--- /dev/null
+package org.apache.lucene.facet.enhancements.association;
+
+import org.apache.lucene.facet.index.attributes.CategoryAttribute;
+import org.apache.lucene.facet.index.attributes.CategoryProperty;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * A {@link CategoryProperty} associating a single integer value to a
+ * {@link CategoryAttribute}. It should be used to describe the association
+ * between the category and the document.
+ * <p>
+ * This class leave to extending classes the definition of
+ * {@link #merge(CategoryProperty)} policy for the integer associations.
+ * <p>
+ * <B>Note:</B> The association value is added both to a special category list,
+ * and to the category tokens.
+ *
+ * @see AssociationEnhancement
+ * @lucene.experimental
+ */
+public abstract class AssociationProperty implements CategoryProperty {
+
+ protected long association = Integer.MAX_VALUE + 1;
+
+ /**
+ * Construct an {@link AssociationProperty}.
+ *
+ * @param value
+ * The association value.
+ */
+ public AssociationProperty(int value) {
+ this.association = value;
+ }
+
+ /**
+ * Returns the association value.
+ *
+ * @return The association value.
+ */
+ public int getAssociation() {
+ return (int) association;
+ }
+
+ /**
+ * Returns whether this attribute has been set (not all categories have an
+ * association).
+ */
+ public boolean hasBeenSet() {
+ return this.association <= Integer.MAX_VALUE;
+ }
+
+ @Override
+ public String toString() {
+ return getClass().getSimpleName() + ": " + association;
+ }
+
+}