Learn flattenExpr about single alt Case expressions.

[matthijs/master-project/cλash.git] / Flatten.hs

diff --git a/Flatten.hs b/Flatten.hs
index 4157e1b28d405c3f88b27dcd2dc9a1864fe2d881..14fd781c5c6653ca989c393eb038f5af42cb38ab 100644 (file)
--- a/Flatten.hs
+++ b/Flatten.hs
@@ -1,6 +1,7 @@
 module Flatten where
 import CoreSyn
 import Control.Monad
+import qualified Var
 import qualified Type
 import qualified Name
 import qualified TyCon
@@ -258,11 +259,101 @@ flattenExpr binds app@(App _ _) = do
       let ((Var f), args) = collectArgs app in
       flattenApplicationExpr binds (CoreUtils.exprType app) f args
   where
-    flattenBuildTupleExpr = error $ "Tuple construction not supported: " ++ (showSDoc $ ppr app)
-    flattenApplicationExpr binds ty f args = error $ "Function application not supported: " ++ (showSDoc $ ppr app)
-
+    flattenBuildTupleExpr binds args = do
+      -- Flatten each of our args
+      flat_args <- (State.mapM (flattenExpr binds) args)
+      -- Check and split each of the arguments
+      let (_, arg_ress) = unzip (zipWith checkArg args flat_args)
+      let res = Tuple arg_ress
+      return ([], res)
+
+    -- | Flatten a normal application expression
+    flattenApplicationExpr binds ty f args = do
+      -- Find the function to call
+      let func = appToHsFunction ty f args
+      -- Flatten each of our args
+      flat_args <- (State.mapM (flattenExpr binds) args)
+      -- Check and split each of the arguments
+      let (_, arg_ress) = unzip (zipWith checkArg args flat_args)
+      -- Generate signals for our result
+      res <- genSignalUses ty
+      -- Create the function application
+      let app = FApp {
+        appFunc = func,
+        appArgs = arg_ress,
+        appRes  = useMapToDefMap res
+      }
+      addApp app
+      return ([], res)
+    -- | Check a flattened expression to see if it is valid to use as a
+    --   function argument. The first argument is the original expression for
+    --   use in the error message.
+    checkArg arg flat =
+      let (args, res) = flat in
+      if not (null args)
+        then error $ "Passing lambda expression or function as a function argument not supported: " ++ (showSDoc $ ppr arg)
+        else flat 
+
+flattenExpr binds l@(Let (NonRec b bexpr) expr) = do
+  (b_args, b_res) <- flattenExpr binds bexpr
+  if not (null b_args)
+    then
+      error $ "Higher order functions not supported in let expression: " ++ (showSDoc $ ppr l)
+    else
+      let binds' = (b, Left b_res) : binds in
+      flattenExpr binds' expr
+
+flattenExpr binds l@(Let (Rec _) _) = error $ "Recursive let definitions not supported: " ++ (showSDoc $ ppr l)
+
+flattenExpr binds expr@(Case (Var v) b _ alts) =
+  case alts of
+    [alt] -> flattenSingleAltCaseExpr binds v b alt
+    otherwise -> error $ "Multiple alternative case expression not supported: " ++ (showSDoc $ ppr expr)
+  where
+    flattenSingleAltCaseExpr ::
+      BindMap
+                                -- A list of bindings in effect
+      -> Var.Var                -- The scrutinee
+      -> CoreBndr               -- The binder to bind the scrutinee to
+      -> CoreAlt                -- The single alternative
+      -> FlattenState ( [SignalDefMap], SignalUseMap)
+                                           -- See expandExpr
+    flattenSingleAltCaseExpr binds v b alt@(DataAlt datacon, bind_vars, expr) =
+      if not (DataCon.isTupleCon datacon) 
+        then
+          error $ "Dataconstructors other than tuple constructors not supported in case pattern of alternative: " ++ (showSDoc $ ppr alt)
+        else
+          let
+            -- Lookup the scrutinee (which must be a variable bound to a tuple) in
+            -- the existing bindings list and get the portname map for each of
+            -- it's elements.
+            Left (Tuple tuple_sigs) = Maybe.fromMaybe 
+              (error $ "Case expression uses unknown scrutinee " ++ Name.getOccString v)
+              (lookup v binds)
+            -- TODO include b in the binds list
+            -- Merge our existing binds with the new binds.
+            binds' = (zip bind_vars (map Left tuple_sigs)) ++ binds 
+          in
+            -- Expand the expression with the new binds list
+            flattenExpr binds' expr
+    flattenSingleAltCaseExpr _ _ _ alt = error $ "Case patterns other than data constructors not supported in case alternative: " ++ (showSDoc $ ppr alt)
+
+
+      
 flattenExpr _ _ = do
   return ([], Tuple [])
 
+appToHsFunction ::
+  Type.Type       -- ^ The return type
+  -> Var.Var      -- ^ The function to call
+  -> [CoreExpr]   -- ^ The function arguments
+  -> HsFunction   -- ^ The needed HsFunction
+
+appToHsFunction ty f args =
+  HsFunction hsname hsargs hsres
+  where
+    hsname = Name.getOccString f
+    hsargs = map (useAsPort . mkHsValueMap . CoreUtils.exprType) args
+    hsres  = useAsPort (mkHsValueMap ty)
 
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