Index filter for Pandoc

indexfilter.jl

#!/usr/bin/env runhaskell

import Text.Pandoc
import Text.Pandoc.Shared
import Text.Pandoc.JSON
import Text.Parsec
import Text.Regex
import Control.Applicative
import Data.Monoid
import Data.List
import Data.String

main :: IO ()
main = toJSONFilter index

index :: Maybe Format -> Inline -> [Inline]
index (Just (Format f)) (Code a c)
      | (take 2 c) == "# " = drawIndex f c
      | otherwise = [Code a c]
index _ x = [x]

rawHtml :: [String] -> Inline
rawHtml [t] = RawInline (Format "html") ("<a id=" ++ (intercalate ":" [t]) ++ " class=\"index\"></a>")

rawLaTeX :: [String] -> Inline
rawLaTeX [t] = RawInline (Format "latex") ("\\index{" ++ (intercalate "!" [t]) ++ "}")

drawIndex :: String -> String -> [Inline]
drawIndex f c =
  case f of
    "html"  -> [rawHtml  (terms c)]
    "latex" -> [rawLaTeX (terms c)]
    _ -> []

terms :: String -> [String]
terms c = splitRegex (mkRegex "\\s*,\\s*") (drop 2 c)