UpdatePropagationLatch.java

package org.robobinding.viewattribute.property;

/**
 * 
 * @since 1.0
 * @version $Revision: 1.0 $
 * @author Cheng Wei
 */
public class UpdatePropagationLatch {
	private State state;

	public UpdatePropagationLatch() {
		state = State.NEUTRAL;
	}

	public void turnOn() {
		state = State.LOCKED;
	}

	public void turnOff() {
		state = State.NEUTRAL;
	}

	public boolean tryToPass() {
		boolean isPassible = state.isPassible();
		state = state.getNextState();
		return isPassible;
	}

	private static enum State {
		NEUTRAL {
			@Override
			public boolean isPassible() {
				return true;
			}

			@Override
			public State getNextState() {
				return NEUTRAL;
			}

		},

		LOCKED {
			@Override
			public boolean isPassible() {
				return false;
			}

			@Override
			public State getNextState() {
				return UNLOCKED;
			}

		},

		UNLOCKED {
			@Override
			public boolean isPassible() {
				return true;
			}

			@Override
			public State getNextState() {
				return UNLOCKED;
			}

		};

		public abstract boolean isPassible();

		public abstract State getNextState();

	}
}