1 files changed, 80 insertions, 0 deletions
diff --git a/lib/Hakyll/Core/Identifier.hs b/lib/Hakyll/Core/Identifier.hs
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+++ b/lib/Hakyll/Core/Identifier.hs
@@ -0,0 +1,80 @@
+--------------------------------------------------------------------------------
+-- | An identifier is a type used to uniquely identify an item. An identifier is
+-- conceptually similar to a file path. Examples of identifiers are:
+--
+-- * @posts/foo.markdown@
+--
+-- * @index@
+--
+-- * @error/404@
+{-# LANGUAGE DeriveDataTypeable         #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+module Hakyll.Core.Identifier
+    ( Identifier
+    , fromFilePath
+    , toFilePath
+    , identifierVersion
+    , setVersion
+    ) where
+
+
+--------------------------------------------------------------------------------
+import           Control.DeepSeq     (NFData (..))
+import           Data.List           (intercalate)
+import           System.FilePath     (dropTrailingPathSeparator, splitPath)
+
+
+--------------------------------------------------------------------------------
+import           Data.Binary         (Binary (..))
+import           Data.Typeable       (Typeable)
+import           GHC.Exts            (IsString, fromString)
+
+
+--------------------------------------------------------------------------------
+data Identifier = Identifier
+    { identifierVersion :: Maybe String
+    , identifierPath    :: String
+    } deriving (Eq, Ord, Typeable)
+
+
+--------------------------------------------------------------------------------
+instance Binary Identifier where
+    put (Identifier v p) = put v >> put p
+    get = Identifier <$> get <*> get
+
+
+--------------------------------------------------------------------------------
+instance IsString Identifier where
+    fromString = fromFilePath
+
+
+--------------------------------------------------------------------------------
+instance NFData Identifier where
+    rnf (Identifier v p) = rnf v `seq` rnf p `seq` ()
+
+
+--------------------------------------------------------------------------------
+instance Show Identifier where
+    show i = case identifierVersion i of
+        Nothing -> toFilePath i
+        Just v  -> toFilePath i ++ " (" ++ v ++ ")"
+
+
+--------------------------------------------------------------------------------
+-- | Parse an identifier from a string
+fromFilePath :: String -> Identifier
+fromFilePath = Identifier Nothing .
+    intercalate "/" . filter (not . null) . split'
+  where
+    split' = map dropTrailingPathSeparator . splitPath
+
+
+--------------------------------------------------------------------------------
+-- | Convert an identifier to a relative 'FilePath'
+toFilePath :: Identifier -> FilePath
+toFilePath = identifierPath
+
+
+--------------------------------------------------------------------------------
+setVersion :: Maybe String -> Identifier -> Identifier
+setVersion v i = i {identifierVersion = v}