Merge pull request #331 from ivanbrennan/toggle-recent-workspace

CycleRecentWS: add non-empty and toggle functionality

CHANGES.md

@@ -65,6 +65,18 @@
     When we calculate dragger widths, we first try to get the border width of
     the focused window, before failing over to using the initial `borderWidth`.
 
+  * `XMonad.Actions.CycleRecentWS`
+
+    - Added `cycleRecentNonEmptyWS` function which behaves like `cycleRecentWS`
+      but is constrainded to non-empty workspaces.
+
+    - Added `toggleRecentWS` and `toggleRecentNonEmptyWS` functions which toggle
+      between the current and most recent workspace, and continue to toggle back
+      and forth on repeated presses, rather than cycling through other workspaces.
+
+    - Added `recentWS` function which allows the recency list to be filtered with
+      a user-provided predicate.
+
 ## 0.16
 
 ### Breaking Changes

XMonad/Actions/CycleRecentWS.hs

@@ -19,11 +19,16 @@ module XMonad.Actions.CycleRecentWS (
                                 -- * Usage
                                 -- $usage
                                 cycleRecentWS,
-                                cycleWindowSets
+                                cycleRecentNonEmptyWS,
+                                cycleWindowSets,
+                                toggleRecentWS,
+                                toggleRecentNonEmptyWS,
+                                toggleWindowSets,
+                                recentWS
 ) where
 
 import XMonad hiding (workspaces)
-import XMonad.StackSet
+import XMonad.StackSet hiding (filter)
 
 -- $usage
 -- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@ file:
@@ -47,9 +52,41 @@ cycleRecentWS :: [KeySym] -- ^ A list of modifier keys used when invoking this a
               -> KeySym   -- ^ Key used to switch to previous (more recent) workspace.
                           --   If it's the same as the nextWorkspace key, it is effectively ignored.
               -> X ()
-cycleRecentWS = cycleWindowSets options
- where options w = map (view `flip` w) (recentTags w)
-       recentTags w = map tag $ tail (workspaces w) ++ [head (workspaces w)]
+cycleRecentWS = cycleWindowSets $ recentWS (const True)
+
+
+-- | Like 'cycleRecentWS', but restricted to non-empty workspaces.
+cycleRecentNonEmptyWS :: [KeySym] -- ^ A list of modifier keys used when invoking this action.
+                                  --   As soon as one of them is released, the final switch is made.
+                      -> KeySym   -- ^ Key used to switch to next (less recent) workspace.
+                      -> KeySym   -- ^ Key used to switch to previous (more recent) workspace.
+                                  --   If it's the same as the nextWorkspace key, it is effectively ignored.
+                      -> X ()
+cycleRecentNonEmptyWS = cycleWindowSets $ recentWS (not . null . stack)
+
+
+-- | Switch to the most recent workspace. The stack of most recently used workspaces
+-- is updated, so repeated use toggles between a pair of workspaces.
+toggleRecentWS :: X ()
+toggleRecentWS = toggleWindowSets $ recentWS (const True)
+
+
+-- | Like 'toggleRecentWS', but restricted to non-empty workspaces.
+toggleRecentNonEmptyWS :: X ()
+toggleRecentNonEmptyWS = toggleWindowSets $ recentWS (not . null . stack)
+
+
+-- | Given a predicate p and the current WindowSet w, create a list of recent WindowSets,
+-- most recent first, where the focused workspace satisfies p.
+recentWS :: (WindowSpace -> Bool) -- ^ A workspace predicate.
+         -> WindowSet             -- ^ The current WindowSet
+         -> [WindowSet]
+recentWS p w = map (`view` w) recentTags
+ where recentTags = map tag
+                  $ filter p
+                  $ map workspace (visible w)
+                    ++ hidden w
+                    ++ [workspace (current w)]
 
 
 cycref :: [a] -> Int -> a
@@ -83,3 +120,12 @@ cycleWindowSets genOptions mods keyNext keyPrev = do
   io $ grabKeyboard d root False grabModeAsync grabModeAsync currentTime
   setOption 0
   io $ ungrabKeyboard d currentTime
+
+
+-- | Switch to the first of a finite list of WindowSets.
+toggleWindowSets :: (WindowSet -> [WindowSet]) -> X ()
+toggleWindowSets genOptions = do
+  options <- gets $ genOptions . windowset
+  case options of
+    []  -> return ()
+    o:_ -> windows (const o)