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/* CharsetProvider.java -- charset service provider interface

   Copyright (C) 2002, 2005, 2006 Free Software Foundation

This file is 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

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath is distributed in the hope that it will be useful, but

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.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, 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

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package java.nio.charset.spi;

import java.nio.charset.Charset;

import java.util.Iterator;

/**

 * This class allows an implementor to provide additional character sets. The

 * subclass must have a nullary constructor, and be attached to charset

 * implementation classes. These extensions are loaded via the context class

 * loader. To provide the charset extension, all files named

 * <code>META-INF/services/java.nio.charset.spi.CharsetProvider</code> are

 * read from the classpath. Each one should be a UTF-8 encoded list of

 * fully-qualified names of concrete subclasses of this class; whitespace is

 * ignored, and '#' starts comments. Duplicates are ignored. The

 * implementations must be accessible to the classloader that requests them.

 *

 * @author Eric Blake (ebb9@email.byu.edu)

 * @see Charset

 * @since 1.4

 * @status updated to 1.4

 */

public abstract class CharsetProvider

{

  /**

   * Initialize a new charset provider. This performs a security check on

   * RuntimePermission("charsetProvider").

   *

   * @throws SecurityException if building a new set is not allowed

   */

  protected CharsetProvider()

  {

    // We only do the security check for custom providers, not for the

    // built in ones.

    SecurityManager s = System.getSecurityManager();

    if (s != null &&

        ! (this instanceof gnu.java.nio.charset.Provider

        || this instanceof gnu.java.nio.charset.iconv.IconvProvider))

      s.checkPermission(new RuntimePermission("charsetProvider"));

  }

  /**

   * Returns an iterator over the charsets defined by this provider.

   *

   * @return the iterator

   * @see Charset#availableCharsets()

   */

  public abstract Iterator<Charset> charsets();

  /**

   * Returns the named charset, by canonical name or alias.

   *

   * @param name the name of the character

   *

   * @return the charset, or null if not supported

   */

  public abstract Charset charsetForName(String name);

} // class CharsetProvider