From bbc8c39af8c4c2810de8fef985737c5c86acd06f Mon Sep 17 00:00:00 2001
From: Andrea Rossato <andrea.rossato@unibz.it>
Date: Tue, 29 Jan 2008 20:29:03 +0100
Subject: Add a LayoutCombinator class and a CombinedLayout and port
 PerWorkspace to the new system

darcs-hash:20080129192903-32816-de07daf3f32a823c1f3a0e593ff6229b78ae0494.gz
---
 XMonad/Layout/PerWorkspace.hs | 78 ++++++++-----------------------------------
 1 file changed, 14 insertions(+), 64 deletions(-)

(limited to 'XMonad/Layout/PerWorkspace.hs')

diff --git a/XMonad/Layout/PerWorkspace.hs b/XMonad/Layout/PerWorkspace.hs
index bc51a96..448e3ab 100644
--- a/XMonad/Layout/PerWorkspace.hs
+++ b/XMonad/Layout/PerWorkspace.hs
@@ -31,8 +31,7 @@ module XMonad.Layout.PerWorkspace (
 import XMonad
 import qualified XMonad.StackSet as W
 
-import Data.Maybe (fromMaybe)
-
+import XMonad.Layout.LayoutCombinators
 -- $usage
 -- You can use this module by importing it into your ~\/.xmonad\/xmonad.hs file:
 --
@@ -59,21 +58,19 @@ import Data.Maybe (fromMaybe)
 -- | Specify one layout to use on a particular workspace, and another
 --   to use on all others.  The second layout can be another call to
 --   'onWorkspace', and so on.
-onWorkspace :: (LayoutClass l1 a, LayoutClass l2 a)
-               => WorkspaceId -- ^ the tag of the workspace to match
-               -> (l1 a)      -- ^ layout to use on the matched workspace
-               -> (l2 a)      -- ^ layout to use everywhere else
-               -> PerWorkspace l1 l2 a
-onWorkspace wsId l1 l2 = PerWorkspace [wsId] Nothing l1 l2
+onWorkspace :: WorkspaceId  -- ^ tags of workspaces to match
+                -> (l1 a)         -- ^ layout to use on matched workspaces
+                -> (l2 a)         -- ^ layout to use everywhere else
+                -> CombinedLayout PerWorkspace l1 l2 a
+onWorkspace wsId l1 l2 = CombinedLayout (PerWorkspace [wsId]) l1 l2
 
 -- | Specify one layout to use on a particular set of workspaces, and
 --   another to use on all other workspaces.
-onWorkspaces :: (LayoutClass l1 a, LayoutClass l2 a)
-                => [WorkspaceId]  -- ^ tags of workspaces to match
+onWorkspaces :: [WorkspaceId]  -- ^ tags of workspaces to match
                 -> (l1 a)         -- ^ layout to use on matched workspaces
                 -> (l2 a)         -- ^ layout to use everywhere else
-                -> PerWorkspace l1 l2 a
-onWorkspaces wsIds l1 l2 = PerWorkspace wsIds Nothing l1 l2
+                -> CombinedLayout PerWorkspace l1 l2 a
+onWorkspaces wsIds l1 l2 = CombinedLayout (PerWorkspace wsIds) l1 l2
 
 -- | Structure for representing a workspace-specific layout along with
 --   a layout for all other workspaces.  We store the tags of workspaces
@@ -83,60 +80,13 @@ onWorkspaces wsIds l1 l2 = PerWorkspace wsIds Nothing l1 l2
 --   to be able to correctly implement the 'description' method of
 --   LayoutClass, since a call to description is not able to query the
 --   WM state to find out which workspace it was called in.
-data PerWorkspace l1 l2 a = PerWorkspace [WorkspaceId]
-                                         (Maybe Bool)
-                                         (l1 a)
-                                         (l2 a)
-    deriving (Read, Show)
-
-instance (LayoutClass l1 a, LayoutClass l2 a) => LayoutClass (PerWorkspace l1 l2) a where
+data PerWorkspace a = PerWorkspace [WorkspaceId] deriving (Read, Show)
 
-    -- do layout with l1, then return a modified PerWorkspace caching
-    --   the fact that we're in the matched workspace.
-    doLayout p@(PerWorkspace _ (Just True) lt _) r s = do
-        (wrs, mlt') <- doLayout lt r s
-        return (wrs, Just $ mkNewPerWorkspaceT p mlt')
-
-    -- do layout with l1, then return a modified PerWorkspace caching
-    --   the fact that we're not in the matched workspace.
-    doLayout p@(PerWorkspace _ (Just False) _ lf) r s = do
-        (wrs, mlf') <- doLayout lf r s
-        return (wrs, Just $ mkNewPerWorkspaceF p mlf')
-
-    -- figure out which layout to use based on the current workspace.
-    doLayout (PerWorkspace wsIds Nothing l1 l2) r s = do
+instance LayoutCombinator PerWorkspace a where
+    chooser (PerWorkspace wsIds) = do
         t <- getCurrentTag
-        doLayout (PerWorkspace wsIds (Just $ t `elem` wsIds) l1 l2) r s
-
-    -- handle messages; same drill as doLayout.
-    handleMessage p@(PerWorkspace _ (Just True) lt _) m = do
-        mlt' <- handleMessage lt m
-        return . Just $ mkNewPerWorkspaceT p mlt'
-
-    handleMessage p@(PerWorkspace _ (Just False) _ lf) m = do
-        mlf' <- handleMessage lf m
-        return . Just $ mkNewPerWorkspaceF p mlf'
-
-    handleMessage (PerWorkspace _ Nothing _ _) _ = return Nothing
-
-    description (PerWorkspace _ (Just True ) l1 _) = description l1
-    description (PerWorkspace _ (Just False) _ l2) = description l2
-
-    -- description's result is not in the X monad, so we have to wait
-    -- until a doLayout for the information about which workspace
-    -- we're in to get cached.
-    description _ = "PerWorkspace"
-
--- | Construct new PerWorkspace values with possibly modified layouts.
-mkNewPerWorkspaceT :: PerWorkspace l1 l2 a -> Maybe (l1 a) ->
-                      PerWorkspace l1 l2 a
-mkNewPerWorkspaceT (PerWorkspace wsIds b lt lf) mlt' =
-    (\lt' -> PerWorkspace wsIds b lt' lf) $ fromMaybe lt mlt'
-
-mkNewPerWorkspaceF :: PerWorkspace l1 l2 a -> Maybe (l2 a) ->
-                      PerWorkspace l1 l2 a
-mkNewPerWorkspaceF (PerWorkspace wsIds b lt lf) mlf' =
-    (\lf' -> PerWorkspace wsIds b lt lf') $ fromMaybe lf mlf'
+        return $ if t `elem` wsIds then DoFirst else DoSecond
+    doFirst (PerWorkspace _) = True
 
 -- | Get the tag of the currently active workspace.  Note that this
 --   is only guaranteed to be the same workspace for which doLayout
-- 
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