Add ifWindow and ifWindows and simplify WindowGo

This patch adds ifWindow and ifWindows as helper functions to
X.A.WindowGo and removes some boilerplate by rewriting other functions
in terms of those. Also some minor simplifications.

XMonad/Actions/WindowGo.hs

@@ -28,13 +28,17 @@ module XMonad.Actions.WindowGo (
                  runOrRaiseMaster,
                  raiseAndDo,
                  raiseMaster,
+
+                 ifWindows,
+                 ifWindow,
+                 raiseHook,
                  module XMonad.ManageHook
                 ) where
 
-import Control.Monad (filterM)
+import Control.Monad
 import Data.Char (toLower)
-
-import XMonad (Query(), X(), withWindowSet, runQuery, liftIO)
+import Data.Monoid
+import XMonad (Query(), X(), ManageHook, withWindowSet, runQuery, liftIO, ask)
 import Graphics.X11 (Window)
 import XMonad.ManageHook
 import XMonad.Operations (windows)
@@ -60,6 +64,21 @@ appropriate one, or cover your bases by using instead something like
 For detailed instructions on editing your key bindings, see
 "XMonad.Doc.Extending#Editing_key_bindings". -}
 
+-- | If windows that satisfy the query exist, apply the supplied
+-- function to them, otherwise run the action given as
+-- second parameter.
+ifWindows :: Query Bool -> ([Window] -> X ()) -> X () -> X ()
+ifWindows qry f el = withWindowSet $ \wins -> do
+  matches <- filterM (runQuery qry) $ W.allWindows wins
+  case matches of
+    [] -> el
+    ws -> f ws
+
+-- | The same as ifWindows, but applies a ManageHook to the first match
+-- instead and discards the other matches
+ifWindow :: Query Bool -> ManageHook -> X () -> X ()
+ifWindow qry mh = ifWindows qry (windows . appEndo <=< runQuery mh . head)
+
 -- | 'action' is an executable to be run via 'safeSpawnProg' (of "XMonad.Util.Run") if the Window cannot be found.
 --   Presumably this executable is the same one that you were looking for.
 runOrRaise :: String -> Query Bool -> X ()
@@ -96,11 +115,11 @@ raise = raiseMaybe $ return ()
   > , ((modm, xK_m), raiseMaybe (runInTerm "-title mutt" "mutt") (title =? "mutt"))
 -}
 raiseMaybe :: X () -> Query Bool -> X ()
-raiseMaybe f thatUserQuery = withWindowSet $ \s -> do
-    maybeResult <- filterM (runQuery thatUserQuery) (W.allWindows s)
-    case maybeResult of
-      []     -> f
-      (x:_)  -> windows $ W.focusWindow x
+raiseMaybe f qry = ifWindow qry raiseHook f
+
+-- | A manage hook that raises the window.
+raiseHook :: ManageHook
+raiseHook = ask >>= doF . W.focusWindow
 
 -- | See 'runOrRaise' and 'raiseNextMaybe'. Version that allows cycling through matches.
 runOrRaiseNext :: String -> Query Bool -> X ()
@@ -116,18 +135,14 @@ raiseNext = raiseNextMaybe $ return ()
      query the next matching window is raised. If no matches are found
      the function f is executed.
 -}
+
 raiseNextMaybe :: X () -> Query Bool -> X ()
-raiseNextMaybe f thatUserQuery = withWindowSet $ \s -> do
-  ws <- filterM (runQuery thatUserQuery) (W.allWindows s)
-  case ws of
-    []    -> f
-    (x:_) -> let go (Just w) | (w `elem` ws) = next w $ cycle ws
-                 go _ = windows $ W.focusWindow x
-             in go $ W.peek s
-  where
-    next w (x:y:_) | x==w = windows $ W.focusWindow y
-    next w (_:xs)         = next w xs
-    next _ _ = error "raiseNextMaybe: empty list"
+raiseNextMaybe f qry = flip (ifWindows qry) f $ \ws -> do
+  foc <- withWindowSet $ return . W.peek
+  case foc of
+    Just w | w `elem` ws -> let (_:y:_) = dropWhile (/=w) $ cycle ws -- cannot fail to match
+                            in windows $ W.focusWindow y
+    _ -> windows . W.focusWindow . head $ ws
 
 -- | Given a function which gets us a String, we try to raise a window with that classname,
 --   or we then interpret that String as a executable name.
@@ -145,12 +160,8 @@ raiseEditor  = raiseVar getEditor
      otherwise, the first argument is called
      See 'raiseMaster' for an example. -}
 raiseAndDo :: X () -> Query Bool -> (Window -> X ())-> X ()
-raiseAndDo raisef thatUserQuery afterRaise = withWindowSet $ \s -> do
-    maybeResult <- filterM (runQuery thatUserQuery) (W.allWindows s)
-    case maybeResult of
-      []     -> raisef
-      (x:_)  -> do windows $ W.focusWindow x
-                   afterRaise x
+raiseAndDo f qry after = ifWindow qry (afterRaise `mappend` raiseHook) f
+    where afterRaise = ask >>= (>> idHook) . liftX . after
 
 {- | If a window matching the second arugment is found, the window is focused and the third argument is called;
      otherwise, the first argument is called. -}