/* 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.
 */

package java.nio.charset.spi;

import java.nio.charset.Charset;
import java.util.Iterator;

/**
 * The service provider class for character sets.
 */
public abstract class CharsetProvider {

    // The permission required to construct a new provider.
    private static final RuntimePermission CONSTRUCT_PERM = new RuntimePermission(
            "charsetProvider");

    /**
     * Constructor for subclassing with concrete types.
     *
     * @throws SecurityException
     *             if there is a security manager installed that does not permit
     *             the runtime permission labeled "charsetProvider".
     */
    protected CharsetProvider() {
        SecurityManager securityManager = System.getSecurityManager();
        if (securityManager != null)
            securityManager.checkPermission(CONSTRUCT_PERM);
    }

    /**
     * Returns an iterator over all the available charsets.
     *
     * @return the iterator.
     */
    public abstract Iterator<Charset> charsets();

    /**
     * Returns the named charset.
     * <p>
     * If the charset is unavailable the method returns <code>null</code>.
     * </p>
     *
     * @param charsetName
     *            the canonical or alias name of a character set.
     * @return the charset, or <code>null</code> if unavailable.
     */
    public abstract Charset charsetForName(String charsetName);
}
