content: package org.apache.lucene.search;
  
  /**
   * 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 clause in a BooleanQuery. */
  public class BooleanClause implements java.io.Serializable {
    
    /** Specifies how clauses are to occur in matching documents. */
    public static enum Occur {
  
      /** Use this operator for clauses that <i>must</i> appear in the matching documents. */
      MUST     { @Override public String toString() { return "+"; } },
  
      /** Use this operator for clauses that <i>should</i> appear in the 
       * matching documents. For a BooleanQuery with no <code>MUST</code> 
       * clauses one or more <code>SHOULD</code> clauses must match a document 
       * for the BooleanQuery to match.
       * @see BooleanQuery#setMinimumNumberShouldMatch
       */
      SHOULD   { @Override public String toString() { return "";  } },
  
      /** Use this operator for clauses that <i>must not</i> appear in the matching documents.
       * Note that it is not possible to search for queries that only consist
       * of a <code>MUST_NOT</code> clause. */
      MUST_NOT { @Override public String toString() { return "-"; } };
  
    }
  
    /** The query whose matching documents are combined by the boolean query.
     */
    private Query query;
  
    private Occur occur;
  
  
    /** Constructs a BooleanClause.
    */ 
    public BooleanClause(Query query, Occur occur) {
      this.query = query;
      this.occur = occur;
      
    }
  
    public Occur getOccur() {
      return occur;
    }
  
    public void setOccur(Occur occur) {
      this.occur = occur;
  
    }
  
    public Query getQuery() {
      return query;
    }
  
    public void setQuery(Query query) {
      this.query = query;
    }
    
    public boolean isProhibited() {
      return Occur.MUST_NOT == occur;
    }
  
    public boolean isRequired() {
      return Occur.MUST == occur;
    }
  
  
  
    /** Returns true if <code>o</code> is equal to this. */
    @Override
    public boolean equals(Object o) {
      if (o == null || !(o instanceof BooleanClause))
        return false;
      BooleanClause other = (BooleanClause)o;
      return this.query.equals(other.query)
        && this.occur == other.occur;
    }
  
    /** Returns a hash code value for this object.*/
    @Override
    public int hashCode() {
      return query.hashCode() ^ (Occur.MUST == occur?1:0) ^ (Occur.MUST_NOT == occur?2:0);
    }
  
  
    @Override
    public String toString() {
      return occur.toString() + query.toString();
    }
  }
  