public Nullable <DateTime> Step()
{
IsStarted = true;
if (Stacks.Count == 0)
{
IsCompleted = true;
return(null);
}
ExecStackItem current = Stacks.Peek();
if (!current.HasMoreExecution)
{
return(EndCall(current));
}
object execution;
ExecutionCallback callback;
current.HasMoreExecution = (current.Execution.PopStack(out execution, out callback, current.Environment));
//Console.WriteLine("current is " + execution);
if (execution is Execution2)
{
Execution2 exec = execution as Execution2;
ExecutionEnvironment e = exec.StartCall(current.Environment);
Stacks.Push(new ExecStackItem(exec, callback, e, current.Environment));
}
else
{
return(EndCall(current));
}
return(null);
}
void HandleException(Exception e)
{
Console.WriteLine("Exception occur");
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
ExecutionCallback callback = null;
while (Stacks.Count > 0)
{
ExecStackItem item = Stacks.Peek();
bool handle = false;
try
{
handle = item.Execution.HandleException(e);
callback(null, e, item.Previous);
}
catch (Exception excption) { }
if (handle)
{
return;
}
else
{
Stacks.Pop();
callback = item.Callback;
}
}
Console.WriteLine("Exception occur and no try block, so exit");
//TO DO terminate execution
}
Nullable <DateTime> EndCall(ExecStackItem current)
{
Exception ex = null;
Completion retVal = null;
try
{
retVal = current.Execution.EndCall(current.Environment);
}
catch (Exception e)
{
ex = e;
}
if (ex != null)
{
HandleException(ex);
return(null);
}
Stacks.Pop();
if (current.Execution is ReturnStatement)
{
ExecStackItem func = Stacks.Peek();
while (!(func.Execution is Function))
{
Stacks.Pop();
func = Stacks.Peek();
}
ExecCallBack(func.Callback, retVal.ReturnValue, null, func.Previous);
return(null);
}
else if (current.Execution is BreakStatement)
{
ExecStackItem func = Stacks.Peek();
while (!(func.Execution is Loop))
{
Stacks.Pop();
func = Stacks.Peek();
if (Stacks.Count == 1)
{
break;
}
}
func = Stacks.Pop();
if (!(func.Execution is Loop))
{
HandleException(new Exception("Break must be in a loop"));
return(null);
}
ExecCallBack(func.Callback, retVal.ReturnValue, null, func.Previous);
return(null);
}
else if (current.Execution is ContinueStatement)
{
ExecStackItem func = Stacks.Peek();
ExecStackItem last = null;
ExecutionCallback callBack = null;
while (!(func.Execution is Loop))
{
callBack = func.Callback;
last = func;
Stacks.Pop();
func = Stacks.Peek();
if (Stacks.Count == 1)
{
break;
}
}
if (!(func.Execution is Loop))
{
HandleException(new Exception("continue must be in a loop"));
return(null);
}
return(ExecCallBack(last.Callback, retVal.ReturnValue, null, last.Environment));
}
return(ExecCallBack(current.Callback, retVal.ReturnValue, null, current.Previous));
}