MnemonicRepository.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.framework.resources;

/**
 * This interface provides a convenient protocol for clients
 * to fetch the mnemonic for a given key. The key is typically the
 * same key used to fetch the mnemonic's string from a
 * StringRepository.
 *
 * @see org.eclipse.persistence.tools.workbench.utility.StringRepository
 */
public interface MnemonicRepository {

    /**
     * Return whether a mnemonic exists for this key.
     * Use this before calling getMnemonic(String) to
     * avoid creating numerous MissingMnemonicExceptions
     */
    boolean hasMnemonic(String key);

    /**
     * Return the mnemonic character for the specified key.
     * The character will be uppercase (as required by Swing...).
     *
     * @see javax.swing.Jlabel#setDisplayedMnemonic(int)
     */
    int getMnemonic(String key);

    /**
     * Return the index of the mnemonic character for the specified key.
     * Use this method if you want to use a character as the
     * mnemonic which appears more than once in the resource string.
     * This way you can choose something other than the first
     * occurrence of the letter in the string.
     *
     * @see javax.swing.Jlabel#setDisplayedMnemonicIndex(int)
     */
    int getMnemonicIndex(String key);


    // ********** null implementation **********

    /**
     * This instance will throw an exception for any non-null key
     * and return -1 for any null key.
     */
    MnemonicRepository NULL_INSTANCE =
        new MnemonicRepository() {
            public boolean hasMnemonic(String key) {
                return key == null;
            }
            public int getMnemonic(String key) {
                return this.getMnemonicIndex(key);
            }
            public int getMnemonicIndex(String key) {
                if (key == null) {
                    return -1;
                }
                throw new MissingMnemonicException("Missing mnemonic: " + key, key);
            }
            public String toString() {
                return "NullMnemonicRepository";
            }
        };

}