{--
JVM-Bridge -- bridge from FP languages and others to the Java VM
Copyright (C) 2001 Ashley Yakeley <ashley@semantic.org>

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
--}

module Foreign.JavaVM.VM.Throwable(checkCall,vmThrow,vmCatch) where
{
	import Foreign.JavaVM.VM.Ref;
	import Foreign.JavaVM.VM.Types;
	import Foreign.JavaVM.Raw;
	import Platform.JavaVM;

	exceptionPending :: VM Jboolean;
	exceptionPending = do
	{
		xp <- rawExceptionPending ?jvmenv;
		return (fromRawBoolean xp); 
	};
	
	checkCall :: VM a -> VM a;
	checkCall foo = do
	{
		result <- foo;
		ex <- exceptionPending;
		if ex 
		then ioError (userError "pending VM exception")
		else return result;
	};

	vmThrow :: VMRef -> VM a;
	vmThrow th = do
	{
		checkCall (withVMRefRawGlobal th (\rawTh -> rawThrowException ?jvmenv rawTh));
		fail "couldn't throw Java VM exception";
	};

	getClearException :: VM VMRef;
	getClearException = do
	{
		x <- rawGetClearException ?jvmenv;
		makeVMRefFromLocal x; 
	};

	vmCatch :: VM a -> (VMRef -> VM a) -> VM a;
	vmCatch foo catchClause = catch foo (\x -> do
	{
		pending <- exceptionPending;
		if pending
		then do
		{
			exRef <- getClearException;
			catchClause exRef;
		}
		else ioError x;
	});
}