1 files changed, 61 insertions, 0 deletions
diff --git a/src/Hakyll/Core/Resource/MetadataCache.hs b/src/Hakyll/Core/Resource/MetadataCache.hs
new file mode 100644
index 0000000..b459674
--- /dev/null
+++ b/src/Hakyll/Core/Resource/MetadataCache.hs
@@ -0,0 +1,61 @@
+--------------------------------------------------------------------------------
+module Hakyll.Core.Resource.MetadataCache
+    ( resourceMetadata
+    , resourceBody
+    , resourceInvalidateMetadataCache
+    ) where
+
+
+--------------------------------------------------------------------------------
+import           Hakyll.Core.Resource
+import           Hakyll.Core.Resource.Metadata
+import           Hakyll.Core.Resource.Provider.Internal
+import qualified Hakyll.Core.Store                      as Store
+
+
+--------------------------------------------------------------------------------
+resourceMetadata :: ResourceProvider -> Resource -> IO Metadata
+resourceMetadata rp r = do
+    load rp r
+    Store.Found md <- Store.get (resourceStore rp)
+        [name, unResource r, "metadata"]
+    return md
+
+
+--------------------------------------------------------------------------------
+resourceBody :: ResourceProvider -> Resource -> IO String
+resourceBody rp r = do
+    load rp r
+    Store.Found bd <- Store.get (resourceStore rp)
+        [name, unResource r, "body"]
+    maybe (resourceString r) return bd
+
+
+--------------------------------------------------------------------------------
+resourceInvalidateMetadataCache :: ResourceProvider -> Resource -> IO ()
+resourceInvalidateMetadataCache rp r = do
+    Store.delete (resourceStore rp) [name, unResource r, "metadata"]
+    Store.delete (resourceStore rp) [name, unResource r, "body"]
+
+
+--------------------------------------------------------------------------------
+load :: ResourceProvider -> Resource -> IO ()
+load rp r = do
+    mmd <- Store.get store mdk :: IO (Store.Result Metadata)
+    case mmd of
+        -- Already loaded
+        Store.Found _  -> return ()
+        -- Not yet loaded
+        _ -> do
+            (metadata, body) <- loadMetadata rp r
+            Store.set store mdk metadata
+            Store.set store bk  body
+  where
+    store = resourceStore rp
+    mdk   = [name, unResource r, "metadata"]
+    bk    = [name, unResource r, "body"]
+
+
+--------------------------------------------------------------------------------
+name :: String
+name = "Hakyll.Core.Resource.Provider.MetadataCache"