58 lines
1.7 KiB
Haskell
58 lines
1.7 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module PDF.Content (
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Content(..)
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, ContentUnit(..)
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, GraphicContextUnit(..)
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, TextContext
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, content
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, parse
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) where
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import Control.Applicative ((<|>))
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import Control.Monad.State (evalStateT, modify)
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import Data.Attoparsec.ByteString.Char8 (sepBy)
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import Data.ByteString (ByteString)
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import PDF.Object (blank, directObject)
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import PDF.Parser (MonadParser, (<?>), evalParser, string)
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import PDF.Content.Operator (Instruction, operator)
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data GraphicContextUnit =
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GraphicInstruction Instruction
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| ContentUnit ContentUnit
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deriving Show
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type TextContext = [Instruction]
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data ContentUnit =
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GraphicContext [GraphicContextUnit]
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| TextContext TextContext
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deriving Show
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newtype Content = Content [ContentUnit] deriving Show
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content :: MonadParser m => m Content
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content = Content <$> contentUnit `sepBy` blank <?> "content"
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contentUnit :: MonadParser m => m ContentUnit
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contentUnit =
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(GraphicContext <$> graphicContext)
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<|> (TextContext <$> textContext)
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where
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graphicContext =
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string "q" *> blank *> graphicContextUnit `sepBy` blank <* blank <* string "Q"
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graphicContextUnit :: MonadParser m => m GraphicContextUnit
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graphicContextUnit =
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(GraphicInstruction <$> instruction)
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<|> (ContentUnit <$> contentUnit)
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instruction :: MonadParser m => m Instruction
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instruction = evalStateT stackParser []
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where
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stackParser = ((directObject <* blank) >>= push) <|> operator
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push arg = modify (arg:) *> stackParser
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parse :: ByteString -> Either String Content
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parse = evalParser content ()
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textContext :: MonadParser m => m TextContext
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textContext =
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string "BT" *> blank *> instruction `sepBy` blank <* blank <* string "ET"
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