FCC/Applications/Share/WayneLib_WayneLibraries/StateEngine/PseudoState.cs

/*===============================================================================
 * PseudoState
 * 
 * Change history
 * When         Who     Comment
 * ----------   ------  ------------------------------------
 * 2006-07-18   RMa     Changed transition handling.
 * 2006-02-03   RMa     FXCop updates: protected methods.
 * 2006-01-27   RMa     Removed interface Event. Use Event class instead. 
 * 2005-12-05   RMa     This header added.
 * 
---------------------------------------------------------------------------------*/
using System;

namespace Wayne.Lib.StateEngine
{
    /// <summary>
    /// A pseudo state is a state that can be entered, but it must transition directly. 
    /// The state machine can not stay in this state,but must continue directly. Therefore
    /// the Enter, and exit methods are sealed and can not be overriden. Insted, the abstract method CreatePseudoStateTransition method
    /// must be overriden. It receives the entry information and must return a transition direclty.
    /// The pseudo state can be used to implement choce states, and is the base class for initial states.
    /// </summary>
    abstract public class PseudoState : State
    {
        #region Sealed Methods
        /// <summary>
        /// The Exit method may not be used in a Pseudo state. 
        /// It must transition directly after enter.
        /// </summary>        
        protected sealed override void Enter(StateEntry stateEntry, ref Transition transition)
        {
            base.Enter(stateEntry, ref transition);
            transition = this.CreatePseudoStateTransition(stateEntry);
        }

        /// <summary>
        /// The Exit method may not be used in a Pseudo state. 
        /// It must transition directly after enter.
        /// </summary>
        protected override sealed void Exit()
        {
            base.Exit();
        }
  
        #endregion

        #region Abstract Methods

        /// <summary>
        /// The CreatePseudoStateTransition method must be overriden. It receives the state
        /// entry, and must make a new transition directly.
        /// </summary>
        /// <param name="stateEntry"></param>
        /// <returns></returns>
        protected abstract Transition CreatePseudoStateTransition(StateEntry stateEntry);

        #endregion
    }

    /// <summary>
    /// Initial state is the first state to be entered in a state machine. There should only be one initial state, and 
    /// the state engine automatically enters that state at startup. It is a pseudo state so it must direclty transition to 
    /// another state. 
    /// 
    /// The class does not introduce any new behaviour from pseudostate, but marks that it is an intial state.
    /// </summary>
    abstract public class InitialState : PseudoState
    {

    }
}