EntityRefProperty.java

package rescuecore2.worldmodel.properties;

import static rescuecore2.misc.EncodingTools.readInt32;
import static rescuecore2.misc.EncodingTools.writeInt32;

import rescuecore2.worldmodel.EntityID;
import rescuecore2.worldmodel.Property;
import rescuecore2.worldmodel.AbstractProperty;

import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;

/**
   A property that refers to an entity ID.
 */
public class EntityRefProperty extends AbstractProperty {
    private EntityID value;

    /**
       Construct an EntityRefProperty with no defined value.
       @param urn The urn of this property.
    */
    public EntityRefProperty(String urn) {
        super(urn);
    }

    /**
       Construct an EntityRefProperty with no defined value.
       @param urn The urn of this property.
    */
    public EntityRefProperty(Enum<?> urn) {
        super(urn);
    }

    /**
       Construct an EntityRefProperty with a defined value.
       @param urn The urn of this property.
       @param value The initial value of the property.
    */
    public EntityRefProperty(String urn, EntityID value) {
        super(urn, true);
        this.value = value;
    }

    /**
       Construct an EntityRefProperty with a defined value.
       @param urn The urn of this property.
       @param value The initial value of the property.
    */
    public EntityRefProperty(Enum<?> urn, EntityID value) {
        super(urn, true);
        this.value = value;
    }

    /**
       EntityRefProperty copy constructor.
       @param other The EntityRefProperty to copy.
     */
    public EntityRefProperty(EntityRefProperty other) {
        super(other);
        this.value = other.value;
    }

    @Override
    public EntityID getValue() {
        if (!isDefined()) {
            return null;
        }
        return value;
    }

    /**
       Set the value of this property. Future calls to {@link #isDefined()} will return true.
       @param value The new value.
    */
    public void setValue(EntityID value) {
        EntityID old = this.value;
        boolean wasDefined = isDefined();
        this.value = value;
        setDefined();
        if (!wasDefined || !old.equals(value)) {
            fireChange(old, value);
        }
    }

    @Override
    public void takeValue(Property p) {
        if (p instanceof EntityRefProperty) {
            EntityRefProperty e = (EntityRefProperty)p;
            if (e.isDefined()) {
                setValue(e.getValue());
            }
            else {
                undefine();
            }
        }
        else {
            throw new IllegalArgumentException(this + " cannot take value from " + p);
        }
    }

    @Override
    public void write(OutputStream out) throws IOException {
        writeInt32(value.getValue(), out);
    }

    @Override
    public void read(InputStream in) throws IOException {
        setValue(new EntityID(readInt32(in)));
    }

    @Override
    public EntityRefProperty copy() {
        return new EntityRefProperty(this);
    }
}