X.U.Stack: Add zipperFocusedAtFirstOf

CHANGES.md

@@ -265,6 +265,11 @@
     - Added `passOTPTypePrompt` to type out one-time-passwords via
       `xdotool`.
 
+  * `XMonad.Util.Stack`
+
+    - Added `zipperFocusedAtFirstOf` to differentiate two lists into a
+      zipper.
+
 ### Other changes
 
 ## 0.17.1 (September 3, 2022)

XMonad/Layout/Combo.hs

@@ -1,5 +1,8 @@
-{-# LANGUAGE FlexibleContexts, FlexibleInstances, MultiParamTypeClasses,
-             UndecidableInstances, PatternGuards #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE PatternGuards #-}
+{-# LANGUAGE UndecidableInstances #-}
 
 -----------------------------------------------------------------------------
 -- |
@@ -24,10 +27,10 @@ module XMonad.Layout.Combo (
                            ) where
 
 import XMonad hiding (focus)
+import XMonad.Layout.WindowNavigation (MoveWindowToWindow (..))
 import XMonad.Prelude (delete, fromMaybe, intersect, isJust, (\\))
-import XMonad.StackSet ( integrate', Workspace (..), Stack(..) )
-import XMonad.Layout.WindowNavigation ( MoveWindowToWindow(..) )
-import qualified XMonad.StackSet as W ( differentiate )
+import XMonad.StackSet (Stack (..), Workspace (..), integrate')
+import XMonad.Util.Stack (zipperFocusedAtFirstOf)
 
 -- $usage
 -- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
@@ -94,8 +97,8 @@ instance (LayoutClass l (), LayoutClass l1 a, LayoutClass l2 a, Read a, Show a,
                                                                   [] -> init x
                                                                   _ -> x
                          superstack = Stack { focus=(), up=[], down=[()] }
-                         s1 = differentiate f' (origws \\ w2')
-                         s2 = differentiate f' w2'
+                         s1 = zipperFocusedAtFirstOf f' (origws \\ w2')
+                         s2 = zipperFocusedAtFirstOf f' w2'
                          f' = case s of (Just s') -> focus s':delete (focus s') f
                                         Nothing -> f
                      ([((),r1),((),r2)], msuper') <- runLayout (Workspace "" super (Just superstack)) rinput
@@ -128,14 +131,6 @@ instance (LayoutClass l (), LayoutClass l1 a, LayoutClass l2 a, Read a, Show a,
     description (C2 _ _ super l1 l2) = "combining "++ description l1 ++" and "++
                                        description l2 ++" with "++ description super
 
-
-differentiate :: Eq q => [q] -> [q] -> Maybe (Stack q)
-differentiate (z:zs) xs | z `elem` xs = Just $ Stack { focus=z
-                                                     , up = reverse $ takeWhile (/=z) xs
-                                                     , down = drop 1 $ dropWhile (/=z) xs }
-                        | otherwise = differentiate zs xs
-differentiate [] xs = W.differentiate xs
-
 broadcastPrivate :: LayoutClass l b => SomeMessage -> [l b] -> X (Maybe [l b])
 broadcastPrivate a ol = do nml <- mapM f ol
                            if any isJust nml

XMonad/Layout/ComboP.hs

@@ -25,12 +25,13 @@ module XMonad.Layout.ComboP (
                              Property(..)
                             ) where
 
-import XMonad.Prelude
 import XMonad hiding (focus)
-import XMonad.StackSet ( Workspace (..), Stack(..) )
 import XMonad.Layout.WindowNavigation
-import XMonad.Util.WindowProperties
+import XMonad.Prelude
+import XMonad.StackSet ( Workspace (..), Stack(..) )
 import qualified XMonad.StackSet as W
+import XMonad.Util.Stack (zipperFocusedAtFirstOf)
+import XMonad.Util.WindowProperties
 
 -- $usage
 -- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
@@ -99,10 +100,10 @@ instance (LayoutClass l (), LayoutClass l1 Window, LayoutClass l2 Window) =>
             f' = focus s:delete (focus s) f  -- list of focused windows, contains 2 elements at most
         in do
             matching <- hasProperty prop `filterM` new  -- new windows matching predecate
-            let w1' = w1c ++ matching                     -- updated first pane windows
-                w2' = w2c ++ (new \\ matching)            -- updated second pane windows
-                s1 = differentiate f' w1'                 -- first pane stack
-                s2 = differentiate f' w2'                 -- second pane stack
+            let w1' = w1c ++ matching                   -- updated first pane windows
+                w2' = w2c ++ (new \\ matching)          -- updated second pane windows
+                s1 = zipperFocusedAtFirstOf f' w1'      -- first pane stack
+                s2 = zipperFocusedAtFirstOf f' w2'      -- second pane stack
             ([((),r1),((),r2)], msuper') <- runLayout (Workspace "" super superstack) rinput
             (wrs1, ml1') <- runLayout (Workspace "" l1 s1) r1
             (wrs2, ml2') <- runLayout (Workspace "" l2 s2) r2
@@ -177,15 +178,4 @@ forwardIfFocused l w m = do
                 then handleMessage l m
                 else return Nothing
 
--- code from CombineTwo
--- given two sets of zs and xs takes the first z from zs that also belongs to xs
--- and turns xs into a stack with z being current element. Acts as
--- StackSet.differentiate if zs and xs don't intersect
-differentiate :: Eq q => [q] -> [q] -> Maybe (Stack q)
-differentiate (z:zs) xs | z `elem` xs = Just $ Stack { focus=z
-                                                     , up = reverse $ takeWhile (/=z) xs
-                                                     , down = tail $ dropWhile (/=z) xs }
-                        | otherwise = differentiate zs xs
-differentiate [] xs = W.differentiate xs
-
 -- vim:ts=4:shiftwidth=4:softtabstop=4:expandtab:foldlevel=20:

XMonad/Layout/LayoutBuilder.hs

@@ -57,9 +57,11 @@ module XMonad.Layout.LayoutBuilder (
   LayoutN,
 ) where
 
+import Data.Maybe (maybeToList)
 import XMonad
 import XMonad.Prelude (foldM, (<|>), isJust, fromMaybe, isNothing, listToMaybe)
 import qualified XMonad.StackSet as W
+import XMonad.Util.Stack (zipperFocusedAtFirstOf)
 import XMonad.Util.WindowProperties
 
 --------------------------------------------------------------------------------
@@ -452,11 +454,4 @@ calcArea (SubBox xpos ypos width height) rect =
 
 --------------------------------------------------------------------------------
 differentiate' :: Eq q => Maybe q -> [q] -> Maybe (W.Stack q)
-differentiate' _ [] = Nothing
-differentiate' Nothing w = W.differentiate w
-differentiate' (Just f) w
-    | f `elem` w = Just W.Stack { W.focus = f
-                                , W.up    = reverse $ takeWhile (/=f) w
-                                , W.down  = tail $ dropWhile (/=f) w
-                                }
-    | otherwise = W.differentiate w
+differentiate' = zipperFocusedAtFirstOf . maybeToList

XMonad/Layout/TallMastersCombo.hs

@@ -42,12 +42,13 @@ module XMonad.Layout.TallMastersCombo (
 ) where
 
 import XMonad hiding (focus, (|||))
-import XMonad.Prelude (delete, find, foldM, fromMaybe, isJust)
-import XMonad.StackSet (Workspace(..),integrate',Stack(..))
-import qualified XMonad.StackSet as W
 import qualified XMonad.Layout as LL
-import XMonad.Layout.Simplest (Simplest(..))
 import XMonad.Layout.Decoration
+import XMonad.Layout.Simplest (Simplest (..))
+import XMonad.Prelude (delete, find, foldM, fromMaybe, isJust)
+import XMonad.StackSet (Stack (..), Workspace (..), integrate')
+import qualified XMonad.StackSet as W
+import XMonad.Util.Stack (zipperFocusedAtFirstOf)
 
 ---------------------------------------------------------------------------------
 -- $usage
@@ -302,19 +303,6 @@ instance (GetFocused l1 Window, GetFocused l2 Window) => LayoutClass (TMSCombine
               mlayout2 <- handleMessage layout2 m
               return $ mergeSubLayouts mlayout1 mlayout2 i False
 
-
-
--- code from CombineTwo
--- given two sets of zs and xs takes the first z from zs that also belongs to xs
--- and turns xs into a stack with z being current element. Acts as
--- StackSet.differentiate if zs and xs don't intersect
-differentiate :: Eq q => [q] -> [q] -> Maybe (Stack q)
-differentiate (z:zs) xs | z `elem` xs = Just $ Stack { focus=z
-                                                     , up = reverse $ takeWhile (/=z) xs
-                                                     , down = tail $ dropWhile (/=z) xs }
-                        | otherwise = differentiate zs xs
-differentiate [] xs = W.differentiate xs
-
 -- | Swap a given window with the focused window.
 swapWindow :: (Eq a) => a -> Stack a -> Stack a
 swapWindow w (Stack foc upLst downLst)
@@ -388,9 +376,9 @@ splitStack f nmaster frac s =
                        Nothing   -> f
         snum = length slst
         (slst1, slst2) = splitAt nmaster slst
-        s0 = differentiate f' slst
-        s1' = differentiate f' slst1
-        s2' = differentiate f' slst2
+        s0 = zipperFocusedAtFirstOf f' slst
+        s1' = zipperFocusedAtFirstOf f' slst1
+        s2' = zipperFocusedAtFirstOf f' slst2
         (s1,s2,frac') | nmaster == 0    = (Nothing,s0,0)
                       | nmaster >= snum = (s0,Nothing,1)
                       | otherwise       = (s1',s2',frac)

XMonad/Util/Stack.hs

@@ -27,6 +27,7 @@ module XMonad.Util.Stack ( -- * Usage
                          , toIndex
                          , fromTags
                          , toTags
+                         , zipperFocusedAtFirstOf
 
                            -- * 'Zipper' manipulation functions
                            -- ** Insertion, movement
@@ -123,6 +124,18 @@ toTags Nothing = []
 toTags (Just s) = map Left (reverse . W.up $ s) ++ [Right . W.focus $ s]
                   ++ map Left (W.down s)
 
+-- | @differentiate zs xs@ takes the first @z@ from @z2 that also belongs to
+-- @xs@ and turns @xs@ into a stack with @z@ being the current element. Acts
+-- as 'XMonad.StackSet.differentiate' if @zs@ and @xs@ don't intersect.
+zipperFocusedAtFirstOf :: Eq q => [q] -> [q] -> Zipper q
+zipperFocusedAtFirstOf []       xs = W.differentiate xs
+zipperFocusedAtFirstOf (z : zs) xs
+  | z `elem` xs = Just $
+        W.Stack { W.focus = z
+                , W.up    = reverse $ takeWhile (/= z) xs
+                , W.down  = drop 1  $ dropWhile (/= z) xs
+                }
+  | otherwise = zipperFocusedAtFirstOf zs xs
 
 -- * Zipper functions