bindings: switch "jump to urgent" to "toggle pidgin conversation"

Moreover, we define a more generic function to toggle a window that
can be used for windows with urgency hint or for any group of
windows. The undo stack will skip windows that cannnot be restored
yet (not visible) and will be cleaned up if it becomes too large.

rc/bindings.lua

@@ -16,29 +16,31 @@ local function screenshot(client)
    awful.util.spawn("import -window " .. client .. " " .. path, false)
 end
 
--- Pull the first window with urgent flag in the current workspace if
--- not displayed. If displayed, just raise it. If no urgent window,
--- push back the previous urgent window to its original tag
-local urgent_undo_stack = {}
-local function pull_urgent()
-   local cl = awful.client.urgent.get()
+
+-- Function to toggle a given window to the currently selected and
+-- focused tag. We need a filter. This function can be used to focus a
+-- particular window. When the filter is unable to select something,
+-- we undo previous actions (hence "toggle"). This function returns a
+-- function that will effectively toggle things.
+local function toggle_window(filter)
+   local undo = {}		-- undo stack
+   local toggle = function()
+      -- "Current" screen
       local s = client.focus and client.focus.screen or mouse.screen
-   if cl then
+      local cl = filter()	-- Client to toggle
+      if cl and client.focus ~= cl then
 	 -- So, we have a client.
 	 if not cl:isvisible() then
 	    -- But it is not visible. So we will add it to the current
 	    -- tag of the current screen.
-	 local t = awful.tag.selected(s)
-	 if not t then
-	    return awful.client.urgent.jumpto()
-	 end
+	    local t = assert(awful.tag.selected(s))
 	    -- Before adding the tag to the client, we should ensure it
 	    -- is on the same screen.
 	    if s ~= cl.screen then
 	       sharetags.tag_move(cl:tags()[1], s)
 	    end
 	    -- Add our tag to the client
-	 urgent_undo_stack[#urgent_undo_stack + 1] = { cl, t }
+	    undo[#undo + 1] = { cl, t }
 	    awful.client.toggletag(t, cl)
 	 end
 
@@ -51,21 +53,39 @@ local function pull_urgent()
       else
 	 -- OK, we need to restore the previously pushed window to its
 	 -- original state.
-      while #urgent_undo_stack > 0 do
-	 local cl, t = unpack(table.remove(urgent_undo_stack,
-					   #urgent_undo_stack))
+	 local i = #undo
+	 while i > 0 do
+	    local cl, t = unpack(undo[i])
 	    -- We only handle visible clients that are attached to the
-	 -- appropriate tag. Otherwise, the client is discarded (and
-	 -- won't be restored later).
+	    -- appropriate tag. Otherwise, we try the next one.
 	    if cl and cl:isvisible() and
 	       awful.util.table.hasitem(cl:tags(), t) then
 	       awful.client.toggletag(t, cl)
+	       table.remove(undo, i)
 	       return
 	    end
 	 end
+	 -- Clean up...
+	 while #undo > 10 do
+	    table.remove(undo, 1)
 	 end
+      end
+   end
+   return toggle
 end
 
+-- Toggle pidgin conversation window
+local toggle_pidgin = toggle_window(
+   function ()
+      return awful.client.cycle(function(c)
+			    return awful.rules.match(c, { class = "Pidgin",
+							  role = "conversation" })
+			 end)()
+   end)
+
+-- Toggle urgent window
+local toggle_urgent = toggle_window(awful.client.urgent.get)
+
 config.keys.global = awful.util.table.join(
    keydoc.group("Focus"),
    awful.key({ modkey,           }, "j",
@@ -88,8 +108,8 @@ config.keys.global = awful.util.table.join(
 		end
 	     end,
 	     "Focus previously focused window"),
-   awful.key({ modkey,           }, "u", pull_urgent,
-	    "Jump to urgent-flagged window"),
+   awful.key({ modkey,           }, "u", toggle_pidgin,
+	    "Toggle Pidgin conversation window"),
    awful.key({ modkey, "Control" }, "j", function () awful.screen.focus_relative( 1) end,
 	     "Jump to next screen"),
    awful.key({ modkey, "Control" }, "k", function () awful.screen.focus_relative(-1) end),