first commit

game/state.py

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+"""Base classes for states."""
+
+from __future__ import annotations
+
+from typing import Protocol, TypeAlias
+
+import attrs
+import tcod.console
+import tcod.event
+
+
+class State(Protocol):
+    """An abstract game state."""
+
+    __slots__ = ()
+
+    def on_event(self, event: tcod.event.Event) -> StateResult:
+        """Called on events."""
+
+    def on_draw(self, console: tcod.console.Console) -> None:
+        """Called when the state is being drawn."""
+
+
+@attrs.define()
+class Push:
+    """Push a new state on top of the stack."""
+
+    state: State
+
+
+@attrs.define()
+class Pop:
+    """Remove the current state from the stack."""
+
+
+@attrs.define()
+class Reset:
+    """Replace the entire stack with a new state."""
+
+    state: State
+
+
+StateResult: TypeAlias = "Push | Pop | Reset | None"
+"""Union of state results."""