chore: initial commit

Assets/Scripts/Core/GameStateMachine.cs

@@ -0,0 +1,45 @@
+using System.Collections.Generic;
+using System.Linq;
+using UnityEngine;
+using BaseGames.Core.Events;
+
+namespace BaseGames.Core
+{
+    /// <summary>
+    /// 状态机核心，持有状态注册表与当前状态。
+    /// GameManager 持有一个实例；状态对象在 Awake 注入。
+    /// </summary>
+    public class GameStateMachine
+    {
+        private readonly Dictionary<GameStateId, IGameState> _states = new();
+        private IGameState _current;
+
+        public GameStateId CurrentStateId => _current?.Id ?? default;
+
+        /// <summary>注册状态实现（同 Id 注册多次以最后一次为准）。</summary>
+        public void Register(IGameState state) => _states[state.Id] = state;
+
+        /// <summary>转换到目标状态。失败时返回 false 并填充 error 字符串。</summary>
+        public bool TransitionTo(GameStateId nextId, out string error)
+        {
+            if (!_states.TryGetValue(nextId, out var next))
+            {
+                error = $"[GameStateMachine] 未知状态 '{nextId}'";
+                return false;
+            }
+            if (_current != null && !_current.ValidNextStates.Contains(nextId))
+            {
+                error = $"[GameStateMachine] 非法转换 {_current.Id} → {nextId}";
+                return false;
+            }
+            var prev = _current?.Id ?? default;
+            _current?.OnExit(nextId);
+            _current = next;
+            _current.OnEnter(prev);
+            error = null;
+            return true;
+        }
+
+        public void Tick(float deltaTime) => _current?.Tick(deltaTime);
+    }
+}