from collections import deque
from collections.abc import Iterable, MutableSet
from types import GeneratorType
from typing import Any, Generic, TypeVar, Union, get_args
from pydantic import GetCoreSchemaHandler
from pydantic_core import core_schema
from pydantic_core.core_schema import DictSchema, TypedDictSchema
from napari.utils.events.containers._set import EventedSet
from napari.utils.events.event import EmitterGroup
_T = TypeVar('_T')
_S = TypeVar('_S')
def sequence_like(v: Any) -> bool:
"""Check whether an object is sequence-like."""
return isinstance(v, (list, tuple, set, frozenset, GeneratorType, deque))
[docs]
class Selection(EventedSet[_T]):
"""A model of selected items, with ``active`` and ``current`` item.
There can only be one ``active`` and one ``current`` item, but there can be
multiple selected items. An "active" item is defined as a single selected
item (if multiple items are selected, there is no active item). The
"current" item is mostly useful for (e.g.) keyboard actions: even with
multiple items selected, you may only have one current item, and keyboard
events (like up and down) can modify that current item. It's possible to
have a current item without an active item, but an active item will always
be the current item.
An item can be the current item and selected at the same time. Qt views
will ensure that there is always a current item as keyboard navigation,
for example, requires a current item.
This pattern mimics current/selected items from Qt:
https://doc.qt.io/qt-5/model-view-programming.html#current-item-and-selected-items
Parameters
----------
data : iterable, optional
Elements to initialize the set with.
Attributes
----------
active : Any, optional
The active item, if any. An active item is the one being edited.
_current : Any, optional
The current item, if any. This is used primarily by GUI views when
handling mouse/key events.
Events
------
changed (added: Set[_T], removed: Set[_T])
Emitted when the set changes, includes item(s) that have been added and/or removed from the set.
active (value: _T)
emitted when the current item has changed.
_current (value: _T)
emitted when the current item has changed. (Private event)
"""
def __init__(self, data: Iterable[_T] = ()) -> None:
self._active: _T | None = None
self._current_: _T | None = None
self.events = EmitterGroup(source=self, _current=None, active=None)
super().__init__(data=data)
self._update_active()
def _emit_change(
self,
added: set[_T] | None = None,
removed: set[_T] | None = None,
) -> None:
if added is None:
added = set()
if removed is None:
removed = set()
self._update_active()
return super()._emit_change(added=added, removed=removed)
def __repr__(self) -> str:
return f'{type(self).__name__}({self._set!r})'
def __hash__(self) -> int:
"""Make selection hashable."""
return id(self)
@property
def _current(self) -> _T | None:
"""Get current item."""
return self._current_
@_current.setter
def _current(self, index: _T | None) -> None:
"""Set current item."""
if index == self._current_:
return
self._current_ = index
self.events._current(value=index)
@property
def active(self) -> _T | None:
"""Return the currently active item or None."""
return self._active
@active.setter
def active(self, value: _T | None) -> None:
"""Set the active item.
This make `value` the only selected item, and make it current.
"""
if value == self._active:
return
self._active = value
self.clear() if value is None else self.select_only(value)
self._current = value
self.events.active(value=value)
def _update_active(self) -> None:
"""On a selection event, update the active item based on selection.
(An active item is a single selected item).
"""
if len(self) == 1:
self.active = next(iter(self))
elif self._active is not None:
self._active = None
self.events.active(value=None)
[docs]
def clear(self, keep_current: bool = False) -> None:
"""Clear the selection."""
if not keep_current:
self._current = None
super().clear()
[docs]
def toggle(self, obj: _T) -> None:
"""Toggle selection state of obj."""
self.symmetric_difference_update({obj})
[docs]
def select_only(self, obj: _T) -> None:
"""Unselect everything but `obj`. Add to selection if not present."""
self.intersection_update({obj})
self.add(obj)
@classmethod
def __get_pydantic_core_schema__(
cls, source: Any, handler: GetCoreSchemaHandler
) -> core_schema.CoreSchema:
instance_schema = core_schema.is_instance_schema(cls)
args = get_args(source)
dict_schema: DictSchema | TypedDictSchema
if args:
item_schema = handler.generate_schema(args[0])
mutableset_t_schema = handler.generate_schema(MutableSet[args[0]]) # type: ignore
current_schema = core_schema.union_schema(
[item_schema, core_schema.none_schema()]
)
dict_schema = core_schema.typed_dict_schema(
{
'selection': core_schema.typed_dict_field(
core_schema.list_schema(item_schema)
),
'_current': core_schema.typed_dict_field(
current_schema, required=False
),
}
)
else:
mutableset_t_schema = handler.generate_schema(MutableSet)
dict_schema = core_schema.dict_schema(
keys_schema=core_schema.str_schema(),
values_schema=core_schema.any_schema(),
)
input_schema = core_schema.union_schema(
[mutableset_t_schema, dict_schema]
)
non_instance_schema = core_schema.no_info_after_validator_function(
cls._validate_selection, input_schema
)
def _serialize(v: Selection) -> dict:
return {
'selection': EventedSet(v)._json_encode(),
'_current': v._current,
}
serialize = core_schema.plain_serializer_function_ser_schema(
_serialize,
when_used='json',
)
return core_schema.union_schema(
[instance_schema, non_instance_schema], serialization=serialize
)
@classmethod
def _validate_selection(
cls,
v: Union['Selection', dict],
) -> 'Selection':
"""Pydantic validator."""
if isinstance(v, dict):
data = v.get('selection', [])
current = v.get('_current', None)
elif isinstance(v, Selection):
data = v._set
current = v._current
else:
data = v
current = None
obj = cls(data=data)
obj._current_ = current
return obj
def _json_encode(self) -> dict: # type: ignore[override]
"""Return an object that can be used by json.dumps."""
# we don't serialize active, as it's gleaned from the selection.
return {'selection': super()._json_encode(), '_current': self._current}
class Selectable(Generic[_S]):
"""Mixin that adds a selection model to an object."""
def __init__(self, *args: Any, **kwargs: Any) -> None:
self._selection: Selection[_S] = Selection()
super().__init__(*args, **kwargs)
@property
def selection(self) -> Selection[_S]:
"""Get current selection."""
return self._selection
@selection.setter
def selection(self, new_selection: Iterable[_S]) -> None:
"""Set selection, without deleting selection model object."""
self._selection.intersection_update(new_selection)
self._selection.update(new_selection)
