content: package org.apache.lucene.search.regex;
  
  /**
   * 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 java.util.regex.Pattern;
  
  /**
   * An implementation tying Java's built-in java.util.regex to RegexQuery.
   *
   * Note that because this implementation currently only returns null from
   * {@link #prefix} that queries using this implementation will enumerate and
   * attempt to {@link #match} each term for the specified field in the index.
   */
  public class JavaUtilRegexCapabilities implements RegexCapabilities {
    private Pattern pattern;
    private int flags = 0;
    
    // Define the optional flags from Pattern that can be used.
    // Do this here to keep Pattern contained within this class.
    
    public static final int FLAG_CANON_EQ = Pattern.CANON_EQ;
    public static final int FLAG_CASE_INSENSITIVE = Pattern.CASE_INSENSITIVE;
    public static final int FLAG_COMMENTS = Pattern.COMMENTS;
    public static final int FLAG_DOTALL = Pattern.DOTALL;
    public static final int FLAG_LITERAL = Pattern.LITERAL;
    public static final int FLAG_MULTILINE = Pattern.MULTILINE;
    public static final int FLAG_UNICODE_CASE = Pattern.UNICODE_CASE;
    public static final int FLAG_UNIX_LINES = Pattern.UNIX_LINES;
    
    /**
     * Default constructor that uses java.util.regex.Pattern 
     * with its default flags.
     */
    public JavaUtilRegexCapabilities()  {
      this.flags = 0;
    }
    
    /**
     * Constructor that allows for the modification of the flags that
     * the java.util.regex.Pattern will use to compile the regular expression.
     * This gives the user the ability to fine-tune how the regular expression 
     * to match the functionality that they need. 
     * The {@link java.util.regex.Pattern Pattern} class supports specifying 
     * these fields via the regular expression text itself, but this gives the caller
     * another option to modify the behavior. Useful in cases where the regular expression text
     * cannot be modified, or if doing so is undesired.
     * 
     * @param flags The flags that are ORed together.
     */
    public JavaUtilRegexCapabilities(int flags) {
      this.flags = flags;
    }
    
    public void compile(String pattern) {
      this.pattern = Pattern.compile(pattern, this.flags);
    }
  
    public boolean match(String string) {
      return pattern.matcher(string).matches();
    }
  
    public String prefix() {
      return null;
    }
  
    @Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (o == null || getClass() != o.getClass()) return false;
  
      final JavaUtilRegexCapabilities that = (JavaUtilRegexCapabilities) o;
  
      if (pattern != null ? !pattern.equals(that.pattern) : that.pattern != null) return false;
  
      return true;
    }
  
    @Override
    public int hashCode() {
      return (pattern != null ? pattern.hashCode() : 0);
    }
  }
  