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The OpenTripPlanner multimodal journey planning system
There is a newer version: 2.5.0
package org.opentripplanner.routing.graph;

import java.util.Objects;
import org.locationtech.jts.geom.LineString;
import org.opentripplanner.model.Trip;
import org.opentripplanner.routing.core.State;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import org.opentripplanner.util.I18NString;

/**
 * This is the standard implementation of an edge with fixed from and to Vertex instances;
 * all standard OTP edges are subclasses of this.
 */
public abstract class Edge implements Serializable {

    private static final long serialVersionUID = 1L;

    protected Vertex fromv;

    protected Vertex tov;

    protected Edge(Vertex v1, Vertex v2) {
        if (v1 == null || v2 == null) {
            String err = String.format("%s constructed with null vertex : %s %s", this.getClass(),
                    v1, v2);
            throw new IllegalStateException(err);
        }
        this.fromv = v1;
        this.tov = v2;
        fromv.addOutgoing(this);
        tov.addIncoming(this);
    }

    public Vertex getFromVertex() {
        return fromv;
    }

    public Vertex getToVertex() {
        return tov;
    }
    
    /**
     * Returns true if this edge is partial - overriden by subclasses.
     */
    public boolean isPartial() {
        return false;
    }
    
    /**
     * Checks equivalency to another edge. Default implementation is trivial equality, but subclasses may want to do something more tricky.
     */
    public boolean isEquivalentTo(Edge e) {
        return this == e;
    }
    
    /**
     * Returns true if this edge is the reverse of another.
     */
    public boolean isReverseOf(Edge e) {
        return (this.getFromVertex() == e.getToVertex() &&
                this.getToVertex() == e.getFromVertex());
    }
    
    /**
     * Get a direction on paths where it matters, or null
     * 
     * @return
     */
    public String getDirection() {
        return null;
    }

    /**
     * This should only be called inside State; other methods should call
     * org.opentripplanner.routing.core.State.getBackTrip()
     * 
     * @author mattwigway
     */
    public Trip getTrip() {
        return null;
    }

    // Notes are now handled by State

    @Override
    public int hashCode() {
        return Objects.hash(fromv, tov);
    }

    /**
     * Edges are not roundabouts by default.
     */
    public boolean isRoundabout() {
        return false;
    }

    /**
     * Traverse this edge.
     *
     * @param s0 The State coming into the edge.
     * @return The State upon exiting the edge.
     */
    public abstract State traverse(State s0);

    /**
     * Returns the default name of the edge
     */
    public String getDefaultName() {
        I18NString name = getName();
        return name != null ? name.toString() : null;
    }

    /**
     * Returns the name of the edge
     */
    public abstract I18NString getName();

    // TODO Add comments about what a "bogus name" is.
    public boolean hasBogusName() {
        return false;
    }

    public String toString() {
        return String.format("%s (%s -> %s)", getClass().getName(), fromv, tov);
    }

    // The next few functions used to live in EdgeNarrative, which has now been
    // removed
    // @author mattwigway

    public LineString getGeometry() {
        return null;
    }

    public double getDistanceMeters() {
        return 0;
    }

    /**
     * The distance to walk adjusted for elevation and obstacles. This is used together
     * with the walking speed to find the actual walking transfer time. This plus
     * {@link #getDistanceIndependentTime()} is used to calculate the actual-transfer-time
     * given a walking speed.
     * 
     * Unit: meters. Default: 0.
     */
    public double getEffectiveWalkDistance(){
        return 0;
    }

    /**
     * This is the transfer time(duration) spent NOT moving like time in in elevators, escalators
     * and waiting on read light when crossing a street. This is used together with
     * {@link #getEffectiveWalkDistance()} to calculate the actual-transfer-time.
     * 
     * Unit: seconds. Default: 0.
     */
    public int getDistanceIndependentTime() {
        return 0;
    }

    /* SERIALIZATION */

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        // edge lists are transient, reconstruct them
        fromv.addOutgoing(this);
        tov.addIncoming(this);
    }

    private void writeObject(ObjectOutputStream out) throws IOException, ClassNotFoundException {
        if (fromv == null) {
            System.out.printf("fromv null %s \n", this);
        }
        if (tov == null) {
            System.out.printf("tov null %s \n", this);
        }
        out.defaultWriteObject();
    }
}