org.apache.lucene.facet.FacetField.java Source code

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Here is the source code for org.apache.lucene.facet.FacetField.java

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/*
 * 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.
 */
package org.apache.lucene.facet;

import java.util.Arrays;

import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.index.IndexOptions;

/**
 * Add an instance of this to your {@link Document} for every facet label.
 * 
 * <p>
 * <b>NOTE:</b> you must call {@link FacetsConfig#build(Document)} before
 * you add the document to IndexWriter.
 */
public class FacetField extends Field {

    /** Field type used for storing facet values: docs, freqs, and positions. */
    public static final FieldType TYPE = new FieldType();
    static {
        TYPE.setIndexOptions(IndexOptions.DOCS_AND_FREQS_AND_POSITIONS);
        TYPE.freeze();
    }

    /** Dimension for this field. */
    public final String dim;

    /** Path for this field. */
    public final String[] path;

    /** Creates the this from {@code dim} and
     *  {@code path}. */
    public FacetField(String dim, String... path) {
        super("dummy", TYPE);
        verifyLabel(dim);
        for (String label : path) {
            verifyLabel(label);
        }
        this.dim = dim;
        if (path.length == 0) {
            throw new IllegalArgumentException("path must have at least one element");
        }
        this.path = path;
    }

    @Override
    public String toString() {
        return "FacetField(dim=" + dim + " path=" + Arrays.toString(path) + ")";
    }

    /** Verifies the label is not null or empty string.
     * 
     *  @lucene.internal */
    public static void verifyLabel(String label) {
        if (label == null || label.isEmpty()) {
            throw new IllegalArgumentException("empty or null components not allowed; got: " + label);
        }
    }
}