Reference.java

/*
 * Copyright (c) 2011 Derek Murray <Derek.Murray@cl.cam.ac.uk>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

package com.asgow.ciel.references;

import java.io.Serializable;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;


public abstract class Reference implements Serializable {

	private String id;
	
	protected Reference (String id) {
		this.id = id;
	}
	
	public String getId() {
		return this.id;
	}
	
	abstract public boolean isConsumable();
	
	public abstract JsonObject toJson();
	
	public static Reference fromJson(JsonObject jsonRef) {
		JsonArray refTuple = jsonRef.get("__ref__").getAsJsonArray();
		switch (JsonReferenceType.fromString(refTuple.get(0).getAsString())) {
		case CONCRETE:
			return new ConcreteReference(refTuple);
		case FUTURE:
			return new FutureReference(refTuple);
		case STREAM:
			return new StreamReference(refTuple);
		case SWEETHEART:
			return new SweetheartReference(refTuple);
		case VALUE:
			return new ValueReference(refTuple);
		case COMPLETED:
			return new CompletedReference(refTuple);
		default:
			throw new UnsupportedOperationException("Cannot handle references of type: " + refTuple.get(0).getAsString());
		}
	}
	
	protected static JsonObject wrapAsReference(JsonElement refTuple) {
		JsonObject ret = new JsonObject();
		ret.add("__ref__", refTuple);
		return ret;
	}
	
}