1 /*
   2  * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
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  25 
  26 /*
  27  * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved
  28  * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved
  29  *
  30  *   The original version of this source code and documentation is copyrighted
  31  * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
  32  * materials are provided under terms of a License Agreement between Taligent
  33  * and Sun. This technology is protected by multiple US and International
  34  * patents. This notice and attribution to Taligent may not be removed.
  35  *   Taligent is a registered trademark of Taligent, Inc.
  36  *
  37  */
  38 
  39 package java.text;
  40 
  41 import java.io.Serializable;
  42 
  43 /**
  44  * <code>Format</code> is an abstract base class for formatting locale-sensitive
  45  * information such as dates, messages, and numbers.
  46  *
  47  * <p>
  48  * <code>Format</code> defines the programming interface for formatting
  49  * locale-sensitive objects into <code>String</code>s (the
  50  * <code>format</code> method) and for parsing <code>String</code>s back
  51  * into objects (the <code>parseObject</code> method).
  52  *
  53  * <p>
  54  * Generally, a format's <code>parseObject</code> method must be able to parse
  55  * any string formatted by its <code>format</code> method. However, there may
  56  * be exceptional cases where this is not possible. For example, a
  57  * <code>format</code> method might create two adjacent integer numbers with
  58  * no separator in between, and in this case the <code>parseObject</code> could
  59  * not tell which digits belong to which number.
  60  *
  61  * <h3>Subclassing</h3>
  62  *
  63  * <p>
  64  * The Java Platform provides three specialized subclasses of <code>Format</code>--
  65  * <code>DateFormat</code>, <code>MessageFormat</code>, and
  66  * <code>NumberFormat</code>--for formatting dates, messages, and numbers,
  67  * respectively.
  68  * <p>
  69  * Concrete subclasses must implement three methods:
  70  * <ol>
  71  * <li> <code>format(Object obj, StringBuffer toAppendTo, FieldPosition pos)</code>
  72  * <li> <code>formatToCharacterIterator(Object obj)</code>
  73  * <li> <code>parseObject(String source, ParsePosition pos)</code>
  74  * </ol>
  75  * These general methods allow polymorphic parsing and formatting of objects
  76  * and are used, for example, by <code>MessageFormat</code>.
  77  * Subclasses often also provide additional <code>format</code> methods for
  78  * specific input types as well as <code>parse</code> methods for specific
  79  * result types. Any <code>parse</code> method that does not take a
  80  * <code>ParsePosition</code> argument should throw <code>ParseException</code>
  81  * when no text in the required format is at the beginning of the input text.
  82  *
  83  * <p>
  84  * Most subclasses will also implement the following factory methods:
  85  * <ol>
  86  * <li>
  87  * <code>getInstance</code> for getting a useful format object appropriate
  88  * for the current locale
  89  * <li>
  90  * <code>getInstance(Locale)</code> for getting a useful format
  91  * object appropriate for the specified locale
  92  * </ol>
  93  * In addition, some subclasses may also implement other
  94  * <code>getXxxxInstance</code> methods for more specialized control. For
  95  * example, the <code>NumberFormat</code> class provides
  96  * <code>getPercentInstance</code> and <code>getCurrencyInstance</code>
  97  * methods for getting specialized number formatters.
  98  *
  99  * <p>
 100  * Subclasses of <code>Format</code> that allow programmers to create objects
 101  * for locales (with <code>getInstance(Locale)</code> for example)
 102  * must also implement the following class method:
 103  * <blockquote>
 104  * <pre>
 105  * public static Locale[] getAvailableLocales()
 106  * </pre>
 107  * </blockquote>
 108  *
 109  * <p>
 110  * And finally subclasses may define a set of constants to identify the various
 111  * fields in the formatted output. These constants are used to create a FieldPosition
 112  * object which identifies what information is contained in the field and its
 113  * position in the formatted result. These constants should be named
 114  * <code><em>item</em>_FIELD</code> where <code><em>item</em></code> identifies
 115  * the field. For examples of these constants, see <code>ERA_FIELD</code> and its
 116  * friends in {@link DateFormat}.
 117  *
 118  * <h4><a name="synchronization">Synchronization</a></h4>
 119  *
 120  * <p>
 121  * Formats are generally not synchronized.
 122  * It is recommended to create separate format instances for each thread.
 123  * If multiple threads access a format concurrently, it must be synchronized
 124  * externally.
 125  *
 126  * @see          java.text.ParsePosition
 127  * @see          java.text.FieldPosition
 128  * @see          java.text.NumberFormat
 129  * @see          java.text.DateFormat
 130  * @see          java.text.MessageFormat
 131  * @author       Mark Davis
 132  */
 133 public abstract class Format implements Serializable, Cloneable {
 134 
 135     private static final long serialVersionUID = -299282585814624189L;
 136 
 137     /**
 138      * Sole constructor.  (For invocation by subclass constructors, typically
 139      * implicit.)
 140      */
 141     protected Format() {
 142     }
 143 
 144     /**
 145      * Formats an object to produce a string. This is equivalent to
 146      * <blockquote>
 147      * {@link #format(Object, StringBuffer, FieldPosition) format}<code>(obj,
 148      *         new StringBuffer(), new FieldPosition(0)).toString();</code>
 149      * </blockquote>
 150      *
 151      * @param obj    The object to format
 152      * @return       Formatted string.
 153      * @exception IllegalArgumentException if the Format cannot format the given
 154      *            object
 155      */
 156     public final String format (Object obj) {
 157         return format(obj, new StringBuffer(), new FieldPosition(0)).toString();
 158     }
 159 
 160     /**
 161      * Formats an object and appends the resulting text to a given string
 162      * buffer.
 163      * If the <code>pos</code> argument identifies a field used by the format,
 164      * then its indices are set to the beginning and end of the first such
 165      * field encountered.
 166      *
 167      * @param obj    The object to format
 168      * @param toAppendTo    where the text is to be appended
 169      * @param pos    A <code>FieldPosition</code> identifying a field
 170      *               in the formatted text
 171      * @return       the string buffer passed in as <code>toAppendTo</code>,
 172      *               with formatted text appended
 173      * @exception NullPointerException if <code>toAppendTo</code> or
 174      *            <code>pos</code> is null
 175      * @exception IllegalArgumentException if the Format cannot format the given
 176      *            object
 177      */
 178     public abstract StringBuffer format(Object obj,
 179                     StringBuffer toAppendTo,
 180                     FieldPosition pos);
 181 
 182     /**
 183      * Formats an Object producing an <code>AttributedCharacterIterator</code>.
 184      * You can use the returned <code>AttributedCharacterIterator</code>
 185      * to build the resulting String, as well as to determine information
 186      * about the resulting String.
 187      * <p>
 188      * Each attribute key of the AttributedCharacterIterator will be of type
 189      * <code>Field</code>. It is up to each <code>Format</code> implementation
 190      * to define what the legal values are for each attribute in the
 191      * <code>AttributedCharacterIterator</code>, but typically the attribute
 192      * key is also used as the attribute value.
 193      * <p>The default implementation creates an
 194      * <code>AttributedCharacterIterator</code> with no attributes. Subclasses
 195      * that support fields should override this and create an
 196      * <code>AttributedCharacterIterator</code> with meaningful attributes.
 197      *
 198      * @exception NullPointerException if obj is null.
 199      * @exception IllegalArgumentException when the Format cannot format the
 200      *            given object.
 201      * @param obj The object to format
 202      * @return AttributedCharacterIterator describing the formatted value.
 203      * @since 1.4
 204      */
 205     public AttributedCharacterIterator formatToCharacterIterator(Object obj) {
 206         return createAttributedCharacterIterator(format(obj));
 207     }
 208 
 209     /**
 210      * Parses text from a string to produce an object.
 211      * <p>
 212      * The method attempts to parse text starting at the index given by
 213      * <code>pos</code>.
 214      * If parsing succeeds, then the index of <code>pos</code> is updated
 215      * to the index after the last character used (parsing does not necessarily
 216      * use all characters up to the end of the string), and the parsed
 217      * object is returned. The updated <code>pos</code> can be used to
 218      * indicate the starting point for the next call to this method.
 219      * If an error occurs, then the index of <code>pos</code> is not
 220      * changed, the error index of <code>pos</code> is set to the index of
 221      * the character where the error occurred, and null is returned.
 222      *
 223      * @param source A <code>String</code>, part of which should be parsed.
 224      * @param pos A <code>ParsePosition</code> object with index and error
 225      *            index information as described above.
 226      * @return An <code>Object</code> parsed from the string. In case of
 227      *         error, returns null.
 228      * @exception NullPointerException if <code>pos</code> is null.
 229      * @throws NullPointerException if {@code source} is null.
 230      */
 231     public abstract Object parseObject (String source, ParsePosition pos);
 232 
 233     /**
 234      * Parses text from the beginning of the given string to produce an object.
 235      * The method may not use the entire text of the given string.
 236      *
 237      * @param source A <code>String</code> whose beginning should be parsed.
 238      * @return An <code>Object</code> parsed from the string.
 239      * @exception ParseException if the beginning of the specified string
 240      *            cannot be parsed.
 241      * @throws NullPointerException if {@code source} is null.
 242      */
 243     public Object parseObject(String source) throws ParseException {
 244         ParsePosition pos = new ParsePosition(0);
 245         Object result = parseObject(source, pos);
 246         if (pos.index == 0) {
 247             throw new ParseException("Format.parseObject(String) failed",
 248                 pos.errorIndex);
 249         }
 250         return result;
 251     }
 252 
 253     /**
 254      * Creates and returns a copy of this object.
 255      *
 256      * @return a clone of this instance.
 257      */
 258     public Object clone() {
 259         try {
 260             return super.clone();
 261         } catch (CloneNotSupportedException e) {
 262             // will never happen
 263             throw new InternalError(e);
 264         }
 265     }
 266 
 267     //
 268     // Convenience methods for creating AttributedCharacterIterators from
 269     // different parameters.
 270     //
 271 
 272     /**
 273      * Creates an <code>AttributedCharacterIterator</code> for the String
 274      * <code>s</code>.
 275      *
 276      * @param s String to create AttributedCharacterIterator from
 277      * @return AttributedCharacterIterator wrapping s
 278      */
 279     AttributedCharacterIterator createAttributedCharacterIterator(String s) {
 280         AttributedString as = new AttributedString(s);
 281 
 282         return as.getIterator();
 283     }
 284 
 285     /**
 286      * Creates an <code>AttributedCharacterIterator</code> containing the
 287      * concatenated contents of the passed in
 288      * <code>AttributedCharacterIterator</code>s.
 289      *
 290      * @param iterators AttributedCharacterIterators used to create resulting
 291      *                  AttributedCharacterIterators
 292      * @return AttributedCharacterIterator wrapping passed in
 293      *         AttributedCharacterIterators
 294      */
 295     AttributedCharacterIterator createAttributedCharacterIterator(
 296                        AttributedCharacterIterator[] iterators) {
 297         AttributedString as = new AttributedString(iterators);
 298 
 299         return as.getIterator();
 300     }
 301 
 302     /**
 303      * Returns an AttributedCharacterIterator with the String
 304      * <code>string</code> and additional key/value pair <code>key</code>,
 305      * <code>value</code>.
 306      *
 307      * @param string String to create AttributedCharacterIterator from
 308      * @param key Key for AttributedCharacterIterator
 309      * @param value Value associated with key in AttributedCharacterIterator
 310      * @return AttributedCharacterIterator wrapping args
 311      */
 312     AttributedCharacterIterator createAttributedCharacterIterator(
 313                       String string, AttributedCharacterIterator.Attribute key,
 314                       Object value) {
 315         AttributedString as = new AttributedString(string);
 316 
 317         as.addAttribute(key, value);
 318         return as.getIterator();
 319     }
 320 
 321     /**
 322      * Creates an AttributedCharacterIterator with the contents of
 323      * <code>iterator</code> and the additional attribute <code>key</code>
 324      * <code>value</code>.
 325      *
 326      * @param iterator Initial AttributedCharacterIterator to add arg to
 327      * @param key Key for AttributedCharacterIterator
 328      * @param value Value associated with key in AttributedCharacterIterator
 329      * @return AttributedCharacterIterator wrapping args
 330      */
 331     AttributedCharacterIterator createAttributedCharacterIterator(
 332               AttributedCharacterIterator iterator,
 333               AttributedCharacterIterator.Attribute key, Object value) {
 334         AttributedString as = new AttributedString(iterator);
 335 
 336         as.addAttribute(key, value);
 337         return as.getIterator();
 338     }
 339 
 340 
 341     /**
 342      * Defines constants that are used as attribute keys in the
 343      * <code>AttributedCharacterIterator</code> returned
 344      * from <code>Format.formatToCharacterIterator</code> and as
 345      * field identifiers in <code>FieldPosition</code>.
 346      *
 347      * @since 1.4
 348      */
 349     public static class Field extends AttributedCharacterIterator.Attribute {
 350 
 351         // Proclaim serial compatibility with 1.4 FCS
 352         private static final long serialVersionUID = 276966692217360283L;
 353 
 354         /**
 355          * Creates a Field with the specified name.
 356          *
 357          * @param name Name of the attribute
 358          */
 359         protected Field(String name) {
 360             super(name);
 361         }
 362     }
 363 
 364 
 365     /**
 366      * FieldDelegate is notified by the various <code>Format</code>
 367      * implementations as they are formatting the Objects. This allows for
 368      * storage of the individual sections of the formatted String for
 369      * later use, such as in a <code>FieldPosition</code> or for an
 370      * <code>AttributedCharacterIterator</code>.
 371      * <p>
 372      * Delegates should NOT assume that the <code>Format</code> will notify
 373      * the delegate of fields in any particular order.
 374      *
 375      * @see FieldPosition#getFieldDelegate
 376      * @see CharacterIteratorFieldDelegate
 377      */
 378     interface FieldDelegate {
 379         /**
 380          * Notified when a particular region of the String is formatted. This
 381          * method will be invoked if there is no corresponding integer field id
 382          * matching <code>attr</code>.
 383          *
 384          * @param attr Identifies the field matched
 385          * @param value Value associated with the field
 386          * @param start Beginning location of the field, will be >= 0
 387          * @param end End of the field, will be >= start and <= buffer.length()
 388          * @param buffer Contains current formatted value, receiver should
 389          *        NOT modify it.
 390          */
 391         public void formatted(Format.Field attr, Object value, int start,
 392                               int end, StringBuffer buffer);
 393 
 394         /**
 395          * Notified when a particular region of the String is formatted.
 396          *
 397          * @param fieldID Identifies the field by integer
 398          * @param attr Identifies the field matched
 399          * @param value Value associated with the field
 400          * @param start Beginning location of the field, will be >= 0
 401          * @param end End of the field, will be >= start and <= buffer.length()
 402          * @param buffer Contains current formatted value, receiver should
 403          *        NOT modify it.
 404          */
 405         public void formatted(int fieldID, Format.Field attr, Object value,
 406                               int start, int end, StringBuffer buffer);
 407     }
 408 }
--- EOF ---