org.apache.solr.highlight.SolrHighlighter.java Source code

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Here is the source code for org.apache.solr.highlight.SolrHighlighter.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.solr.highlight;

import org.apache.lucene.search.Query;
import org.apache.solr.common.params.CommonParams;
import org.apache.solr.common.params.HighlightParams;
import org.apache.solr.common.params.SolrParams;
import org.apache.solr.common.util.NamedList;
import org.apache.solr.request.SolrQueryRequest;
import org.apache.solr.search.DocList;
import org.apache.solr.util.SolrPluginUtils;

import java.io.IOException;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Set;

public abstract class SolrHighlighter {

    public static int DEFAULT_MAX_CHARS = 51200;
    public static int DEFAULT_PHRASE_LIMIT = 5000;

    /**
     * Check whether Highlighting is enabled for this request.
     * @param params The params controlling Highlighting
     * @return <code>true</code> if highlighting enabled, <code>false</code> if not.
     */
    public boolean isHighlightingEnabled(SolrParams params) {
        return params.getBool(HighlightParams.HIGHLIGHT, false);
    }

    /**
     * Return a String array of the fields to be highlighted.
     * Falls back to the programmatic defaults, or the default search field if the list of fields
     * is not specified in either the handler configuration or the request.
     * @param query The current Query
     * @param request The current SolrQueryRequest
     * @param defaultFields Programmatic default highlight fields, used if nothing is specified in the handler config or the request.
     */
    public String[] getHighlightFields(Query query, SolrQueryRequest request, String[] defaultFields) {
        String fields[] = request.getParams().getParams(HighlightParams.FIELDS);

        // if no fields specified in the request, or the handler, fall back to programmatic default, or default search field.
        if (emptyArray(fields)) {
            // use default search field from request if highlight fieldlist not specified.
            if (emptyArray(defaultFields)) {
                String defaultSearchField = request.getParams().get(CommonParams.DF);
                fields = null == defaultSearchField ? new String[] {} : new String[] { defaultSearchField };
            } else {
                fields = defaultFields;
            }
        } else {
            Set<String> expandedFields = new LinkedHashSet<String>();
            Collection<String> storedHighlightFieldNames = request.getSearcher().getDocFetcher()
                    .getStoredHighlightFieldNames();
            for (String field : fields) {
                expandWildcardsInHighlightFields(expandedFields, storedHighlightFieldNames,
                        SolrPluginUtils.split(field));
            }
            fields = expandedFields.toArray(new String[] {});
        }

        // Trim them now in case they haven't been yet.  Not needed for all code-paths above but do it here.
        for (int i = 0; i < fields.length; i++) {
            fields[i] = fields[i].trim();
        }
        return fields;
    }

    protected boolean emptyArray(String[] arr) {
        return (arr == null || arr.length == 0 || arr[0] == null || arr[0].trim().length() == 0);
    }

    static private void expandWildcardsInHighlightFields(Set<String> expandedFields,
            Collection<String> storedHighlightFieldNames, String... fields) {
        for (String field : fields) {
            if (field.contains("*")) {
                // create a Java regular expression from the wildcard string
                String fieldRegex = field.replaceAll("\\*", ".*");
                for (String storedFieldName : storedHighlightFieldNames) {
                    if (storedFieldName.matches(fieldRegex)) {
                        expandedFields.add(storedFieldName);
                    }
                }
            } else {
                expandedFields.add(field);
            }
        }
    }

    /**
     * Generates a list of Highlighted query fragments for each item in a list
     * of documents, or returns null if highlighting is disabled.
     *
     * @param docs query results
     * @param query the query
     * @param req the current request
     * @param defaultFields default list of fields to summarize
     *
     * @return NamedList containing a NamedList for each document, which in
     * turns contains sets (field, summary) pairs.
     */
    @SuppressWarnings("unchecked")
    public abstract NamedList<Object> doHighlighting(DocList docs, Query query, SolrQueryRequest req,
            String[] defaultFields) throws IOException;
}