From 6af9f6bb534f121d9acce6f49cf7acd18973ccde Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Tue, 2 Feb 2016 19:14:43 +0100
Subject: Extended tex & math support

---
 src/Tex.hs | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 src/Tex.hs

(limited to 'src/Tex.hs')

diff --git a/src/Tex.hs b/src/Tex.hs
new file mode 100644
index 0000000..a247218
--- /dev/null
+++ b/src/Tex.hs
@@ -0,0 +1,72 @@
+module Tex
+       ( compileTex
+       ) where
+
+import System.IO (stdout, stderr, hPutStrLn, writeFile, readFile)
+import System.IO.Temp (withSystemTempDirectory)
+import System.Process (callProcess, readProcessWithExitCode)
+import System.Directory (copyFile, getCurrentDirectory, setCurrentDirectory)
+import System.FilePath (takeFileName, FilePath(..), (</>))
+import System.Exit (ExitCode(..))
+
+import Control.Monad (when)
+import Control.Exception (bracket, throwIO)
+import Data.Maybe (fromMaybe, listToMaybe)
+
+import Control.Monad.Writer.Strict (WriterT(..), execWriterT, tell)
+import Control.Monad.Trans (liftIO)
+
+import Control.DeepSeq (($!!))
+
+import Text.Regex.TDFA ((=~))
+
+instance Monoid ExitCode where
+  mempty = ExitSuccess
+  (ExitFailure a) `mappend` _ = ExitFailure a
+  ExitSuccess `mappend` x@(ExitFailure _) = x
+  ExitSuccess `mappend` ExitSuccess = ExitSuccess
+  
+
+compileTex :: String -> IO (String, String)
+compileTex = withSystemTempDirectory "tex" . compileTex'
+
+compileTex' :: String -> FilePath -> IO (String, String)
+compileTex' input tmpDir = do
+  mapM_ (copyToTmp . ("provider/tex" </>)) [ "preview.dtx"
+                                           , "preview.ins"
+                                           ]
+  (exitCode, out, err) <- withCurrentDirectory tmpDir $ execWriterT $ do
+    run "latex" [ "-interaction=batchmode"
+                , "preview.ins"
+                ] ""
+    liftIO $ writeFile (tmpDir </> "image.tex") input
+    run "latex" [ {- "-interaction=batchmode"
+                , -} "image.tex"
+                ] ""
+    run "dvisvgm" [ "--exact"
+                  , "--no-fonts"
+                  , tmpDir </> "image.dvi"
+                  ] ""
+  when (exitCode /= ExitSuccess) $ do
+    hPutStrLn stdout out
+    hPutStrLn stderr err
+    throwIO exitCode
+  (\x -> return $!! (x, extractAlignment err)) =<< (readFile $ tmpDir </> "image.svg")
+  where
+    copyToTmp fp = copyFile fp (tmpDir </> takeFileName fp)
+    run :: String -> [String] -> String -> WriterT (ExitCode, String, String) IO ()
+    run bin args stdin = tell =<< liftIO (readProcessWithExitCode bin args stdin)
+
+withCurrentDirectory :: FilePath  -- ^ Directory to execute in
+                     -> IO a      -- ^ Action to be executed
+                     -> IO a
+withCurrentDirectory dir action =
+  bracket getCurrentDirectory setCurrentDirectory $ \ _ -> do
+    setCurrentDirectory dir
+    action
+
+extractAlignment :: String -> String
+extractAlignment = fromMaybe "0pt" . extract . (=~ "depth=([^\\s]+)")
+  where
+    extract :: (String, String, String, [String]) -> Maybe String
+    extract (_, _, _, xs) = listToMaybe xs
-- 
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