starting splendor

python/splendor/sim.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+import copy
+
+from .base import Action, GameState, PlayerState, apply_action, check_nobles_for_player
+from .bot import RandomBot
+
+
+class SimStrategy(RandomBot):
+    """Strategy used in simulate_step.
+
+    We never call choose_action here (caller chooses actions),
+    but we reuse discard/noble-selection logic.
+    """
+
+    def choose_action(self, game: GameState, player: PlayerState) -> Action | None:
+        msg = "SimStrategy.choose_action should not be used in simulate_step"
+        raise RuntimeError(msg)
+
+
+def simulate_step(game: GameState, action: Action) -> GameState:
+    """Return a deep-copied next state after applying action for the current player.
+
+    Useful for tree search / MCTS:
+
+        next_state = simulate_step(state, action)
+    """
+    next_state = copy.deepcopy(game)
+    sim_strategy = SimStrategy()
+    apply_action(next_state, sim_strategy, action)
+    check_nobles_for_player(next_state, sim_strategy, next_state.current_player)
+    next_state.next_player()
+    return next_state