private object Dispatch(object expr, Environment env)
{
if (_capEx != null)
{
CaptureException capEx = _capEx;
_capEx = null;
if (capEx.Continuation == null)
{
capEx.AddContext(new HaltContext());
}
Continuation k = new Continuation(capEx.Continuation);
return(ResumeWithProcedure(capEx.Continuation,
capEx.Procedure, k));
}
else if (_invEx != null)
{
InvokeException invEx = _invEx;
_invEx = null;
return(ResumeWithValue(invEx.Continuation, invEx.ReturnValue));
}
else
{
return(Execute(expr, Pair.EmptyList, env));
}
}
public Interpreter(TextReader reader)
{
StandardLibrary sl = StandardLibrary.Instance();
_globalEnv = new Environment(sl.Symbols, sl.Values);
_compiler = new Compiler(new MacroExpander(new Parser(
new Scanner(reader)), this));
_capEx = null;
_invEx = null;
}
private object Evaluate(object expr, Environment env)
{
for (;;)
{
try {
return(Dispatch(expr, env));
} catch (CaptureException captureEx) {
_capEx = captureEx;
} catch (InvokeException invEx) {
_invEx = invEx;
}
}
}