/**
 * The connections between parent and child neurons.
 *
 * Contains the neurons which it connects, and the weights between them.
 *
 * @author Jeff Chen
 * @version %I%,%G%
 */
public class Edge{

	private Neuron parent;
	private Neuron child;
	private double weight;
	private double output;

	/**
	 * Creates the Edge with the specified parent and child Neurons.
	 *
	 * @param parent the parent Neuron
	 * @param child the child Neuron
	 */
	public Edge(Neuron parent, Neuron child){
	
		this.parent=parent;
		this.child=child;
	}

	/**
	 * Gets the child Neuron.
	 *
	 * @return the child Neuron
	 */
	public Neuron getChild(){
	
		return child;
	}

	/**
	 * Gets the output from the parent Neuron.
	 *
	 * @return the output from the parent Neuron
	 */
	public double getOutput(){
	
		return output;
	}
	
	/**
	 * Gets the parent Neuron.
	 *
	 * @return the parent Neuron
	 */
	public Neuron getParent(){
	
		return parent;
	}

	/**
	 * Gets the weight from the child Neuron to the parent Neuron.
	 *
	 * @return the weight from the child Neuron
	 */
	public double getWeight(){
	
		return weight;
	}

	/**
	 * Sets the child Neuron to the specified Neuron.
	 *
	 * @param child the new child Neuron
	 */
	public void setChild(Neuron child){
	
		this.child=child;
	}

	/**
	 * Sets the output from the parent Neuron.
	 *
	 * @param output the output from the parent Neuron
	 */
	public void setOutput(double output){
	
		this.output=output;
	}

	/**
	 * Sets the parent Neuron to the specified Neuron.
	 *
	 * @param parent the new parent Neuron
	 */
	public void setParent(Neuron parent){
	
		this.parent=parent;
	}

	/**
	 * Sets the weight from the child Neuron.
	 * 
	 * This weight is the weight from the child Neuron to the parent Neuron, 
	 * and should be updated every time the weights in the child are changed, 
	 * for fast and accurate lookup while training the neural network.
	 *
	 * @param weight the weight from the child Neuron to the parent Neuron
	 */
	public void setWeight(double weight){
	
		this.weight=weight;
	}
}