private Signal ScanSignal()
        {
            string name = ScanTextIdentifier();
            Signal s;

            if (!system.TryLookupNamedSignal(name, out s))
            {
                s = system.CreateNamedSignal(name);
            }
            return(s);
        }
        private void ScanDefineArchitecture()
        {
            tokenizer.Match(TokenTypes.TextIdentifier, "architecture");
            MathIdentifier architectureId = ScanEntityMathIdentifierOrLabel(true);
            MathIdentifier entityId       = ScanEntityMathIdentifierOrLabel(true);
            IEntity        entity         = library.LookupEntity(entityId);

            tokenizer.Match("{");
            IMathSystem originalSystem = system;
            IMathSystem tempSystem     = Binder.CreateSystem();

            system = tempSystem;
            while (tokenizer.LookaheadFistToken.Text != "}")
            {
                NextStatement();
            }
            foreach (string input in entity.InputSignals)
            {
                tempSystem.PromoteAsInput(tempSystem.LookupNamedSignal(input));
            }
            foreach (string output in entity.OutputSignals)
            {
                tempSystem.AddSignalTree(tempSystem.LookupNamedSignal(output), tempSystem.GetAllInputs(), true, false);
            }
            ReadOnlySignalSet leafs = tempSystem.GetAllLeafSignals();

            foreach (Signal s in leafs)
            {
                Signal so;
                if (originalSystem.TryLookupNamedSignal(s.Label, out so) && so.Value != null)
                {
                    s.PostNewValue(so.Value);
                }
            }
            Service <ISimulationMediator> .Instance.SimulateInstant();

            system = originalSystem;
            tokenizer.Match("}");
            tempSystem.RemoveUnusedObjects();
            tempSystem.PublishToLibrary(architectureId, entity.EntityId);
        }