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Source/Engine/Utilities/State.cs

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+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+namespace FlaxEngine.Utilities
+{
+    /// <summary>
+    /// State machine state
+    /// </summary>
+    public abstract class State
+    {
+        internal StateMachine owner;
+
+        /// <summary>
+        /// Gets the state machine.
+        /// </summary>
+        /// <value>
+        /// The state machine.
+        /// </value>
+        public StateMachine StateMachine => owner;
+
+        /// <summary>
+        /// Gets a value indicating whether this state is active.
+        /// </summary>
+        public bool IsActive => owner != null && owner.CurrentState == this;
+
+        /// <summary>
+        /// Checks if can enter to that state
+        /// </summary>
+        /// <returns>True if can enter to that state, otherwise false</returns>
+        public virtual bool CanEnter()
+        {
+            return true;
+        }
+
+        /// <summary>
+        /// Checks if can exit from that state
+        /// </summary>
+        /// <param name="nextState">Next state to enter after exit from the current state</param>
+        /// <returns>True if can exit from that state, otherwise false</returns>
+        public virtual bool CanExit(State nextState)
+        {
+            return true;
+        }
+
+        /// <summary>
+        /// Called when state is starting to be active.
+        /// </summary>
+        public virtual void OnEnter()
+        {
+        }
+
+        /// <summary>
+        /// Called when state is ending to be active.
+        /// </summary>
+        /// <param name="nextState">The next state.</param>
+        public virtual void OnExit(State nextState)
+        {
+        }
+    }
+}