更新:
再次感谢你的例子，它们对我很有帮助，我并不是说
夺走他们的一切。
Aren't the currently given examples, as far as I understand them & state-machines, only half of what we usually understand by a state-machine?
In the sense that the examples do change state but that's only represented by changing the value of a variable (and allowing different value- changes in different states), while usually, a state machine should also change its behavior, and behavior not (only) in the sense of allowing different value changes for a variable depending on the state, but in the sense of allowing different methods to be executed for different states.
还是我对状态机及其常用用法有误解?
最初的问题:
我发现了关于c#中的状态机和迭代器块的讨论，以及用于创建状态机和c#的工具，所以我发现了很多抽象的东西，但作为一个新手，所有这些都有点令人困惑。
因此，如果有人能提供一个c#源代码-示例，实现一个简单的状态机，可能只有3,4个状态，那就太好了，只是为了了解它的要点。
我推荐state.cs。我个人使用state.js (JavaScript版本)，并且非常满意。c#版本以类似的方式工作。
你实例化状态:
// create the state machine
var player = new StateMachine<State>( "player" );
// create some states
var initial = player.CreatePseudoState( "initial", PseudoStateKind.Initial );
var operational = player.CreateCompositeState( "operational" );
...
你实例化了一些转换:
var t0 = player.CreateTransition( initial, operational );
player.CreateTransition( history, stopped );
player.CreateTransition<String>( stopped, running, ( state, command ) => command.Equals( "play" ) );
player.CreateTransition<String>( active, stopped, ( state, command ) => command.Equals( "stop" ) );
在状态和转场上定义动作:
t0.Effect += DisengageHead;
t0.Effect += StopMotor;
差不多就是这样了。更多信息请查看网站。
您可以编写一个迭代器块，使您能够以编排的方式执行代码块。代码块是如何分解的并不一定要对应于任何东西，这只是你想要如何编码它。例如:
IEnumerable<int> CountToTen()
{
System.Console.WriteLine("1");
yield return 0;
System.Console.WriteLine("2");
System.Console.WriteLine("3");
System.Console.WriteLine("4");
yield return 0;
System.Console.WriteLine("5");
System.Console.WriteLine("6");
System.Console.WriteLine("7");
yield return 0;
System.Console.WriteLine("8");
yield return 0;
System.Console.WriteLine("9");
System.Console.WriteLine("10");
}
在本例中，当调用CountToTen时，还没有实际执行任何东西。您得到的实际上是一个状态机生成器，您可以为它创建一个状态机的新实例。可以通过调用GetEnumerator()来实现。生成的IEnumerator实际上是一个状态机，您可以通过调用MoveNext(…)来驱动它。
因此，在本例中，第一次调用MoveNext(…)时，您将看到“1”写入控制台，下一次调用MoveNext(…)时，您将看到2、3、4，然后是5、6、7、8，然后是9、10。正如您所看到的，这是一种编排事情应该如何发生的有用机制。
让我们从这个简单的状态图开始:
我们有:
4种状态(非活动、活动、暂停和退出)
5种状态转换(开始命令，结束命令，暂停命令，恢复命令，退出命令)。
您可以通过几种方式将其转换为c#，例如在当前状态和命令上执行switch语句，或者在转换表中查找转换。对于这个简单的状态机，我更喜欢一个转换表，它很容易使用Dictionary表示:
using System;
using System.Collections.Generic;
namespace Juliet
{
public enum ProcessState
{
Inactive,
Active,
Paused,
Terminated
}
public enum Command
{
Begin,
End,
Pause,
Resume,
Exit
}
public class Process
{
class StateTransition
{
readonly ProcessState CurrentState;
readonly Command Command;
public StateTransition(ProcessState currentState, Command command)
{
CurrentState = currentState;
Command = command;
}
public override int GetHashCode()
{
return 17 + 31 * CurrentState.GetHashCode() + 31 * Command.GetHashCode();
}
public override bool Equals(object obj)
{
StateTransition other = obj as StateTransition;
return other != null && this.CurrentState == other.CurrentState && this.Command == other.Command;
}
}
Dictionary<StateTransition, ProcessState> transitions;
public ProcessState CurrentState { get; private set; }
public Process()
{
CurrentState = ProcessState.Inactive;
transitions = new Dictionary<StateTransition, ProcessState>
{
{ new StateTransition(ProcessState.Inactive, Command.Exit), ProcessState.Terminated },
{ new StateTransition(ProcessState.Inactive, Command.Begin), ProcessState.Active },
{ new StateTransition(ProcessState.Active, Command.End), ProcessState.Inactive },
{ new StateTransition(ProcessState.Active, Command.Pause), ProcessState.Paused },
{ new StateTransition(ProcessState.Paused, Command.End), ProcessState.Inactive },
{ new StateTransition(ProcessState.Paused, Command.Resume), ProcessState.Active }
};
}
public ProcessState GetNext(Command command)
{
StateTransition transition = new StateTransition(CurrentState, command);
ProcessState nextState;
if (!transitions.TryGetValue(transition, out nextState))
throw new Exception("Invalid transition: " + CurrentState + " -> " + command);
return nextState;
}
public ProcessState MoveNext(Command command)
{
CurrentState = GetNext(command);
return CurrentState;
}
}
public class Program
{
static void Main(string[] args)
{
Process p = new Process();
Console.WriteLine("Current State = " + p.CurrentState);
Console.WriteLine("Command.Begin: Current State = " + p.MoveNext(Command.Begin));
Console.WriteLine("Command.Pause: Current State = " + p.MoveNext(Command.Pause));
Console.WriteLine("Command.End: Current State = " + p.MoveNext(Command.End));
Console.WriteLine("Command.Exit: Current State = " + p.MoveNext(Command.Exit));
Console.ReadLine();
}
}
}
根据个人喜好，我喜欢用GetNext函数来确定地返回下一个状态，用MoveNext函数来改变状态机。
