"""Connector adapters.
To register connectors implemented in this module, it is imported in
gaphor.adapter package.
"""
from __future__ import annotations
import functools
import itertools
from collections.abc import Iterator
from typing import Protocol, TypeVar
from gaphas.connections import Connection
from gaphas.connector import ConnectionSink, Handle, Port
from gaphas.connector import Connector as ConnectorAspect
from generic.multidispatch import FunctionDispatcher, multidispatch
from gaphor.core.modeling import Base, Diagram, Presentation
from gaphor.core.modeling.event import RevertibleEvent
from gaphor.core.modeling.properties import association, redefine, relation
from gaphor.diagram.copypaste import copy, paste
from gaphor.diagram.presentation import ElementPresentation, LinePresentation
from gaphor.diagram.support import get_diagram_item_metadata, get_model_element
T = TypeVar("T", bound=Base)
class ConnectorProtocol(Protocol):
def __init__(
self,
element: Presentation,
line: Presentation,
) -> None: ...
def allow(self, handle: Handle, port: Port) -> bool: ...
def connect(self, handle: Handle, port: Port) -> bool: ...
def disconnect(self, handle: Handle) -> None: ...
[docs]
class BaseConnector:
"""Connection adapter for Gaphor diagram items.
Line item ``line`` connects with a handle to a connectable item ``element``.
:param line: connecting item
:param element: connectable item
By convention the adapters are registered by (element, line) -- in that order.
"""
def __init__(
self,
element: Presentation[Base],
line: Presentation[Base],
) -> None:
self.element = element
self.line = line
# Try to find the diagram. Any diagram can be None, when called while an element is unlinking
assert (
element.diagram is line.diagram
or element.diagram is None
or line.diagram is None
)
self.diagram: Diagram = element.diagram or line.diagram
assert self.diagram
[docs]
def get_connected(self, handle: Handle) -> Presentation[Base] | None:
"""Get item connected to a handle."""
if cinfo := self.diagram.connections.get_connection(handle):
return cinfo.connected # type: ignore[no-any-return] # noqa: F723
return None
[docs]
def allow(self, handle: Handle, port: Port) -> bool:
"""Determine if items can be connected.
Is the connection allowed at all (during mouse movement for example)?
Returns `True` if connection is allowed.
"""
return bool(self.element.diagram) and self.element.diagram is self.line.diagram
[docs]
def connect(self, handle: Handle, port: Port) -> bool:
"""Connect to an element.
Establish a connection between element and line. Also takes care of
disconnects, if required (e.g. 1:1 relationships).
Note that at this point the line may be
connected to some other, or the same element. The connection at model
level also still exists.
Returns `True` if a connection is established.
"""
return True
[docs]
def disconnect(self, handle: Handle) -> None:
"""Disconnect model level connections.
Break connection, called when dropping a handle on a
point where it can not connect.
"""
class NoConnector:
def __init__(
self,
element,
line,
) -> None:
pass
def allow(self, handle: Handle, port: Port) -> bool:
return False
def connect(self, handle: Handle, port: Port) -> bool:
return False
def disconnect(self, handle: Handle) -> None:
pass
# Work around issue https://github.com/python/mypy/issues/3135 (Class decorators are not type checked)
# This definition, along with the ignore below, seems to fix the behaviour for mypy at least.
Connector: FunctionDispatcher[type[ConnectorProtocol]] = multidispatch(object, object)(
NoConnector
)
@functools.lru_cache
def can_connect(parent, element_type) -> bool:
parent_type = type(parent)
get_registration = Connector.registry.get_registration
for t1, t2 in itertools.product(parent_type.__mro__, element_type.__mro__):
if r := get_registration(t1, t2):
return r is not NoConnector
return False
class RelationshipConnect(BaseConnector):
"""Base class for relationship connections, such as associations,
dependencies and implementations.
Unary relationships are allowed to connect both ends to the same element.
This class introduces a new method: `relationship()`, which is used to
find an existing relationship in the model that does not yet exist
on the diagram.
"""
element: Presentation
line: LinePresentation[Base]
def __init__(self, element: Presentation[Base], line: Presentation[Base]) -> None:
super().__init__(element, line)
self.copy_buffer = dict(copy(line.subject)) if line.subject else {}
def relationship(
self, required_type: type[T], head: relation, tail: relation
) -> T | None:
"""Find an existing relationship in the model that meets the required
type and is connected to the same model element the head and tail of
the line are connected to.
type - the type of relationship we're looking for
head - tuple (association name on the line, association name on the element)
tail - tuple (association name on the line, association name on the element)
"""
assert isinstance(head, association | redefine), f"head is {head}"
assert isinstance(tail, association | redefine), f"tail is {tail}"
line = self.line
line_head = self.get_connected(line.head)
line_tail = self.get_connected(line.tail)
assert line_head
assert line_tail
head_subject = line_head.subject
tail_subject = line_tail.subject
# First check if the right subject is already connected:
if (
line.subject
and head.get(line.subject) is head_subject
and tail.get(line.subject) is tail_subject
):
return line.subject # type: ignore[return-value]
# Try to find a relationship, that is already created, but not
# yet displayed in the diagram on the tail side, since tail should
# have a reference to head at least.
if not (head_subject and tail.opposite):
return None
gen: Base
for gen in getattr(tail_subject, tail.opposite):
if not isinstance(gen, required_type):
continue
gen_head = head.get(gen)
try:
if head_subject not in gen_head:
continue
except TypeError:
if gen_head is not head_subject:
continue
# Check for this entry on line.diagram
item: ElementPresentation | LinePresentation
for item in gen.presentation:
# Allow line to be returned. Avoids strange
# behaviour during loading
if item.diagram is line.diagram and item is not line:
break
else:
return gen
return None
def new_relation(self, type: type[T]) -> T:
return self.line.model.create(type)
def new_relation_from_copy(self, type: type[T]) -> T | None:
if not self.copy_buffer:
return None
for e in paste_model(self.copy_buffer, self.diagram):
if isinstance(e, type):
return e
raise AssertionError(
f"Copied elements, but no {type} found ({self.copy_buffer})"
)
def relationship_or_new(self, type: type[T], head: relation, tail: relation) -> T:
"""Like relation(), but create a new instance if none was found."""
relation = self.relationship(type, head, tail)
if relation:
return relation
line = self.line
relation = self.new_relation_from_copy(type) or self.new_relation(type)
assert isinstance(relation, type)
line_head = self.get_connected(line.head)
line_tail = self.get_connected(line.tail)
assert line_head
assert line_tail
head.set(relation, line_head.subject)
tail.set(relation, line_tail.subject)
# TODO uncomment the following after Dependency is made a subclass of PackageableElement
# owning_package = line_tail.subject.owningPackage
# relation.owningPackage = owning_package
assert isinstance(relation, type)
return relation
def connect_connected_items(self, connections: None = None) -> None:
"""Cause items connected to ``line`` to reconnect, allowing them to
establish or destroy relationships at model level."""
line = self.line
diagram = self.diagram
# First make sure coordinates match
diagram.connections.solver.solve()
for cinfo in connections or diagram.connections.get_connections(connected=line):
if line is cinfo.connected:
continue
adapter = Connector(line, cinfo.connected)
assert adapter, f"No element to connect {line} and {cinfo.connected}"
adapter.connect(cinfo.handle, cinfo.port)
def disconnect_connected_items(self) -> list[Connection]:
"""Cause items connected to @line to be disconnected. This is necessary
if the subject of the @line is to be removed.
Returns a list of (item, handle) pairs that were connected (this
list can be used to connect items again with
connect_connected_items()).
"""
line = self.line
diagram = self.diagram
# First make sure coordinates match
diagram.connections.solver.solve()
connections = list(diagram.connections.get_connections(connected=line))
for cinfo in connections:
adapter = Connector(cinfo.item, cinfo.connected)
adapter.disconnect(cinfo.handle)
return connections
def connect_subject(self, handle: Handle) -> bool:
"""Establish the relationship at model level."""
raise NotImplementedError("Implement connect_subject() in a subclass")
def disconnect_subject(self, handle: Handle) -> None:
"""Disconnect the diagram item from its model element."""
del self.line.subject
def connect(self, handle: Handle, port: Port) -> bool:
"""Connect the items to each other.
The model level relationship is created by create_subject()
"""
if not super().connect(handle, port):
return False
opposite = self.line.opposite(handle)
if self.get_connected(opposite):
self.connect_subject(handle)
line = self.line
if line.subject:
self.connect_connected_items()
return True
def disconnect(self, handle: Handle) -> None:
"""Disconnect model element."""
line = self.line
opposite = line.opposite(handle)
oct = self.get_connected(opposite)
hct = self.get_connected(handle)
if hct and oct:
# Both sides of line are connected => disconnect
self.disconnect_connected_items()
self.disconnect_subject(handle)
super().disconnect(handle)
class DirectionalRelationshipConnect(RelationshipConnect):
"""Base for relationship connections between unique elements."""
def allow(self, handle: Handle, port: Port) -> bool:
"""In addition to the normal check, both relationship ends may not be
connected to the same element.
Same goes for subjects.
"""
opposite = self.line.opposite(handle)
element = self.element
connected_to = self.get_connected(opposite)
# Element can not be a parent of itself.
if connected_to is element:
return False
# Same goes for subjects:
if (
connected_to
and not connected_to.subject
and not element.subject
and connected_to.subject is element.subject
):
return False
return super().allow(handle, port)
@Connector.register(ElementPresentation, LinePresentation)
class MetadataRelationConnect(DirectionalRelationshipConnect):
"""A generic relationship connector."""
def allow(self, handle, port):
if not super().allow(handle, port):
return False
element = self.element
opposite_element = self.get_connected(self.line.opposite(handle))
if metadata := get_diagram_item_metadata(type(self.line)):
return (
(
isinstance(element.subject, metadata["head"].type)
and (
not opposite_element
or isinstance(opposite_element.subject, metadata["tail"].type)
)
)
if handle is self.line.head
else (
isinstance(element.subject, metadata["tail"].type)
and (
not opposite_element
or isinstance(opposite_element.subject, metadata["head"].type)
)
)
)
return False
def connect_subject(self, handle):
subject_type = get_model_element(type(self.line))
metadata = get_diagram_item_metadata(type(self.line))
if not metadata:
return False
self.line.subject = self.relationship_or_new(
subject_type, metadata["head"], metadata["tail"]
)
return True
def paste_model(copy_data, diagram) -> Iterator[Base]:
new_elements: dict[str, Base] = {}
def create(ref: str):
if ref in new_elements:
return new_elements[ref]
if ref in copy_data:
paster = paste(copy_data[ref], diagram, create)
new_elements[ref] = next(paster)
next(paster, None)
return new_elements[ref]
for old_id in copy_data:
if old_id in new_elements:
continue
create(old_id)
for element in new_elements.values():
assert element
element.postload()
return iter(new_elements.values())
class ItemConnected(RevertibleEvent):
def __init__(self, element, handle, connected, port):
super().__init__(element)
self.handle_index = element.handles().index(handle)
self.connected_id = connected.id
self.port_index = connected.ports().index(port)
def revert(self, target):
# Reverse only the diagram level connection.
# Associations have their own handlers
connections = target.diagram.connections
handle = target.handles()[self.handle_index]
connector = ConnectorAspect(target, handle, connections)
connector.disconnect_handle()
class ItemDisconnected(RevertibleEvent):
def __init__(self, element, handle, connected, port):
super().__init__(element)
self.handle_index = element.handles().index(handle)
self.connected_id = connected.id
self.port_index = connected.ports().index(port)
def revert(self, target):
# Reverse only the diagram level connection.
# Associations have their own handlers
handle = target.handles()[self.handle_index]
connections = target.diagram.connections
connected = target.diagram.lookup(self.connected_id)
sink = ConnectionSink(connected)
sink.port = connected.ports()[self.port_index]
connector = ConnectorAspect(target, handle, connections)
connector.connect_handle(sink)
class ItemTemporaryDisconnected(RevertibleEvent):
def __init__(self, element, handle, connected, port):
super().__init__(element)
self.handle_index = element.handles().index(handle)
self.connected_id = connected.id
self.port_index = connected.ports().index(port)
def revert(self, target):
handle = target.handles()[self.handle_index]
connections = target.diagram.connections
connected = target.diagram.lookup(self.connected_id)
sink = ConnectionSink(connected)
sink.port = connected.ports()[self.port_index]
connector = ConnectorAspect(target, handle, connections)
connector.reconnect_handle(sink)
class ItemReconnected(RevertibleEvent):
def __init__(self, element, handle, connected, port):
super().__init__(element)
self.handle_index = element.handles().index(handle)
self.connected_id = connected.id
self.port_index = connected.ports().index(port)
def revert(self, target):
connections = target.diagram.connections
handle = target.handles()[self.handle_index]
cinfo = connections.get_connection(handle)
connections.solver.remove_constraint(cinfo.constraint)
target.handle(
ItemTemporaryDisconnected(target, handle, cinfo.connected, cinfo.port)
)