Occurrence], IndexedObjects) -> OBuilder
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outputBody (occurrences, objects) =
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output (outputOccurrence objects <$> occurrences) <* saveOffset StartXRef
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instance Output Content where
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output (Content {occurrences, objects, docStructure}) =
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fmap (updateXrefs xRef) <$> getOffsets (outputBody (occurrences, objects))
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>>= \(body, (xref, startXRef)) -> Output.concat [
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body
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, Output.line "xref"
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, output xref
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, Output.line "trailer"
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, output trailer, newLine
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, Output.line "startxref"
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, Output.line (printf "%d" (getOffset startXRef))
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, byteString eofMarker
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]
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where
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Structure {xRef, trailer} = docStructure
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