icuSources/i18n/unicode/msgfmt.h

   1 /*
   2 * Copyright (C) {1997-2004}, International Business Machines Corporation and others. All Rights Reserved.
   3 ********************************************************************************
   4 *
   5 * File MSGFMT.H
   6 *
   7 * Modification History:
   8 *
   9 *   Date        Name        Description
  10 *   02/19/97    aliu        Converted from java.
  11 *   03/20/97    helena      Finished first cut of implementation.
  12 *   07/22/98    stephen     Removed operator!= (defined in Format)
  13 *   08/19/2002  srl         Removing Javaisms
  14 ********************************************************************************
  15 */
  16
  17 #ifndef MSGFMT_H
  18 #define MSGFMT_H
  19
  20 #include "unicode/utypes.h"
  21
  22 #if !UCONFIG_NO_FORMATTING
  23
  24 #include "unicode/format.h"
  25 #include "unicode/locid.h"
  26 #include "unicode/parseerr.h"
  27
  28 U_NAMESPACE_BEGIN
  29
  30 class NumberFormat;
  31 class DateFormat;
  32
  33 /**
  34  * A MessageFormat produces concatenated messages in a
  35  * language-neutral way.  It should be used for all string
  36  * concatenations that are visible to end users.
  37  * <P>
  38  * A MessageFormat contains an array of <EM>subformats</EM> arranged
  39  * within a <EM>template string</EM>.  Together, the subformats and
  40  * template string determine how the MessageFormat will operate during
  41  * formatting and parsing.
  42  * <P>
  43  * Typically, both the subformats and the template string are
  44  * specified at once in a <EM>pattern</EM>.  By using different
  45  * patterns for different locales, messages may be localized.
  46  * <P>
  47  * During formatting, the MessageFormat takes an array of arguments
  48  * and produces a user-readable string.  Each argument is a
  49  * Formattable object; they may be passed in in an array, or as a
  50  * single Formattable object which itself contains an array.  Each
  51  * argument is matched up with its corresponding subformat, which then
  52  * formats it into a string.  The resultant strings are then assembled
  53  * within the string template of the MessageFormat to produce the
  54  * final output string.
  55  * <P>
  56  * During parsing, an input string is matched against the string
  57  * template of the MessageFormat to produce an array of Formattable
  58  * objects.  Plain text of the template string is matched directly
  59  * against intput text.  At each position in the template string where
  60  * a subformat is located, the subformat is called to parse the
  61  * corresponding segment of input text to produce an output argument.
  62  * In this way, an array of arguments is created which together
  63  * constitute the parse result.
  64  * <P>
  65  * Parsing may fail or produce unexpected results in a number of
  66  * circumstances.
  67  * <UL>
  68  * <LI>If one of the arguments does not occur in the pattern, it
  69  * will be returned as a default Formattable.
  70  * <LI>If the format of an argument is loses information, such as with
  71  * a choice format where a large number formats to "many", then the
  72  * parse may not correspond to the originally formatted argument.
  73  * <LI>MessageFormat does not handle ChoiceFormat recursion during
  74  * parsing; such parses will fail.
  75  * <LI>Parsing will not always find a match (or the correct match) if
  76  * some part of the parse is ambiguous.  For example, if the pattern
  77  * "{1},{2}" is used with the string arguments {"a,b", "c"}, it will
  78  * format as "a,b,c".  When the result is parsed, it will return {"a",
  79  * "b,c"}.
  80  * <LI>If a single argument is formatted more than once in the string,
  81  * then the rightmost subformat in the pattern string will produce the
  82  * parse result; prior subformats with the same argument index will
  83  * have no effect.
  84  * </UL>
  85  * Here are some examples of usage:
  86  * <P>
  87  * Example 1:
  88  * <pre>
  89  * \code
  90  *     UErrorCode success = U_ZERO_ERROR;
  91  *     GregorianCalendar cal(success);
  92  *     Formattable arguments[] = {
  93  *         7L,
  94  *         Formattable( (Date) cal.getTime(success), Formattable::kIsDate),
  95  *         "a disturbance in the Force"
  96  *     };
  97  *
  98  *     UnicodeString result;
  99  *     MessageFormat::format(
 100  *          "At {1,time} on {1,date}, there was {2} on planet {0,number}.",
 101  *          arguments, 3, result, success );
 102  *
 103  *     cout << "result: " << result << endl;
 104  *     //<output>: At 4:34:20 PM on 23-Mar-98, there was a disturbance
 105  *     //             in the Force on planet 7.
 106  * \endcode
 107  * </pre>
 108  * Typically, the message format will come from resources, and the
 109  * arguments will be dynamically set at runtime.
 110  * <P>
 111  * Example 2:
 112  * <pre>
 113  *  \code
 114  *     success = U_ZERO_ERROR;
 115  *     Formattable testArgs[] = {3L, "MyDisk"};
 116  *
 117  *     MessageFormat form(
 118  *         "The disk \"{1}\" contains {0} file(s).", success );
 119  *
 120  *     UnicodeString string;
 121  *     FieldPosition fpos = 0;
 122  *     cout << "format: " << form.format(testArgs, 2, string, fpos, success ) << endl;
 123  *
 124  *     // output, with different testArgs:
 125  *     // output: The disk "MyDisk" contains 0 file(s).
 126  *     // output: The disk "MyDisk" contains 1 file(s).
 127  *     // output: The disk "MyDisk" contains 1,273 file(s).
 128  *  \endcode
 129  *  </pre>
 130  *
 131  *  The pattern is of the following form.  Legend:
 132  *  <pre>
 133  * \code
 134  *       {optional item}
 135  *       (group that may be repeated)*
 136  * \endcode
 137  *  </pre>
 138  *  Do not confuse optional items with items inside quotes braces, such
 139  *  as this: "{".  Quoted braces are literals.
 140  *  <pre>
 141  *  \code
 142  *       messageFormatPattern := string ( "{" messageFormatElement "}" string )*
 143  *
 144  *       messageFormatElement := argumentIndex { "," elementFormat }
 145  *
 146  *       elementFormat := "time" { "," datetimeStyle }
 147  *                      | "date" { "," datetimeStyle }
 148  *                      | "number" { "," numberStyle }
 149  *                      | "choice" "," choiceStyle
 150  *
 151  *       datetimeStyle := "short"
 152  *                      | "medium"
 153  *                      | "long"
 154  *                      | "full"
 155  *                      | dateFormatPattern
 156  *
 157  *       numberStyle :=   "currency"
 158  *                      | "percent"
 159  *                      | "integer"
 160  *                      | numberFormatPattern
 161  *
 162  *       choiceStyle :=   choiceFormatPattern
 163  * \endcode
 164  * </pre>
 165  * If there is no elementFormat, then the argument must be a string,
 166  * which is substituted. If there is no dateTimeStyle or numberStyle,
 167  * then the default format is used (e.g.  NumberFormat::createInstance(),
 168  * DateFormat::createTimeInstance(DateFormat::kDefault, ...) or DateFormat::createDateInstance(DateFormat::kDefault, ...). For
 169  * a ChoiceFormat, the pattern must always be specified, since there
 170  * is no default.
 171  * <P>
 172  * In strings, single quotes can be used to quote syntax characters.
 173  * A literal single quote is represented by '', both within and outside
 174  * of single-quoted segments.  Inside a
 175  * messageFormatElement, quotes are <EM>not</EM> removed. For example,
 176  * {1,number,$'#',##} will produce a number format with the pound-sign
 177  * quoted, with a result such as: "$#31,45".
 178  * <P>
 179  * If a pattern is used, then unquoted braces in the pattern, if any,
 180  * must match: that is, "ab {0} de" and "ab '}' de" are ok, but "ab
 181  * {0'}' de" and "ab } de" are not.
 182  * <P>
 183  * The argumentIndex is a non-negative integer, which corresponds to the
 184  * index of the arguments presented in an array to be formatted.  The
 185  * first argument has argumentIndex 0.
 186  * <P>
 187  * It is acceptable to have unused arguments in the array.  With missing
 188  * arguments or arguments that are not of the right class for the
 189  * specified format, a failing UErrorCode result is set.
 190  * <P>
 191  * For more sophisticated patterns, you can use a ChoiceFormat to get
 192  * output:
 193  * <pre>
 194  * \code
 195  *     UErrorCode success = U_ZERO_ERROR;
 196  *     MessageFormat* form("The disk \"{1}\" contains {0}.", success);
 197  *     double filelimits[] = {0,1,2};
 198  *     UnicodeString filepart[] = {"no files","one file","{0,number} files"};
 199  *     ChoiceFormat* fileform = new ChoiceFormat(filelimits, filepart, 3);
 200  *     form.setFormat(1, *fileform); // NOT zero, see below
 201  *
 202  *     Formattable testArgs[] = {1273L, "MyDisk"};
 203  *
 204  *     UnicodeString string;
 205  *     FieldPosition fpos = 0;
 206  *     cout << form.format(testArgs, 2, string, fpos, success) << endl;
 207  *
 208  *     // output, with different testArgs
 209  *     // output: The disk "MyDisk" contains no files.
 210  *     // output: The disk "MyDisk" contains one file.
 211  *     // output: The disk "MyDisk" contains 1,273 files.
 212  * \endcode
 213  * </pre>
 214  * You can either do this programmatically, as in the above example,
 215  * or by using a pattern (see ChoiceFormat for more information) as in:
 216  * <pre>
 217  * \code
 218  *    form.applyPattern(
 219  *      "There {0,choice,0#are no files|1#is one file|1<are {0,number,integer} files}.");
 220  * \endcode
 221  * </pre>
 222  * <P>
 223  * <EM>Note:</EM> As we see above, the string produced by a ChoiceFormat in
 224  * MessageFormat is treated specially; occurences of '{' are used to
 225  * indicated subformats, and cause recursion.  If you create both a
 226  * MessageFormat and ChoiceFormat programmatically (instead of using
 227  * the string patterns), then be careful not to produce a format that
 228  * recurses on itself, which will cause an infinite loop.
 229  * <P>
 230  * <EM>Note:</EM> Subformats are numbered by their order in the pattern.
 231  * This is <EM>not</EM> the same as the argumentIndex.
 232  * <pre>
 233  * \code
 234  *    For example: with "abc{2}def{3}ghi{0}...",
 235  *
 236  *    format0 affects the first variable {2}
 237  *    format1 affects the second variable {3}
 238  *    format2 affects the second variable {0}
 239  * \endcode
 240  * </pre>
 241  *
 242  * <p><em>User subclasses are not supported.</em> While clients may write
 243  * subclasses, such code will not necessarily work and will not be
 244  * guaranteed to work stably from release to release.
 245  */
 246 class U_I18N_API MessageFormat : public Format {
 247 public:
 248     /**
 249      * Enum type for kMaxFormat.
 250      * @obsolete ICU 3.0.  The 10-argument limit was removed as of ICU 2.6,
 251      * rendering this enum type obsolete.
 252      */
 253     enum EFormatNumber {
 254         /**
 255          * The maximum number of arguments.
 256          * @obsolete ICU 3.0.  The 10-argument limit was removed as of ICU 2.6,
 257          * rendering this constant obsolete.
 258          */
 259         kMaxFormat = 10
 260     };
 261
 262     /**
 263      * Constructs a new MessageFormat using the given pattern and the
 264      * default locale.
 265      *
 266      * @param pattern   Pattern used to construct object.
 267      * @param status    Input/output error code.  If the
 268      *                  pattern cannot be parsed, set to failure code.
 269      * @stable ICU 2.0
 270      */
 271     MessageFormat(const UnicodeString& pattern,
 272                   UErrorCode &status);
 273
 274     /**
 275      * Constructs a new MessageFormat using the given pattern and locale.
 276      * @param pattern   Pattern used to construct object.
 277      * @param newLocale The locale to use for formatting dates and numbers.
 278      * @param status    Input/output error code.  If the
 279      *                  pattern cannot be parsed, set to failure code.
 280      * @stable ICU 2.0
 281      */
 282     MessageFormat(const UnicodeString& pattern,
 283                   const Locale& newLocale,
 284                         UErrorCode& status);
 285     /**
 286      * Constructs a new MessageFormat using the given pattern and locale.
 287      * @param pattern   Pattern used to construct object.
 288      * @param newLocale The locale to use for formatting dates and numbers.
 289      * @param parseError Struct to recieve information on position
 290      *                   of error within the pattern.
 291      * @param status    Input/output error code.  If the
 292      *                  pattern cannot be parsed, set to failure code.
 293      * @stable ICU 2.0
 294      */
 295     MessageFormat(const UnicodeString& pattern,
 296                   const Locale& newLocale,
 297                   UParseError& parseError,
 298                   UErrorCode& status);
 299     /**
 300      * Constructs a new MessageFormat from an existing one.
 301      * @stable ICU 2.0
 302      */
 303     MessageFormat(const MessageFormat&);
 304
 305     /**
 306      * Assignment operator.
 307      * @stable ICU 2.0
 308      */
 309     const MessageFormat& operator=(const MessageFormat&);
 310
 311     /**
 312      * Destructor.
 313      * @stable ICU 2.0
 314      */
 315     virtual ~MessageFormat();
 316
 317     /**
 318      * Clones this Format object polymorphically.  The caller owns the
 319      * result and should delete it when done.
 320      * @stable ICU 2.0
 321      */
 322     virtual Format* clone(void) const;
 323
 324     /**
 325      * Returns true if the given Format objects are semantically equal.
 326      * Objects of different subclasses are considered unequal.
 327      * @param other  the object to be compared with.
 328      * @return       true if the given Format objects are semantically equal.
 329      * @stable ICU 2.0
 330      */
 331     virtual UBool operator==(const Format& other) const;
 332
 333     /**
 334      * Sets the locale. This locale is used for fetching default number or date
 335      * format information.
 336      * @param theLocale    the new locale value to be set.
 337      * @stable ICU 2.0
 338      */
 339     virtual void setLocale(const Locale& theLocale);
 340
 341     /**
 342      * Gets the locale. This locale is used for fetching default number or date
 343      * format information.
 344      * @return    the locale of the object.
 345      * @stable ICU 2.0
 346      */
 347     virtual const Locale& getLocale(void) const;
 348
 349     /**
 350      * Applies the given pattern string to this message format.
 351      *
 352      * @param pattern   The pattern to be applied.
 353      * @param status    Input/output error code.  If the
 354      *                  pattern cannot be parsed, set to failure code.
 355      * @stable ICU 2.0
 356      */
 357     virtual void applyPattern(const UnicodeString& pattern,
 358                               UErrorCode& status);
 359     /**
 360      * Applies the given pattern string to this message format.
 361      *
 362      * @param pattern    The pattern to be applied.
 363      * @param parseError Struct to recieve information on position
 364      *                   of error within pattern.
 365      * @param status    Input/output error code.  If the
 366      *                  pattern cannot be parsed, set to failure code.
 367      * @stable ICU 2.0
 368      */
 369     virtual void applyPattern(const UnicodeString& pattern,
 370                              UParseError& parseError,
 371                              UErrorCode& status);
 372
 373     /**
 374      * Returns a pattern that can be used to recreate this object.
 375      *
 376      * @param appendTo  Output parameter to receive the pattern.
 377      *                  Result is appended to existing contents.
 378      * @return          Reference to 'appendTo' parameter.
 379      * @stable ICU 2.0
 380      */
 381     virtual UnicodeString& toPattern(UnicodeString& appendTo) const;
 382
 383     /**
 384      * Sets subformats.
 385      * See the class description about format numbering.
 386      * The caller should not delete the Format objects after this call.
 387      * <EM>The array formatsToAdopt is not itself adopted.</EM> Its
 388      * ownership is retained by the caller. If the call fails because
 389      * memory cannot be allocated, then the formats will be deleted
 390      * by this method, and this object will remain unchanged.
 391      *
 392      * @stable ICU 2.0
 393      * @param formatsToAdopt    the format to be adopted.
 394      * @param count             the size of the array.
 395      */
 396     virtual void adoptFormats(Format** formatsToAdopt, int32_t count);
 397
 398     /**
 399      * Sets subformats.
 400      * See the class description about format numbering.
 401      * Each item in the array is cloned into the internal array.
 402      * If the call fails because memory cannot be allocated, then this
 403      * object will remain unchanged.
 404      *
 405      * @stable ICU 2.0
 406      * @param newFormats the new format to be set.
 407      * @param cnt        the size of the array.
 408      */
 409     virtual void setFormats(const Format** newFormats,int32_t cnt);
 410
 411
 412     /**
 413      * Sets one subformat.
 414      * See the class description about format numbering.
 415      * The caller should not delete the Format object after this call.
 416      * If the number is over the number of formats already set,
 417      * the item will be deleted and ignored.
 418      * @stable ICU 2.0
 419      * @param formatNumber     index of the subformat.
 420      * @param formatToAdopt    the format to be adopted.
 421      */
 422     virtual void adoptFormat(int32_t formatNumber, Format* formatToAdopt);
 423
 424     /**
 425      * Sets one subformat.
 426      * See the class description about format numbering.
 427      * If the number is over the number of formats already set,
 428      * the item will be ignored.
 429      * @param formatNumber     index of the subformat.
 430      * @param format    the format to be set.
 431      * @stable ICU 2.0
 432      */
 433     virtual void setFormat(int32_t formatNumber, const Format& format);
 434
 435     /**
 436      * Gets an array of subformats of this object.  The returned array
 437      * should not be deleted by the caller, nor should the pointers
 438      * within the array.  The array and its contents remain valid only
 439      * until the next call to any method of this class is made with
 440      * this object.  See the class description about format numbering.
 441      * @param count output parameter to receive the size of the array
 442      * @return an array of count Format* objects, or NULL if out of
 443      * memory.  Any or all of the array elements may be NULL.
 444      * @stable ICU 2.0
 445      */
 446     virtual const Format** getFormats(int32_t& count) const;
 447
 448     /**
 449      * Formats the given array of arguments into a user-readable string.
 450      * Does not take ownership of the Formattable* array or its contents.
 451      *
 452      * @param source    An array of objects to be formatted.
 453      * @param count     The number of elements of 'source'.
 454      * @param appendTo  Output parameter to receive result.
 455      *                  Result is appended to existing contents.
 456      * @param ignore    Not used; inherited from base class API.
 457      * @param status    Input/output error code.  If the
 458      *                  pattern cannot be parsed, set to failure code.
 459      * @return          Reference to 'appendTo' parameter.
 460      * @stable ICU 2.0
 461      */
 462     UnicodeString& format(  const Formattable* source,
 463                             int32_t count,
 464                             UnicodeString& appendTo,
 465                             FieldPosition& ignore,
 466                             UErrorCode& status) const;
 467
 468     /**
 469      * Formats the given array of arguments into a user-readable string
 470      * using the given pattern.
 471      *
 472      * @param pattern   The pattern.
 473      * @param arguments An array of objects to be formatted.
 474      * @param count     The number of elements of 'source'.
 475      * @param appendTo  Output parameter to receive result.
 476      *                  Result is appended to existing contents.
 477      * @param status    Input/output error code.  If the
 478      *                  pattern cannot be parsed, set to failure code.
 479      * @return          Reference to 'appendTo' parameter.
 480      * @stable ICU 2.0
 481      */
 482     static UnicodeString& format(   const UnicodeString& pattern,
 483                                     const Formattable* arguments,
 484                                     int32_t count,
 485                                     UnicodeString& appendTo,
 486                                     UErrorCode& status);
 487
 488     /**
 489      * Formats the given array of arguments into a user-readable
 490      * string.  The array must be stored within a single Formattable
 491      * object of type kArray. If the Formattable object type is not of
 492      * type kArray, then returns a failing UErrorCode.
 493      *
 494      * @param obj       A Formattable of type kArray containing
 495      *                  arguments to be formatted.
 496      * @param appendTo  Output parameter to receive result.
 497      *                  Result is appended to existing contents.
 498      * @param pos       On input: an alignment field, if desired.
 499      *                  On output: the offsets of the alignment field.
 500      * @param status    Input/output error code.  If the
 501      *                  pattern cannot be parsed, set to failure code.
 502      * @return          Reference to 'appendTo' parameter.
 503      * @stable ICU 2.0
 504      */
 505     virtual UnicodeString& format(const Formattable& obj,
 506                                   UnicodeString& appendTo,
 507                                   FieldPosition& pos,
 508                                   UErrorCode& status) const;
 509
 510     /**
 511      * Formats the given array of arguments into a user-readable
 512      * string.  The array must be stored within a single Formattable
 513      * object of type kArray. If the Formattable object type is not of
 514      * type kArray, then returns a failing UErrorCode.
 515      *
 516      * @param obj       The object to format
 517      * @param appendTo  Output parameter to receive result.
 518      *                  Result is appended to existing contents.
 519      * @param status    Input/output error code.  If the
 520      *                  pattern cannot be parsed, set to failure code.
 521      * @return          Reference to 'appendTo' parameter.
 522      * @stable ICU 2.0
 523      */
 524     UnicodeString& format(const Formattable& obj,
 525                           UnicodeString& appendTo,
 526                           UErrorCode& status) const;
 527
 528     /**
 529      * Parses the given string into an array of output arguments.
 530      *
 531      * @param source    String to be parsed.
 532      * @param pos       On input, starting position for parse. On output,
 533      *                  final position after parse.  Unchanged if parse
 534      *                  fails.
 535      * @param count     Output parameter to receive the number of arguments
 536      *                  parsed.
 537      * @return an array of parsed arguments.  The caller owns both
 538      * the array and its contents.
 539      * @stable ICU 2.0
 540      */
 541     virtual Formattable* parse( const UnicodeString& source,
 542                                 ParsePosition& pos,
 543                                 int32_t& count) const;
 544
 545     /**
 546      * Parses the given string into an array of output arguments.
 547      *
 548      * @param source    String to be parsed.
 549      * @param count     Output param to receive size of returned array.
 550      * @param status    Input/output error code.  If the
 551      *                  pattern cannot be parsed, set to failure code.
 552      * @return an array of parsed arguments.  The caller owns both
 553      * the array and its contents.
 554      * @stable ICU 2.0
 555      */
 556     virtual Formattable* parse( const UnicodeString& source,
 557                                 int32_t& count,
 558                                 UErrorCode& status) const;
 559
 560     /**
 561      * Parses the given string into an array of output arguments
 562      * stored within a single Formattable of type kArray.
 563      *
 564      * @param source    The string to be parsed into an object.
 565      * @param result    Formattable to be set to the parse result.
 566      *                  If parse fails, return contents are undefined.
 567      * @param pos       On input, starting position for parse. On output,
 568      *                  final position after parse.  Unchanged if parse
 569      *                  fails.
 570      * @stable ICU 2.0
 571      */
 572     virtual void parseObject(const UnicodeString& source,
 573                              Formattable& result,
 574                              ParsePosition& pos) const;
 575
 576     /**
 577      * Returns a unique class ID POLYMORPHICALLY.  Pure virtual override.
 578      * This method is to implement a simple version of RTTI, since not all
 579      * C++ compilers support genuine RTTI.  Polymorphic operator==() and
 580      * clone() methods call this method.
 581      *
 582      * @return          The class ID for this object. All objects of a
 583      *                  given class have the same class ID.  Objects of
 584      *                  other classes have different class IDs.
 585      * @stable ICU 2.0
 586      */
 587     virtual UClassID getDynamicClassID(void) const;
 588
 589     /**
 590      * Return the class ID for this class.  This is useful only for
 591      * comparing to a return value from getDynamicClassID().  For example:
 592      * <pre>
 593      * .   Base* polymorphic_pointer = createPolymorphicObject();
 594      * .   if (polymorphic_pointer->getDynamicClassID() ==
 595      * .      Derived::getStaticClassID()) ...
 596      * </pre>
 597      * @return          The class ID for all objects of this class.
 598      * @stable ICU 2.0
 599      */
 600     static UClassID U_EXPORT2 getStaticClassID(void);
 601
 602 private:
 603
 604     Locale              fLocale;
 605     UnicodeString       fPattern;
 606     Format**            formatAliases; // see getFormats
 607     int32_t             formatAliasesCapacity;
 608
 609     MessageFormat(); // default constructor not implemented
 610
 611     /*
 612      * A structure representing one subformat of this MessageFormat.
 613      * Each subformat has a Format object, an offset into the plain
 614      * pattern text fPattern, and an argument number.  The argument
 615      * number corresponds to the array of arguments to be formatted.
 616      * @internal
 617      */
 618     class Subformat {
 619     public:
 620         /**
 621          * @internal
 622          */
 623         Format* format; // formatter
 624         /**
 625          * @internal
 626          */
 627         int32_t offset; // offset into fPattern
 628         /**
 629          * @internal
 630          */
 631         int32_t arg;    // 0-based argument number
 632
 633         /**
 634          * Clone that.format and assign it to this.format
 635          * Do NOT delete this.format
 636          * @internal
 637          */
 638         Subformat& operator=(const Subformat& that) {
 639             format = that.format ? that.format->clone() : NULL;
 640             offset = that.offset;
 641             arg = that.arg;
 642             return *this;
 643         }
 644
 645         /**
 646          * @internal
 647          */
 648         UBool operator==(const Subformat& that) const {
 649             // Do cheap comparisons first
 650             return offset == that.offset &&
 651                    arg == that.arg &&
 652                    ((format == that.format) || // handles NULL
 653                     (*format == *that.format));
 654         }
 655
 656         /**
 657          * @internal
 658          */
 659         UBool operator!=(const Subformat& that) const {
 660             return !operator==(that);
 661         }
 662     };
 663
 664     /**
 665      * A MessageFormat contains an array of subformats.  This array
 666      * needs to grow dynamically if the MessageFormat is modified.
 667      */
 668     Subformat* subformats;
 669     int32_t    subformatCount;
 670     int32_t    subformatCapacity;
 671
 672     /**
 673      * A MessageFormat formats an array of arguments.  Each argument
 674      * has an expected type, based on the pattern.  For example, if
 675      * the pattern contains the subformat "{3,number,integer}", then
 676      * we expect argument 3 to have type Formattable::kLong.  This
 677      * array needs to grow dynamically if the MessageFormat is
 678      * modified.
 679      */
 680     Formattable::Type* argTypes;
 681     int32_t            argTypeCount;
 682     int32_t            argTypeCapacity;
 683
 684     // Variable-size array management
 685     UBool allocateSubformats(int32_t capacity);
 686     UBool allocateArgTypes(int32_t capacity);
 687
 688     /**
 689      * Default Format objects used when no format is specified and a
 690      * numeric or date argument is formatted.  These are volatile
 691      * cache objects maintained only for performance.  They do not
 692      * participate in operator=(), copy constructor(), nor
 693      * operator==().
 694      */
 695     NumberFormat* defaultNumberFormat;
 696     DateFormat*   defaultDateFormat;
 697
 698     /**
 699      * Method to retrieve default formats (or NULL on failure).
 700      * These are semantically const, but may modify *this.
 701      */
 702     const NumberFormat* getDefaultNumberFormat(UErrorCode&) const;
 703     const DateFormat*   getDefaultDateFormat(UErrorCode&) const;
 704
 705     /**
 706      * Finds the word s, in the keyword list and returns the located index.
 707      * @param s the keyword to be searched for.
 708      * @param list the list of keywords to be searched with.
 709      * @return the index of the list which matches the keyword s.
 710      */
 711     static int32_t findKeyword( const UnicodeString& s,
 712                                 const UChar * const *list);
 713
 714     /**
 715      * Formats the array of arguments and copies the result into the
 716      * result buffer, updates the field position.
 717      *
 718      * @param arguments The formattable objects array.
 719      * @param cnt       The array count.
 720      * @param appendTo  Output parameter to receive result.
 721      *                  Result is appended to existing contents.
 722      * @param status    Field position status.
 723      * @param recursionProtection
 724      *                  Initially zero. Bits 0..9 are used to indicate
 725      *                  that a parameter has already been seen, to
 726      *                  avoid recursion.  Currently unused.
 727      * @param success   The error code status.
 728      * @return          Reference to 'appendTo' parameter.
 729      */
 730     UnicodeString&  format( const Formattable* arguments,
 731                             int32_t cnt,
 732                             UnicodeString& appendTo,
 733                             FieldPosition& status,
 734                             int32_t recursionProtection,
 735                             UErrorCode& success) const;
 736
 737     void             makeFormat(int32_t offsetNumber,
 738                                 UnicodeString* segments,
 739                                 UParseError& parseError,
 740                                 UErrorCode& success);
 741
 742     /**
 743      * Convenience method that ought to be in NumberFormat
 744      */
 745     NumberFormat* createIntegerFormat(const Locale& locale, UErrorCode& status) const;
 746
 747     /**
 748      * Checks the range of the source text to quote the special
 749      * characters, { and ' and copy to target buffer.
 750      * @param source
 751      * @param start the text offset to start the process of in the source string
 752      * @param end the text offset to end the process of in the source string
 753      * @param appendTo  Output parameter to receive result.
 754      *                  Result is appended to existing contents.
 755      */
 756     static void copyAndFixQuotes(const UnicodeString& appendTo, int32_t start, int32_t end, UnicodeString& target);
 757
 758     /**
 759      * Returns array of argument types in the parsed pattern
 760      * for use in C API.  Only for the use of umsg_vformat().  Not
 761      * for public consumption.
 762      * @param listCount  Output parameter to receive the size of array
 763      * @return           The array of formattable types in the pattern
 764      * @internal
 765      */
 766     const Formattable::Type* getArgTypeList(int32_t& listCount) const {
 767         listCount = argTypeCount;
 768         return argTypes;
 769     }
 770
 771     friend class MessageFormatAdapter; // getFormatTypeList() access
 772 };
 773
 774 inline UnicodeString&
 775 MessageFormat::format(const Formattable& obj,
 776                       UnicodeString& appendTo,
 777                       UErrorCode& status) const {
 778     return Format::format(obj, appendTo, status);
 779 }
 780 U_NAMESPACE_END
 781
 782 #endif /* #if !UCONFIG_NO_FORMATTING */
 783
 784 #endif // _MSGFMT
 785 //eof
 786