From b5b9fdb37eba97892e67097f9729949bf6d890c5 Mon Sep 17 00:00:00 2001
From: Zachary Snow <zach@zachjs.com>
Date: Fri, 8 Mar 2019 16:55:03 -0500
Subject: [PATCH] support for null call arguments

---
 src/Convert/Traverse.hs                   |  7 +++++--
 src/Language/SystemVerilog/AST.hs         |  8 ++++----
 src/Language/SystemVerilog/Parser/Parse.y | 14 ++++++++------
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/src/Convert/Traverse.hs b/src/Convert/Traverse.hs
index 4cc4b61..89b0acf 100644
--- a/src/Convert/Traverse.hs
+++ b/src/Convert/Traverse.hs
@@ -180,6 +180,9 @@ traverseNestedExprsM :: Monad m => MapperM m Expr -> MapperM m Expr
 traverseNestedExprsM mapper = exprMapper
     where
         exprMapper e = mapper e >>= em
+        maybeExprMapper Nothing = return Nothing
+        maybeExprMapper (Just e) =
+            exprMapper e >>= return . Just
         em (String     s) = return $ String    s
         em (Number     s) = return $ Number    s
         em (ConstBool  b) = return $ ConstBool b
@@ -200,7 +203,7 @@ traverseNestedExprsM mapper = exprMapper
         em (Concat     l) =
             mapM exprMapper l >>= return . Concat
         em (Call       f l) =
-            mapM exprMapper l >>= return . Call f
+            mapM maybeExprMapper l >>= return . Call f
         em (UniOp      o e) =
             exprMapper e >>= return . UniOp o
         em (BinOp      o e1 e2) = do
@@ -277,7 +280,7 @@ traverseExprsM mapper = moduleItemMapper
         exprMapper cc >>= \cc' -> return $ If cc' s1 s2
     flatStmtMapper (Timing event stmt) = return $ Timing event stmt
     flatStmtMapper (Subroutine f exprs) =
-        mapM exprMapper exprs >>= return . Subroutine f
+        mapM maybeExprMapper exprs >>= return . Subroutine f
     flatStmtMapper (Return expr) =
         exprMapper expr >>= return . Return
     flatStmtMapper (Null) = return Null
diff --git a/src/Language/SystemVerilog/AST.hs b/src/Language/SystemVerilog/AST.hs
index b5c39d4..4392424 100644
--- a/src/Language/SystemVerilog/AST.hs
+++ b/src/Language/SystemVerilog/AST.hs
@@ -269,7 +269,7 @@ data Expr
   | Bit        Expr Expr
   | Repeat     Expr [Expr]
   | Concat     [Expr]
-  | Call       Identifier [Expr]
+  | Call       Identifier [Maybe Expr]
   | UniOp      UniOp Expr
   | BinOp      BinOp Expr Expr
   | Mux        Expr Expr Expr
@@ -369,7 +369,7 @@ instance Show Expr where
     Range      a (b, c) -> printf "%s[%s:%s]" (show a) (show b) (show c)
     Repeat     a b      -> printf "{%s {%s}}" (show a) (commas $ map show b)
     Concat     a        -> printf "{%s}" (commas $ map show a)
-    Call       a b      -> printf "%s(%s)" a (commas $ map show b)
+    Call       a b      -> printf "%s(%s)" a (commas $ map (maybe "" show) b)
     UniOp      a b      -> printf "(%s %s)" (show a) (show b)
     BinOp      a b c    -> printf "(%s %s %s)" (show b) (show a) (show c)
     Mux        a b c    -> printf "(%s ? %s : %s)" (show a) (show b) (show c)
@@ -431,7 +431,7 @@ data Stmt
   | If      Expr Stmt Stmt
   | Timing  Timing Stmt
   | Return  Expr
-  | Subroutine Identifier [Expr]
+  | Subroutine Identifier [Maybe Expr]
   | Null
   deriving Eq
 
@@ -462,7 +462,7 @@ instance Show Stmt where
   show (If a b Null) = printf "if (%s) %s"         (show a) (show b)
   show (If a b c   ) = printf "if (%s) %s\nelse %s" (show a) (show b) (show c)
   show (Return e   ) = printf "return %s;" (show e)
-  show (Subroutine x a) = printf "%s(%s);" x (commas $ map show a)
+  show (Subroutine x a) = printf "%s(%s);" x (commas $ map (maybe "" show) a)
   show (Timing t s ) = printf "%s%s" (show t) rest
     where
       rest = case s of
diff --git a/src/Language/SystemVerilog/Parser/Parse.y b/src/Language/SystemVerilog/Parser/Parse.y
index 2f9c20b..2c5066e 100644
--- a/src/Language/SystemVerilog/Parser/Parse.y
+++ b/src/Language/SystemVerilog/Parser/Parse.y
@@ -479,12 +479,14 @@ Number :: { String }
 String :: { String }
   : string { tail $ init $ tokenString $1 }
 
-CallArgs :: { [Expr] }
-  : {- empty -}      { [] }
-  | CallArgsNonEmpty { $1 }
-CallArgsNonEmpty :: { [Expr] }
-  : Expr                      { [$1] }
-  | CallArgsNonEmpty "," Expr { $1 ++ [$3] }
+CallArgs :: { [Maybe Expr] }
+  : {- empty -}         { [] }
+  | Expr                { [Just $1] }
+  |      CallArgsFollow { (Nothing) : $1 }
+  | Expr CallArgsFollow { (Just $1) : $2 }
+CallArgsFollow :: { [Maybe Expr] }
+  : "," opt(Expr)                { [$2] }
+  | "," opt(Expr) CallArgsFollow { $2 : $3 }
 
 Exprs :: { [Expr] }
 :           Expr  { [$1] }