/*

 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

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

 * 2 along with this work; if not, write to the Free Software Foundation,

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

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.security;

/**

 * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)

 * for the {@code Policy} class.

 * All the abstract methods in this class must be implemented by each

 * service provider who wishes to supply a Policy implementation.

 *

 * <p> Subclass implementations of this abstract class must provide

 * a public constructor that takes a {@code Policy.Parameters}

 * object as an input parameter.  This constructor also must throw

 * an IllegalArgumentException if it does not understand the

 * {@code Policy.Parameters} input.

 *

 *

 * @since 1.6

 */

public abstract class PolicySpi {

    /**

     * Check whether the policy has granted a Permission to a ProtectionDomain.

     *

     * @param domain the ProtectionDomain to check.

     *

     * @param permission check whether this permission is granted to the

     *          specified domain.

     *

     * @return boolean true if the permission is granted to the domain.

     */

    protected abstract boolean engineImplies

        (ProtectionDomain domain, Permission permission);

    /**

     * Refreshes/reloads the policy configuration. The behavior of this method

     * depends on the implementation. For example, calling {@code refresh}

     * on a file-based policy will cause the file to be re-read.

     *

     * <p> The default implementation of this method does nothing.

     * This method should be overridden if a refresh operation is supported

     * by the policy implementation.

     */

    protected void engineRefresh() { }

    /**

     * Return a PermissionCollection object containing the set of

     * permissions granted to the specified CodeSource.

     *

     * <p> The default implementation of this method returns

     * Policy.UNSUPPORTED_EMPTY_COLLECTION object.  This method can be

     * overridden if the policy implementation can return a set of

     * permissions granted to a CodeSource.

     *

     * @param codesource the CodeSource to which the returned

     *          PermissionCollection has been granted.

     *

     * @return a set of permissions granted to the specified CodeSource.

     *          If this operation is supported, the returned

     *          set of permissions must be a new mutable instance

     *          and it must support heterogeneous Permission types.

     *          If this operation is not supported,

     *          Policy.UNSUPPORTED_EMPTY_COLLECTION is returned.

     */

    protected PermissionCollection engineGetPermissions

                                        (CodeSource codesource) {

        return Policy.UNSUPPORTED_EMPTY_COLLECTION;

    }

    /**

     * Return a PermissionCollection object containing the set of

     * permissions granted to the specified ProtectionDomain.

     *

     * <p> The default implementation of this method returns

     * Policy.UNSUPPORTED_EMPTY_COLLECTION object.  This method can be

     * overridden if the policy implementation can return a set of

     * permissions granted to a ProtectionDomain.

     *

     * @param domain the ProtectionDomain to which the returned

     *          PermissionCollection has been granted.

     *

     * @return a set of permissions granted to the specified ProtectionDomain.

     *          If this operation is supported, the returned

     *          set of permissions must be a new mutable instance

     *          and it must support heterogeneous Permission types.

     *          If this operation is not supported,

     *          Policy.UNSUPPORTED_EMPTY_COLLECTION is returned.

     */

    protected PermissionCollection engineGetPermissions

                                        (ProtectionDomain domain) {

        return Policy.UNSUPPORTED_EMPTY_COLLECTION;

    }

}