Revert "Removed TemplateDirectory and replaced it with HeistT which p…

…rovides similar functionality."

This reverts commit e3727be.

heist.cabal

@@ -1,5 +1,5 @@
 name:           heist
-version:        0.3.0
+version:        0.2.3
 synopsis:       An xhtml templating system
 license:        BSD3
 license-file:   LICENSE
@@ -80,7 +80,7 @@ Library
     Text.Templating.Heist.Splices.Ignore,
     Text.Templating.Heist.Splices.Markdown,
     Text.Templating.Heist.Splices.Static,
-    Text.Templating.Heist.Monad
+    Text.Templating.Heist.TemplateDirectory
 
   other-modules:
     Text.Templating.Heist.Internal,
@@ -95,7 +95,7 @@ Library
     directory,
     directory-tree,
     filepath,
-    hexpat >= 0.16 && <= 0.17,
+    hexpat >= 0.16 && <0.17,
     MonadCatchIO-transformers >= 0.2.1 && < 0.3,
     monads-fd,
     process,

src/Text/Templating/Heist/TemplateDirectory.hs

@@ -0,0 +1,85 @@
+{-|
+
+This module defines a TemplateDirectory data structure for convenient
+interaction with templates within web apps.
+
+-}
+
+module Text.Templating.Heist.TemplateDirectory
+    ( TemplateDirectory
+    , newTemplateDirectory
+    , newTemplateDirectory'
+
+    , getDirectoryTS
+    , reloadTemplateDirectory
+    ) where
+
+------------------------------------------------------------------------------
+import           Control.Concurrent
+import           Control.Monad
+import           Control.Monad.Trans
+import           Data.ByteString.Char8 (ByteString)
+import           Text.Templating.Heist
+import           Text.Templating.Heist.Splices.Static
+
+
+------------------------------------------------------------------------------
+-- | Structure representing a template directory.
+data TemplateDirectory m
+    = TemplateDirectory
+        FilePath
+        (TemplateState m)
+        (MVar (TemplateState m))
+        StaticTagState
+
+
+------------------------------------------------------------------------------
+-- | Creates and returns a new 'TemplateDirectory' wrapped in an Either for
+-- error handling.
+newTemplateDirectory :: (MonadIO m, MonadIO n)
+                     => FilePath
+                     -> TemplateState m
+                     -> n (Either String (TemplateDirectory m))
+newTemplateDirectory dir templateState = liftIO $ do
+    (origTs,sts) <- bindStaticTag templateState
+    ets <- loadTemplates dir origTs
+    leftPass ets $ \ts -> do
+        tsMVar <- newMVar $ ts
+        return $ TemplateDirectory dir origTs tsMVar sts
+
+
+------------------------------------------------------------------------------
+-- | Creates and returns a new 'TemplateDirectory', using the monad's fail
+-- function on error.
+newTemplateDirectory' :: (MonadIO m, MonadIO n)
+                      => FilePath
+                      -> TemplateState m
+                      -> n (TemplateDirectory m)
+newTemplateDirectory' = ((either fail return =<<) .) . newTemplateDirectory
+
+
+------------------------------------------------------------------------------
+-- | Gets the 'TemplateState' from a TemplateDirectory.
+getDirectoryTS :: (Monad m, MonadIO n)
+               => TemplateDirectory m
+               -> n (TemplateState m)
+getDirectoryTS (TemplateDirectory _ _ tsMVar _) = liftIO $ readMVar $ tsMVar
+
+
+------------------------------------------------------------------------------
+-- | Clears cached content and reloads templates from disk.
+reloadTemplateDirectory :: (MonadIO m, MonadIO n)
+                        => TemplateDirectory m
+                        -> n (Either String ())
+reloadTemplateDirectory (TemplateDirectory p origTs tsMVar sts) = liftIO $ do
+    clearStaticTagCache sts
+    ets <- loadTemplates p origTs
+    leftPass ets $ \ts -> modifyMVar_ tsMVar (const $ return ts)
+
+
+------------------------------------------------------------------------------
+-- | Prepends an error onto a Left.
+leftPass :: Monad m => Either String b -> (b -> m c) -> m (Either String c)
+leftPass e m = either (return . Left . loadError) (liftM Right . m) e
+  where
+    loadError = (++) "Error loading templates: "