b_asic/GUI/port_button.py

+
+import sys
+
+from PyQt5.QtWidgets import QPushButton, QMenu
+from PyQt5.QtCore import Qt, pyqtSignal
+
+class PortButton(QPushButton):
+    connectionRequested = pyqtSignal(QPushButton)
+    moved = pyqtSignal()
+    def __init__(self, name, operation, window, parent=None):
+        self.pressed = False
+        self.window = window
+        self.operation = operation
+        self.clicked = 0
+        super(PortButton, self).__init__(name, operation)
+
+    def contextMenuEvent(self, event):
+        menu = QMenu()
+        menu.addAction("Connect", lambda: self.connectionRequested.emit(self))
+        menu.exec_(self.cursor().pos())
+
+    def mousePressEvent(self, event):
+        
+        if event.button() == Qt.LeftButton:
+            self.clicked += 1
+            if self.clicked == 1:
+                self.setStyleSheet("background-color: grey")
+                self.pressed = True
+                self.window.pressed_ports.append(self)
+            elif self.clicked == 2:
+                self.setStyleSheet("background-color: white")
+                self.pressed = False                
+                self.clicked = 0
+                self.window.pressed_ports.remove(self)
+        super(PortButton, self).mousePressEvent(event)
+            
+    def mouseReleaseEvent(self, event):
+        super(PortButton, self).mouseReleaseEvent(event)
+

b_asic/GUI/utils.py

+from PyQt5.QtWidgets import QErrorMessage
+from traceback import format_exc
+
+def handle_error(fn):
+    def wrapper(self, *args, **kwargs):
+        try:
+            return fn(self, *args, **kwargs)
+        except Exception as e:
+            QErrorMessage(self._window).showMessage(f"Unexpected error: {format_exc()}")
+
+    return wrapper
+
+def decorate_class(decorator):
+    def decorate(cls):
+        for attr in cls.__dict__:
+            if callable(getattr(cls, attr)):
+                setattr(cls, attr, decorator(getattr(cls, attr)))
+        return cls
+    return decorate
\ No newline at end of file

b_asic/__init__.py

@@ -4,11 +4,9 @@ TODO: More info.
 """
 from b_asic.core_operations import *
 from b_asic.graph_component import *
-from b_asic.graph_id import *
 from b_asic.operation import *
-from b_asic.precedence_chart import *
 from b_asic.port import *
-from b_asic.schema import *
 from b_asic.signal_flow_graph import *
 from b_asic.signal import *
 from b_asic.simulation import *
+from b_asic.special_operations import *

b_asic/core_operations.py

@@ -4,43 +4,39 @@ TODO: More info.
 """
 
 from numbers import Number
-from typing import Any
+from typing import Optional
 from numpy import conjugate, sqrt, abs as np_abs
-from b_asic.port import InputPort, OutputPort
-from b_asic.graph_id import GraphIDType
+
+from b_asic.port import SignalSourceProvider, InputPort, OutputPort
 from b_asic.operation import AbstractOperation
 from b_asic.graph_component import Name, TypeName
 
 
-class Input(AbstractOperation):
-    """Input operation.
-    TODO: More info.
-    """
-
-    # TODO: Implement all functions.
-
-    @property
-    def type_name(self) -> TypeName:
-        return "in"
-
-
 class Constant(AbstractOperation):
     """Constant value operation.
     TODO: More info.
     """
 
     def __init__(self, value: Number = 0, name: Name = ""):
-        super().__init__(name)
+        super().__init__(input_count=0, output_count=1, name=name)
+        self.set_param("value", value)
 
-        self._output_ports = [OutputPort(0, self)]
-        self._parameters["value"] = value
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "c"
 
     def evaluate(self):
         return self.param("value")
 
     @property
-    def type_name(self) -> TypeName:
-        return "c"
+    def value(self) -> Number:
+        """Get the constant value of this operation."""
+        return self.param("value")
+
+    @value.setter
+    def value(self, value: Number) -> None:
+        """Set the constant value of this operation."""
+        return self.set_param("value", value)
 
 
 class Addition(AbstractOperation):
@@ -48,134 +44,86 @@ class Addition(AbstractOperation):
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "add"
 
     def evaluate(self, a, b):
         return a + b
 
-    @property
-    def type_name(self) -> TypeName:
-        return "add"
-
 
 class Subtraction(AbstractOperation):
     """Binary subtraction operation.
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "sub"
 
     def evaluate(self, a, b):
         return a - b
 
-    @property
-    def type_name(self) -> TypeName:
-        return "sub"
-
 
 class Multiplication(AbstractOperation):
     """Binary multiplication operation.
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "mul"
 
     def evaluate(self, a, b):
         return a * b
 
-    @property
-    def type_name(self) -> TypeName:
-        return "mul"
-
 
 class Division(AbstractOperation):
     """Binary division operation.
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "div"
 
     def evaluate(self, a, b):
         return a / b
 
-    @property
-    def type_name(self) -> TypeName:
-        return "div"
 
-
-class SquareRoot(AbstractOperation):
-    """Unary square root operation.
-    TODO: More info.
-    """
-
-    def __init__(self, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
-
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-
-    def evaluate(self, a):
-        return sqrt((complex)(a))
-
-    @property
-    def type_name(self) -> TypeName:
-        return "sqrt"
-
-
-class ComplexConjugate(AbstractOperation):
-    """Unary complex conjugate operation.
+class Min(AbstractOperation):
+    """Binary min operation.
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-
-    def evaluate(self, a):
-        return conjugate(a)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "min"
 
-    @property
-    def type_name(self) -> TypeName:
-        return "conj"
+    def evaluate(self, a, b):
+        assert not isinstance(a, complex) and not isinstance(b, complex), \
+            ("core_operations.Min does not support complex numbers.")
+        return a if a < b else b
 
 
 class Max(AbstractOperation):
@@ -183,155 +131,112 @@ class Max(AbstractOperation):
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=1,
+                         name=name, input_sources=[src0, src1])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "max"
 
     def evaluate(self, a, b):
         assert not isinstance(a, complex) and not isinstance(b, complex), \
             ("core_operations.Max does not support complex numbers.")
         return a if a > b else b
 
-    @property
-    def type_name(self) -> TypeName:
-        return "max"
-
-
-class Min(AbstractOperation):
-    """Binary min operation.
-    TODO: More info.
-    """
-
-    def __init__(self, source1: OutputPort = None, source2: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self), InputPort(1, self)]
-        self._output_ports = [OutputPort(0, self)]
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
-        if source2 is not None:
-            self._input_ports[1].connect(source2)
-
-    def evaluate(self, a, b):
-        assert not isinstance(a, complex) and not isinstance(b, complex), \
-            ("core_operations.Min does not support complex numbers.")
-        return a if a < b else b
-
-    @property
-    def type_name(self) -> TypeName:
-        return "min"
-
-
-class Absolute(AbstractOperation):
-    """Unary absolute value operation.
+class SquareRoot(AbstractOperation):
+    """Unary square root operation.
     TODO: More info.
     """
 
-    def __init__(self, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=1, output_count=1,
+                         name=name, input_sources=[src0])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "sqrt"
 
     def evaluate(self, a):
-        return np_abs(a)
+        return sqrt(complex(a))
 
-    @property
-    def type_name(self) -> TypeName:
-        return "abs"
 
-
-class ConstantMultiplication(AbstractOperation):
-    """Unary constant multiplication operation.
+class ComplexConjugate(AbstractOperation):
+    """Unary complex conjugate operation.
     TODO: More info.
     """
 
-    def __init__(self, coefficient: Number, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
-        self._parameters["coefficient"] = coefficient
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=1, output_count=1,
+                         name=name, input_sources=[src0])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "conj"
 
     def evaluate(self, a):
-        return a * self.param("coefficient")
-
-    @property
-    def type_name(self) -> TypeName:
-        return "cmul"
+        return conjugate(a)
 
 
-class ConstantAddition(AbstractOperation):
-    """Unary constant addition operation.
+class Absolute(AbstractOperation):
+    """Unary absolute value operation.
     TODO: More info.
     """
 
-    def __init__(self, coefficient: Number, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
-        self._parameters["coefficient"] = coefficient
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=1, output_count=1,
+                         name=name, input_sources=[src0])
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "abs"
 
     def evaluate(self, a):
-        return a + self.param("coefficient")
-
-    @property
-    def type_name(self) -> TypeName:
-        return "cadd"
+        return np_abs(a)
 
 
-class ConstantSubtraction(AbstractOperation):
-    """Unary constant subtraction operation.
+class ConstantMultiplication(AbstractOperation):
+    """Unary constant multiplication operation.
     TODO: More info.
     """
 
-    def __init__(self, coefficient: Number, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
-        self._parameters["coefficient"] = coefficient
+    def __init__(self, value: Number = 0, src0: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=1, output_count=1,
+                         name=name, input_sources=[src0])
+        self.set_param("value", value)
 
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "cmul"
 
     def evaluate(self, a):
-        return a - self.param("coefficient")
+        return a * self.param("value")
 
     @property
-    def type_name(self) -> TypeName:
-        return "csub"
+    def value(self) -> Number:
+        """Get the constant value of this operation."""
+        return self.param("value")
+
+    @value.setter
+    def value(self, value: Number) -> None:
+        """Set the constant value of this operation."""
+        return self.set_param("value", value)
 
 
-class ConstantDivision(AbstractOperation):
-    """Unary constant division operation.
+class Butterfly(AbstractOperation):
+    """Butterfly operation that returns two outputs.
+    The first output is a + b and the second output is a - b.
     TODO: More info.
     """
 
-    def __init__(self, coefficient: Number, source1: OutputPort = None, name: Name = ""):
-        super().__init__(name)
-        self._input_ports = [InputPort(0, self)]
-        self._output_ports = [OutputPort(0, self)]
-        self._parameters["coefficient"] = coefficient
-
-        if source1 is not None:
-            self._input_ports[0].connect(source1)
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, src1: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=2, output_count=2,
+                         name=name, input_sources=[src0, src1])
 
-    def evaluate(self, a):
-        return a / self.param("coefficient")
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "bfly"
 
-    @property
-    def type_name(self) -> TypeName:
-        return "cdiv"
+    def evaluate(self, a, b):
+        return a + b, a - b

b_asic/graph_component.py

@@ -4,10 +4,15 @@ TODO: More info.
 """
 
 from abc import ABC, abstractmethod
-from typing import NewType
+from collections import deque
+from copy import copy, deepcopy
+from typing import NewType, Any, Dict, Mapping, Iterable, Generator
+
 
 Name = NewType("Name", str)
 TypeName = NewType("TypeName", str)
+GraphID = NewType("GraphID", str)
+GraphIDNumber = NewType("GraphIDNumber", int)
 
 
 class GraphComponent(ABC):
@@ -15,35 +20,90 @@ class GraphComponent(ABC):
     TODO: More info.
     """
 
-    @property
+    @classmethod
     @abstractmethod
-    def type_name(self) -> TypeName:
-        """Return the type name of the graph component"""
+    def type_name(cls) -> TypeName:
+        """Get the type name of this graph component"""
         raise NotImplementedError
 
     @property
     @abstractmethod
     def name(self) -> Name:
-        """Return the name of the graph component."""
+        """Get the name of this graph component."""
         raise NotImplementedError
 
     @name.setter
     @abstractmethod
     def name(self, name: Name) -> None:
-        """Set the name of the graph component to the entered name."""
+        """Set the name of this graph component to the given name."""
+        raise NotImplementedError
+
+    @property
+    @abstractmethod
+    def graph_id(self) -> GraphID:
+        """Get the graph id of this graph component."""
+        raise NotImplementedError
+
+    @graph_id.setter
+    @abstractmethod
+    def graph_id(self, graph_id: GraphID) -> None:
+        """Set the graph id of this graph component to the given id.
+        Note that this id will be ignored if this component is used to create a new graph,
+        and that a new local id will be generated for it instead."""
+        raise NotImplementedError
+
+    @property
+    @abstractmethod
+    def params(self) -> Mapping[str, Any]:
+        """Get a dictionary of all parameter values."""
+        raise NotImplementedError
+
+    @abstractmethod
+    def param(self, name: str) -> Any:
+        """Get the value of a parameter.
+        Returns None if the parameter is not defined.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def set_param(self, name: str, value: Any) -> None:
+        """Set the value of a parameter.
+        Adds the parameter if it is not already defined.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def copy_component(self, *args, **kwargs) -> "GraphComponent":
+        """Get a new instance of this graph component type with the same name, id and parameters."""
+        raise NotImplementedError
+
+    @property
+    @abstractmethod
+    def neighbors(self) -> Iterable["GraphComponent"]:
+        """Get all components that are directly connected to this operation."""
+        raise NotImplementedError
+
+    @abstractmethod
+    def traverse(self) -> Generator["GraphComponent", None, None]:
+        """Get a generator that recursively iterates through all components that are connected to this operation,
+        as well as the ones that they are connected to.
+        """
         raise NotImplementedError
 
 
 class AbstractGraphComponent(GraphComponent):
     """Abstract Graph Component class which is a component of a signal flow graph.
-
     TODO: More info.
     """
 
     _name: Name
+    _graph_id: GraphID
+    _parameters: Dict[str, Any]
 
     def __init__(self, name: Name = ""):
         self._name = name
+        self._graph_id = ""
+        self._parameters = {}
 
     @property
     def name(self) -> Name:
@@ -52,3 +112,41 @@ class AbstractGraphComponent(GraphComponent):
     @name.setter
     def name(self, name: Name) -> None:
         self._name = name
+
+    @property
+    def graph_id(self) -> GraphID:
+        return self._graph_id
+
+    @graph_id.setter
+    def graph_id(self, graph_id: GraphID) -> None:
+        self._graph_id = graph_id
+
+    @property
+    def params(self) -> Mapping[str, Any]:
+        return self._parameters.copy()
+
+    def param(self, name: str) -> Any:
+        return self._parameters.get(name)
+
+    def set_param(self, name: str, value: Any) -> None:
+        self._parameters[name] = value
+
+    def copy_component(self, *args, **kwargs) -> GraphComponent:
+        new_component = self.__class__(*args, **kwargs)
+        new_component.name = copy(self.name)
+        new_component.graph_id = copy(self.graph_id)
+        for name, value in self.params.items():
+            new_component.set_param(copy(name), deepcopy(value))  # pylint: disable=no-member
+        return new_component
+
+    def traverse(self) -> Generator[GraphComponent, None, None]:
+        # Breadth first search.
+        visited = {self}
+        fontier = deque([self])
+        while fontier:
+            component = fontier.popleft()
+            yield component
+            for neighbor in component.neighbors:
+                if neighbor not in visited:
+                    visited.add(neighbor)
+                    fontier.append(neighbor)

b_asic/graph_id.py

-"""@package docstring
-B-ASIC Graph ID module for handling IDs of different objects in a graph.
-TODO: More info
-"""
-
-from collections import defaultdict
-from typing import NewType, DefaultDict
-
-GraphID = NewType("GraphID", str)
-GraphIDType = NewType("GraphIDType", str)
-GraphIDNumber = NewType("GraphIDNumber", int)
-
-
-class GraphIDGenerator:
-    """A class that generates Graph IDs for objects."""
-
-    _next_id_number: DefaultDict[GraphIDType, GraphIDNumber]
-
-    def __init__(self):
-        self._next_id_number = defaultdict(lambda: 1)       # Initalises every key element to 1
-
-    def get_next_id(self, graph_id_type: GraphIDType) -> GraphID:
-        """Return the next graph id for a certain graph id type."""
-        graph_id = graph_id_type + str(self._next_id_number[graph_id_type])
-        self._next_id_number[graph_id_type] += 1            # Increase the current id number
-        return graph_id

b_asic/port.py

@@ -4,12 +4,15 @@ TODO: More info.
 """
 
 from abc import ABC, abstractmethod
-from typing import NewType, Optional, List
+from copy import copy
+from typing import Optional, List, Iterable, TYPE_CHECKING
 
-from b_asic.operation import Operation
 from b_asic.signal import Signal
+from b_asic.graph_component import Name
+
+if TYPE_CHECKING:
+    from b_asic.operation import Operation
 
-PortIndex = NewType("PortIndex", int)
 
 class Port(ABC):
     """Port Interface.
@@ -19,59 +22,33 @@ class Port(ABC):
 
     @property
     @abstractmethod
-    def operation(self) -> Operation:
+    def operation(self) -> "Operation":
         """Return the connected operation."""
         raise NotImplementedError
 
     @property
     @abstractmethod
-    def index(self) -> PortIndex:
-        """Return the unique PortIndex."""
+    def index(self) -> int:
+        """Return the index of the port."""
         raise NotImplementedError
 
     @property
-    @abstractmethod
-    def signals(self) -> List[Signal]:
-        """Return a list of all connected signals."""
-        raise NotImplementedError
-
-    @abstractmethod
-    def signal(self, i: int = 0) -> Signal:
-        """Return the connected signal at index i.
-
-        Keyword argumens:
-        i: integer index of the signal requsted.
-        """
-        raise NotImplementedError
-
-    @property
-    @abstractmethod
-    def connected_ports(self) -> List["Port"]:
-        """Return a list of all connected Ports."""
-        raise NotImplementedError
-
     @abstractmethod
     def signal_count(self) -> int:
         """Return the number of connected signals."""
         raise NotImplementedError
 
+    @property
     @abstractmethod
-    def connect(self, port: "Port") -> Signal:
-        """Create and return a signal that is connected to this port and the entered
-        port and connect this port to the signal and the entered port to the signal."""
+    def signals(self) -> Iterable[Signal]:
+        """Return all connected signals."""
         raise NotImplementedError
 
     @abstractmethod
     def add_signal(self, signal: Signal) -> None:
         """Connect this port to the entered signal. If the entered signal isn't connected to
-        this port then connect the entered signal to the port aswell."""
-        raise NotImplementedError
-
-    @abstractmethod
-    def disconnect(self, port: "Port") -> None:
-        """Disconnect the entered port from the port by removing it from the ports signal.
-        If the entered port is still connected to this ports signal then disconnect the entered
-        port from the signal aswell."""
+        this port then connect the entered signal to the port aswell.
+        """
         raise NotImplementedError
 
     @abstractmethod
@@ -97,22 +74,34 @@ class AbstractPort(Port):
     Handles functionality for port id and saves the connection to the parent operation.
     """
 
+    _operation: "Operation"
     _index: int
-    _operation: Operation
 
-    def __init__(self, index: int, operation: Operation):
-        self._index = index
+    def __init__(self, operation: "Operation", index: int):
         self._operation = operation
+        self._index = index
 
     @property
-    def operation(self) -> Operation:
+    def operation(self) -> "Operation":
         return self._operation
 
     @property
-    def index(self) -> PortIndex:
+    def index(self) -> int:
         return self._index
 
 
+class SignalSourceProvider(ABC):
+    """Signal source provider interface.
+    TODO: More info.
+    """
+
+    @property
+    @abstractmethod
+    def source(self) -> "OutputPort":
+        """Get the main source port provided by this object."""
+        raise NotImplementedError
+
+
 class InputPort(AbstractPort):
     """Input port.
     TODO: More info.
@@ -120,104 +109,82 @@ class InputPort(AbstractPort):
 
     _source_signal: Optional[Signal]
 
-    def __init__(self, port_id: PortIndex, operation: Operation):
-        super().__init__(port_id, operation)
+    def __init__(self, operation: "Operation", index: int):
+        super().__init__(operation, index)
         self._source_signal = None
 
     @property
-    def signals(self) -> List[Signal]:
-        return [] if self._source_signal is None else [self._source_signal]
-
-    def signal(self, i: int = 0) -> Signal:
-        assert 0 <= i < self.signal_count(), "Signal index out of bound."
-        assert self._source_signal is not None, "No Signal connect to InputPort."
-        return self._source_signal
-
-    @property
-    def connected_ports(self) -> List[Port]:
-        return [] if self._source_signal is None or self._source_signal.source is None \
-            else [self._source_signal.source]
-
     def signal_count(self) -> int:
         return 0 if self._source_signal is None else 1
 
-    def connect(self, port: "OutputPort") -> Signal:
-        assert self._source_signal is None, "Connecting new port to already connected input port."
-        return Signal(port, self)        # self._source_signal is set by the signal constructor
+    @property
+    def signals(self) -> Iterable[Signal]:
+        return [] if self._source_signal is None else [self._source_signal]
 
     def add_signal(self, signal: Signal) -> None:
-        assert self._source_signal is None, "Connecting new port to already connected input port."
-        self._source_signal: Signal = signal
-        if self is not signal.destination:
-            # Connect this inputport as destination for this signal if it isn't already.
-            signal.set_destination(self)
-
-    def disconnect(self, port: "OutputPort") -> None:
-        assert self._source_signal.source is port, "The entered port is not connected to this port."
-        self._source_signal.remove_source()
+        assert self._source_signal is None, "Input port may have only one signal added."
+        assert signal is not self._source_signal, "Attempted to add already connected signal."
+        self._source_signal = signal
+        signal.set_destination(self)
 
     def remove_signal(self, signal: Signal) -> None:
-        old_signal: Signal = self._source_signal
+        assert signal is self._source_signal, "Attempted to remove already removed signal."
         self._source_signal = None
-        if self is old_signal.destination:
-            # Disconnect the dest of the signal if this inputport currently is the dest
-            old_signal.remove_destination()
+        signal.remove_destination()
 
     def clear(self) -> None:
-        self.remove_signal(self._source_signal)
+        if self._source_signal is not None:
+            self.remove_signal(self._source_signal)
 
-class OutputPort(AbstractPort):
+    @property
+    def connected_source(self) -> Optional["OutputPort"]:
+        """Get the output port that is currently connected to this input port,
+        or None if it is unconnected.
+        """
+        return None if self._source_signal is None else self._source_signal.source
+
+    def connect(self, src: SignalSourceProvider, name: Name = "") -> Signal:
+        """Connect the provided signal source to this input port by creating a new signal.
+        Returns the new signal.
+        """
+        assert self._source_signal is None, "Attempted to connect already connected input port."
+        # self._source_signal is set by the signal constructor.
+        return Signal(source=src.source, destination=self, name=name)
+
+
+class OutputPort(AbstractPort, SignalSourceProvider):
     """Output port.
     TODO: More info.
     """
 
     _destination_signals: List[Signal]
 
-    def __init__(self, port_id: PortIndex, operation: Operation):
-        super().__init__(port_id, operation)
+    def __init__(self, operation: "Operation", index: int):
+        super().__init__(operation, index)
         self._destination_signals = []
 
     @property
-    def signals(self) -> List[Signal]:
-        return self._destination_signals.copy()
-
-    def signal(self, i: int = 0) -> Signal:
-        assert 0 <= i < self.signal_count(), "Signal index out of bounds."
-        return self._destination_signals[i]
-
-    @property
-    def connected_ports(self) -> List[Port]:
-        return [signal.destination for signal in self._destination_signals \
-            if signal.destination is not None]
-
     def signal_count(self) -> int:
         return len(self._destination_signals)
 
-    def connect(self, port: InputPort) -> Signal:
-        return Signal(self, port)      # Signal is added to self._destination_signals in signal constructor
+    @property
+    def signals(self) -> Iterable[Signal]:
+        return self._destination_signals
 
     def add_signal(self, signal: Signal) -> None:
-        assert signal not in self.signals, \
-                "Attempting to connect to Signal already connected."
+        assert signal not in self._destination_signals, "Attempted to add already connected signal."
         self._destination_signals.append(signal)
-        if self is not signal.source:
-            # Connect this outputport to the signal if it isn't already
-            signal.set_source(self)
-
-    def disconnect(self, port: InputPort) -> None:
-        assert port in self.connected_ports, "Attempting to disconnect port that isn't connected."
-        for sig in self._destination_signals:
-            if sig.destination is port:
-                sig.remove_destination()
-                break
+        signal.set_source(self)
 
     def remove_signal(self, signal: Signal) -> None:
-        i: int = self._destination_signals.index(signal)
-        old_signal: Signal = self._destination_signals[i]
-        del self._destination_signals[i]
-        if self is old_signal.source:
-            old_signal.remove_source()
+        assert signal in self._destination_signals, "Attempted to remove already removed signal."
+        self._destination_signals.remove(signal)
+        signal.remove_source()
 
     def clear(self) -> None:
-        for signal in self._destination_signals:
+        for signal in copy(self._destination_signals):
             self.remove_signal(signal)
+
+    @property
+    def source(self) -> "OutputPort":
+        return self

b_asic/precedence_chart.py

-"""@package docstring
-B-ASIC Precedence Chart Module.
-TODO: More info.
-"""
-
-from b_asic.signal_flow_graph import SFG
-
-
-class PrecedenceChart:
-    """Precedence chart constructed from a signal flow graph.
-    TODO: More info.
-    """
-
-    sfg: SFG
-    # TODO: More members.
-
-    def __init__(self, sfg: SFG):
-        self.sfg = sfg
-        # TODO: Implement.
-
-    # TODO: More stuff.

b_asic/schema.py

-"""@package docstring
-B-ASIC Schema Module.
-TODO: More info.
-"""
-
-from b_asic.precedence_chart import PrecedenceChart
-
-
-class Schema:
-    """Schema constructed from a precedence chart.
-    TODO: More info.
-    """
-
-    pc: PrecedenceChart
-    # TODO: More members.
-
-    def __init__(self, pc: PrecedenceChart):
-        self.pc = pc
-        # TODO: Implement.
-
-    # TODO: More stuff.

b_asic/signal.py

 """@package docstring
 B-ASIC Signal Module.
 """
-from typing import Optional, TYPE_CHECKING
+from typing import Optional, Iterable, TYPE_CHECKING
 
-from b_asic.graph_component import AbstractGraphComponent, TypeName, Name
+from b_asic.graph_component import GraphComponent, AbstractGraphComponent, TypeName, Name
 
 if TYPE_CHECKING:
     from b_asic.port import InputPort, OutputPort
@@ -12,30 +12,34 @@ if TYPE_CHECKING:
 class Signal(AbstractGraphComponent):
     """A connection between two ports."""
 
-    _source: "OutputPort"
-    _destination: "InputPort"
-
-    def __init__(self, source: Optional["OutputPort"] = None, \
-                destination: Optional["InputPort"] = None, name: Name = ""):
+    _source: Optional["OutputPort"]
+    _destination: Optional["InputPort"]
 
+    def __init__(self, source: Optional["OutputPort"] = None, destination: Optional["InputPort"] = None, bits: Optional[int] = None, name: Name = ""):
         super().__init__(name)
-
-        self._source = source
-        self._destination = destination
-
+        self._source = None
+        self._destination = None
         if source is not None:
             self.set_source(source)
-
         if destination is not None:
             self.set_destination(destination)
+        self.set_param("bits", bits)
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "s"
 
     @property
-    def source(self) -> "OutputPort":
+    def neighbors(self) -> Iterable[GraphComponent]:
+        return [p.operation for p in [self.source, self.destination] if p is not None]
+
+    @property
+    def source(self) -> Optional["OutputPort"]:
         """Return the source OutputPort of the signal."""
         return self._source
 
     @property
-    def destination(self) -> "InputPort":
+    def destination(self) -> Optional["InputPort"]:
         """Return the destination "InputPort" of the signal."""
         return self._destination
 
@@ -47,11 +51,11 @@ class Signal(AbstractGraphComponent):
         Keyword arguments:
         - src: OutputPort to connect as source to the signal.
         """
-        self.remove_source()
-        self._source = src
-        if self not in src.signals:
-            # If the new source isn't connected to this signal then connect it.
-            src.add_signal(self)
+        if src is not self._source:
+            self.remove_source()
+            self._source = src
+            if self not in src.signals:
+                src.add_signal(self)
 
     def set_destination(self, dest: "InputPort") -> None:
         """Disconnect the previous destination InputPort of the signal and
@@ -61,36 +65,44 @@ class Signal(AbstractGraphComponent):
         Keywords argments:
         - dest: InputPort to connect as destination to the signal.
         """
-        self.remove_destination()
-        self._destination = dest
-        if self not in dest.signals:
-            # If the new destination isn't connected to tis signal then connect it.
-            dest.add_signal(self)
-
-    @property
-    def type_name(self) -> TypeName:
-        return "s"
+        if dest is not self._destination:
+            self.remove_destination()
+            self._destination = dest
+            if self not in dest.signals:
+                dest.add_signal(self)
 
     def remove_source(self) -> None:
         """Disconnect the source OutputPort of the signal. If the source port
         still is connected to this signal then also disconnect the source port."""
-        if self._source is not None:
-            old_source: "OutputPort" = self._source
+        src = self._source
+        if src is not None:
             self._source = None
-            if self in old_source.signals:
-                # If the old destination port still is connected to this signal, then disconnect it.
-                old_source.remove_signal(self)
+            if self in src.signals:
+                src.remove_signal(self)
 
     def remove_destination(self) -> None:
         """Disconnect the destination InputPort of the signal."""
-        if self._destination is not None:
-            old_destination: "InputPort" = self._destination
+        dest = self._destination
+        if dest is not None:
             self._destination = None
-            if self in old_destination.signals:
-                # If the old destination port still is connected to this signal, then disconnect it.
-                old_destination.remove_signal(self)
+            if self in dest.signals:
+                dest.remove_signal(self)
 
-    def is_connected(self) -> bool:
-        """Returns true if the signal is connected to both a source and a destination,
+    def dangling(self) -> bool:
+        """Returns true if the signal is missing either a source or a destination,
         else false."""
-        return self._source is not None and self._destination is not None
+        return self._source is None or self._destination is None
+
+    @property
+    def bits(self) -> Optional[int]:
+        """Get the number of bits that this operations using this signal as an input should truncate received values to.
+        None = unlimited."""
+        return self.param("bits")
+
+    @bits.setter
+    def bits(self, bits: Optional[int]) -> None:
+        """Set the number of bits that operations using this signal as an input should truncate received values to.
+        None = unlimited."""
+        assert bits is None or (isinstance(bits, int)
+                                and bits >= 0), "Bits must be non-negative."
+        self.set_param("bits", bits)

b_asic/simulation.py

@@ -3,33 +3,116 @@ B-ASIC Simulation Module.
 TODO: More info.
 """
 
+from collections import defaultdict
 from numbers import Number
-from typing import List
+from typing import List, Dict, DefaultDict, Callable, Sequence, Mapping, Union, Optional
 
+from b_asic.operation import OutputKey, OutputMap
+from b_asic.signal_flow_graph import SFG
 
-class OperationState:
-    """Simulation state of an operation.
+
+InputProvider = Union[Number, Sequence[Number], Callable[[int], Number]]
+
+
+class Simulation:
+    """Simulation.
     TODO: More info.
     """
 
-    output_values: List[Number]
-    iteration: int
+    _sfg: SFG
+    _results: DefaultDict[int, Dict[str, Number]]
+    _registers: Dict[str, Number]
+    _iteration: int
+    _input_functions: Sequence[Callable[[int], Number]]
+    _current_input_values: Sequence[Number]
+    _latest_output_values: Sequence[Number]
+    _save_results: bool
 
-    def __init__(self):
-        self.output_values = []
-        self.iteration = 0
+    def __init__(self, sfg: SFG, input_providers: Optional[Sequence[Optional[InputProvider]]] = None, save_results: bool = False):
+        self._sfg = sfg
+        self._results = defaultdict(dict)
+        self._registers = {}
+        self._iteration = 0
+        self._input_functions = [
+            lambda _: 0 for _ in range(self._sfg.input_count)]
+        self._current_input_values = [0 for _ in range(self._sfg.input_count)]
+        self._latest_output_values = [0 for _ in range(self._sfg.output_count)]
+        self._save_results = save_results
+        if input_providers is not None:
+            self.set_inputs(input_providers)
 
+    def set_input(self, index: int, input_provider: InputProvider) -> None:
+        """Set the input function used to get values for the specific input at the given index to the internal SFG."""
+        if index < 0 or index >= len(self._input_functions):
+            raise IndexError(
+                f"Input index out of range (expected 0-{len(self._input_functions) - 1}, got {index})")
+        if callable(input_provider):
+            self._input_functions[index] = input_provider
+        elif isinstance(input_provider, Number):
+            self._input_functions[index] = lambda _: input_provider
+        else:
+            self._input_functions[index] = lambda n: input_provider[n]
 
-class SimulationState:
-    """Simulation state.
-    TODO: More info.
-    """
+    def set_inputs(self, input_providers: Sequence[Optional[InputProvider]]) -> None:
+        """Set the input functions used to get values for the inputs to the internal SFG."""
+        if len(input_providers) != self._sfg.input_count:
+            raise ValueError(
+                f"Wrong number of inputs supplied to simulation (expected {self._sfg.input_count}, got {len(input_providers)})")
+        self._input_functions = [None for _ in range(self._sfg.input_count)]
+        for index, input_provider in enumerate(input_providers):
+            if input_provider is not None:
+                self.set_input(index, input_provider)
+
+    @property
+    def save_results(self) -> bool:
+        """Get the flag that determines if the results of ."""
+        return self._save_results
+
+    @save_results.setter
+    def save_results(self, save_results) -> None:
+        self._save_results = save_results
+
+    def run(self) -> Sequence[Number]:
+        """Run one iteration of the simulation and return the resulting output values."""
+        return self.run_for(1)
+
+    def run_until(self, iteration: int) -> Sequence[Number]:
+        """Run the simulation until its iteration is greater than or equal to the given iteration
+        and return the resulting output values.
+        """
+        while self._iteration < iteration:
+            self._current_input_values = [self._input_functions[i](
+                self._iteration) for i in range(self._sfg.input_count)]
+            self._latest_output_values = self._sfg.evaluate_outputs(
+                self._current_input_values, self._results[self._iteration], self._registers)
+            if not self._save_results:
+                del self._results[self.iteration]
+            self._iteration += 1
+        return self._latest_output_values
+
+    def run_for(self, iterations: int) -> Sequence[Number]:
+        """Run a given number of iterations of the simulation and return the resulting output values."""
+        return self.run_until(self._iteration + iterations)
+
+    @property
+    def iteration(self) -> int:
+        """Get the current iteration number of the simulation."""
+        return self._iteration
 
-    # operation_states: Dict[OperationId, OperationState]
-    iteration: int
+    @property
+    def results(self) -> Mapping[int, OutputMap]:
+        """Get a mapping of all results, including intermediate values, calculated for each iteration up until now.
+        The outer mapping maps from iteration number to value mapping. The value mapping maps output port identifiers to values.
+        Example: {0: {"c1": 3, "c2": 4, "bfly1.0": 7, "bfly1.1": -1, "0": 7}}
+        """
+        return self._results
 
-    def __init__(self):
-        self.operation_states = {}
-        self.iteration = 0
+    def clear_results(self) -> None:
+        """Clear all results that were saved until now."""
+        self._results.clear()
 
-    # TODO: More stuff.
+    def clear_state(self) -> None:
+        """Clear all current state of the simulation, except for the results and iteration."""
+        self._registers.clear()
+        self._current_input_values = [0 for _ in range(self._sfg.input_count)]
+        self._latest_output_values = [0 for _ in range(self._sfg.output_count)]

b_asic/special_operations.py

+"""@package docstring
+B-ASIC Special Operations Module.
+TODO: More info.
+"""
+
+from numbers import Number
+from typing import Optional, Sequence
+
+from b_asic.operation import AbstractOperation, OutputKey, RegisterMap, MutableOutputMap, MutableRegisterMap
+from b_asic.graph_component import Name, TypeName
+from b_asic.port import SignalSourceProvider
+
+
+class Input(AbstractOperation):
+    """Input operation.
+    TODO: More info.
+    """
+
+    def __init__(self, name: Name = ""):
+        super().__init__(input_count=0, output_count=1, name=name)
+        self.set_param("value", 0)
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "in"
+
+    def evaluate(self):
+        return self.param("value")
+
+    @property
+    def value(self) -> Number:
+        """Get the current value of this input."""
+        return self.param("value")
+
+    @value.setter
+    def value(self, value: Number) -> None:
+        """Set the current value of this input."""
+        self.set_param("value", value)
+
+
+class Output(AbstractOperation):
+    """Output operation.
+    TODO: More info.
+    """
+
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, name: Name = ""):
+        super().__init__(input_count=1, output_count=0,
+                         name=name, input_sources=[src0])
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "out"
+
+    def evaluate(self, _):
+        return None
+
+
+class Register(AbstractOperation):
+    """Unit delay operation.
+    TODO: More info.
+    """
+
+    def __init__(self, src0: Optional[SignalSourceProvider] = None, initial_value: Number = 0, name: Name = ""):
+        super().__init__(input_count=1, output_count=1,
+                         name=name, input_sources=[src0])
+        self.set_param("initial_value", initial_value)
+
+    @classmethod
+    def type_name(cls) -> TypeName:
+        return "reg"
+
+    def evaluate(self, a):
+        return self.param("initial_value")
+
+    def current_output(self, index: int, registers: Optional[RegisterMap] = None, prefix: str = "") -> Optional[Number]:
+        if registers is not None:
+            return registers.get(self.key(index, prefix), self.param("initial_value"))
+        return self.param("initial_value")
+
+    def evaluate_output(self, index: int, input_values: Sequence[Number], results: Optional[MutableOutputMap] = None, registers: Optional[MutableRegisterMap] = None, prefix: str = "") -> Number:
+        if index != 0:
+            raise IndexError(
+                f"Output index out of range (expected 0-0, got {index})")
+        if len(input_values) != 1:
+            raise ValueError(
+                f"Wrong number of inputs supplied to SFG for evaluation (expected 1, got {len(input_values)})")
+
+        key = self.key(index, prefix)
+        value = self.param("initial_value")
+        if registers is not None:
+            value = registers.get(key, value)
+            registers[key] = self.truncate_inputs(input_values)[0]
+        if results is not None:
+            results[key] = value
+        return value

src/main.cpp

-#include <pybind11/pybind11.h>
-
-namespace py = pybind11;
-
-namespace asic {
-
-int add(int a, int b) {
-	return a + b;
-}
-
-int sub(int a, int b) {
-	return a - b;
-}
-
-} // namespace asic
-
-PYBIND11_MODULE(_b_asic, m) {
-	m.doc() = "Better ASIC Toolbox Extension Module.";
-	m.def("add", &asic::add, "A function which adds two numbers.", py::arg("a"), py::arg("b"));
-	m.def("sub", &asic::sub, "A function which subtracts two numbers.", py::arg("a"), py::arg("b"));
+#include <pybind11/pybind11.h>
+
+namespace py = pybind11;
+
+namespace asic {
+
+int add(int a, int b) {
+	return a + b;
+}
+
+int sub(int a, int b) {
+	return a - b;
+}
+
+} // namespace asic
+
+PYBIND11_MODULE(_b_asic, m) {
+	m.doc() = "Better ASIC Toolbox Extension Module.";
+	m.def("add", &asic::add, "A function which adds two numbers.", py::arg("a"), py::arg("b"));
+	m.def("sub", &asic::sub, "A function which subtracts two numbers.", py::arg("a"), py::arg("b"));
 }
\ No newline at end of file

test/conftest.py

 from test.fixtures.signal import signal, signals
 from test.fixtures.operation_tree import *
 from test.fixtures.port import *
+from test.fixtures.signal_flow_graph import *
 import pytest

test/fixtures/operation_tree.py

-from b_asic.core_operations import Addition, Constant
-from b_asic.signal import Signal
-
 import pytest
 
+from b_asic import Addition, Constant, Signal, Butterfly
+
+
 @pytest.fixture
 def operation():
     return Constant(2)
 
-def create_operation(_type, dest_oper, index, **kwargs):
-    oper = _type(**kwargs)
-    oper_signal = Signal()
-    oper._output_ports[0].add_signal(oper_signal)
-
-    dest_oper._input_ports[index].add_signal(oper_signal)
-    return oper
-
 @pytest.fixture
 def operation_tree():
-    """Return a addition operation connected with 2 constants.
-    ---C---+
-           ---A
-    ---C---+
+    """Valid addition operation connected with 2 constants.
+    2---+
+        |
+        v
+       add = 2 + 3 = 5
+        ^
+        |
+    3---+
     """
-    add_oper = Addition()
-    create_operation(Constant, add_oper, 0, value=2)
-    create_operation(Constant, add_oper, 1, value=3)
-    return add_oper
+    return Addition(Constant(2), Constant(3))
 
 @pytest.fixture
 def large_operation_tree():
-    """Return a constant operation connected with a large operation tree with 3 other constants and 3 additions.
-    ---C---+
-           ---A---+
-    ---C---+      |
-                  +---A
-    ---C---+      |
-           ---A---+
-    ---C---+
+    """Valid addition operation connected with a large operation tree with 2 other additions and 4 constants.
+    2---+
+        |
+        v
+       add---+
+        ^    |
+        |    |
+    3---+    v
+            add = (2 + 3) + (4 + 5) = 14
+    4---+    ^
+        |    |
+        v    |
+       add---+
+        ^
+        |
+    5---+
     """
-    add_oper = Addition()
-    add_oper_2 = Addition()
-
-    const_oper = create_operation(Constant, add_oper, 0, value=2)
-    create_operation(Constant, add_oper, 1, value=3)
+    return Addition(Addition(Constant(2), Constant(3)), Addition(Constant(4), Constant(5)))
 
-    create_operation(Constant, add_oper_2, 0, value=4)
-    create_operation(Constant, add_oper_2, 1, value=5)
+@pytest.fixture
+def large_operation_tree_names():
+    """Valid addition operation connected with a large operation tree with 2 other additions and 4 constants.
+    With names.
+    2---+
+        |
+        v
+       add---+
+        ^    |
+        |    |
+    3---+    v
+            add = (2 + 3) + (4 + 5) = 14
+    4---+    ^
+        |    |
+        v    |
+       add---+
+        ^
+        |
+    5---+
+    """
+    return Addition(Addition(Constant(2, name="constant2"), Constant(3, name="constant3")), Addition(Constant(4, name="constant4"), Constant(5, name="constant5")))
 
-    add_oper_3 = Addition()
-    add_oper_signal = Signal(add_oper.output(0), add_oper_3.output(0))
-    add_oper._output_ports[0].add_signal(add_oper_signal)
-    add_oper_3._input_ports[0].add_signal(add_oper_signal)
+@pytest.fixture
+def butterfly_operation_tree():
+    """Valid butterfly operations connected to eachother with 3 butterfly operations and 2 constants as inputs and 2 outputs.
+    2 ---+       +--- (2 + 4) ---+       +--- (6 + (-2)) ---+       +--- (4 + 8) ---> out1 = 12
+         |       |               |       |                  |       |
+         v       ^               v       ^                  v       ^
+         butterfly               butterfly                  butterfly
+         ^       v               ^       v                  ^       v
+         |       |               |       |                  |       |               
+    4 ---+       +--- (2 - 4) ---+       +--- (6 - (-2)) ---+       +--- (4 - 8) ---> out2 = -4
+    """
+    return Butterfly(*(Butterfly(*(Butterfly(Constant(2), Constant(4), name="bfly3").outputs), name="bfly2").outputs), name="bfly1")
 
-    add_oper_2_signal = Signal(add_oper_2.output(0), add_oper_3.output(0))
-    add_oper_2._output_ports[0].add_signal(add_oper_2_signal)
-    add_oper_3._input_ports[1].add_signal(add_oper_2_signal)
-    return const_oper
+@pytest.fixture
+def operation_graph_with_cycle():
+    """Invalid addition operation connected with an operation graph containing a cycle.
+     +-+
+     | |
+     v |
+    add+---+
+     ^     |
+     |     v
+     7    add = (? + 7) + 6 = ?
+           ^
+           |
+           6
+    """
+    add1 = Addition(None, Constant(7))
+    add1.input(0).connect(add1)
+    return Addition(add1, Constant(6))

test/fixtures/port.py

 import pytest
-from b_asic.port import InputPort, OutputPort
+
+from b_asic import InputPort, OutputPort
+
 
 @pytest.fixture
 def input_port():
-    return InputPort(0, None)
+    return InputPort(None, 0)
 
 @pytest.fixture
 def output_port():
-    return OutputPort(0, None)
+    return OutputPort(None, 0)
+
+@pytest.fixture
+def list_of_input_ports():
+    return [InputPort(None, i) for i in range(0, 3)]
+
+@pytest.fixture
+def list_of_output_ports():
+    return [OutputPort(None, i) for i in range(0, 3)]