From b7272ba8c84f254c3b7efcaf3d8e20686eeb0b1c Mon Sep 17 00:00:00 2001
From: Josh Rahm <rahm@google.com>
Date: Fri, 12 Nov 2021 13:08:24 -0700
Subject: Change swapMaster.

Swap master now swaps the master window with the prior master window if
swapMaster is called while the master window is focused.
---
 src/Internal/Keys.hs       |  3 ++-
 src/Internal/Marking.hs    | 17 +----------------
 src/Internal/SwapMaster.hs | 41 +++++++++++++++++++++++++++++++++++++++++
 src/Internal/Windows.hs    | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+), 17 deletions(-)
 create mode 100644 src/Internal/SwapMaster.hs
 create mode 100644 src/Internal/Windows.hs

(limited to 'src')

diff --git a/src/Internal/Keys.hs b/src/Internal/Keys.hs
index 591861f..3b61dac 100644
--- a/src/Internal/Keys.hs
+++ b/src/Internal/Keys.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE RankNTypes #-}
 module Internal.Keys where
 
+import Internal.SwapMaster (swapMaster)
 import XMonad.Hooks.ManageDocks
 import XMonad.Layout.MosaicAlt
 import Graphics.X11.ExtraTypes.XorgDefault
@@ -85,7 +86,7 @@ newKeys =
         , ((modm .|. shiftMask, xK_l),          windows W.swapDown)
         , ((modm              , xK_f),          sendMessage FlipLayout)
         , ((modm .|. shiftMask, xK_f),          sendMessage HFlipLayout)
-        , ((modm              , xK_Return),     windows W.swapMaster)
+        , ((modm              , xK_Return),     swapMaster)
         , ((modm,               xK_j),          sendMessage Shrink)
         , ((modm,               xK_k),          sendMessage Expand)
         , ((modm .|. shiftMask, xK_r),          sendMessage DoRotate)
diff --git a/src/Internal/Marking.hs b/src/Internal/Marking.hs
index 229ea02..fc1c082 100644
--- a/src/Internal/Marking.hs
+++ b/src/Internal/Marking.hs
@@ -1,6 +1,7 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 module Internal.Marking where
 
+import Internal.Windows (mapWindows)
 import XMonad
 import XMonad.StackSet hiding (focus)
 import Data.IORef
@@ -57,22 +58,6 @@ jumpToMark mark = do
       saveLastMark
       focus w
 
-mapWindows :: (Ord a, Ord b) => (a -> b) -> StackSet i l a s sd -> StackSet i l b s sd
-mapWindows fn (StackSet cur vis hid float) =
-  StackSet
-    (mapWindowsScreen cur)
-    (map mapWindowsScreen vis)
-    (map mapWindowsWorkspace hid)
-    (Map.mapKeys fn float)
-  where
-    mapWindowsScreen (Screen work a b) = Screen (mapWindowsWorkspace work) a b
-    mapWindowsWorkspace (Workspace t l stack) =
-      Workspace t l (fmap (mapStack fn) stack)
-
--- | What genius decided to hide the instances for the Stack type!!???
-mapStack :: (a -> b) -> Stack a -> Stack b
-mapStack fn (Stack focus up down) = Stack (fn focus) (map fn up) (map fn down)
-
 setFocusedWindow :: a -> StackSet i l a s sd -> StackSet i l a s sd
 setFocusedWindow
   window
diff --git a/src/Internal/SwapMaster.hs b/src/Internal/SwapMaster.hs
new file mode 100644
index 0000000..c73cbd9
--- /dev/null
+++ b/src/Internal/SwapMaster.hs
@@ -0,0 +1,41 @@
+{- Swap window with the master, but save it. -}
+module Internal.SwapMaster (swapMaster) where
+
+import qualified XMonad.StackSet as W
+
+import Internal.Windows (mapWindows, getMaster, swapWindows)
+import Control.Monad.Trans.Maybe
+import XMonad (Window, ExtensionClass(..), X(..), windows, windowset)
+import Control.Monad (void)
+import Control.Monad.Trans (lift)
+import Data.Maybe (fromMaybe)
+import Control.Monad.State (get)
+
+import qualified XMonad.Util.ExtensibleState as XS
+
+data LastWindow = LastWindow {
+    lastWindow :: (Maybe Window)
+  } deriving (Show, Read)
+
+instance ExtensionClass LastWindow where
+  initialValue = LastWindow Nothing
+
+hoist :: (Monad m) => Maybe a -> MaybeT m a
+hoist = MaybeT . return
+
+swapMaster :: X ()
+swapMaster = void $ runMaybeT $ do
+    ss <- lift $ windowset <$> get
+
+    focused <- hoist $ W.peek ss
+    master <- hoist $ getMaster ss
+
+    if focused == master
+        then do
+          lw <- MaybeT $ lastWindow <$> XS.get
+          lift $ windows (swapWindows focused lw)
+        else lift $ windows (swapWindows focused master)
+
+    lift $ do
+      XS.put (LastWindow $ Just master)
+      windows W.focusMaster
diff --git a/src/Internal/Windows.hs b/src/Internal/Windows.hs
new file mode 100644
index 0000000..0f109b7
--- /dev/null
+++ b/src/Internal/Windows.hs
@@ -0,0 +1,32 @@
+module Internal.Windows where
+
+import XMonad.StackSet (Stack(..), StackSet(..), Screen(..), Workspace(..), integrate)
+import Data.Maybe (listToMaybe)
+import qualified Data.Map as Map
+
+mapWindows :: (Ord a, Ord b) => (a -> b) -> StackSet i l a s sd -> StackSet i l b s sd
+mapWindows fn (StackSet cur vis hid float) =
+  StackSet
+    (mapWindowsScreen cur)
+    (map mapWindowsScreen vis)
+    (map mapWindowsWorkspace hid)
+    (Map.mapKeys fn float)
+  where
+    mapWindowsScreen (Screen work a b) = Screen (mapWindowsWorkspace work) a b
+    mapWindowsWorkspace (Workspace t l stack) =
+      Workspace t l (fmap (mapStack fn) stack)
+
+-- | What genius decided to hide the instances for the Stack type!!???
+mapStack :: (a -> b) -> Stack a -> Stack b
+mapStack fn (Stack focus up down) = Stack (fn focus) (map fn up) (map fn down)
+
+getMaster :: StackSet i l a s sd -> Maybe a
+getMaster (StackSet (Screen (Workspace _ _ ss) _ _) _ _ _) =
+  head . integrate <$> ss
+
+swapWindows :: (Ord a) => a -> a -> StackSet i l a s d -> StackSet i l a s d
+swapWindows wa wb = mapWindows $ \w ->
+  case w of
+    _ | w == wa -> wb
+    _ | w == wb -> wa
+    _ -> w
-- 
cgit