do not generate code for unused constructor arguments in "case"

src/Sapl/Target/JS/CodeGeneratorJS.icl

@@ -318,6 +318,17 @@ containsUnsafeSelect s (SCase _ ps) = isUnsafeSelect s ps || any (containsUnsafe
 containsUnsafeSelect s (SLet b _) = containsUnsafeSelect s b
 containsUnsafeSelect s _ = False
 
+isUsed :: SaplTerm SaplVar -> Bool
+isUsed body var = w (unpackVar var) body
+where
+	w vn (SVar bvar) = unpackVar bvar == vn
+	w vn (SApplication bvar bargs) = w vn bvar || any (w vn) bargs
+	w vn (SCase bexpr branches) = w vn bexpr || any (w vn) (map snd branches)
+	w vn (SLet bexpr bdefs) = w vn bexpr || any (w vn) (map unpackBindExpr bdefs)
+	w vn (SSelect bexpr _ _) = w vn bexpr
+	w vn (SUpdate bexpr _ updates) = w vn bexpr || any (w vn) (map snd updates)
+	w _ _ = False
+
 isUnsafeSelect :: !CoderState ![(SaplPattern, SaplTerm)] -> Bool
 isUnsafeSelect s patterns
 	= case ps of
@@ -352,11 +363,16 @@ where
 				True = a
 				_ 	 = a <++ "case " <++ toString get_cons.index <++ ": "
 
-		= a <++ "var " <++ instargs args 0 s <++ callWrapper body s
+		# (fargs, _) = foldl (\(fs, i) a -> if (isUsed body a) ([(a,i):fs],i+1) (fs,i+1)) ([], 0) args 
+
+		= case fargs of
+			[] = a <++ callWrapper body s
+			fargs = a <++ "var " <++ instargs (reverse fargs) s <++ callWrapper body s
+						
 	where 
-		instargs [t] i s a = a <++ termCoder t s <++ "=ys[" <++ i+2 <++ "];"
-		instargs [t:ts] i s a = a <++ termCoder t s <++ "=ys[" <++ i+2 <++ "]," <++ instargs ts (i+1) s
-		instargs [] i s a = a
+		instargs [(t,i)] s a = a <++ termCoder t s <++ "=ys[" <++ i+2 <++ "];"
+		instargs [(t,i):ts] s a = a <++ termCoder t s <++ "=ys[" <++ i+2 <++ "]," <++ instargs ts s
+		instargs [] s a = a
 
 		get_cons   = get_cons_or_die s cons