109 lines
3.9 KiB
C#
109 lines
3.9 KiB
C#
#nullable enable
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using System;
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using System.Runtime.CompilerServices;
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/// <summary>
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/// Base context for an FSM.
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/// MUST inherit from imm.Recorded<TSelf> or Timed<TSelf> in your concrete class.
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/// </summary>
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/// <typeparam name="TSelf">The concrete Context type.</typeparam>
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public abstract record class FsmContextBase<TSelf> : imm.Recorded<TSelf>
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where TSelf : FsmContextBase<TSelf>
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{
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// Required for 'with' expressions.
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protected FsmContextBase(imm.Recorded<TSelf> original) : base(original) { }
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protected FsmContextBase() { }
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}
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/// <summary>
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/// Base state for an FSM.
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/// MUST inherit from imm.Recorded<TSelf> or Timed<TSelf> in your concrete class.
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/// </summary>
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/// <typeparam name="TSelf">The concrete State type.</typeparam>
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/// <typeparam name="TCtx">The concrete Context type (must be based on FsmContextBase).</typeparam>
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public abstract record class FsmStateBase<TSelf, TCtx> : imm.Recorded<TSelf>
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where TSelf : FsmStateBase<TSelf, TCtx>
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where TCtx : FsmContextBase<TCtx>
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{
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/// <summary>
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/// Called when entering this state.
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/// </summary>
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public virtual (TCtx Context, TSelf State) OnEnter(TCtx context, FsmStateBase<TSelf, TCtx> oldState)
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{
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return (context, (TSelf)this);
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}
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/// <summary>
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/// Called when exiting this state.
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/// </summary>
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public virtual (TCtx Context, TSelf State) OnExit(TCtx context, FsmStateBase<TSelf, TCtx> newState)
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{
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return (context, (TSelf)this);
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}
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// Required for 'with' expressions.
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protected FsmStateBase(imm.Recorded<TSelf> original) : base(original) { }
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protected FsmStateBase() { }
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}
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/// <summary>
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/// An immutable FSM base class.
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/// MUST inherit from imm.Recorded<TSelf> or Timed<TSelf> in your concrete class.
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/// </summary>
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/// <typeparam name="TSelf">The concrete FSM type.</typeparam>
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/// <typeparam name="TState">The concrete State type.</typeparam>
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/// <typeparam name="TCtx">The concrete Context type.</typeparam>
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public abstract record class FsmBase<TSelf, TState, TCtx> : imm.Recorded<TSelf>
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where TSelf : FsmBase<TSelf, TState, TCtx>
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where TState : FsmStateBase<TState, TCtx>
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where TCtx : FsmContextBase<TCtx>
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{
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public TCtx Context { get; init; }
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public TState State { get; init; }
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protected FsmBase(TCtx initialContext, TState initialState)
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{
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Context = initialContext;
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State = initialState;
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}
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// Required for 'with' expressions.
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protected FsmBase(imm.Recorded<TSelf> original) : base(original)
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{
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var o = original as FsmBase<TSelf, TState, TCtx>;
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Context = o!.Context;
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State = o!.State;
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}
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/// <summary>
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/// Transitions the FSM. It automatically uses the 'Process'
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/// method appropriate for imm.Recorded or Timed, thanks to virtual overrides.
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/// </summary>
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public TSelf Transition(
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TState newState,
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string reason,
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[CallerMemberName] string memberName = "",
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[CallerFilePath] string filePath = "",
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[CallerLineNumber] int lineNumber = 0,
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[CallerArgumentExpression("newState")] string expression = "")
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{
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Console.WriteLine($"[FSM] Transition: {State.GetType().Name} -> {newState.GetType().Name}. Reason: {reason}");
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var (ctxAfterExit, stateAfterExit) = State.OnExit(Context, newState);
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var (ctxAfterEnter, stateAfterEnter) = newState.OnEnter(ctxAfterExit, stateAfterExit);
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// Since 'this' is at least 'imm.Recorded<TSelf>', we can call the
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// detailed 'Process'. If 'this' is actually 'Timed<TSelf>', C#'s
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// virtual dispatch will call the 'Timed' override automatically.
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return Process(
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fsm => (TSelf)fsm with
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{
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Context = ctxAfterEnter,
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State = stateAfterEnter
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},
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$"Transition to {newState.GetType().Name}: {reason}",
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memberName, filePath, lineNumber, expression
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);
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}
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} |