Move Rahm.Desktop.Layout.Layout to Rahm.Desktop.Layout

1 files changed, 35 insertions, 0 deletions

diff --git a/src/Rahm/Desktop/Layout/Redescribe.hs b/src/Rahm/Desktop/Layout/Redescribe.hs
new file mode 100644
index 0000000..c5c7472
--- /dev/null
+++ b/src/Rahm/Desktop/Layout/Redescribe.hs
@@ -0,0 +1,35 @@
+
+-- Module to enable redescribing layouts. Unlike LayoutModifiers though, this
+-- class is aware of the underlying type as it may need to access some internals
+-- to generate the new description.
+module Rahm.Desktop.Layout.Redescribe where
+
+import XMonad
+
+import qualified XMonad.StackSet as W
+import Data.Typeable (Typeable)
+
+-- Type-class to modify the description of a layout.
+class Describer m l where
+  
+  -- Returns the new description from the given description modifier, the layout
+  -- and the existing description.
+  newDescription :: m -> l a -> String -> String
+
+-- With a DescriptionModifier,
+data Redescribe m l a = Redescribe m (l a)
+  deriving (Show, Read)
+
+-- Delegates to the underlying Layout, except for the description
+instance (Typeable m, Show m, Describer m l, LayoutClass l a) =>
+    LayoutClass (Redescribe m l) a where
+
+  runLayout (W.Workspace t (Redescribe m l) a) rect = do
+    (rects, maybeNewLayout) <- runLayout (W.Workspace t l a) rect
+    return (rects, fmap (Redescribe m) maybeNewLayout)
+
+  handleMessage (Redescribe m l) a = do
+    maybeNewLayout <- handleMessage l a
+    return (Redescribe m <$> maybeNewLayout)
+
+  description (Redescribe m l) = newDescription m l (description l)