FTC Programming with ElectronVolts

StateMachine is responsible for managing the linkage of the states while running. It is usually created from a StateMachineBuilder. To run it, call the act() method each time through the loop. This will have the current State act and then determine the next State based on what the current State returned. For debugging, you can call getCurrentStateName() each time in the loop and store it to a file or display it on the telemetry.

ftc/electronvolts/statemachine/StateMachine.java

package ftc.electronvolts.statemachine;

import java.util.Map;

/**
 * This file was made by the electronVolts, FTC team 7393
 *
 * This class uses the stateMap made by the stateMachineBuilder to run the
 * states and perform the transitions between them
 */
public class StateMachine {
    // This links the names of each state to the actual state
    private final Map<StateName, State> stateMap;
    
    // the current active state
    private State currentState;
    
    // the name of the current state
    private StateName currentStateName;

    /**
     * @param stateMap the state machine structure
     * @param firstStateName the name of the state to start with
     */
    public StateMachine(Map<StateName, State> stateMap, StateName firstStateName) {
        this.stateMap = stateMap;
        currentStateName = firstStateName;
        currentState = stateMap.get(firstStateName);
        // if the stateMap does not have the firstStateName as a key, there is
        // no way to fix it here
    }

    /**
     * call this each time through the loop
     * It runs the current state, then looks up the next state based on the name
     * given by the current state.
     */
    public void act() {
        // tell the current state to act and return the next state
        StateName nextStateName = currentState.act();
        // if the next state name returned is null or the same as this state,
        // stay in the current state
        if (nextStateName != null && nextStateName != currentStateName) {
            // if the state requested exists
            if (stateMap.containsKey(nextStateName)) {
                // update the current state
                currentStateName = nextStateName;
                currentState = stateMap.get(currentStateName);
            }
        }
    }

    /**
     * used for telemetry purposes
     *
     * @return the name of the current state
     */
    public StateName getCurrentStateName() {
        return currentStateName;
    }
}