Source code for simvx.core.selection

"""Multi-select selection system for editor use."""


from __future__ import annotations

import logging

log = logging.getLogger(__name__)

class _Signal:
    def __init__(self):
        self._callbacks: list = []

    def connect(self, fn):
        self._callbacks.append(fn)

    def emit(self):
        for cb in self._callbacks:
            cb()




class Selection:
    """Tracks an ordered set of selected items with change notification."""

    def __init__(self):
        self._items: list = []
        self.selection_changed = _Signal()

    # -- properties ----------------------------------------------------------

    @property
    def items(self) -> list:
        return list(self._items)

    @property
    def count(self) -> int:
        return len(self._items)

    @property
    def primary(self) -> object | None:
        return self._items[0] if self._items else None

    @property
    def empty(self) -> bool:
        return not self._items

    # -- mutators -------------------------------------------------------------



    def select(self, item, *, additive: bool = False):
        """Select *item*.  If *additive*, toggle it; otherwise replace."""
        if additive:
            self.toggle(item)
            return
        changed = self._items != [item]
        self._items = [item]
        if changed:
            self.selection_changed.emit()




    def deselect(self, item):
        if item in self._items:
            self._items.remove(item)
            self.selection_changed.emit()




    def toggle(self, item):
        if item in self._items:
            self._items.remove(item)
        else:
            self._items.append(item)
        self.selection_changed.emit()




    def clear(self):
        if self._items:
            self._items.clear()
            self.selection_changed.emit()




    def select_all(self, items):
        self._items = list(items)
        self.selection_changed.emit()


    # -- queries --------------------------------------------------------------



    def is_selected(self, item) -> bool:
        return item in self._items




    def __contains__(self, item):
        return item in self._items




    def __iter__(self):
        return iter(self._items)




    def __len__(self) -> int:
        return len(self._items)