org.apache.cayenne.commitlog.model.MutableChangeMap Maven / Gradle / Ivy

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package org.apache.cayenne.commitlog.model;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;

import org.apache.cayenne.ObjectId;

/**
 * A mutable implementation of {@link ChangeMap}.
 * 
 * @since 4.0
 */
public class MutableChangeMap implements ChangeMap {

	private Map changes;

	public MutableObjectChange getOrCreate(ObjectId id, ObjectChangeType type) {
		MutableObjectChange changeSet = getOrCreate(id);
		changeSet.setType(type);
		return changeSet;
	}

	private MutableObjectChange getOrCreate(ObjectId id) {

		MutableObjectChange objectChange = changes != null ? changes.get(id) : null;

		if (objectChange == null) {

			if (changes == null) {
				changes = new HashMap<>();
			}

			objectChange = new MutableObjectChange(id);
			changes.put(id, objectChange);
		}

		return objectChange;
	}

	public MutableObjectChange aliasId(ObjectId preCommitId, ObjectId postCommitId) {
		MutableObjectChange changeSet = getOrCreate(preCommitId);
		changeSet.setPostCommitId(postCommitId);
		changes.put(postCommitId, changeSet);
		return changeSet;
	}

	@Override
	public Collection getUniqueChanges() {
		// ensure distinct change set
		return changes == null ? Collections. emptySet() : new HashSet<>(changes.values());
	}

	@Override
	public Map getChanges() {
		return changes == null ? Collections. emptyMap() : changes;
	}
}