/* PRNGFactory.java -- 
   Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc.

This file is a part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
USA

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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permission to link this library with independent modules to produce an
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package gnu.java.security.prng;

import gnu.java.security.Registry;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * A Factory to instantiate pseudo random number generators.
 */
public class PRNGFactory
    implements Registry
{
  /** Trivial constructor to enforce <i>Singleton</i> pattern. */
  protected PRNGFactory()
  {
  }

  /**
   * Returns an instance of a padding algorithm given its name.
   * 
   * @param prng the case-insensitive name of the PRNG.
   * @return an instance of the pseudo-random number generator.
   * @exception InternalError if the implementation does not pass its self-
   *              test.
   */
  public static final IRandom getInstance(String prng)
  {
    if (prng == null)
      return null;

    prng = prng.trim();
    IRandom result = null;
    if (prng.equalsIgnoreCase(MD_PRNG))
      result = new MDGenerator();

    return result;
  }

  /**
   * Returns a {@link Set} of names of padding algorithms supported by this
   * <i>Factory</i>.
   * 
   * @return a {@link Set} of pseudo-random number generator algorithm names
   *         (Strings).
   */
  public static final Set getNames()
  {
    HashSet hs = new HashSet();
    hs.add(MD_PRNG);
    return Collections.unmodifiableSet(hs);
  }
}