Make $screensaver available

Relates: nomeata#39

categorize.cfg

@@ -17,6 +17,9 @@ aliases (
 -- causes this sample to be ignored by default.
 $idle > 60 ==> tag inactive,
 
+-- TODO
+$screensaver ==> tag inactive,
+
 -- A rule that matches on a list of strings
 current window $program == ["Navigator","galeon"] ==> tag Web,
 

doc/arbtt.xml

@@ -230,6 +230,10 @@
       <command>arbtt-stats</command>, as can be seen in <xref linkend="catex"/>.
     </para>
 
+    <para>
+      The variable <literal>$screensaver</literal> …
+    </para>
+
     <para>
       When applying the rules, the categorizer has a notion of
       the <emphasis>window in scope</emphasis>, and the variables
@@ -421,6 +425,7 @@
          <nonterminal def="#g-timediff"/> </rhs>
             <rhs> <nonterminal def="#g-date"/> <nonterminal def="#g-cmpop"/>
          <nonterminal def="#g-date"/> </rhs>
+            <rhs> <quote>$screensaver</quote> </rhs>
             <rhs> <quote>current window</quote> <nonterminal def="#g-cond"/> </rhs>
             <rhs> <quote>any window</quote> <nonterminal def="#g-cond"/> </rhs>
             <rhs> <quote>$</quote> Literal </rhs>

src/Categorize.hs

@@ -81,6 +81,8 @@ data TimeVar = TvTime | TvSampleAge
 
 data NumVar = NvIdle
 
+data BoolVar = BvScreenSaver
+
 runParserStack :: Stream s (ReaderT r Identity) t
                => r
                -> ParsecT s () (ReaderT r Identity) a
@@ -141,6 +143,7 @@ lang = makeTokenParser LanguageDef
                                    , "date"
                                    , "now"
                                    , "desktop"
+                                   , "screensaver"
                                    ]
                 , caseSensitive  = True
                 }
@@ -412,6 +415,7 @@ parseCondPrim = choice
                       , reserved lang "date" >> return (CondDate (getDateVar DvDate))
                       , reserved lang "now" >> return (CondDate (getDateVar DvNow))
                       , reserved lang "desktop" >> return (CondString (getVar "desktop"))
+                      , reserved lang "screensaver" >> return (CondCond (checkBoolVar BvScreenSaver))
                       , do varname <- identifier lang
                            inEnvironment <- (lift (asks (Map.lookup varname . snd)))
                            case inEnvironment of
@@ -551,6 +555,9 @@ getDateVar :: DateVar -> CtxFun UTCTime
 getDateVar DvDate = Just . tlTime . cNow
 getDateVar DvNow = Just . cCurrentTime
 
+checkBoolVar :: BoolVar -> Cond
+checkBoolVar BvScreenSaver ctx = guard (cScreenSaver (tlData (cNow ctx))) >> return []
+
 findActive :: [(Bool, t, t1)] -> Maybe (Bool, t, t1)
 findActive = find (\(a,_,_) -> a)