From c97e1e27f90b2c05bf4fdffe877a7f29fd227da3 Mon Sep 17 00:00:00 2001
From: David Roundy <droundy@darcs.net>
Date: Sun, 23 Sep 2007 23:59:56 +0200
Subject: rename LayoutHelpers to LayoutModifier.

darcs-hash:20070923215956-72aca-af065b4b5a9aaf57adca7eb93aa72ae843656cd1.gz
---
 LayoutModifier.hs | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 LayoutModifier.hs

(limited to 'LayoutModifier.hs')

diff --git a/LayoutModifier.hs b/LayoutModifier.hs
new file mode 100644
index 0000000..8b60b4d
--- /dev/null
+++ b/LayoutModifier.hs
@@ -0,0 +1,55 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module       : XMonadContrib.LayoutModifier
+-- Copyright    : (c) David Roundy <droundy@darcs.net>
+-- License      : BSD
+--
+-- Maintainer   : David Roundy <droundy@darcs.net>
+-- Stability    : unstable
+-- Portability  : portable
+--
+-- A module for writing easy Layouts
+-----------------------------------------------------------------------------
+
+module XMonadContrib.LayoutModifier (
+    -- * Usage
+    -- $usage
+    LayoutModifier(..), ModifiedLayout(..)
+    ) where
+
+import Graphics.X11.Xlib ( Rectangle )
+import XMonad
+import StackSet ( Stack )
+import Operations ( UnDoLayout(UnDoLayout) )
+
+-- $usage
+-- Use LayoutHelpers to help write easy Layouts.
+
+class (Show (m a), Read (m a)) => LayoutModifier m a where
+    modifyModify :: m a -> SomeMessage -> X (Maybe (m l))
+    modifyModify m mess | Just UnDoLayout <- fromMessage mess = do unhook m; return Nothing
+                        | otherwise = return Nothing
+    redoLayout :: m a -> Rectangle -> Stack a -> [(a, Rectangle)]
+               -> X ([(a, Rectangle)], Maybe (m l))
+    redoLayout m _ _ wrs = do hook m; return (wrs, Nothing)
+    hook :: m a -> X ()
+    hook _ = return ()
+    unhook :: m a -> X ()
+    unhook _ = return ()
+
+instance (LayoutModifier m a, Layout l a) => Layout (ModifiedLayout m l) a where
+    doLayout (ModifiedLayout m l) r s =
+        do (ws, ml') <- doLayout l r s
+           (ws', mm') <- redoLayout m r s ws
+           let ml'' = case mm' of
+                      Just m' -> Just $ (ModifiedLayout m') $ maybe l id ml'
+                      Nothing -> ModifiedLayout m `fmap` ml'
+           return (ws', ml'')
+    modifyLayout (ModifiedLayout m l) mess =
+        do ml' <- modifyLayout l mess
+           mm' <- modifyModify m mess
+           return $ case mm' of
+                    Just m' -> Just $ (ModifiedLayout m') $ maybe l id ml'
+                    Nothing -> (ModifiedLayout m) `fmap` ml'
+
+data ModifiedLayout m l a = ModifiedLayout (m a) (l a) deriving ( Read, Show )
-- 
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