1 files changed, 45 insertions, 18 deletions

diff --git a/src/Math.hs b/src/Math.hs
index e927fdd..db01f75 100644
--- a/src/Math.hs
+++ b/src/Math.hs
@@ -2,40 +2,61 @@ module Math
        ( compileMath
        ) where
 
+import System.IO (stdout, stderr, hPutStrLn, writeFile, readFile)
 import System.IO.Temp (withSystemTempDirectory)
-import System.Process (callProcess)
+import System.Process (callProcess, readProcessWithExitCode)
 import System.Directory (copyFile, getCurrentDirectory, setCurrentDirectory)
 import System.FilePath (takeFileName, FilePath(..), (</>))
+import System.Exit (ExitCode(..))
 
-import Control.Monad
-import Control.Exception (bracket)
+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 (($!!))
 
-compileMath :: String -> IO String
+import Text.Regex.TDFA ((=~))
+
+instance Monoid ExitCode where
+  mempty = ExitSuccess
+  (ExitFailure a) `mappend` _ = ExitFailure a
+  ExitSuccess `mappend` x@(ExitFailure _) = x
+  ExitSuccess `mappend` ExitSuccess = ExitSuccess
+  
+
+compileMath :: String -> IO (String, String)
 compileMath = withSystemTempDirectory "math" . compileMath'
 
-compileMath' :: String -> FilePath -> IO String
+compileMath' :: String -> FilePath -> IO (String, String)
 compileMath' input tmpDir = do
   mapM_ (copyToTmp . ("tex" </>)) [ "preamble.tex"
                                   , "preview.dtx"
                                   , "preview.ins"
                                   ]
-  withCurrentDirectory tmpDir $ do
-    callProcess "latex" [ "-interaction=batchmode"
-                        , "preview.ins"
-                        ]
-    writeFile (tmpDir </> "image.tex") input
-    callProcess "latex" [ "-interaction=batchmode"
-                        , "image.tex"
-                        ]
-    callProcess "dvisvgm" [ "--exact"
-                          , "--no-fonts"
-                          , tmpDir </> "image.dvi"
-                          ]
-  (\x -> return $!! x) =<< (readFile $ tmpDir </> "image.svg")
+  (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
@@ -44,3 +65,9 @@ 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