src/main/org/apache/tools/ant/types/selectors/modifiedselector/Cache.java

/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "Ant" and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.tools.ant.types.selectors.modifiedselector;


import java.util.Iterator;


/**
 * A Cache let the user store key-value-pairs in a permanent manner and access
 * them.
 * It is possible that a client uses get() before load() therefore the
 * implementation must ensure that no error occured because of the wrong
 * <i>order</i>.
 * The implementing class should implement a useful toString() method.
 *
 * @author Jan Mat\u00e8rne
 * @version 2003-09-13
 * @since  Ant 1.6
 */
public interface Cache {

    /**
     * Checks its prerequisites.
     * @return <i>true</i> if all is ok, otherwise <i>false</i>.
     */
    boolean isValid();

    /** Deletes the cache. If file based the file has to be deleted also. */
    void delete();

    /** Loads the cache, must handle not existing cache. */
    void load();

    /** Saves modification of the cache. */
    void save();

    /**
     * Returns a value for a given key from the cache.
     * @param key the key
     * @return the stored value
     */
    Object get(Object key);

    /**
     * Saves a key-value-pair in the cache.
     * @param key the key
     * @param value the value
     */
    void put(Object key, Object value);

    /**
     * Returns an iterator over the keys in the cache.
     * @return An iterator over the keys.
     */
    Iterator iterator();
}