modules/luni/src/main/java/org/apache/harmony/luni/internal/nls/Messages.java

/*
 *  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.
 */

/*
 * THE FILE HAS BEEN AUTOGENERATED BY MSGTOOL TOOL.
 * All changes made to this file manually will be overwritten 
 * if this tool runs again. Better make changes in the template file.
 */

package org.apache.harmony.luni.internal.nls;


import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.apache.harmony.kernel.vm.VM;

/**
 * This class retrieves strings from a resource bundle and returns them,
 * formatting them with MessageFormat when required.
 * <p>
 * It is used by the system classes to provide national language support, by
 * looking up messages in the <code>
 *    org.apache.harmony.luni.internal.nls.messages
 * </code>
 * resource bundle. Note that if this file is not available, or an invalid key
 * is looked up, or resource bundle support is not available, the key itself
 * will be returned as the associated message. This means that the <em>KEY</em>
 * should a reasonable human-readable (english) string.
 * 
 */
public class Messages {

    // ResourceBundle holding the system messages.
    static private ResourceBundle bundle = null;

    /**
     * Retrieves a message which has no arguments.
     * 
     * @param msg
     *            String the key to look up.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg) {
        if (bundle == null)
            return msg;
        try {
            return bundle.getString(msg);
        } catch (MissingResourceException e) {
            return "Missing message: " + msg; //$NON-NLS-1$
        }
    }

    /**
     * Retrieves a message which takes 1 argument.
     * 
     * @param msg
     *            String the key to look up.
     * @param arg
     *            Object the object to insert in the formatted output.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg, Object arg) {
        return getString(msg, new Object[] { arg });
    }

    /**
     * Retrieves a message which takes 1 integer argument.
     * 
     * @param msg
     *            String the key to look up.
     * @param arg
     *            int the integer to insert in the formatted output.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg, int arg) {
        return getString(msg, new Object[] { Integer.toString(arg) });
    }

    /**
     * Retrieves a message which takes 1 character argument.
     * 
     * @param msg
     *            String the key to look up.
     * @param arg
     *            char the character to insert in the formatted output.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg, char arg) {
        return getString(msg, new Object[] { String.valueOf(arg) });
    }

    /**
     * Retrieves a message which takes 2 arguments.
     * 
     * @param msg
     *            String the key to look up.
     * @param arg1
     *            Object an object to insert in the formatted output.
     * @param arg2
     *            Object another object to insert in the formatted output.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg, Object arg1, Object arg2) {
        return getString(msg, new Object[] { arg1, arg2 });
    }

    /**
     * Retrieves a message which takes several arguments.
     * 
     * @param msg
     *            String the key to look up.
     * @param args
     *            Object[] the objects to insert in the formatted output.
     * @return String the message for that key in the system message bundle.
     */
    static public String getString(String msg, Object[] args) {
        String format = msg;

        if (bundle != null) {
            try {
                format = bundle.getString(msg);
            } catch (MissingResourceException e) {
            }
        }

        return format(format, args);
    }
    
    /**
     * Generates a formatted text string given a source string containing
     * "argument markers" of the form "{argNum}" where each argNum must be in
     * the range 0..9. The result is generated by inserting the toString of each
     * argument into the position indicated in the string.
     * <p>
     * To insert the "{" character into the output, use a single backslash
     * character to escape it (i.e. "\{"). The "}" character does not need to be
     * escaped.
     * 
     * @param format
     *            String the format to use when printing.
     * @param args
     *            Object[] the arguments to use.
     * @return String the formatted message.
     */
    public static String format(String format, Object[] args) {
        StringBuilder answer = new StringBuilder(format.length()
                + (args.length * 20));
        String[] argStrings = new String[args.length];
        for (int i = 0; i < args.length; ++i) {
            if (args[i] == null)
                argStrings[i] = "<null>";	//$NON-NLS-1$
            else
                argStrings[i] = args[i].toString();
        }
        int lastI = 0;
        for (int i = format.indexOf('{', 0); i >= 0; i = format.indexOf('{',
                lastI)) {
            if (i != 0 && format.charAt(i - 1) == '\\') {
                // It's escaped, just print and loop.
                if (i != 1)
                    answer.append(format.substring(lastI, i - 1));
                answer.append('{');
                lastI = i + 1;
            } else {
                // It's a format character.
                if (i > format.length() - 3) {
                    // Bad format, just print and loop.
                    answer.append(format.substring(lastI, format.length()));
                    lastI = format.length();
                } else {
                    int argnum = (byte) Character.digit(format.charAt(i + 1),
                            10);
                    if (argnum < 0 || format.charAt(i + 2) != '}') {
                        // Bad format, just print and loop.
						answer.append(format.substring(lastI, i + 1));
						lastI = i + 1;
                    } else {
                        // Got a good one!
                        answer.append(format.substring(lastI, i));
                        if (argnum >= argStrings.length)
                            answer.append("<missing argument>");	//$NON-NLS-1$
                        else
                            answer.append(argStrings[argnum]);
						lastI = i + 3;
                    }
                }
            }
        }
        if (lastI < format.length())
            answer.append(format.substring(lastI, format.length()));
        return answer.toString();
    }

    /**
     * Changes the locale of the messages.
     * 
     * @param locale
     *            Locale the locale to change to.
     */
    static public ResourceBundle setLocale(final Locale locale,
            final String resource) {
        try {
            final ClassLoader loader = VM.bootCallerClassLoader();
            return (ResourceBundle) AccessController
                    .doPrivileged(new PrivilegedAction<Object>() {
                        public Object run() {
                            return ResourceBundle.getBundle(resource, locale,
                                    loader != null ? loader : ClassLoader.getSystemClassLoader());
                        }
                    });
        } catch (MissingResourceException e) {
        }
        return null;
    }

    static {
        // Attempt to load the messages.
        try {
            bundle = setLocale(Locale.getDefault(),
                    "org.apache.harmony.luni.internal.nls.messages"); //$NON-NLS-1$
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }
}