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Setting up a State Machine

This guide will walk you through the setup process for creating and managing state machines using the StateNet library. We’ll cover:

  1. Using the Factory method to define states.
  2. Creating transitions between states.
  3. Setting up state-specific events.

1. Initializing with the Factory Method​

To start building a state machine, use the Factory method provided by the StateMachine class. The Factory method accepts a machine builder (mb), which is an instance of MutableStateMachine. We'll explain MutableStateMachine in detail later, but for now, understand that mb is used to define and organize your machine’s states.

Example:

string initialState = "..."; // <- We will define this later

var machineBlueprint = StateMachine<string, string, string>.Factory((mb) => {
    // Define states here
}, initialState);

Notice that the Factory<S, A, C> Method accepts three generic types.

  • S: defines the states type.
  • A: defines the actions type.
  • C: defines the context type.

In the following examples both types will be set to string, but you can use whatever type you like (it is recommended to use enum values).

Adding states​

Inside the Factory method, use mb.AddState to define each state in your state machine. For instance:

string initialState = "IDLE"; // Initial state must be a defined state (see below)

var machineBlueprint = StateMachine<string, string, string>.Factory((mb) => {
    // IDLE and RUNNING will be the state identifiers
    var idleState = mb.AddState("IDLE");
    var runningState = mb.AddState("RUNNING");
}, initialState);

2. Creating Transitions​

Transitions determine the paths between states. They consist of a origin state, the action that should be triggered to initiate transition, and the target state.

Example:

string initialState = "IDLE";

var machineBlueprint = StateMachine<string, string, string>.Factory((mb) => {
    var idleState = mb.AddState("IDLE");
    var runningState = mb.AddState("RUNNING");

    // The first parameter represents the action that triggers a change to the state from a defined state
    idleState.AddTransition("start", "RUNNING"); // When "start" is triggered while the machine is on "IDLE" state it will transition to "RUNNING"
    runningState.AddTransition("stop", "IDLE");
}, initialState);

3. Setting Up Events​

Events in StateNet allow you to perform actions whenever the state machine enters a state.

Example:

string initialState = "IDLE";

var machineBlueprint = StateMachine<string, string, string>.Factory((mb) => {
    var idleState = mb.AddState("IDLE");
    var runningState = mb.AddState("RUNNING");

    idleState.AddTransition("start", "RUNNING");
    runningState.AddTransition("stop", "IDLE");

    // On enter IDLE state
    idleState.OnState((info) => {
        Console.WriteLine($"Entered IDLE state from {info.FromState}");
    });

    // On enter RUNNING state
    runningState.OnState((info) => {
        Console.WriteLine($"Entered RUNNING state from {info.FromState}")
    });
}, initialState);

In this example, the OnState method defines an action that will be triggered each time the machine enters a specified state.