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Fork of LuaJ with added serialization support

There is a newer version: 3.4.3

package nl.weeaboo.lua2.io;

import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Map;

/**
 * 'External' environment used by {@link ObjectSerializer}. When serializing an object stored in the
 * environment, instead the object's id is stored. During deserialization, the id is used to retrieve the
 * object from the environment again.
 */
public final class Environment {

    private final Map idObjMap = new HashMap<>();
    private final IdentityHashMap objIdMap = new IdentityHashMap<>();

    /**
     * Adds a named object to the environment. A particular object instance may only have one name.
     */
    public void add(String id, Object object) {
        if (id == null) {
            throw new IllegalArgumentException("Id may not be null");
        }
        if (object == null) {
            throw new IllegalArgumentException("Object may not be null");
        }

        remove(id, object);

        idObjMap.put(id, object);
        objIdMap.put(object, id);
    }

    /**
     * Removes a named object from the environment.
     */
    public void remove(String id, Object obj) {
        idObjMap.remove(id);
        objIdMap.remove(obj);
    }

    /**
     * Returns the named object with the given ID, or {@code null} if not found.
     */
    public Object getObject(String id) {
        return idObjMap.get(id);
    }

    /**
     * Returns the identifier
     */
    public String getId(Object obj) {
        return objIdMap.get(obj);
    }

    /**
     * The number of objects in the environment.
     */
    public int size() {
        return objIdMap.size();
    }

}