content: package org.apache.lucene.queryparser.flexible.aqp.util;
  
  /*
   * 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.
   */
  
  import org.apache.lucene.analysis.Analyzer;
  import org.apache.lucene.queryparser.flexible.aqp.AqpQueryParser;
  import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
  import org.apache.lucene.search.BooleanClause;
  import org.apache.lucene.search.BooleanQuery;
  import org.apache.lucene.search.BooleanQuery.Builder;
  import org.apache.lucene.search.Query;
  
  /**
   * This class defines utility methods to (help) parse query strings into
   * {@link Query} objects.
   */
  final public class AqpQueryParserUtil {
  
      /**
       * Parses a query which searches on the fields specified.
       * <p>
       * If x fields are specified, this effectively constructs:
       *
       * <pre>
       * &lt;code&gt;
       * (field1:query1) (field2:query2) (field3:query3)...(fieldx:queryx)
       * &lt;/code&gt;
       * </pre>
       *
       * @param qp      Analyzer to use
       * @param queries Queries strings to parse
       * @param fields  Fields to search on
       * @throws IllegalArgumentException if the length of the queries array differs from the length of the
       *                                  fields array
       */
      public static Query parse(AqpQueryParser qp, String[] queries, String[] fields)
              throws QueryNodeException {
          if (queries.length != fields.length)
              throw new IllegalArgumentException("queries.length != fields.length");
          Builder bQuery = new BooleanQuery.Builder();
  
          for (int i = 0; i < fields.length; i++) {
              Query q = qp.parse(queries[i], fields[i]);
  
              if (q != null && // q never null, just being defensive
                      (!(q instanceof BooleanQuery) || ((BooleanQuery) q).clauses().size() > 0)) {
                  bQuery.add(q, BooleanClause.Occur.SHOULD);
              }
          }
          return bQuery.build();
      }
  
      /**
       * Parses a query, searching on the fields specified. Use this if you need to
       * specify certain fields as required, and others as prohibited.
       *
       * <pre>
       * Usage:
       * &lt;code&gt;
       * String[] fields = {&quot;filename&quot;, &quot;contents&quot;, &quot;description&quot;};
       * BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
       *                BooleanClause.Occur.MUST,
       *                BooleanClause.Occur.MUST_NOT};
       * MultiFieldQueryParser.parse(&quot;query&quot;, fields, flags, analyzer);
       * &lt;/code&gt;
       * </pre>
       * <p>
       * The code above would construct a query:
       *
       * <pre>
       * &lt;code&gt;
       * (filename:query) +(contents:query) -(description:query)
       * &lt;/code&gt;
       * </pre>
       *
       * @param query    Query string to parse
       * @param fields   Fields to search on
       * @param flags    Flags describing the fields
       * @param analyzer Analyzer to use
       * @throws IllegalArgumentException if the length of the fields array differs from the length of the
       *                                  flags array
       */
      public static Query parse(AqpQueryParser qp, String query, String[] fields,
                                BooleanClause.Occur[] flags, Analyzer analyzer) throws QueryNodeException {
          if (fields.length != flags.length)
              throw new IllegalArgumentException("fields.length != flags.length");
          Builder bQuery = new BooleanQuery.Builder();
  
          for (int i = 0; i < fields.length; i++) {
              Query q = qp.parse(query, fields[i]);
  
              if (q != null && // q never null, just being defensive
                      (!(q instanceof BooleanQuery) || ((BooleanQuery) q).clauses().size() > 0)) {
                  bQuery.add(q, flags[i]);
              }
          }
          return bQuery.build();
      }
  
      /**
       * Parses a query, searching on the fields specified. Use this if you need to
       * specify certain fields as required, and others as prohibited.
       *
       * <pre>
       * Usage:
       * &lt;code&gt;
       * String[] query = {&quot;query1&quot;, &quot;query2&quot;, &quot;query3&quot;};
       * String[] fields = {&quot;filename&quot;, &quot;contents&quot;, &quot;description&quot;};
       * BooleanClause.Occur[] flags = {BooleanClause.Occur.SHOULD,
       *                BooleanClause.Occur.MUST,
       *                BooleanClause.Occur.MUST_NOT};
       * MultiFieldQueryParser.parse(query, fields, flags, analyzer);
       * &lt;/code&gt;
       * </pre>
       * <p>
       * The code above would construct a query:
       *
       * <pre>
       * &lt;code&gt;
       * (filename:query1) +(contents:query2) -(description:query3)
       * &lt;/code&gt;
       * </pre>
       *
       * @param queries  Queries string to parse
       * @param fields   Fields to search on
       * @param flags    Flags describing the fields
       * @param analyzer Analyzer to use
       * @throws IllegalArgumentException if the length of the queries, fields, and flags array differ
       */
      public static Query parse(AqpQueryParser qp, String[] queries,
                                String[] fields, BooleanClause.Occur[] flags, Analyzer analyzer)
              throws QueryNodeException {
          if (!(queries.length == fields.length && queries.length == flags.length))
              throw new IllegalArgumentException(
                      "queries, fields, and flags array have have different length");
          Builder bQuery = new BooleanQuery.Builder();
  
          for (int i = 0; i < fields.length; i++) {
              Query q = qp.parse(queries[i], fields[i]);
  
              if (q != null && // q never null, just being defensive
                      (!(q instanceof BooleanQuery) || ((BooleanQuery) q).clauses().size() > 0)) {
                  bQuery.add(q, flags[i]);
              }
          }
          return bQuery.build();
      }
  
      /**
       * Returns a String where those characters that TextParser expects to be
       * escaped are escaped by a preceding <code>\</code>.
       */
      public static String escape(String s) {
          StringBuilder sb = new StringBuilder();
          for (int i = 0; i < s.length(); i++) {
              char c = s.charAt(i);
              // These characters are part of the query syntax and must be escaped
              if (c == '\\' || c == '+' || c == '-' || c == '!' || c == '(' || c == ')' || c == ':'
                      || c == '^' || c == '[' || c == ']' || c == '\"' || c == '{' || c == '}' || c == '~'
                      || c == '*' || c == '?' || c == '|' || c == '&') {
                  sb.append('\\');
              }
              sb.append(c);
          }
          return sb.toString();
      }
  
  }
  