WorkspaceCompare: some refactoring.

  * Export WorkspaceCompare and WorkspaceSort types.
  * Extract commonality in sort methods into mkWsSort, which creates
    a workspace sort from a workspace comparison function.
  * Rename getSortByTag to getSortByIndex, since it did not actually sort
    by tag at all; it sorts by index of workspace tags in the user's config.
  * Create a new getSortByTag function which actually does sort
    lexicographically by tag.
  * Enhance documentation.

darcs-hash:20080201120430-bd4d7-71310db2b8d4248ddfb77e3fa25dd0f3b98ea00b.gz

1 files changed, 42 insertions, 17 deletions

diff --git a/XMonad/Util/WorkspaceCompare.hs b/XMonad/Util/WorkspaceCompare.hs
index 3517100..fbf139d 100644
--- a/XMonad/Util/WorkspaceCompare.hs
+++ b/XMonad/Util/WorkspaceCompare.hs
@@ -9,8 +9,13 @@
 -- Portability :  unportable
 --
 
-module XMonad.Util.WorkspaceCompare ( getWsIndex
+module XMonad.Util.WorkspaceCompare ( WorkspaceCompare, WorkspaceSort
+                                    , getWsIndex
                                     , getWsCompare
+                                    , getWsCompareByTag
+                                    , getXineramaWsCompare
+                                    , mkWsSort
+                                    , getSortByIndex
                                     , getSortByTag
                                     , getSortByXineramaRule ) where
 
@@ -21,6 +26,9 @@ import Data.Monoid
 import Data.Ord
 import Data.Maybe
 
+type WorkspaceCompare = WorkspaceId -> WorkspaceId -> Ordering
+type WorkspaceSort = [WindowSpace] -> [WindowSpace]
+
 -- | Lookup the index of a workspace id in the user's config, return Nothing
 -- if that workspace does not exist in the config.
 getWsIndex :: X (WorkspaceId -> Maybe Int)
@@ -28,8 +36,9 @@ getWsIndex = do
     spaces <- asks (workspaces . config)
     return $ flip elemIndex spaces
 
--- | A comparison function for WorkspaceId
-getWsCompare :: X (WorkspaceId -> WorkspaceId -> Ordering)
+-- | A comparison function for WorkspaceId, based on the index of the
+--   tags in the user's config.
+getWsCompare :: X WorkspaceCompare
 getWsCompare = do
     wsIndex <- getWsIndex
     return $ \a b -> f (wsIndex a) (wsIndex b) `mappend` compare a b
@@ -39,9 +48,15 @@ getWsCompare = do
     f Nothing (Just _)  = GT
     f (Just x) (Just y) = compare x y
 
--- | A comparison function for Xinerama based on visibility, workspace and
--- screen id. It produces same ordering as pprWindowSetXinerama does.
-getXineramaWsCompare :: X(WorkspaceId -> WorkspaceId -> Ordering)
+-- | A simple comparison function that orders workspaces
+--   lexicographically by tag.
+getWsCompareByTag :: X WorkspaceCompare
+getWsCompareByTag = return compare
+
+-- | A comparison function for Xinerama based on visibility, workspace
+--   and screen id. It produces the same ordering as
+--   'XMonad.Hooks.DynamicLog.pprWindowSetXinerama'.
+getXineramaWsCompare :: X WorkspaceCompare
 getXineramaWsCompare = do
     w <- gets windowset
     return $ \ a b -> case (isOnScreen a w, isOnScreen b w) of
@@ -53,17 +68,27 @@ getXineramaWsCompare = do
     onScreen w =  S.current w : S.visible w
     isOnScreen a w  = a `elem` map (S.tag . S.workspace) (onScreen w)
     tagToSid s x = S.screen $ fromJust $ find ((== x) . S.tag . S.workspace) s
-                 --S.screen $ head $ filter ((== x) . S.tag . S.workspace) s
 
--- | Sort several workspaces according to the order in getWsCompare
-getSortByTag :: X ([WindowSpace] -> [WindowSpace])
-getSortByTag = do
-    cmp <- getWsCompare
-    return $ sortBy (\a b -> cmp (S.tag a) (S.tag b))
+-- | Create a workspace sorting function from a workspace comparison
+--   function.
+mkWsSort :: X WorkspaceCompare -> X WorkspaceSort
+mkWsSort cmpX = do
+  cmp <- cmpX
+  return $ sortBy (\a b -> cmp (S.tag a) (S.tag b))
+
+-- | Sort several workspaces according to their tags' indices in the
+--   user's config.
+getSortByIndex :: X WorkspaceSort
+getSortByIndex = mkWsSort getWsCompare
+
+-- | Sort workspaces lexicographically by tag.
+getSortByTag :: X WorkspaceSort
+getSortByTag = mkWsSort getWsCompareByTag
 
--- | Sort serveral workspaces for xinerama displays
-getSortByXineramaRule :: X ([WindowSpace] -> [WindowSpace])
-getSortByXineramaRule = do
-    cmp <- getXineramaWsCompare
-    return $ sortBy (\a b -> cmp (S.tag a) (S.tag b))
+-- | Sort serveral workspaces for xinerama displays, in the same order
+--   produced by 'XMonad.Hooks.DynamicLog.pprWindowSetXinerama': first
+--   visible workspaces, sorted by screen, then hidden workspaces,
+--   sorted by tag.
+getSortByXineramaRule :: X WorkspaceSort
+getSortByXineramaRule = mkWsSort getXineramaWsCompare