signal_flow_graph.py

                        new_signal = self._original_components_to_new[
                            original_signal
                        ]
                        new_signal.set_destination(
                            new_op.input(original_input_port.index)
                        )

                        self._components_dfs_order.extend(
                            [new_signal, new_signal.source.operation]
                        )
                        self._operations_dfs_order.append(
                            new_signal.source.operation
                        )

                    # Check if the signal has not been added before.
                    elif (
                        original_signal not in self._original_components_to_new
                    ):
                        if original_signal.source is None:
                            raise ValueError(
                                "Dangling signal without source in SFG"
                            )

                        new_signal = self._add_component_unconnected_copy(
                            original_signal
                        )
                        new_signal.set_destination(
                            new_op.input(original_input_port.index)
                        )

                        self._components_dfs_order.append(new_signal)

                        original_connected_op = (
                            original_signal.source.operation
                        )
                        # Check if connected Operation has been added before.
                        if (
                            original_connected_op
                            in self._original_components_to_new
                        ):
                            # Set source to the already added operations port.
                            new_signal.set_source(
                                self._original_components_to_new[
                                    original_connected_op
                                ].output(original_signal.source.index)
                            )
                        else:
                            # Create new operation, set signal source to it.
                            new_connected_op = (
                                self._add_component_unconnected_copy(
                                    original_connected_op
                                )
                            )
                            new_signal.set_source(
                                new_connected_op.output(
                                    original_signal.source.index
                                )
                            )

                            self._components_dfs_order.append(new_connected_op)
                            self._operations_dfs_order.append(new_connected_op)

                            # Add connected operation to queue of operations to visit.
                            op_stack.append(original_connected_op)

            # Connect output ports.
            for original_output_port in original_op.outputs:
                for original_signal in original_output_port.signals:
                    # Check if the signal is one of the SFG's output signals.
                    if (
                        original_signal
                        in self._original_output_signals_to_indices
                    ):
                        # New signal already created during first step of constructor.
                        new_signal = self._original_components_to_new[
                            original_signal
                        ]
                        new_signal.set_source(
                            new_op.output(original_output_port.index)
                        )

                        self._components_dfs_order.extend(
                            [new_signal, new_signal.destination.operation]
                        )
                        self._operations_dfs_order.append(
                            new_signal.destination.operation
                        )

                    # Check if signal has not been added before.
                    elif (
                        original_signal not in self._original_components_to_new
                    ):
                        if original_signal.source is None:
                            raise ValueError(
                                "Dangling signal without source in SFG"
                            )

                        new_signal = self._add_component_unconnected_copy(
                            original_signal
                        )
                        new_signal.set_source(
                            new_op.output(original_output_port.index)
                        )

                        self._components_dfs_order.append(new_signal)

                        original_connected_op = (
                            original_signal.destination.operation
                        )
                        # Check if connected operation has been added.
                        if (
                            original_connected_op
                            in self._original_components_to_new
                        ):
                            # Set destination to the already connected operations port.
                            new_signal.set_destination(
                                self._original_components_to_new[
                                    original_connected_op
                                ].input(original_signal.destination.index)
                            )
                        else:
                            # Create new operation, set destination to it.
                            new_connected_op = (
                                self._add_component_unconnected_copy(
                                    original_connected_op
                                )
                            )
                            new_signal.set_destination(
                                new_connected_op.input(
                                    original_signal.destination.index
                                )
                            )

                            self._components_dfs_order.append(new_connected_op)
                            self._operations_dfs_order.append(new_connected_op)

                            # Add connected operation to the queue of operations to visit.
                            op_stack.append(original_connected_op)

    def _evaluate_source(
        self,
        src: OutputPort,
        results: MutableResultMap,
        delays: MutableDelayMap,
        prefix: str,
        bits_override: Optional[int],
        truncate: bool,
        deferred_delays: DelayQueue,
    ) -> Number:
        key_base = (
            (prefix + "." + src.operation.graph_id)
            if prefix
            else src.operation.graph_id
        )
        key = src.operation.key(src.index, key_base)
        if key in results:
            value = results[key]
            if value is None:
                raise RuntimeError(
                    "Direct feedback loop detected when evaluating operation."
                )
            return value

        value = src.operation.current_output(src.index, delays, key_base)
        results[key] = value
        if value is None:
            value = self._do_evaluate_source(
                key_base,
                key,
                src,
                results,
                delays,
                prefix,
                bits_override,
                truncate,
                deferred_delays,
            )
        else:
            # Evaluate later. Use current value for now.
            deferred_delays.append((key_base, key, src))
        return value

    def _do_evaluate_source(
        self,
        key_base: str,
        key: ResultKey,
        src: OutputPort,
        results: MutableResultMap,
        delays: MutableDelayMap,
        prefix: str,
        bits_override: Optional[int],
        truncate: bool,
        deferred_delays: DelayQueue,
    ) -> Number:
        input_values = [
            self._evaluate_source(
                input_port.signals[0].source,
                results,
                delays,
                prefix,
                bits_override,
                truncate,
                deferred_delays,
            )
            for input_port in src.operation.inputs
        ]
        value = src.operation.evaluate_output(
            src.index,
            input_values,
            results,
            delays,
            key_base,
            bits_override,
            truncate,
        )
        results[key] = value
        return value

    def sfg(self, show_id=False, engine=None) -> Digraph:
        """
        Returns a Digraph of the SFG. Can be directly displayed in IPython.

        Parameters
        ----------
        show_id : Boolean, optional
            If True, the graph_id:s of signals are shown. The default is False.

        engine : string, optional
            Graphviz layout engine to be used, see https://graphviz.org/documentation/.
            Most common are "dot" and "neato". Default is None leading to dot.

        Returns
        -------
        Digraph
            Digraph of the SFG.

        """
        dg = Digraph()
        dg.attr(rankdir="LR")
        if engine is not None:
            dg.engine = engine
        for op in self._components_by_id.values():
            if isinstance(op, Signal):
                if show_id:
                    dg.edge(
                        op.source.operation.graph_id,
                        op.destination.operation.graph_id,
                        label=op.graph_id,
                    )
                else:
                    dg.edge(
                        op.source.operation.graph_id,
                        op.destination.operation.graph_id,
                    )
            else:
                if op.type_name() == Delay.type_name():
                    dg.node(op.graph_id, shape="square")
                else:
                    dg.node(op.graph_id)
        return dg

    def _repr_svg_(self):
        return self.sfg()._repr_svg_()

    def show_sfg(self, format=None, show_id=False, engine=None) -> None:
        """
        Shows a visual representation of the SFG using the default system viewer.

        Parameters
        ----------
        format : string, optional
            File format of the generated graph. Output formats can be found at
            https://www.graphviz.org/doc/info/output.html
            Most common are "pdf", "eps", "png", and "svg". Default is None which leads to PDF.

        show_id : Boolean, optional
            If True, the graph_id:s of signals are shown. The default is False.

        engine : string, optional
            Graphviz layout engine to be used, see https://graphviz.org/documentation/.
            Most common are "dot" and "neato". Default is None leading to dot.
        """

        dg = self.sfg(show_id=show_id)
        if engine is not None:
            dg.engine = engine
        if format is not None:
            dg.format = format
        dg.view()