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

  *

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

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  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

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  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 /*

  * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved

  * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved

  *

  *   The original version of this source code and documentation is copyrighted

  * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These

  * materials are provided under terms of a License Agreement between Taligent

  * and Sun. This technology is protected by multiple US and International

  * patents. This notice and attribution to Taligent may not be removed.

  *   Taligent is a registered trademark of Taligent, Inc.

  *

  */

 package java.text;

 import java.io.Serializable;

 /**

  * <code>Format</code> is an abstract base class for formatting locale-sensitive

  * information such as dates, messages, and numbers.

  *

  * <p>

  * <code>Format</code> defines the programming interface for formatting

  * locale-sensitive objects into <code>String</code>s (the

  * <code>format</code> method) and for parsing <code>String</code>s back

  * into objects (the <code>parseObject</code> method).

  *

  * <p>

  * Generally, a format's <code>parseObject</code> method must be able to parse

  * any string formatted by its <code>format</code> method. However, there may

  * be exceptional cases where this is not possible. For example, a

  * <code>format</code> method might create two adjacent integer numbers with

  * no separator in between, and in this case the <code>parseObject</code> could

  * not tell which digits belong to which number.

  *

  * <h4>Subclassing</h4>

  *

  * <p>

  * The Java Platform provides three specialized subclasses of <code>Format</code>--

  * <code>DateFormat</code>, <code>MessageFormat</code>, and

  * <code>NumberFormat</code>--for formatting dates, messages, and numbers,

  * respectively.

  * <p>

  * Concrete subclasses must implement three methods:

  * <ol>

  * <li> <code>format(Object obj, StringBuffer toAppendTo, FieldPosition pos)</code>

  * <li> <code>formatToCharacterIterator(Object obj)</code>

  * <li> <code>parseObject(String source, ParsePosition pos)</code>

  * </ol>

  * These general methods allow polymorphic parsing and formatting of objects

  * and are used, for example, by <code>MessageFormat</code>.

  * Subclasses often also provide additional <code>format</code> methods for

  * specific input types as well as <code>parse</code> methods for specific

  * result types. Any <code>parse</code> method that does not take a

  * <code>ParsePosition</code> argument should throw <code>ParseException</code>

  * when no text in the required format is at the beginning of the input text.

  *

  * <p>

  * Most subclasses will also implement the following factory methods:

  * <ol>

  * <li>

  * <code>getInstance</code> for getting a useful format object appropriate

  * for the current locale

  * <li>

  * <code>getInstance(Locale)</code> for getting a useful format

  * object appropriate for the specified locale

  * </ol>

  * In addition, some subclasses may also implement other

  * <code>getXxxxInstance</code> methods for more specialized control. For

  * example, the <code>NumberFormat</code> class provides

  * <code>getPercentInstance</code> and <code>getCurrencyInstance</code>

  * methods for getting specialized number formatters.

  *

  * <p>

  * Subclasses of <code>Format</code> that allow programmers to create objects

  * for locales (with <code>getInstance(Locale)</code> for example)

  * must also implement the following class method:

  * <blockquote>

  * <pre>

  * public static Locale[] getAvailableLocales()

  * </pre>

  * </blockquote>

  *

  * <p>

  * And finally subclasses may define a set of constants to identify the various

  * fields in the formatted output. These constants are used to create a FieldPosition

  * object which identifies what information is contained in the field and its

  * position in the formatted result. These constants should be named

  * <code><em>item</em>_FIELD</code> where <code><em>item</em></code> identifies

  * the field. For examples of these constants, see <code>ERA_FIELD</code> and its

  * friends in {@link DateFormat}.

  *

  * <h4><a name="synchronization">Synchronization</a></h4>

  *

  * <p>

  * Formats are generally not synchronized.

  * It is recommended to create separate format instances for each thread.

  * If multiple threads access a format concurrently, it must be synchronized

  * externally.

  *

  * @see          java.text.ParsePosition

  * @see          java.text.FieldPosition

  * @see          java.text.NumberFormat

  * @see          java.text.DateFormat

  * @see          java.text.MessageFormat

  * @author       Mark Davis

  */

 public abstract class Format implements Serializable, Cloneable {

     private static final long serialVersionUID = -299282585814624189L;

     /**

      * Sole constructor.  (For invocation by subclass constructors, typically

      * implicit.)

      */

     protected Format() {

     }

     /**

      * Formats an object to produce a string. This is equivalent to

      * <blockquote>

      * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,

      *         new StringBuffer(), new FieldPosition(0)).toString();</code>

      * </blockquote>

      *

      * @param obj    The object to format

      * @return       Formatted string.

      * @exception IllegalArgumentException if the Format cannot format the given

      *            object

      */

     public final String format (Object obj) {

         return format(obj, new StringBuffer(), new FieldPosition(0)).toString();

     }

     /**

      * Formats an object and appends the resulting text to a given string

      * buffer.

      * If the <code>pos</code> argument identifies a field used by the format,

      * then its indices are set to the beginning and end of the first such

      * field encountered.

      *

      * @param obj    The object to format

      * @param toAppendTo    where the text is to be appended

      * @param pos    A <code>FieldPosition</code> identifying a field

      *               in the formatted text

      * @return       the string buffer passed in as <code>toAppendTo</code>,

      *               with formatted text appended

      * @exception NullPointerException if <code>toAppendTo</code> or

      *            <code>pos</code> is null

      * @exception IllegalArgumentException if the Format cannot format the given

      *            object

      */

     public abstract StringBuffer format(Object obj,

                     StringBuffer toAppendTo,

                     FieldPosition pos);

     /**

      * Formats an Object producing an <code>AttributedCharacterIterator</code>.

      * You can use the returned <code>AttributedCharacterIterator</code>

      * to build the resulting String, as well as to determine information

      * about the resulting String.

      * <p>

      * Each attribute key of the AttributedCharacterIterator will be of type

      * <code>Field</code>. It is up to each <code>Format</code> implementation

      * to define what the legal values are for each attribute in the

      * <code>AttributedCharacterIterator</code>, but typically the attribute

      * key is also used as the attribute value.

      * <p>The default implementation creates an

      * <code>AttributedCharacterIterator</code> with no attributes. Subclasses

      * that support fields should override this and create an

      * <code>AttributedCharacterIterator</code> with meaningful attributes.

      *

      * @exception NullPointerException if obj is null.

      * @exception IllegalArgumentException when the Format cannot format the

      *            given object.

      * @param obj The object to format

      * @return AttributedCharacterIterator describing the formatted value.

      * @since 1.4

      */

     public AttributedCharacterIterator formatToCharacterIterator(Object obj) {

         return createAttributedCharacterIterator(format(obj));

     }

     /**

      * Parses text from a string to produce an object.

      * <p>

      * The method attempts to parse text starting at the index given by

      * <code>pos</code>.

      * If parsing succeeds, then the index of <code>pos</code> is updated

      * to the index after the last character used (parsing does not necessarily

      * use all characters up to the end of the string), and the parsed

      * object is returned. The updated <code>pos</code> can be used to

      * indicate the starting point for the next call to this method.

      * If an error occurs, then the index of <code>pos</code> is not

      * changed, the error index of <code>pos</code> is set to the index of

      * the character where the error occurred, and null is returned.

      *

      * @param source A <code>String</code>, part of which should be parsed.

      * @param pos A <code>ParsePosition</code> object with index and error

      *            index information as described above.

      * @return An <code>Object</code> parsed from the string. In case of

      *         error, returns null.

      * @exception NullPointerException if <code>pos</code> is null.

      */

     public abstract Object parseObject (String source, ParsePosition pos);

     /**

      * Parses text from the beginning of the given string to produce an object.

      * The method may not use the entire text of the given string.

      *

      * @param source A <code>String</code> whose beginning should be parsed.

      * @return An <code>Object</code> parsed from the string.

      * @exception ParseException if the beginning of the specified string

      *            cannot be parsed.

      */

     public Object parseObject(String source) throws ParseException {

         ParsePosition pos = new ParsePosition(0);

         Object result = parseObject(source, pos);

         if (pos.index == 0) {

             throw new ParseException("Format.parseObject(String) failed",

                 pos.errorIndex);

         }

         return result;

     }

     /**

      * Creates and returns a copy of this object.

      *

      * @return a clone of this instance.

      */

     public Object clone() {

         try {

             return super.clone();

         } catch (CloneNotSupportedException e) {

             // will never happen

             return null;

         }

     }

     //

     // Convenience methods for creating AttributedCharacterIterators from

     // different parameters.

     //

     /**

      * Creates an <code>AttributedCharacterIterator</code> for the String

      * <code>s</code>.

      *

      * @param s String to create AttributedCharacterIterator from

      * @return AttributedCharacterIterator wrapping s

      */

     AttributedCharacterIterator createAttributedCharacterIterator(String s) {

         AttributedString as = new AttributedString(s);

         return as.getIterator();

     }

     /**

      * Creates an <code>AttributedCharacterIterator</code> containg the

      * concatenated contents of the passed in

      * <code>AttributedCharacterIterator</code>s.

      *

      * @param iterators AttributedCharacterIterators used to create resulting

      *                  AttributedCharacterIterators

      * @return AttributedCharacterIterator wrapping passed in

      *         AttributedCharacterIterators

      */

     AttributedCharacterIterator createAttributedCharacterIterator(

                        AttributedCharacterIterator[] iterators) {

         AttributedString as = new AttributedString(iterators);

         return as.getIterator();

     }

     /**

      * Returns an AttributedCharacterIterator with the String

      * <code>string</code> and additional key/value pair <code>key</code>,

      * <code>value</code>.

      *

      * @param string String to create AttributedCharacterIterator from

      * @param key Key for AttributedCharacterIterator

      * @param value Value associated with key in AttributedCharacterIterator

      * @return AttributedCharacterIterator wrapping args

      */

     AttributedCharacterIterator createAttributedCharacterIterator(

                       String string, AttributedCharacterIterator.Attribute key,

                       Object value) {

         AttributedString as = new AttributedString(string);

         as.addAttribute(key, value);

         return as.getIterator();

     }

     /**

      * Creates an AttributedCharacterIterator with the contents of

      * <code>iterator</code> and the additional attribute <code>key</code>

      * <code>value</code>.

      *

      * @param iterator Initial AttributedCharacterIterator to add arg to

      * @param key Key for AttributedCharacterIterator

      * @param value Value associated with key in AttributedCharacterIterator

      * @return AttributedCharacterIterator wrapping args

      */

     AttributedCharacterIterator createAttributedCharacterIterator(

               AttributedCharacterIterator iterator,

               AttributedCharacterIterator.Attribute key, Object value) {

         AttributedString as = new AttributedString(iterator);

         as.addAttribute(key, value);

         return as.getIterator();

     }

     /**

      * Defines constants that are used as attribute keys in the

      * <code>AttributedCharacterIterator</code> returned

      * from <code>Format.formatToCharacterIterator</code> and as

      * field identifiers in <code>FieldPosition</code>.

      *

      * @since 1.4

      */

     public static class Field extends AttributedCharacterIterator.Attribute {

         // Proclaim serial compatibility with 1.4 FCS

         private static final long serialVersionUID = 276966692217360283L;

         /**

          * Creates a Field with the specified name.

          *

          * @param name Name of the attribute

          */

         protected Field(String name) {

             super(name);

         }

     }

     /**

      * FieldDelegate is notified by the various <code>Format</code>

      * implementations as they are formatting the Objects. This allows for

      * storage of the individual sections of the formatted String for

      * later use, such as in a <code>FieldPosition</code> or for an

      * <code>AttributedCharacterIterator</code>.

      * <p>

      * Delegates should NOT assume that the <code>Format</code> will notify

      * the delegate of fields in any particular order.

      *

      * @see FieldPosition.Delegate

      * @see CharacterIteratorFieldDelegate

      */

     interface FieldDelegate {

         /**

          * Notified when a particular region of the String is formatted. This

          * method will be invoked if there is no corresponding integer field id

          * matching <code>attr</code>.

          *

          * @param attr Identifies the field matched

          * @param value Value associated with the field

          * @param start Beginning location of the field, will be >= 0

          * @param end End of the field, will be >= start and <= buffer.length()

          * @param buffer Contains current formatted value, receiver should

          *        NOT modify it.

          */

         public void formatted(Format.Field attr, Object value, int start,

                               int end, StringBuffer buffer);

         /**

          * Notified when a particular region of the String is formatted.

          *

          * @param fieldID Identifies the field by integer

          * @param attr Identifies the field matched

          * @param value Value associated with the field

          * @param start Beginning location of the field, will be >= 0

          * @param end End of the field, will be >= start and <= buffer.length()

          * @param buffer Contains current formatted value, receiver should

          *        NOT modify it.

          */

         public void formatted(int fieldID, Format.Field attr, Object value,

                               int start, int end, StringBuffer buffer);

     }

 }