X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Debug%2FTrace.hs;h=ebacb6c3d7fa28d37e385a2d240c97b2bd4d8d78;hb=HEAD;hp=00af949724e5343f691156bf0362c64cfa7e978a;hpb=74f9531c9030985a0adcec184f562218dd8aab7c;p=ghc-base.git

diff --git a/Debug/Trace.hs b/Debug/Trace.hs
index 00af949..ebacb6c 100644
--- a/Debug/Trace.hs
+++ b/Debug/Trace.hs
@@ -1,3 +1,5 @@
+{-# LANGUAGE CPP, ForeignFunctionInterface #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Debug.Trace
@@ -12,89 +14,59 @@
 --
 -----------------------------------------------------------------------------
 
-#ifndef __HUGS__
-#include "config.h"
-#endif
-
 module Debug.Trace (
-	-- * Tracing
-	
-	-- ** Tracers
-	-- | The tracer is a function that monitors the trace messages.
-	fileTracer,       -- :: Handle -> String -> IO ()
-#ifdef mingw32_TARGET_OS
-	winDebugTracer,   -- :: String -> IO ()
-#endif
-	addTracer,        -- :: String -> (String -> IO ()) -> IO ()
-	removeTracer,     -- :: String -> IO ()
-	
-	-- ** Messages
-	putTraceMsg,      -- :: String -> IO ()
-	trace             -- :: String -> a -> a
+        -- * Tracing
+        putTraceMsg,      -- :: String -> IO ()
+        trace,            -- :: String -> a -> a
+        traceShow
   ) where
 
 import Prelude
-import Data.IORef
 import System.IO.Unsafe
-import System.IO
 
-#ifdef mingw32_TARGET_OS
+#ifdef __GLASGOW_HASKELL__
 import Foreign.C.String
+#else
+import System.IO (hPutStrLn,stderr)
 #endif
 
-{-# NOINLINE tracers #-}
-tracers :: IORef [(String, String -> IO ())]
-tracers = unsafePerformIO (newIORef [("defaultTracer", fileTracer stderr)])
-
--- | A tracer function that outputs the message to a file
-fileTracer :: Handle     -- ^ file handle
-           -> String     -- ^ trace message
-           -> IO ()
-fileTracer handle msg = do
-   hPutStr handle msg
-   hPutChar handle '\n'
-
-#ifdef mingw32_TARGET_OS
--- | A tracer function that outputs the message to the debuger (Windows only)
-winDebugTracer :: String  -- ^ trace message
-               -> IO ()
-winDebugTracer msg = do
-   withCString (msg++"\n") outputDebugString
-
-foreign import ccall unsafe "OutputDebugStringA"
-  outputDebugString :: CString -> IO ()
-#endif
-
--- | Registering a new tracer
-addTracer :: String             -- ^ the tracer name
-          -> (String -> IO ())  -- ^ tracer
-          -> IO ()
-addTracer name tracer = do
-	ts <- readIORef tracers
-	writeIORef tracers ((name,tracer):filter (\(n,l) -> n /= name) ts)
-
--- | Removing the tracer with the given name
-removeTracer :: String -> IO ()
-removeTracer name = do
-	ts <- readIORef tracers
-	writeIORef tracers (filter (\(n,l) -> n /= name) ts)
-
 -- | 'putTraceMsg' function outputs the trace message from IO monad.
+-- Usually the output stream is 'System.IO.stderr' but if the function is called
+-- from Windows GUI application then the output will be directed to the Windows
+-- debug console.
 putTraceMsg :: String -> IO ()
 putTraceMsg msg = do
-	ts <- readIORef tracers
-	mapM_ (\(n,l) -> l msg) ts
+#ifndef __GLASGOW_HASKELL__
+    hPutStrLn stderr msg
+#else
+    withCString "%s\n" $ \cfmt ->
+     withCString msg  $ \cmsg ->
+      debugBelch cfmt cmsg
+
+-- don't use debugBelch() directly, because we cannot call varargs functions
+-- using the FFI.
+foreign import ccall unsafe "HsBase.h debugBelch2"
+   debugBelch :: CString -> CString -> IO ()
+#endif
 
 {-# NOINLINE trace #-}
 {-|
-When called, 'trace' outputs the string in its first argument using the
-installed tracers, before returning the second argument as its result.
-The 'trace' function is not referentially transparent, and should only
-be used for debugging, or for monitoring execution. Some
-implementations of 'trace' may decorate the string that\'s output to
-indicate that you\'re tracing.
+When called, 'trace' outputs the string in its first argument, before 
+returning the second argument as its result. The 'trace' function is not 
+referentially transparent, and should only be used for debugging, or for 
+monitoring execution. Some implementations of 'trace' may decorate the string 
+that\'s output to indicate that you\'re tracing. The function is implemented on
+top of 'putTraceMsg'.
 -}
 trace :: String -> a -> a
 trace string expr = unsafePerformIO $ do
     putTraceMsg string
     return expr
+
+{-|
+Like 'trace', but uses 'show' on the argument to convert it to a 'String'.
+
+> traceShow = trace . show
+-}
+traceShow :: (Show a) => a -> b -> b
+traceShow = trace . show