From 78d467386729502330d2cd386eb9221f101d6d67 Mon Sep 17 00:00:00 2001
From: David Roundy <droundy@darcs.net>
Date: Sat, 23 Jun 2007 22:14:47 +0200
Subject: support self-modifying layouts.

darcs-hash:20070623201447-72aca-7bfeb7e7ec36b37420a4c670dc23156c52d7e22d.gz
---
 Operations.hs | 14 +++++++++-----
 XMonad.hs     |  6 +++---
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/Operations.hs b/Operations.hs
index cd20c47..c747467 100644
--- a/Operations.hs
+++ b/Operations.hs
@@ -29,7 +29,7 @@ import qualified Data.Set as S
 
 import Control.Monad.State
 import Control.Monad.Reader
-import Control.Arrow ((***), second)
+import Control.Arrow ((***), first, second)
 
 import System.IO
 import Graphics.X11.Xlib
@@ -156,8 +156,10 @@ windows f = do
 
         -- just the tiled windows:
         -- now tile the windows on this workspace, modified by the gap
-        rs <- runLayout l viewrect tiled `catchX` runLayout full viewrect tiled
+        (rs, ml') <- runLayout l viewrect tiled `catchX` runLayout full viewrect tiled
         mapM_ (uncurry tileWindow) rs
+        whenJust ml' $ \l' -> modify $ \ss ->
+                              ss { layouts = M.adjust (first (const l')) n (layouts ss) }
 
         -- now the floating windows:
         -- move/resize the floating windows, if there are any
@@ -368,7 +370,7 @@ instance Message IncMasterN
 -- simple fullscreen mode, just render all windows fullscreen.
 -- a plea for tuple sections: map . (,sc)
 full :: Layout a
-full = Layout { doLayout     = \sc (W.Stack f _ _) -> return [(f, sc)]
+full = Layout { doLayout     = \sc (W.Stack f _ _) -> return ([(f, sc)],Nothing)
               , modifyLayout = const (return Nothing) } -- no changes
 
 --
@@ -376,7 +378,8 @@ full = Layout { doLayout     = \sc (W.Stack f _ _) -> return [(f, sc)]
 --
 tall :: Int -> Rational -> Rational -> Layout a
 tall nmaster delta frac =
-    Layout { doLayout     = \r -> return . ap zip (tile frac r nmaster . length) . W.integrate
+    Layout { doLayout     = \r -> return . (\x->(x,Nothing)) .
+                                  ap zip (tile frac r nmaster . length) . W.integrate
            , modifyLayout = \m -> return $ msum [fmap resize     (fromMessage m)
                                                 ,fmap incmastern (fromMessage m)] }
 
@@ -391,7 +394,8 @@ mirrorRect (Rectangle rx ry rw rh) = (Rectangle ry rx rh rw)
 -- | Mirror a layout, compute its 90 degree rotated form.
 mirror :: Layout a -> Layout a
 mirror (Layout { doLayout = dl, modifyLayout = ml }) =
-    Layout { doLayout     = \sc w -> map (second mirrorRect) `fmap` dl (mirrorRect sc) w
+    Layout { doLayout     = \sc w -> do (wrs, ml') <- dl (mirrorRect sc) w
+                                        return (map (second mirrorRect) wrs, mirror `fmap` ml')
            , modifyLayout = fmap (fmap mirror) . ml }
 
 -- | tile.  Compute the positions for windows using the default 2 pane tiling algorithm.
diff --git a/XMonad.hs b/XMonad.hs
index 7914782..bc54bfd 100644
--- a/XMonad.hs
+++ b/XMonad.hs
@@ -126,11 +126,11 @@ atom_WM_STATE           = getAtom "WM_STATE"
 -- that message and the screen is not refreshed.  Otherwise, 'modifyLayout'
 -- returns an updated 'Layout' and the screen is refreshed.
 --
-data Layout a = Layout { doLayout     :: Rectangle -> Stack a -> X [(a, Rectangle)]
+data Layout a = Layout { doLayout     :: Rectangle -> Stack a -> X ([(a, Rectangle)], Maybe (Layout a))
                        , modifyLayout :: SomeMessage -> X (Maybe (Layout a)) }
 
-runLayout :: Layout a -> Rectangle -> StackOrNot a -> X [(a, Rectangle)]
-runLayout l r = maybe (return []) (doLayout l r)
+runLayout :: Layout a -> Rectangle -> StackOrNot a -> X ([(a, Rectangle)], Maybe (Layout a))
+runLayout l r = maybe (return ([], Nothing)) (doLayout l r)
 
 -- | Based on ideas in /An Extensible Dynamically-Typed Hierarchy of Exceptions/,
 -- Simon Marlow, 2006. Use extensible messages to the modifyLayout handler.
-- 
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