/*

 * Copyright (c) 2016, 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 jdk.internal.jshell.tool;

/**

 * The required functionality jshell uses for persistent storage.  Implementable

 * by both Preferences API and Map.

 */

interface PersistentStorage {

    /**

     * Removes all of the preferences (key-value associations) in

     * preferences.

     *

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     */

    void clear();

    /**

     * Returns all of the keys that have an associated value in

     * preferences.

     *

     * @return an array of the keys that have an associated value in this

     * preference node.

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     */

    String[] keys();

    /**

     * Returns the value associated with the specified key in preferences.

     *

     * @param key key whose associated value is to be returned.

     * @return the value associated with {@code key}, or {@code null} if no

     * value is associated with {@code key}.

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     * @throws NullPointerException if {@code key} is {@code null}.

     */

    String get(String key);

    /**

     * Associates the specified value with the specified key in this

     * preference node.

     *

     * @param key key with which the specified value is to be associated.

     * @param value value to be associated with the specified key.

     * @throws NullPointerException if key or value is {@code null}.

     * @throws IllegalArgumentException if key or value are too long.

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     */

    void put(String key, String value);

    /**

     * Removes the value associated with the specified key in preferences,

     * if any.

     *

     * @param key key whose mapping is to be removed from the preference

     * node.

     * @throws NullPointerException if {@code key} is {@code null}.

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     */

    void remove(String key);

    /**

     * Forces any changes in the contents of this preferences to be stored.

     * Once this method returns successfully, it is safe to assume that all

     * changes have become as permanent as they are going to be.

     * <p>

     * Implementations are free to flush changes into the persistent store

     * at any time. They do not need to wait for this method to be called.

     *

     * @throws IllegalStateException if this operation cannot be completed

     * because of the state of the system.

     */

    void flush();

}