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 * Copyright (c) 1996, 2019, Oracle and/or its affiliates. All rights reserved.

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

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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.

 *

 * <h2>Subclassing</h2>

 *

 * <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}.

 *

 * <h3><a id="synchronization">Synchronization</a></h3>

 *

 * <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

 * @since 1.1

 */

public abstract class Format implements Serializable, Cloneable {

    @java.io.Serial

    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.

     *            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

     *            <code>pos</code> is null

     *            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.

     *

     *            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.

     * @throws NullPointerException if {@code source} or {@code pos} 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.

     *            cannot be parsed.

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

     */

    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

            throw new InternalError(e);

        }

    }

    //

    // 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> containing 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

        @java.io.Serial

        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#getFieldDelegate

     * @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);

    }

}