Retrieving the datacon of an arbitrary closure

[ghc-hetmet.git] / compiler / ghci / ObjLink.lhs

diff --git a/compiler/ghci/ObjLink.lhs b/compiler/ghci/ObjLink.lhs
index 7675c71..135afbb 100644 (file)
--- a/compiler/ghci/ObjLink.lhs
+++ b/compiler/ghci/ObjLink.lhs
@@ -18,9 +18,11 @@ module ObjLink (
    unloadObj,           -- :: String -> IO ()
    insertSymbol,         -- :: String -> String -> Ptr a -> IO ()
    lookupSymbol,        -- :: String -> IO (Maybe (Ptr a))
-   resolveObjs          -- :: IO SuccessFlag
+   resolveObjs,         -- :: IO SuccessFlag
+   lookupDataCon         -- :: Ptr a  -> IO (Maybe String)
   )  where
 
+import ByteCodeItbls    ( StgInfoTable )
 import Panic           ( panic )
 import BasicTypes      ( SuccessFlag, successIf )
 import Config          ( cLeadingUnderscore )
@@ -31,6 +33,10 @@ import Foreign.C
 import Foreign         ( nullPtr )
 import GHC.Exts         ( Ptr(..), unsafeCoerce# )
 
+import Constants        ( wORD_SIZE )
+import Foreign          ( plusPtr )
+
+
 -- ---------------------------------------------------------------------------
 -- RTS Linker Interface
 -- ---------------------------------------------------------------------------
@@ -51,6 +57,14 @@ lookupSymbol str_in = do
        then return Nothing
        else return (Just addr)
 
+-- | Expects a Ptr to an info table, not to a closure
+lookupDataCon :: Ptr StgInfoTable -> IO (Maybe String)
+lookupDataCon ptr = do
+    name <- c_lookupDataCon  (ptr `plusPtr` (wORD_SIZE*2))
+    if name == nullPtr
+       then return Nothing
+       else peekCString name >>= return . Just
+
 prefixUnderscore :: String -> String
 prefixUnderscore
  | cLeadingUnderscore == "YES" = ('_':)
@@ -94,5 +108,6 @@ foreign import ccall unsafe "lookupSymbol" c_lookupSymbol :: CString -> IO (Ptr
 foreign import ccall unsafe "loadObj"      c_loadObj :: CString -> IO Int
 foreign import ccall unsafe "unloadObj"    c_unloadObj :: CString -> IO Int
 foreign import ccall unsafe "resolveObjs"  c_resolveObjs :: IO Int
+foreign import ccall unsafe "lookupDataCon"  c_lookupDataCon :: Ptr a -> IO CString
 
 \end{code}