Check in the pristine copy of ICU 4.6...

icu46/source/i18n/unicode/msgfmt.h

+/*
+* Copyright (C) 2007-2010, International Business Machines Corporation and
+* others. All Rights Reserved.
+********************************************************************************
+*
+* File MSGFMT.H
+*
+* Modification History:
+*
+*   Date        Name        Description
+*   02/19/97    aliu        Converted from java.
+*   03/20/97    helena      Finished first cut of implementation.
+*   07/22/98    stephen     Removed operator!= (defined in Format)
+*   08/19/2002  srl         Removing Javaisms
+*******************************************************************************/
+
+#ifndef MSGFMT_H
+#define MSGFMT_H
+
+#include "unicode/utypes.h"
+
+/**
+ * \file
+ * \brief C++ API: Formats messages in a language-neutral way.
+ */
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "unicode/format.h"
+#include "unicode/locid.h"
+#include "unicode/parseerr.h"
+#include "unicode/uchar.h"
+
+U_NAMESPACE_BEGIN
+
+class NumberFormat;
+class DateFormat;
+
+/**
+ *
+ * MessageFormat produces concatenated messages in a language-neutral
+ * way.  Use this whenever concatenating strings that are displayed to
+ * end users.
+ *
+ * <P>A MessageFormat contains an array of <EM>subformats</EM> arranged
+ * within a <EM>template string</EM>.  Together, the subformats and
+ * template string determine how the MessageFormat will operate during
+ * formatting and parsing.
+ *
+ * <P>Typically, both the subformats and the template string are
+ * specified at once in a <EM>pattern</EM>.  By using different
+ * patterns for different locales, messages may be localized.
+ *
+ * <P>When formatting, MessageFormat takes an array of arguments
+ * and produces a user-readable string.  Each argument is a
+ * Formattable object; they may be passed in in an array, or as a
+ * single Formattable object which itself contains an array.  Each
+ * argument is matched up with its corresponding subformat, which then
+ * formats it into a string.  The resulting strings are then assembled
+ * within the string template of the MessageFormat to produce the
+ * final output string.
+ *
+ * <p><strong>Note:</strong>
+ * In ICU 4.0 MessageFormat supports named arguments.  If a named argument
+ * is used, all arguments must be named.  Names start with a character in
+ * <code>UCHAR_ID_START</code> and continue with characters in
+ * <code>UCHARID_CONTINUE</code>, in particular they do not start with a digit.
+ * If named arguments are used, {@link #usesNamedArguments()} will return true.
+ *
+ * <p>The other new methods supporting named arguments are
+ * {@link #getFormatNames(UErrorCode& status)},
+ * {@link #getFormat(const UnicodeString& formatName, UErrorCode& status)}
+ * {@link #setFormat(const UnicodeString& formatName, const Format& format, UErrorCode& status)},
+ * {@link #adoptFormat(const UnicodeString& formatName, Format* formatToAdopt, UErrorCode& status)},
+ * {@link #format(const UnicodeString* argumentNames, const Formattable* arguments,
+ *  int32_t count, UnicodeString& appendTo,UErrorCode& status)}.
+ * These methods are all compatible with patterns that do not used named arguments--
+ * in these cases the keys in the input or output use <code>UnicodeString</code>s
+ * that name the argument indices, e.g. "0", "1", "2"... etc.
+ *
+ * <p>If this format uses named arguments, certain methods that take or
+ * return arrays do not perform any action, since it is not possible to
+ * identify positions in an array using a name.  Of these methods,
+ * UErrorCode is set to U_ILLEGAL_ARGUMENT_ERROR by format, and to
+ * U_ARGUMENT_TYPE_MISMATCH by parse.
+ * These methods are
+ * {@link #adoptFormats(Format** formatsToAdopt, int32_t count)},
+ * {@link #setFormats(const Format** newFormats,int32_t count)},
+ * {@link #adoptFormat(int32_t n, Format *newFormat)},
+ * {@link #setFormat(int32_t n, Format& newFormat)},
+ * {@link #format(const Formattable* source, int32_t count, UnicodeString& appendTo, FieldPosition& ignore, UErrorCode& success)},
+ * {@link #format(const UnicodeString& pattern,const Formattable* arguments,int32_t cnt,UnicodeString& appendTo,UErrorCode& success)},
+ * {@link #format(const Formattable& source, UnicodeString& appendTo, FieldPosition& ignore, UErrorCode& success)},
+ * {@link #format(const Formattable* arguments, int32_t cnt, UnicodeString& appendTo, FieldPosition& status, int32_t recursionProtection,UErrorCode& success)},
+ * {@link #parse(const UnicodeString& source, ParsePosition& pos, int32_t& count)},
+ * {@link #parse(const UnicodeString& source, int32_t& cnt, UErrorCode& status)}
+ *
+ * <P>
+ * During parsing, an input string is matched against the string
+ * template of the MessageFormat to produce an array of Formattable
+ * objects.  Plain text of the template string is matched directly
+ * against input text.  At each position in the template string where
+ * a subformat is located, the subformat is called to parse the
+ * corresponding segment of input text to produce an output argument.
+ * In this way, an array of arguments is created which together
+ * constitute the parse result.
+ * <P>
+ * Parsing may fail or produce unexpected results in a number of
+ * circumstances.
+ * <UL>
+ * <LI>If one of the arguments does not occur in the pattern, it
+ * will be returned as a default Formattable.
+ * <LI>If the format of an argument loses information, such as with
+ * a choice format where a large number formats to "many", then the
+ * parse may not correspond to the originally formatted argument.
+ * <LI>MessageFormat does not handle ChoiceFormat recursion during
+ * parsing; such parses will fail.
+ * <LI>Parsing will not always find a match (or the correct match) if
+ * some part of the parse is ambiguous.  For example, if the pattern
+ * "{1},{2}" is used with the string arguments {"a,b", "c"}, it will
+ * format as "a,b,c".  When the result is parsed, it will return {"a",
+ * "b,c"}.
+ * <LI>If a single argument is formatted more than once in the string,
+ * then the rightmost subformat in the pattern string will produce the
+ * parse result; prior subformats with the same argument index will
+ * have no effect.
+ * </UL>
+ * Here are some examples of usage:
+ * <P>
+ * Example 1:
+ * <pre>
+ * \code
+ *     UErrorCode success = U_ZERO_ERROR;
+ *     GregorianCalendar cal(success);
+ *     Formattable arguments[] = {
+ *         7L,
+ *         Formattable( (Date) cal.getTime(success), Formattable::kIsDate),
+ *         "a disturbance in the Force"
+ *     };
+ *
+ *     UnicodeString result;
+ *     MessageFormat::format(
+ *          "At {1,time} on {1,date}, there was {2} on planet {0,number}.",
+ *          arguments, 3, result, success );
+ *
+ *     cout << "result: " << result << endl;
+ *     //<output>: At 4:34:20 PM on 23-Mar-98, there was a disturbance
+ *     //             in the Force on planet 7.
+ * \endcode
+ * </pre>
+ * Typically, the message format will come from resources, and the
+ * arguments will be dynamically set at runtime.
+ * <P>
+ * Example 2:
+ * <pre>
+ *  \code
+ *     success = U_ZERO_ERROR;
+ *     Formattable testArgs[] = {3L, "MyDisk"};
+ *
+ *     MessageFormat form(
+ *         "The disk \"{1}\" contains {0} file(s).", success );
+ *
+ *     UnicodeString string;
+ *     FieldPosition fpos = 0;
+ *     cout << "format: " << form.format(testArgs, 2, string, fpos, success ) << endl;
+ *
+ *     // output, with different testArgs:
+ *     // output: The disk "MyDisk" contains 0 file(s).
+ *     // output: The disk "MyDisk" contains 1 file(s).
+ *     // output: The disk "MyDisk" contains 1,273 file(s).
+ *  \endcode
+ *  </pre>
+ *
+ *  The pattern is of the following form.  Legend:
+ *  <pre>
+ * \code
+ *       {optional item}
+ *       (group that may be repeated)*
+ * \endcode
+ *  </pre>
+ *  Do not confuse optional items with items inside quoted braces, such
+ *  as this: "{".  Quoted braces are literals.
+ *  <pre>
+ *  \code
+ *       messageFormatPattern := string ( "{" messageFormatElement "}" string )*
+ *
+ *       messageFormatElement := argumentIndex | argumentName { "," elementFormat }
+ *
+ *       elementFormat := "time" { "," datetimeStyle }
+ *                      | "date" { "," datetimeStyle }
+ *                      | "number" { "," numberStyle }
+ *                      | "choice" "," choiceStyle
+ *                      | "spellout" { "," spelloutStyle }
+ *                      | "ordinal" { "," spelloutStyle }
+ *                      | "duration" { "," spelloutStyle }
+ *                      | "plural" "," pluralStyle
+ *                      | "select" "," selectStyle
+ *
+ *       datetimeStyle := "short"
+ *                      | "medium"
+ *                      | "long"
+ *                      | "full"
+ *                      | dateFormatPattern
+ *
+ *       numberStyle :=   "currency"
+ *                      | "percent"
+ *                      | "integer"
+ *                      | numberFormatPattern
+ *
+ *       choiceStyle :=   choiceFormatPattern
+ *
+ *       pluralStyle :=   pluralFormatPattern
+ *
+ *       selectStyle :=   selectFormatPattern
+ *
+ *       spelloutStyle := ruleSetName
+ * \endcode
+ * </pre>
+ * If there is no elementFormat, then the argument must be a string,
+ * which is substituted. If there is no dateTimeStyle or numberStyle,
+ * then the default format is used (e.g.  NumberFormat::createInstance(),
+ * DateFormat::createTimeInstance(DateFormat::kDefault, ...) or
+ * DateFormat::createDateInstance(DateFormat::kDefault, ...). For
+ * a RuleBasedNumberFormat, if there is no ruleSetName, the default
+ * rule set is used. For a ChoiceFormat or PluralFormat or SelectFormat, the pattern
+ * must always be specified, since there is no default.
+ * <P>
+ * In strings, single quotes can be used to quote syntax characters.
+ * A literal single quote is represented by '', both within and outside
+ * of single-quoted segments.  Inside a
+ * messageFormatElement, quotes are <EM>not</EM> removed. For example,
+ * {1,number,$'#',##} will produce a number format with the pound-sign
+ * quoted, with a result such as: "$#31,45".
+ * <P>
+ * If a pattern is used, then unquoted braces in the pattern, if any,
+ * must match: that is, "ab {0} de" and "ab '}' de" are ok, but "ab
+ * {0'}' de" and "ab } de" are not.
+ * <p>
+ * <dl><dt><b>Warning:</b><dd>The rules for using quotes within message
+ * format patterns unfortunately have shown to be somewhat confusing.
+ * In particular, it isn't always obvious to localizers whether single
+ * quotes need to be doubled or not. Make sure to inform localizers about
+ * the rules, and tell them (for example, by using comments in resource
+ * bundle source files) which strings will be processed by MessageFormat.
+ * Note that localizers may need to use single quotes in translated
+ * strings where the original version doesn't have them.
+ * <br>Note also that the simplest way to avoid the problem is to
+ * use the real apostrophe (single quote) character U+2019 (') for
+ * human-readable text, and to use the ASCII apostrophe (U+0027 ' )
+ * only in program syntax, like quoting in MessageFormat.
+ * See the annotations for U+0027 Apostrophe in The Unicode Standard.</p>
+ * </dl>
+ * <P>
+ * The argumentIndex is a non-negative integer, which corresponds to the
+ * index of the arguments presented in an array to be formatted.  The
+ * first argument has argumentIndex 0.
+ * <P>
+ * It is acceptable to have unused arguments in the array.  With missing
+ * arguments, or arguments that are not of the right class for the
+ * specified format, a failing UErrorCode result is set.
+ * <P>
+ * <strong>Creating internationalized messages that include plural forms, you
+ * can use a PluralFormat:</strong>
+ * <pre>
+ * \code
+ *  UErrorCode err = U_ZERO_ERROR;
+ *  UnicodeString t1("{0, plural, one{C''est # fichier} other{Ce sont # fichiers}} dans la liste.");
+ *  MessageFormat* msgFmt = new MessageFormat(t1, Locale("fr"), err);
+ *  if (U_FAILURE(err)) {
+ *      return err;
+ *  }
+ *
+ *  Formattable args1[] = {(int32_t)0};
+ *  Formattable args2[] = {(int32_t)3};
+ *  FieldPosition ignore(FieldPosition::DONT_CARE);
+ *  UnicodeString result;
+ *  msgFmt->format(args1, 1, result, ignore, status);
+ *  cout << result << endl;
+ *  result.remove();
+ *  msgFmt->format(args2, 1, result, ignore, status);
+ *  cout << result << endl;
+ *
+ *  // output, with different args
+ *  // output: C'est 0,0 fichier dans la liste.
+ *  // output: Ce sont 3 fichiers dans la liste."
+ * \endcode
+ * </pre>
+ * Please check PluralFormat and PluralRules for details.
+ * </P>
+ */
+class U_I18N_API MessageFormat : public Format {
+public:
+    /**
+     * Enum type for kMaxFormat.
+     * @obsolete ICU 3.0.  The 10-argument limit was removed as of ICU 2.6,
+     * rendering this enum type obsolete.
+     */
+    enum EFormatNumber {
+        /**
+         * The maximum number of arguments.
+         * @obsolete ICU 3.0.  The 10-argument limit was removed as of ICU 2.6,
+         * rendering this constant obsolete.
+         */
+        kMaxFormat = 10
+    };
+
+    /**
+     * Constructs a new MessageFormat using the given pattern and the
+     * default locale.
+     *
+     * @param pattern   Pattern used to construct object.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @stable ICU 2.0
+     */
+    MessageFormat(const UnicodeString& pattern,
+                  UErrorCode &status);
+
+    /**
+     * Constructs a new MessageFormat using the given pattern and locale.
+     * @param pattern   Pattern used to construct object.
+     * @param newLocale The locale to use for formatting dates and numbers.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @stable ICU 2.0
+     */
+    MessageFormat(const UnicodeString& pattern,
+                  const Locale& newLocale,
+                        UErrorCode& status);
+    /**
+     * Constructs a new MessageFormat using the given pattern and locale.
+     * @param pattern   Pattern used to construct object.
+     * @param newLocale The locale to use for formatting dates and numbers.
+     * @param parseError Struct to recieve information on position
+     *                   of error within the pattern.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @stable ICU 2.0
+     */
+    MessageFormat(const UnicodeString& pattern,
+                  const Locale& newLocale,
+                  UParseError& parseError,
+                  UErrorCode& status);
+    /**
+     * Constructs a new MessageFormat from an existing one.
+     * @stable ICU 2.0
+     */
+    MessageFormat(const MessageFormat&);
+
+    /**
+     * Assignment operator.
+     * @stable ICU 2.0
+     */
+    const MessageFormat& operator=(const MessageFormat&);
+
+    /**
+     * Destructor.
+     * @stable ICU 2.0
+     */
+    virtual ~MessageFormat();
+
+    /**
+     * Clones this Format object polymorphically.  The caller owns the
+     * result and should delete it when done.
+     * @stable ICU 2.0
+     */
+    virtual Format* clone(void) const;
+
+    /**
+     * Returns true if the given Format objects are semantically equal.
+     * Objects of different subclasses are considered unequal.
+     * @param other  the object to be compared with.
+     * @return       true if the given Format objects are semantically equal.
+     * @stable ICU 2.0
+     */
+    virtual UBool operator==(const Format& other) const;
+
+    /**
+     * Sets the locale. This locale is used for fetching default number or date
+     * format information.
+     * @param theLocale    the new locale value to be set.
+     * @stable ICU 2.0
+     */
+    virtual void setLocale(const Locale& theLocale);
+
+    /**
+     * Gets the locale. This locale is used for fetching default number or date
+     * format information.
+     * @return    the locale of the object.
+     * @stable ICU 2.0
+     */
+    virtual const Locale& getLocale(void) const;
+
+    /**
+     * Applies the given pattern string to this message format.
+     *
+     * @param pattern   The pattern to be applied.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @stable ICU 2.0
+     */
+    virtual void applyPattern(const UnicodeString& pattern,
+                              UErrorCode& status);
+    /**
+     * Applies the given pattern string to this message format.
+     *
+     * @param pattern    The pattern to be applied.
+     * @param parseError Struct to recieve information on position
+     *                   of error within pattern.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @stable ICU 2.0
+     */
+    virtual void applyPattern(const UnicodeString& pattern,
+                             UParseError& parseError,
+                             UErrorCode& status);
+
+    /**
+     * Returns a pattern that can be used to recreate this object.
+     *
+     * @param appendTo  Output parameter to receive the pattern.
+     *                  Result is appended to existing contents.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeString& toPattern(UnicodeString& appendTo) const;
+
+    /**
+     * Sets subformats.
+     * See the class description about format numbering.
+     * The caller should not delete the Format objects after this call.
+     * <EM>The array formatsToAdopt is not itself adopted.</EM> Its
+     * ownership is retained by the caller. If the call fails because
+     * memory cannot be allocated, then the formats will be deleted
+     * by this method, and this object will remain unchanged.
+     *
+     * <p>If this format uses named arguments, the new formats are discarded
+     * and this format remains unchanged.
+     *
+     * @stable ICU 2.0
+     * @param formatsToAdopt    the format to be adopted.
+     * @param count             the size of the array.
+     */
+    virtual void adoptFormats(Format** formatsToAdopt, int32_t count);
+
+    /**
+     * Sets subformats.
+     * See the class description about format numbering.
+     * Each item in the array is cloned into the internal array.
+     * If the call fails because memory cannot be allocated, then this
+     * object will remain unchanged.
+     *
+     * <p>If this format uses named arguments, the new formats are discarded
+     * and this format remains unchanged.
+     *
+     * @stable ICU 2.0
+     * @param newFormats the new format to be set.
+     * @param cnt        the size of the array.
+     */
+    virtual void setFormats(const Format** newFormats, int32_t cnt);
+
+
+    /**
+     * Sets one subformat.
+     * See the class description about format numbering.
+     * The caller should not delete the Format object after this call.
+     * If the number is over the number of formats already set,
+     * the item will be deleted and ignored.
+     *
+     * <p>If this format uses named arguments, the new format is discarded
+     * and this format remains unchanged.
+     *
+     * @stable ICU 2.0
+     * @param formatNumber     index of the subformat.
+     * @param formatToAdopt    the format to be adopted.
+     */
+    virtual void adoptFormat(int32_t formatNumber, Format* formatToAdopt);
+
+    /**
+     * Sets one subformat.
+     * See the class description about format numbering.
+     * If the number is over the number of formats already set,
+     * the item will be ignored.
+     * @param formatNumber     index of the subformat.
+     * @param format    the format to be set.
+     * @stable ICU 2.0
+     */
+    virtual void setFormat(int32_t formatNumber, const Format& format);
+
+    /**
+     * Gets format names. This function returns formatNames in StringEnumerations
+     * which can be used with getFormat() and setFormat() to export formattable
+     * array from current MessageFormat to another.  It is caller's resposibility
+     * to delete the returned formatNames.
+     * @param status  output param set to success/failure code.
+     * @stable ICU 4.0
+     */
+    virtual StringEnumeration* getFormatNames(UErrorCode& status);
+
+    /**
+     * Gets subformat pointer for given format name.
+     * This function supports both named and numbered
+     * arguments-- if numbered, the formatName is the
+     * corresponding UnicodeStrings (e.g. "0", "1", "2"...).
+     * The returned Format object should not be deleted by the caller,
+     * nor should the ponter of other object .  The pointer and its
+     * contents remain valid only until the next call to any method
+     * of this class is made with this object.
+     * @param formatName the name or number specifying a format
+     * @param status  output param set to success/failure code.
+     * @stable ICU 4.0
+     */
+    virtual Format* getFormat(const UnicodeString& formatName, UErrorCode& status);
+
+    /**
+     * Sets one subformat for given format name.
+     * See the class description about format name.
+     * This function supports both named and numbered
+     * arguments-- if numbered, the formatName is the
+     * corresponding UnicodeStrings (e.g. "0", "1", "2"...).
+     * If there is no matched formatName or wrong type,
+     * the item will be ignored.
+     * @param formatName  Name of the subformat.
+     * @param format      the format to be set.
+     * @param status  output param set to success/failure code.
+     * @stable ICU 4.0
+     */
+    virtual void setFormat(const UnicodeString& formatName, const Format& format, UErrorCode& status);
+
+    /**
+     * Sets one subformat for given format name.
+     * See the class description about format name.
+     * This function supports both named and numbered
+     * arguments-- if numbered, the formatName is the
+     * corresponding UnicodeStrings (e.g. "0", "1", "2"...).
+     * If there is no matched formatName or wrong type,
+     * the item will be ignored.
+     * The caller should not delete the Format object after this call.
+     * @param formatName  Name of the subformat.
+     * @param formatToAdopt  Format to be adopted.
+     * @param status      output param set to success/failure code.
+     * @stable ICU 4.0
+     */
+    virtual void adoptFormat(const UnicodeString& formatName, Format* formatToAdopt, UErrorCode& status);
+
+    /**
+     * Gets an array of subformats of this object.  The returned array
+     * should not be deleted by the caller, nor should the pointers
+     * within the array.  The array and its contents remain valid only
+     * until the next call to this format. See the class description
+     * about format numbering.
+     *
+     * @param count output parameter to receive the size of the array
+     * @return an array of count Format* objects, or NULL if out of
+     * memory.  Any or all of the array elements may be NULL.
+     * @stable ICU 2.0
+     */
+    virtual const Format** getFormats(int32_t& count) const;
+
+
+    using Format::format;
+
+    /**
+     * Formats the given array of arguments into a user-readable string.
+     * Does not take ownership of the Formattable* array or its contents.
+     *
+     * <p>If this format uses named arguments, appendTo is unchanged and
+     * status is set to U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * @param source    An array of objects to be formatted.
+     * @param count     The number of elements of 'source'.
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param ignore    Not used; inherited from base class API.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 2.0
+     */
+    UnicodeString& format(const Formattable* source,
+                          int32_t count,
+                          UnicodeString& appendTo,
+                          FieldPosition& ignore,
+                          UErrorCode& status) const;
+
+    /**
+     * Formats the given array of arguments into a user-readable string
+     * using the given pattern.
+     *
+     * <p>If this format uses named arguments, appendTo is unchanged and
+     * status is set to U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * @param pattern   The pattern.
+     * @param arguments An array of objects to be formatted.
+     * @param count     The number of elements of 'source'.
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 2.0
+     */
+    static UnicodeString& format(const UnicodeString& pattern,
+                                 const Formattable* arguments,
+                                 int32_t count,
+                                 UnicodeString& appendTo,
+                                 UErrorCode& status);
+
+    /**
+     * Formats the given array of arguments into a user-readable
+     * string.  The array must be stored within a single Formattable
+     * object of type kArray. If the Formattable object type is not of
+     * type kArray, then returns a failing UErrorCode.
+     *
+     * <p>If this format uses named arguments, appendTo is unchanged and
+     * status is set to U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * @param obj       A Formattable of type kArray containing
+     *                  arguments to be formatted.
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param pos       On input: an alignment field, if desired.
+     *                  On output: the offsets of the alignment field.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 2.0
+     */
+    virtual UnicodeString& format(const Formattable& obj,
+                                  UnicodeString& appendTo,
+                                  FieldPosition& pos,
+                                  UErrorCode& status) const;
+
+    /**
+     * Formats the given array of arguments into a user-readable
+     * string.  The array must be stored within a single Formattable
+     * object of type kArray. If the Formattable object type is not of
+     * type kArray, then returns a failing UErrorCode.
+     *
+     * @param obj       The object to format
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 2.0
+     */
+    UnicodeString& format(const Formattable& obj,
+                          UnicodeString& appendTo,
+                          UErrorCode& status) const;
+
+
+    /**
+     * Formats the given array of arguments into a user-defined argument name
+     * array. This function supports both named and numbered
+     * arguments-- if numbered, the formatName is the
+     * corresponding UnicodeStrings (e.g. "0", "1", "2"...).
+     *
+     * @param argumentNames argument name array
+     * @param arguments An array of objects to be formatted.
+     * @param count     The number of elements of 'argumentNames' and
+     *                  arguments.  The number of argumentNames and arguments
+     *                  must be the same.
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return          Reference to 'appendTo' parameter.
+     * @stable ICU 4.0
+     */
+    UnicodeString& format(const UnicodeString* argumentNames,
+                          const Formattable* arguments,
+                          int32_t count,
+                          UnicodeString& appendTo,
+                          UErrorCode& status) const;
+    /**
+     * Parses the given string into an array of output arguments.
+     *
+     * @param source    String to be parsed.
+     * @param pos       On input, starting position for parse. On output,
+     *                  final position after parse.  Unchanged if parse
+     *                  fails.
+     * @param count     Output parameter to receive the number of arguments
+     *                  parsed.
+     * @return an array of parsed arguments.  The caller owns both
+     * the array and its contents.
+     * @stable ICU 2.0
+     */
+    virtual Formattable* parse(const UnicodeString& source,
+                               ParsePosition& pos,
+                               int32_t& count) const;
+
+    /**
+     * Parses the given string into an array of output arguments.
+     *
+     * <p>If this format uses named arguments, status is set to
+     * U_ARGUMENT_TYPE_MISMATCH.
+     *
+     * @param source    String to be parsed.
+     * @param count     Output param to receive size of returned array.
+     * @param status    Input/output error code.  If the
+     *                  pattern cannot be parsed, set to failure code.
+     * @return an array of parsed arguments.  The caller owns both
+     * the array and its contents. Returns NULL if status is not U_ZERO_ERROR.
+     *
+     * @stable ICU 2.0
+     */
+    virtual Formattable* parse(const UnicodeString& source,
+                               int32_t& count,
+                               UErrorCode& status) const;
+
+    /**
+     * Parses the given string into an array of output arguments
+     * stored within a single Formattable of type kArray.
+     *
+     * @param source    The string to be parsed into an object.
+     * @param result    Formattable to be set to the parse result.
+     *                  If parse fails, return contents are undefined.
+     * @param pos       On input, starting position for parse. On output,
+     *                  final position after parse.  Unchanged if parse
+     *                  fails.
+     * @stable ICU 2.0
+     */
+    virtual void parseObject(const UnicodeString& source,
+                             Formattable& result,
+                             ParsePosition& pos) const;
+
+    /**
+     * Convert an 'apostrophe-friendly' pattern into a standard
+     * pattern.  Standard patterns treat all apostrophes as
+     * quotes, which is problematic in some languages, e.g.
+     * French, where apostrophe is commonly used.  This utility
+     * assumes that only an unpaired apostrophe immediately before
+     * a brace is a true quote.  Other unpaired apostrophes are paired,
+     * and the resulting standard pattern string is returned.
+     *
+     * <p><b>Note</b> it is not guaranteed that the returned pattern
+     * is indeed a valid pattern.  The only effect is to convert
+     * between patterns having different quoting semantics.
+     *
+     * @param pattern the 'apostrophe-friendly' patttern to convert
+     * @param status    Input/output error code.  If the pattern
+     *                  cannot be parsed, the failure code is set.
+     * @return the standard equivalent of the original pattern
+     * @stable ICU 3.4
+     */
+    static UnicodeString autoQuoteApostrophe(const UnicodeString& pattern,
+        UErrorCode& status);
+
+    /**
+     * Returns true if this MessageFormat uses named arguments,
+     * and false otherwise.  See class description.
+     *
+     * @return true if named arguments are used.
+     * @stable ICU 4.0
+     */
+    UBool usesNamedArguments() const;
+
+
+    /**
+     * This API is for ICU internal use only.
+     * Please do not use it.
+     *
+     * Returns argument types count in the parsed pattern.
+     * Used to distinguish pattern "{0} d" and "d".
+     *
+     * @return           The number of formattable types in the pattern
+     * @internal
+     */
+    int32_t getArgTypeCount() const;
+
+    /**
+     * Returns a unique class ID POLYMORPHICALLY.  Pure virtual override.
+     * This method is to implement a simple version of RTTI, since not all
+     * C++ compilers support genuine RTTI.  Polymorphic operator==() and
+     * clone() methods call this method.
+     *
+     * @return          The class ID for this object. All objects of a
+     *                  given class have the same class ID.  Objects of
+     *                  other classes have different class IDs.
+     * @stable ICU 2.0
+     */
+    virtual UClassID getDynamicClassID(void) const;
+
+    /**
+     * Return the class ID for this class.  This is useful only for
+     * comparing to a return value from getDynamicClassID().  For example:
+     * <pre>
+     * .   Base* polymorphic_pointer = createPolymorphicObject();
+     * .   if (polymorphic_pointer->getDynamicClassID() ==
+     * .      Derived::getStaticClassID()) ...
+     * </pre>
+     * @return          The class ID for all objects of this class.
+     * @stable ICU 2.0
+     */
+    static UClassID U_EXPORT2 getStaticClassID(void);
+
+private:
+
+    Locale              fLocale;
+    UnicodeString       fPattern;
+    Format**            formatAliases; // see getFormats
+    int32_t             formatAliasesCapacity;
+    UProperty           idStart;
+    UProperty           idContinue;
+
+    MessageFormat(); // default constructor not implemented
+
+    /*
+     * A structure representing one subformat of this MessageFormat.
+     * Each subformat has a Format object, an offset into the plain
+     * pattern text fPattern, and an argument number.  The argument
+     * number corresponds to the array of arguments to be formatted.
+     * @internal
+     */
+    class Subformat;
+
+    /**
+     * A MessageFormat contains an array of subformats.  This array
+     * needs to grow dynamically if the MessageFormat is modified.
+     */
+    Subformat* subformats;
+    int32_t    subformatCount;
+    int32_t    subformatCapacity;
+
+    /**
+     * A MessageFormat formats an array of arguments.  Each argument
+     * has an expected type, based on the pattern.  For example, if
+     * the pattern contains the subformat "{3,number,integer}", then
+     * we expect argument 3 to have type Formattable::kLong.  This
+     * array needs to grow dynamically if the MessageFormat is
+     * modified.
+     */
+    Formattable::Type* argTypes;
+    int32_t            argTypeCount;
+    int32_t            argTypeCapacity;
+
+    /**
+      * Is true iff all argument names are non-negative numbers.
+      *
+      */
+    UBool isArgNumeric;
+
+    // Variable-size array management
+    UBool allocateSubformats(int32_t capacity);
+    UBool allocateArgTypes(int32_t capacity);
+
+    /**
+     * Default Format objects used when no format is specified and a
+     * numeric or date argument is formatted.  These are volatile
+     * cache objects maintained only for performance.  They do not
+     * participate in operator=(), copy constructor(), nor
+     * operator==().
+     */
+    NumberFormat* defaultNumberFormat;
+    DateFormat*   defaultDateFormat;
+
+    /**
+     * Method to retrieve default formats (or NULL on failure).
+     * These are semantically const, but may modify *this.
+     */
+    const NumberFormat* getDefaultNumberFormat(UErrorCode&) const;
+    const DateFormat*   getDefaultDateFormat(UErrorCode&) const;
+
+    /**
+     * Finds the word s, in the keyword list and returns the located index.
+     * @param s the keyword to be searched for.
+     * @param list the list of keywords to be searched with.
+     * @return the index of the list which matches the keyword s.
+     */
+    static int32_t findKeyword( const UnicodeString& s,
+                                const UChar * const *list);
+
+    /**
+     * Formats the array of arguments and copies the result into the
+     * result buffer, updates the field position.
+     *
+     * @param arguments The formattable objects array.
+     * @param cnt       The array count.
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     * @param status    Field position status.
+     * @param recursionProtection
+     *                  Initially zero. Bits 0..9 are used to indicate
+     *                  that a parameter has already been seen, to
+     *                  avoid recursion.  Currently unused.
+     * @param success   The error code status.
+     * @return          Reference to 'appendTo' parameter.
+     */
+    UnicodeString&  format( const Formattable* arguments,
+                            int32_t cnt,
+                            UnicodeString& appendTo,
+                            FieldPosition& status,
+                            int32_t recursionProtection,
+                            UErrorCode& success) const;
+
+    UnicodeString&  format( const Formattable* arguments,
+                            const UnicodeString *argumentNames,
+                            int32_t cnt,
+                            UnicodeString& appendTo,
+                            FieldPosition& status,
+                            int32_t recursionProtection,
+                            UErrorCode& success) const;
+
+    void             makeFormat(int32_t offsetNumber,
+                                UnicodeString* segments,
+                                UParseError& parseError,
+                                UErrorCode& success);
+
+    /**
+     * Convenience method that ought to be in NumberFormat
+     */
+    NumberFormat* createIntegerFormat(const Locale& locale, UErrorCode& status) const;
+
+    /**
+     * Checks the range of the source text to quote the special
+     * characters, { and ' and copy to target buffer.
+     * @param source
+     * @param start the text offset to start the process of in the source string
+     * @param end the text offset to end the process of in the source string
+     * @param appendTo  Output parameter to receive result.
+     *                  Result is appended to existing contents.
+     */
+    static void copyAndFixQuotes(const UnicodeString& appendTo, int32_t start, int32_t end, UnicodeString& target);
+
+    /**
+     * Returns array of argument types in the parsed pattern
+     * for use in C API.  Only for the use of umsg_vformat().  Not
+     * for public consumption.
+     * @param listCount  Output parameter to receive the size of array
+     * @return           The array of formattable types in the pattern
+     * @internal
+     */
+    const Formattable::Type* getArgTypeList(int32_t& listCount) const {
+        listCount = argTypeCount;
+        return argTypes;
+    }
+
+    /**
+     * Returns FALSE if the argument name is not legal.
+     * @param  argName   argument name.
+     * @return TRUE if the argument name is legal, otherwise return FALSE.
+     */
+    UBool isLegalArgName(const UnicodeString& argName) const;
+
+    friend class MessageFormatAdapter; // getFormatTypeList() access
+};
+
+inline UnicodeString&
+MessageFormat::format(const Formattable& obj,
+                      UnicodeString& appendTo,
+                      UErrorCode& status) const {
+    return Format::format(obj, appendTo, status);
+}
+
+U_NAMESPACE_END
+
+#endif /* #if !UCONFIG_NO_FORMATTING */
+
+#endif // _MSGFMT
+//eof