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Library for checking that a password complies with a custom set of rules

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/*
  $Id: RepeatCharacterRegexRule.java 2704 2013-04-24 21:30:32Z dfisher $

  Copyright (C) 2003-2013 Virginia Tech.
  All rights reserved.

  SEE LICENSE FOR MORE INFORMATION

  Author:  Middleware Services
  Email:   [email protected]
  Version: $Revision: 2704 $
  Updated: $Date: 2013-04-24 17:30:32 -0400 (Wed, 24 Apr 2013) $
*/
package edu.vt.middleware.password;

/**
 * Rule for determining if a password contains a duplicate ASCII keyboard
 * sequence. See {@link java.util.regex.Pattern} /p{ASCII}. The default sequence
 * length is 5 characters.
 *
 * 
 *   Sequences are of the form: 'bbbbb' or '#####'
 * 
 *
 * @author  Middleware Services
 * @version  $Revision: 2704 $ $Date: 2013-04-24 17:30:32 -0400 (Wed, 24 Apr 2013) $
 */
public class RepeatCharacterRegexRule extends RegexRule
{

  /** Default length of sequence, value is {@value}. */
  public static final int DEFAULT_SEQUENCE_LENGTH = 5;

  /** Minimum length of sequence, value is {@value}. */
  public static final int MINIMUM_SEQUENCE_LENGTH = 3;

  /** Regular expression used by this rule, value is {@value}. */
  private static final String REPEAT_CHAR_REGEX = "([^\\x00-\\x1F])\\1{%d}";


  /**
   * Creates a new repeat character regex rule with the default sequence length.
   */
  public RepeatCharacterRegexRule()
  {
    this(DEFAULT_SEQUENCE_LENGTH);
  }


  /**
   * Creates a new repeat character regex rule.
   *
   * @param  sl  sequence length
   */
  public RepeatCharacterRegexRule(final int sl)
  {
    super(String.format(REPEAT_CHAR_REGEX, sl - 1));
    if (sl < MINIMUM_SEQUENCE_LENGTH) {
      throw new IllegalArgumentException(
        String.format(
          "sequence length must be >= %s",
          MINIMUM_SEQUENCE_LENGTH));
    }
  }
}