add LayoutChoice module.

LayoutChoice.hs

@@ -0,0 +1,61 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  XMonadContrib.LayoutChoice
+-- Copyright   :  (c) David Roundy
+-- License     :  BSD-style (see xmonad/LICENSE)
+-- 
+-- Maintainer  :  email@address.com
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A tabbed layout for the Xmonad Window Manager 
+--
+-----------------------------------------------------------------------------
+
+module XMonadContrib.LayoutChoice ( 
+                             -- * Usage:
+                             -- $usage
+                              layoutChoice
+                            , ChangeLayout(..)
+                            ) where
+
+import Data.List ( partition )
+import Data.Maybe ( fromMaybe )
+import XMonad
+import Operations ( tall, UnDoLayout(..) )
+
+-- $usage
+-- You can use this module to replace the default layout handling of
+-- xmonad.  See the docstring docs for example usage.
+
+-- %import XMonadContrib.LayoutChoice
+-- %layout , layoutChoice [("full", full),
+-- %layout                 ("tall", tall 1 0.03 0.5)]
+
+-- %keybind , ((modMask, xK_space), sendMessage NextLayout)
+-- %keybind , ((modMask .|. shiftMask, xK_space), sendMessage PrevLayout)
+-- %keybind , ((modMask, xK_f), sendMessage (JumpToLayout "full"))
+
+data ChangeLayout = NextLayout | PrevLayout | JumpToLayout String
+                 deriving ( Eq, Show, Typeable )
+instance Message ChangeLayout
+
+layoutChoice :: [(String, Layout a)] -> Layout a
+layoutChoice [] = tall 1 0.03 0.5
+layoutChoice ((n,l):ls) = Layout { doLayout = dolay
+                                 , modifyLayout = md }
+    where dolay r s = do (x,ml') <- doLayout l r s
+                         return (x, (\l' -> layoutChoice ((n,l'):ls)) `fmap` ml')
+          md m | Just NextLayout <- fromMessage m = switchl rls
+               | Just PrevLayout <- fromMessage m = switchl rls'
+               | Just (JumpToLayout x) <- fromMessage m = switchl (j x)
+               | otherwise = do ml' <- modifyLayout l m
+                                return $ (\l' -> layoutChoice ((n,l'):ls)) `fmap` ml'
+          
+          rls (x:xs) = xs ++ [x]
+          rls [] = []
+          rls' = reverse . rls . reverse
+          j s zs = case partition (\z -> s == fst z) zs of
+                   (xs,ys) -> xs++ys
+          switchl f = do ml' <- modifyLayout l (SomeMessage UnDoLayout)
+                         return $ Just (layoutChoice $ f $ (n,fromMaybe l ml'):ls)

MetaModule.hs

@@ -41,6 +41,7 @@ import XMonadContrib.FlexibleManipulate ()
 import XMonadContrib.FloatKeys ()
 import XMonadContrib.FocusNth ()
 import XMonadContrib.HintedTile ()
+import XMonadContrib.LayoutChoice ()
 import XMonadContrib.LayoutHelpers ()
 import XMonadContrib.LayoutHints ()
 import XMonadContrib.LayoutScreens ()