// © 2016 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

/*

*******************************************************************************

* Copyright (C) 1997-2015, International Business Machines Corporation and others.

* All Rights Reserved.

*******************************************************************************

*/

#ifndef RBNF_H

#define RBNF_H

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

/**

 * \file

 * \brief C++ API: Rule Based Number Format

 */

/**

 * \def U_HAVE_RBNF

 * This will be 0 if RBNF support is not included in ICU

 * and 1 if it is.

 *

 * @stable ICU 2.4

 */

#if UCONFIG_NO_FORMATTING

#define U_HAVE_RBNF 0

#else

#define U_HAVE_RBNF 1

#include "unicode/dcfmtsym.h"

#include "unicode/fmtable.h"

#include "unicode/locid.h"

#include "unicode/numfmt.h"

#include "unicode/unistr.h"

#include "unicode/strenum.h"

#include "unicode/brkiter.h"

#include "unicode/upluralrules.h"

U_NAMESPACE_BEGIN

class NFRule;

class NFRuleSet;

class LocalizationInfo;

class PluralFormat;

class RuleBasedCollator;

/**

 * Tags for the predefined rulesets.

 *

 * @stable ICU 2.2

 */

enum URBNFRuleSetTag {

    /**

     * Requests predefined ruleset for spelling out numeric values in words.

     * @stable ICU 2.2

     */

    URBNF_SPELLOUT,

    /**

     * Requests predefined ruleset for the ordinal form of a number.

     * @stable ICU 2.2

     */

    URBNF_ORDINAL,

#ifndef U_HIDE_DEPRECATED_API

    /**

     * Requests predefined ruleset for formatting a value as a duration in hours, minutes, and seconds.

     * @deprecated ICU 74 Use MeasureFormat instead.

     */

    URBNF_DURATION,

#endif // U_HIDE_DERECATED_API

    /**

     * Requests predefined ruleset for various non-place-value numbering systems.

     * WARNING: The same resource contains rule sets for a variety of different numbering systems.

     * You need to call setDefaultRuleSet() on the formatter to choose the actual numbering system.

     * @stable ICU 2.2

     */

    URBNF_NUMBERING_SYSTEM = 3,

#ifndef U_HIDE_DEPRECATED_API

    /**

     * One more than the highest normal URBNFRuleSetTag value.

     * @deprecated ICU 58 The numeric value may change over time, see ICU ticket #12420.

     */

    URBNF_COUNT

#endif  // U_HIDE_DEPRECATED_API

};

/**

 * The RuleBasedNumberFormat class formats numbers according to a set of rules.

 *

 * <p>This number formatter is typically used for spelling out numeric values in words (e.g., 25,376

 * as "twenty-five thousand three hundred seventy-six" or "vingt-cinq mille trois

 * cent soixante-seize" or

 * "fünfundzwanzigtausenddreihundertsechsundsiebzig"), but can also be used for

 * other complicated formatting tasks. For example, formatting a number as Roman numerals (e.g. 8 as VIII)

 * or as ordinal digits (e.g. 1st, 2nd, 3rd, 4th).</p>

 *

 * <p>The resources contain three predefined formatters for each locale: spellout, which

 * spells out a value in words (123 is "one hundred twenty-three"); ordinal, which

 * appends an ordinal suffix to the end of a numeral (123 is "123rd"); and

 * numbering system, which shows a number in other non-decimal based systems (e.g. Roman numerals).

 * The client can also define more specialized <code>RuleBasedNumberFormat</code>s

 * by supplying programmer-defined rule sets.</p>

 *

 * <p>The behavior of a <code>RuleBasedNumberFormat</code> is specified by a textual description

 * that is either passed to the constructor as a <code>String</code> or loaded from a resource

 * bundle. In its simplest form, the description consists of a semicolon-delimited list of <em>rules.</em>

 * Each rule has a string of output text and a value or range of values it is applicable to.

 * In a typical spellout rule set, the first twenty rules are the words for the numbers from

 * 0 to 19:</p>

 *

 * <pre>zero; one; two; three; four; five; six; seven; eight; nine;

 * ten; eleven; twelve; thirteen; fourteen; fifteen; sixteen; seventeen; eighteen; nineteen;</pre>

 *

 * <p>For larger numbers, we can use the preceding set of rules to format the ones place, and

 * we only have to supply the words for the multiples of 10:</p>

 *

 * <pre>

 * 20: twenty[->>];

 * 30: thirty[->>];

 * 40: forty[->>];

 * 50: fifty[->>];

 * 60: sixty[->>];

 * 70: seventy[->>];

 * 80: eighty[->>];

 * 90: ninety[-&gt;&gt;];</pre>

 *

 * <p>In these rules, the <em>base value</em> is spelled out explicitly and set off from the

 * rule's output text with a colon. The rules are in a sorted list, and a rule is applicable

 * to all numbers from its own base value to one less than the next rule's base value. The

 * &quot;&gt;&gt;&quot; token is called a <em>substitution</em> and tells the formatter to

 * isolate the number's ones digit, format it using this same set of rules, and place the

 * result at the position of the ">>" token. Text in brackets is omitted if

 * the number being formatted is an even multiple of 10 (the hyphen is a literal hyphen; 24

 * is &quot;twenty-four,&quot; not &quot;twenty four&quot;).</p>

 *

 * <p>For even larger numbers, we can actually look up several parts of the number in the

 * list:</p>

 *

 * <pre>

 * 100: &lt;&lt; hundred[ &gt;&gt;];</pre>

 *

 * <p>The &quot;&lt;&lt;&quot; represents a new kind of substitution. The &lt;&lt; isolates

 * the hundreds digit (and any digits to its left), formats it using this same rule set, and

 * places the result where the "<<" was. Notice also that the meaning of

 * >> has changed: it now refers to both the tens and the ones digits. The meaning of

 * both substitutions depends on the rule's base value. The base value determines the rule's <em>divisor,</em>

 * which is the highest power of 10 that is less than or equal to the base value (the user

 * can change this). To fill in the substitutions, the formatter divides the number being

 * formatted by the divisor. The integral quotient is used to fill in the <<

 * substitution, and the remainder is used to fill in the >> substitution. The meaning

 * of the brackets changes similarly: text in brackets is omitted if the value being

 * formatted is an even multiple of the rule's divisor. The rules are applied recursively, so

 * if a substitution is filled in with text that includes another substitution, that

 * substitution is also filled in.</p>

 *

 * <p>This rule covers values up to 999, at which point we add another rule:</p>

 *

 * <pre>

 * 1000: &lt;&lt; thousand[ &gt;&gt;];</pre>

 *

 * <p>Just like the 100 rule, the meanings of the brackets and substitution tokens shift because the rule's

 * base value is a higher power of 10, changing the rule's divisor. This rule can actually be

 * used all the way up to 999,999. This allows us to finish out the rules as follows:</p>

 *

 * <pre>

 * 1,000,000: << million[ >>];

 * 1,000,000,000: << billion[ >>];

 * 1,000,000,000,000: << trillion[ >>];

 * 1,000,000,000,000,000: OUT OF RANGE!;</pre>

 *

 * <p>Commas, periods, and spaces can be used in the base values to improve legibility and

 * are ignored by the rule parser. The last rule in the list is customarily treated as an

 * "overflow rule", applying to everything from its base value on up, and often (as

 * in this example) being used to print out an error message or default representation.

 * Notice also that the size of the major groupings in large numbers is controlled by the

 * spacing of the rules: because in English we group numbers by thousand, the higher rules

 * are separated from each other by a factor of 1,000.</p>

 *

 * <p>To see how these rules actually work in practice, consider the following example.

 * Formatting 25,340 with this rule set would work like this:</p>

 *

 * <table style="border-collapse: collapse;">

 *   <tr>

 *     <td style="width: 257; vertical-align: top;"><strong>&lt;&lt; thousand &gt;&gt;</strong></td>

 *     <td style="width: 340; vertical-align: top;">[the rule whose base value is 1,000 is applicable to 25,340]</td>

 *   </tr>

 *   <tr>

 *     <td style="width: 257; vertical-align: top;"><strong>twenty-&gt;&gt;</strong> thousand &gt;&gt;</td>

 *     <td style="width: 340; vertical-align: top;">[25,340 over 1,000 is 25. The rule for 20 applies.]</td>

 *   </tr>

 *   <tr>

 *     <td style="width: 257; vertical-align: top;">twenty-<strong>five</strong> thousand &gt;&gt;</td>

 *     <td style="width: 340; vertical-align: top;">[25 mod 10 is 5. The rule for 5 is &quot;five.&quot;</td>

 *   </tr>

 *   <tr>

 *     <td style="width: 257; vertical-align: top;">twenty-five thousand <strong>&lt;&lt; hundred &gt;&gt;</strong></td>

 *     <td style="width: 340; vertical-align: top;">[25,340 mod 1,000 is 340. The rule for 100 applies.]</td>

 *   </tr>

 *   <tr>

 *     <td style="width: 257; vertical-align: top;">twenty-five thousand <strong>three</strong> hundred &gt;&gt;</td>

 *     <td style="width: 340; vertical-align: top;">[340 over 100 is 3. The rule for 3 is &quot;three.&quot;]</td>

 *   </tr>

 *   <tr>

 *     <td style="width: 257; vertical-align: top;">twenty-five thousand three hundred <strong>forty</strong></td>

 *     <td style="width: 340; vertical-align: top;">[340 mod 100 is 40. The rule for 40 applies. Since 40 divides

 *     evenly by 10, the hyphen and substitution in the brackets are omitted.]</td>

 *   </tr>

 * </table>

 *

 * <p>The above syntax suffices only to format positive integers. To format negative numbers,

 * we add a special rule:</p>

 *

 * <pre>-x: minus &gt;&gt;;</pre>

 *

 * <p>This is called a <em>negative-number rule,</em> and is identified by &quot;-x&quot;

 * where the base value would be. This rule is used to format all negative numbers. the

 * >> token here means "find the number's absolute value, format it with these

 * rules, and put the result here.&quot;</p>

 *

 * <p>We also add a special rule called a <em>fraction rule</em> for numbers with fractional

 * parts:</p>

 *

 * <pre>x.x: &lt;&lt; point &gt;&gt;;</pre>

 *

 * <p>This rule is used for all positive non-integers (negative non-integers pass through the

 * negative-number rule first and then through this rule). Here, the << token refers to

 * the number's integral part, and the >> to the number's fractional part. The

 * fractional part is formatted as a series of single-digit numbers (e.g., 123.456 would be

 * formatted as &quot;one hundred twenty-three point four five six&quot;).</p>

 *

 * <p>To see how this rule syntax is applied to various languages, examine the resource data.</p>

 *

 * <p>There is actually much more flexibility built into the rule language than the

 * description above shows. A formatter may own multiple rule sets, which can be selected by

 * the caller, and which can use each other to fill in their substitutions. Substitutions can

 * also be filled in with digits, using a DecimalFormat object. There is syntax that can be

 * used to alter a rule's divisor in various ways. And there is provision for much more

 * flexible fraction handling. A complete description of the rule syntax follows:</p>

 *

 * <hr>

 *

 * <p>The description of a <code>RuleBasedNumberFormat</code>'s behavior consists of one or more <em>rule

 * sets.</em> Each rule set consists of a name, a colon, and a list of <em>rules</em>. A rule

 * set name must begin with a % sign. Rule sets with a name that begins with a single % sign

 * are <em>public</em>, and that name can be referenced to format and parse numbers.

 * Rule sets with names that begin with %% are <em>private.</em>. They exist only for the use

 * of other rule sets. If a formatter only has one rule set, the name may be omitted.</p>

 *

 * <p>The user can also specify a special &quot;rule set&quot; named <code>%%lenient-parse</code>.

 * The body of <code>%%lenient-parse</code> isn't a set of number-formatting rules, but a <code>RuleBasedCollator</code>

 * description which is used to define equivalences for lenient parsing. For more information

 * on the syntax, see <code>RuleBasedCollator</code>. For more information on lenient parsing,

 * see <code>setLenientParse()</code>. <em>Note:</em> symbols that have syntactic meaning

 * in collation rules, such as '&', have no particular meaning when appearing outside

 * of the <code>lenient-parse</code> rule set.</p>

 *

 * <p>The body of a rule set consists of an ordered, semicolon-delimited list of <em>rules.</em>

 * Internally, every rule has a base value, a divisor, rule text, and zero, one, or two <em>substitutions.</em>

 * These parameters are controlled by the description syntax, which consists of a <em>rule

 * descriptor,</em> a colon, and a <em>rule body.</em></p>

 *

 * <p>A rule descriptor can take one of the following forms (text in <em>italics</em> is the

 * name of a token):</p>

 *

 * <table style="border-collapse: collapse;">

 *   <tr>

 *     <th style="padding-left: 1em; padding-right: 1em;">Descriptor</th>

 *     <th>Description</th>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;"><em>bv</em>:</td>

 *     <td style="vertical-align: top;"><em>bv</em> specifies the rule's base value. <em>bv</em> is a decimal

 *     number expressed using ASCII digits. <em>bv</em> may contain spaces, period, and commas,

 *     which are ignored. The rule's divisor is the highest power of 10 less than or equal to

 *     the base value.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;"><em>bv</em>/<em>rad</em>:</td>

 *     <td style="vertical-align: top;"><em>bv</em> specifies the rule's base value. The rule's divisor is the

 *     highest power of <em>rad</em> less than or equal to the base value.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;"><em>bv</em>&gt;:</td>

 *     <td style="vertical-align: top;"><em>bv</em> specifies the rule's base value. To calculate the divisor,

 *     let the radix be 10, and the exponent be the highest exponent of the radix that yields a

 *     result less than or equal to the base value. Every > character after the base value

 *     decreases the exponent by 1. If the exponent is positive or 0, the divisor is the radix

 *     raised to the power of the exponent; otherwise, the divisor is 1.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;"><em>bv</em>/<em>rad</em>&gt;:</td>

 *     <td style="vertical-align: top;"><em>bv</em> specifies the rule's base value. To calculate the divisor,

 *     let the radix be <em>rad</em>, and the exponent be the highest exponent of the radix that

 *     yields a result less than or equal to the base value. Every > character after the radix

 *     decreases the exponent by 1. If the exponent is positive or 0, the divisor is the radix

 *     raised to the power of the exponent; otherwise, the divisor is 1.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">-x:</td>

 *     <td style="vertical-align: top;">The rule is a negative-number rule.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">x.x:</td>

 *     <td style="vertical-align: top;">The rule is an <em>improper fraction rule</em>. If the full stop in

 *     the middle of the rule name is replaced with the decimal point

 *     that is used in the language or DecimalFormatSymbols, then that rule will

 *     have precedence when formatting and parsing this rule. For example, some

 *     languages use the comma, and can thus be written as x,x instead. For example,

 *     you can use "x.x: << point >>;x,x: << comma >>;" to

 *     handle the decimal point that matches the language's natural spelling of

 *     the punctuation of either the full stop or comma.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">0.x:</td>

 *     <td style="vertical-align: top;">The rule is a <em>proper fraction rule</em>. If the full stop in

 *     the middle of the rule name is replaced with the decimal point

 *     that is used in the language or DecimalFormatSymbols, then that rule will

 *     have precedence when formatting and parsing this rule. For example, some

 *     languages use the comma, and can thus be written as 0,x instead. For example,

 *     you can use "0.x: point >>;0,x: comma >>;" to

 *     handle the decimal point that matches the language's natural spelling of

 *     the punctuation of either the full stop or comma</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">x.0:</td>

 *     <td style="vertical-align: top;">The rule is a <em>default rule</em>. If the full stop in

 *     the middle of the rule name is replaced with the decimal point

 *     that is used in the language or DecimalFormatSymbols, then that rule will

 *     have precedence when formatting and parsing this rule. For example, some

 *     languages use the comma, and can thus be written as x,0 instead. For example,

 *     you can use "x.0: << point;x,0: << comma;" to

 *     handle the decimal point that matches the language's natural spelling of

 *     the punctuation of either the full stop or comma</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">Inf:</td>

 *     <td style="vertical-align: top;">The rule for infinity.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">NaN:</td>

 *     <td style="vertical-align: top;">The rule for an IEEE 754 NaN (not a number).</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;"><em>nothing</em></td>

 *     <td style="vertical-align: top;">If the rule's rule descriptor is left out, the base value is one plus the

 *     preceding rule's base value (or zero if this is the first rule in the list) in a normal

 *     rule set. In a fraction rule set, the base value is the same as the preceding rule's

 *     base value.</td>

 *   </tr>

 * </table>

 *

 * <p>A rule set may be either a regular rule set or a <em>fraction rule set,</em> depending

 * on whether it is used to format a number's integral part (or the whole number) or a

 * number's fractional part. Using a rule set to format a rule's fractional part makes it a

 * fraction rule set.</p>

 *

 * <p>Which rule is used to format a number is defined according to one of the following

 * algorithms: If the rule set is a regular rule set, do the following:

 *

 * <ul>

 *   <li>If the rule set includes a default rule (and the number was passed in as a <code>double</code>),

 *     use the default rule. If the number being formatted was passed in as a <code>long</code>,

 *     the default rule is ignored.</li>

 *   <li>If the number is negative, use the negative-number rule.</li>

 *   <li>If the number has a fractional part and is greater than 1, use the improper fraction

 *     rule.</li>

 *   <li>If the number has a fractional part and is between 0 and 1, use the proper fraction

 *     rule.</li>

 *   <li>Binary-search the rule list for the rule with the highest base value less than or equal

 *     to the number. If that rule has two substitutions, its base value is not an even multiple

 *     of its divisor, and the number <em>is</em> an even multiple of the rule's divisor, use the

 *     rule that precedes it in the rule list. Otherwise, use the rule itself.</li>

 * </ul>

 *

 * <p>If the rule set is a fraction rule set, do the following:

 *

 * <ul>

 *   <li>Ignore negative-number and fraction rules.</li>

 *   <li>For each rule in the list, multiply the number being formatted (which will always be

 *     between 0 and 1) by the rule's base value. Keep track of the distance between the result

 *     the nearest integer.</li>

 *   <li>Use the rule that produced the result closest to zero in the above calculation. In the

 *     event of a tie or a direct hit, use the first matching rule encountered. (The idea here is

 *     to try each rule's base value as a possible denominator of a fraction. Whichever

 *     denominator produces the fraction closest in value to the number being formatted wins.) If

 *     the rule following the matching rule has the same base value, use it if the numerator of

 *     the fraction is anything other than 1; if the numerator is 1, use the original matching

 *     rule. (This is to allow singular and plural forms of the rule text without a lot of extra

 *     hassle.)</li>

 * </ul>

 *

 * <p>A rule's body consists of a string of characters terminated by a semicolon. The rule

 * may include zero, one, or two <em>substitution tokens,</em> and a range of text in

 * brackets. The brackets denote optional text (and may also include one or both

 * substitutions). The exact meanings of the substitution tokens, and under what conditions

 * optional text is omitted, depend on the syntax of the substitution token and the context.

 * The rest of the text in a rule body is literal text that is output when the rule matches

 * the number being formatted.</p>

 *

 * <p>A substitution token begins and ends with a <em>token character.</em> The token

 * character and the context together specify a mathematical operation to be performed on the

 * number being formatted. An optional <em>substitution descriptor </em>specifies how the

 * value resulting from that operation is used to fill in the substitution. The position of

 * the substitution token in the rule body specifies the location of the resultant text in

 * the original rule text.</p>

 *

 * <p>The meanings of the substitution token characters are as follows:</p>

 *

 * <table style="border-collapse: collapse;">

 *   <tr>

 *     <th>Syntax</th>

 *     <th>Usage</th>

 *     <th>Description</th>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;" rowspan="4">&gt;&gt;</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in normal rule</td>

 *     <td>Divide the number by the rule's divisor and format the remainder</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in negative-number rule</td>

 *     <td>Find the absolute value of the number and format the result</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in fraction or default rule</td>

 *     <td>Isolate the number's fractional part and format it.</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in rule in fraction rule set</td>

 *     <td>Not allowed.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;" rowspan="2">&gt;&gt;&gt;</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in normal rule</td>

 *     <td>Divide the number by the rule's divisor and format the remainder,

 *       but bypass the normal rule-selection process and just use the

 *       rule that precedes this one in this rule list.</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in all other rules</td>

 *     <td>Not allowed.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;" rowspan="4">&lt;&lt;</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in normal rule</td>

 *     <td>Divide the number by the rule's divisor, perform floor() on the quotient,

 *         and format the resulting value.<br>

 *         If there is a DecimalFormat pattern between the < characters and the

 *         rule does NOT also contain a >> substitution, we DON'T perform

 *         floor() on the quotient. The quotient is passed through to the DecimalFormat

 *         intact.  That is, for the value 1,900:<br>

 *         - "1/1000: &lt;&lt; thousand;" will produce "one thousand"<br>

 *         - "1/1000: &lt;0&lt; thousand;" will produce "2 thousand" (NOT "1 thousand")<br>

 *         - "1/1000: <0< seconds >0> milliseconds;" will produce "1 second 900 milliseconds"

 *     </td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in negative-number rule</td>

 *     <td>Not allowed.</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in fraction or default rule</td>

 *     <td>Isolate the number's integral part and format it.</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in rule in fraction rule set</td>

 *     <td>Multiply the number by the rule's base value and format the result.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;">==</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in all rule sets</td>

 *     <td>Format the number unchanged</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;" rowspan="6">[]<br/>[|]</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in normal rule</td>

 *     <td>

 *       <ul>

 *         <li>When the number is not an even multiple of the rule's divisor, use the text and rules between the beginning square bracket,

 *         and the end square bracket or the | symbol.</li>

 *         <li>When the number is an even multiple of the rule's divisor, and no | symbol is used, omit the text.</li>

 *         <li>When the number is an even multiple of the rule's divisor, and | symbol is used, use the text and rules between the | symbol,

 *         and the end square bracket.</li>

 *       </ul>

 *     </td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in improper-fraction rule</td>

 *     <td>This syntax is the same as specifying both an x.x rule and a 0.x rule.

 *       <ul>

 *         <li>When the number is not between 0 and 1, use the text and rules between the beginning square bracket,

 *         and the end square bracket or the | symbol.</li>

 *         <li>When the number is between 0 and 1, and no | symbol is used, omit the text.</li>

 *         <li>When the number is between 0 and 1, and | symbol is used, use the text and rules between the | symbol,

 *         and the end square bracket.</li>

 *       </ul>

 *     </td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in default rule</td>

 *     <td>This syntax is the same as specifying both an x.x rule and an x.0 rule.

 *       <ul>

 *         <li>When the number is not an integer, use the text and rules between the beginning square bracket,

 *         and the end square bracket or the | symbol.</li>

 *         <li>When the number is an integer, and no | symbol is used, omit the text.</li>

 *         <li>When the number is an integer, and | symbol is used, use the text and rules between the | symbol,

 *         and the end square bracket.</li>

 *       </ul>

 *     </td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in rule in fraction rule set</td>

 *     <td>

 *       <ul>

 *         <li>When multiplying the number by the rule's base value does not yield 1, use the text and rules between the beginning square bracket,

 *         and the end square bracket or the | symbol.</li>

 *         <li>When multiplying the number by the rule's base value yields 1, and no | symbol is used, omit the text.</li>

 *         <li>When multiplying the number by the rule's base value yields 1, and | symbol is used, use the text and rules between the | symbol,

 *         and the end square bracket.</li>

 *       </ul>

 *     </td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in proper-fraction rule</td>

 *     <td>Not allowed.</td>

 *   </tr>

 *   <tr>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in negative-number rule</td>

 *     <td>Not allowed.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;">$(cardinal,<i>plural syntax</i>)$</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in all rule sets</td>

 *     <td>This provides the ability to choose a word based on the number divided by the radix to the power of the

 *     exponent of the base value for the specified locale, which is normally equivalent to the << value.

 *     This uses the cardinal plural rules from {@link PluralFormat}. All strings used in the plural format are treated

 *     as the same base value for parsing.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="white-space: nowrap;">$(ordinal,<i>plural syntax</i>)$</td>

 *     <td style="white-space: nowrap; vertical-align: top; padding-left: 1em; padding-right: 1em;">in all rule sets</td>

 *     <td>This provides the ability to choose a word based on the number divided by the radix to the power of the

 *     exponent of the base value for the specified locale, which is normally equivalent to the << value.

 *     This uses the ordinal plural rules from {@link PluralFormat}. All strings used in the plural format are treated

 *     as the same base value for parsing.</td>

 *   </tr>

 * </table>

 *

 * <p>The substitution descriptor (i.e., the text between the token characters) may take one

 * of three forms:</p>

 *

 * <table style="border-collapse: collapse;">

 *   <tr>

 *     <th>Descriptor</th>

 *     <th>Description</th>

 *   </tr>

 *   <tr>

 *     <td style="vertical-align: top;">a rule set name</td>

 *     <td>Perform the mathematical operation on the number, and format the result using the

 *     named rule set.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">a DecimalFormat pattern</td>

 *     <td>Perform the mathematical operation on the number, and format the result using a

 *     DecimalFormat with the specified pattern. The pattern must begin with 0 or #.</td>

 *   </tr>

 *   <tr style="border-top: 1px solid black;">

 *     <td style="vertical-align: top;">nothing</td>

 *     <td>Perform the mathematical operation on the number, and format the result using the rule

 *     set containing the current rule, except:<ul>

 *       <li>You can't have an empty substitution descriptor with a == substitution.</li>

 *       <li>If you omit the substitution descriptor in a &gt;&gt; substitution in a fraction rule,

 *         format the result one digit at a time using the rule set containing the current rule.</li>

 *       <li>If you omit the substitution descriptor in a &lt;&lt; substitution in a rule in a

 *         fraction rule set, format the result using the default rule set for this formatter.</li>

 *     </ul>

 *     </td>

 *   </tr>

 * </table>

 *

 * <p>Whitespace is ignored between a rule set name and a rule set body, between a rule

 * descriptor and a rule body, or between rules. If a rule body begins with an apostrophe,

 * the apostrophe is ignored, but all text after it becomes significant (this is how you can

 * have a rule's rule text begin with whitespace). There is no escape function: the semicolon

 * is not allowed in rule set names or in rule text, and the colon is not allowed in rule set

 * names. The characters beginning a substitution token are always treated as the beginning

 * of a substitution token.</p>

 *

 * <p>See the resource data and the demo program for annotated examples of real rule sets

 * using these features.</p>

 *

 * <p><em>User subclasses are not supported.</em> While clients may write

 * subclasses, such code will not necessarily work and will not be

 * guaranteed to work stably from release to release.

 *

 * <p><b>Localizations</b></p>

 * <p>Constructors are available that allow the specification of localizations for the

 * public rule sets (and also allow more control over what public rule sets are available).

 * Localization data is represented as a textual description.  The description represents

 * an array of arrays of string.  The first element is an array of the public rule set names,

 * each of these must be one of the public rule set names that appear in the rules.  Only

 * names in this array will be treated as public rule set names by the API.  Each subsequent

 * element is an array of localizations of these names.  The first element of one of these

 * subarrays is the locale name, and the remaining elements are localizations of the

 * public rule set names, in the same order as they were listed in the first array.</p>

 * <p>In the syntax, angle brackets '<', '>' are used to delimit the arrays, and comma ',' is used

 * to separate elements of an array.  Whitespace is ignored, unless quoted.</p>

 * <p>For example:<pre>

 * < < %foo, %bar, %baz >,

 *   < en, Foo, Bar, Baz >,

 *   < fr, 'le Foo', 'le Bar', 'le Baz' >

 *   < zh, \\u7532, \\u4e59, \\u4e19 > >

 * </pre></p>

 * @author Richard Gillam

 * @see NumberFormat

 * @see DecimalFormat

 * @see PluralFormat

 * @see PluralRules

 * @stable ICU 2.0

 */

class U_I18N_API_CLASS RuleBasedNumberFormat : public NumberFormat {

public:

  //-----------------------------------------------------------------------

  // constructors

  //-----------------------------------------------------------------------

    /**

     * Creates a RuleBasedNumberFormat that behaves according to the description

     * passed in.  The formatter uses the default locale.

     * @param rules A description of the formatter's desired behavior.

     * See the class documentation for a complete explanation of the description

     * syntax.

     * @param perror The parse error if an error was encountered.

     * @param status The status indicating whether the constructor succeeded.

     * @stable ICU 3.2

     */

    U_I18N_API RuleBasedNumberFormat(const UnicodeString& rules,

                                     UParseError& perror,

                                     UErrorCode& status);

    /**

     * Creates a RuleBasedNumberFormat that behaves according to the description

     * passed in.  The formatter uses the default locale.

     * <p>

     * The localizations data provides information about the public

     * rule sets and their localized display names for different

     * locales. The first element in the list is an array of the names

     * of the public rule sets.  The first element in this array is

     * the initial default ruleset.  The remaining elements in the

     * list are arrays of localizations of the names of the public

     * rule sets.  Each of these is one longer than the initial array,

     * with the first String being the ULocale ID, and the remaining

     * Strings being the localizations of the rule set names, in the

     * same order as the initial array.  Arrays are nullptr-terminated.

     * @param rules A description of the formatter's desired behavior.

     * See the class documentation for a complete explanation of the description

     * syntax.

     * @param localizations the localization information.

     * names in the description.  These will be copied by the constructor.

     * @param perror The parse error if an error was encountered.

     * @param status The status indicating whether the constructor succeeded.

     * @stable ICU 3.2

     */

    U_I18N_API RuleBasedNumberFormat(const UnicodeString& rules,

                                     const UnicodeString& localizations,

                                     UParseError& perror,

                                     UErrorCode& status);

    /**

     * Creates a RuleBasedNumberFormat that behaves according to the rules

     * passed in.  The formatter uses the specified locale to determine the

     * characters to use when formatting numerals, and to define equivalences

     * for lenient parsing.

     * @param rules The formatter rules.

     * See the class documentation for a complete explanation of the rule

     * syntax.

     * @param locale A locale that governs which characters are used for

     * formatting values in numerals and which characters are equivalent in

     * lenient parsing.

     * @param perror The parse error if an error was encountered.

     * @param status The status indicating whether the constructor succeeded.

     * @stable ICU 2.0

     */

    U_I18N_API RuleBasedNumberFormat(const UnicodeString& rules,

                                     const Locale& locale,

                                     UParseError& perror,

                                     UErrorCode& status);

    /**

     * Creates a RuleBasedNumberFormat that behaves according to the description

     * passed in.  The formatter uses the default locale.

     * <p>

     * The localizations data provides information about the public

     * rule sets and their localized display names for different

     * locales. The first element in the list is an array of the names

     * of the public rule sets.  The first element in this array is

     * the initial default ruleset.  The remaining elements in the

     * list are arrays of localizations of the names of the public

     * rule sets.  Each of these is one longer than the initial array,

     * with the first String being the ULocale ID, and the remaining

     * Strings being the localizations of the rule set names, in the

     * same order as the initial array.  Arrays are nullptr-terminated.

     * @param rules A description of the formatter's desired behavior.

     * See the class documentation for a complete explanation of the description

     * syntax.

     * @param localizations a list of localizations for the rule set

     * names in the description.  These will be copied by the constructor.

     * @param locale A locale that governs which characters are used for

     * formatting values in numerals and which characters are equivalent in

     * lenient parsing.

     * @param perror The parse error if an error was encountered.

     * @param status The status indicating whether the constructor succeeded.

     * @stable ICU 3.2

     */

    U_I18N_API RuleBasedNumberFormat(const UnicodeString& rules,

                                     const UnicodeString& localizations,

                                     const Locale& locale,

                                     UParseError& perror,

                                     UErrorCode& status);

  /**

   * Creates a RuleBasedNumberFormat from a predefined ruleset.  The selector

   * code chose among three possible predefined formats: spellout, ordinal,

   * and duration.

   * @param tag A selector code specifying which kind of formatter to create for that

   * locale.  There are four legal values: URBNF_SPELLOUT, which creates a formatter that

   * spells out a value in words in the desired language, URBNF_ORDINAL, which attaches

   * an ordinal suffix from the desired language to the end of a number (e.g. "123rd"),

   * URBNF_DURATION, which formats a duration in seconds as hours, minutes, and seconds always rounding down,

   * and URBNF_NUMBERING_SYSTEM, which is used to invoke rules for alternate numbering

   * systems such as the Hebrew numbering system, or for Roman Numerals, etc.

   * NOTE: If you use URBNF_NUMBERING_SYSTEM, you must also call setDefaultRuleSet() to

   * specify the exact numbering system you want to use.  If you want the default numbering system

   * for the locale, call NumberFormat::createInstance() instead of creating a RuleBasedNumberFormat directly.

   * @param locale The locale for the formatter.

   * @param status The status indicating whether the constructor succeeded.

   * @stable ICU 2.0

   */

  U_I18N_API RuleBasedNumberFormat(URBNFRuleSetTag tag, const Locale& locale, UErrorCode& status);

  //-----------------------------------------------------------------------

  // boilerplate

  //-----------------------------------------------------------------------

  /**

   * Copy constructor

   * @param rhs    the object to be copied from.

   * @stable ICU 2.6

   */

  U_I18N_API RuleBasedNumberFormat(const RuleBasedNumberFormat& rhs);

  /**

   * Assignment operator

   * @param rhs    the object to be copied from.

   * @stable ICU 2.6

   */

  U_I18N_API RuleBasedNumberFormat& operator=(const RuleBasedNumberFormat& rhs);

  /**

   * Release memory allocated for a RuleBasedNumberFormat when you are finished with it.

   * @stable ICU 2.6

   */

  U_I18N_API virtual ~RuleBasedNumberFormat();

  /**

   * Clone this object polymorphically.  The caller is responsible

   * for deleting the result when done.

   * @return  A copy of the object.

   * @stable ICU 2.6

   */

  U_I18N_API virtual RuleBasedNumberFormat* clone() const override;

  /**

   * Return 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 2.6

   */

  U_I18N_API virtual bool operator==(const Format& other) const override;

//-----------------------------------------------------------------------

// public API functions

//-----------------------------------------------------------------------

  /**

   * return the rules that were provided to the RuleBasedNumberFormat.

   * @return the result String that was passed in

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString getRules() const;

  /**

   * Return the number of public rule set names.

   * @return the number of public rule set names.

   * @stable ICU 2.0

   */

  U_I18N_API virtual int32_t getNumberOfRuleSetNames() const;

  /**

   * Return the name of the index'th public ruleSet.  If index is not valid,

   * the function returns null.

   * @param index the index of the ruleset

   * @return the name of the index'th public ruleSet.

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString getRuleSetName(int32_t index) const;

  /**

   * Return the number of locales for which we have localized rule set display names.

   * @return the number of locales for which we have localized rule set display names.

   * @stable ICU 3.2

   */

  U_I18N_API virtual int32_t getNumberOfRuleSetDisplayNameLocales() const;

  /**

   * Return the index'th display name locale.

   * @param index the index of the locale

   * @param status set to a failure code when this function fails

   * @return the locale

   * @see #getNumberOfRuleSetDisplayNameLocales

   * @stable ICU 3.2

   */

  U_I18N_API virtual Locale getRuleSetDisplayNameLocale(int32_t index, UErrorCode& status) const;

    /**

     * Return the rule set display names for the provided locale.  These are in the same order

     * as those returned by getRuleSetName.  The locale is matched against the locales for

     * which there is display name data, using normal fallback rules.  If no locale matches,

     * the default display names are returned.  (These are the internal rule set names minus

     * the leading '%'.)

     * @param index the index of the rule set

     * @param locale the locale (returned by getRuleSetDisplayNameLocales) for which the localized

     * display name is desired

     * @return the display name for the given index, which might be bogus if there is an error

     * @see #getRuleSetName

     * @stable ICU 3.2

     */

    U_I18N_API virtual UnicodeString getRuleSetDisplayName(int32_t index,

                                                           const Locale& locale = Locale::getDefault());

    /**

     * Return the rule set display name for the provided rule set and locale.

     * The locale is matched against the locales for which there is display name data, using

     * normal fallback rules.  If no locale matches, the default display name is returned.

     * @return the display name for the rule set

     * @stable ICU 3.2

     * @see #getRuleSetDisplayName

     */

    U_I18N_API virtual UnicodeString getRuleSetDisplayName(const UnicodeString& ruleSetName,

                                                           const Locale& locale = Locale::getDefault());

  using NumberFormat::format;

  /**

   * Formats the specified 32-bit number using the default ruleset.

   * @param number The number to format.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @return A textual representation of the number.

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString& format(int32_t number,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos) const override;

  /**

   * Formats the specified 64-bit number using the default ruleset.

   * @param number The number to format.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @return A textual representation of the number.

   * @stable ICU 2.1

   */

  U_I18N_API virtual UnicodeString& format(int64_t number,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos) const override;

  /**

   * Formats the specified number using the default ruleset.

   * @param number The number to format.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @return A textual representation of the number.

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString& format(double number,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos) const override;

  /**

   * Formats the specified number using the named ruleset.

   * @param number The number to format.

   * @param ruleSetName The name of the rule set to format the number with.

   * This must be the name of a valid public rule set for this formatter.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @param status the status

   * @return A textual representation of the number.

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString& format(int32_t number,

                                           const UnicodeString& ruleSetName,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos,

                                           UErrorCode& status) const;

  /**

   * Formats the specified 64-bit number using the named ruleset.

   * @param number The number to format.

   * @param ruleSetName The name of the rule set to format the number with.

   * This must be the name of a valid public rule set for this formatter.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @param status the status

   * @return A textual representation of the number.

   * @stable ICU 2.1

   */

  U_I18N_API virtual UnicodeString& format(int64_t number,

                                           const UnicodeString& ruleSetName,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos,

                                           UErrorCode& status) const;

  /**

   * Formats the specified number using the named ruleset.

   * @param number The number to format.

   * @param ruleSetName The name of the rule set to format the number with.

   * This must be the name of a valid public rule set for this formatter.

   * @param toAppendTo the string that will hold the (appended) result

   * @param pos the fieldposition

   * @param status the status

   * @return A textual representation of the number.

   * @stable ICU 2.0

   */

  U_I18N_API virtual UnicodeString& format(double number,

                                           const UnicodeString& ruleSetName,

                                           UnicodeString& toAppendTo,

                                           FieldPosition& pos,

                                           UErrorCode& status) const;

protected:

    /**

     * Format a decimal number.

     * The number is a DigitList wrapper onto a floating point decimal number.

     * The default implementation in NumberFormat converts the decimal number

     * to a double and formats that.  Subclasses of NumberFormat that want

     * to specifically handle big decimal numbers must override this method.

     * class DecimalFormat does so.

     *

     * @param number    The number, a DigitList format Decimal Floating Point.

     * @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    Output param filled with success/failure status.

     * @return          Reference to 'appendTo' parameter.

     * @internal

     */

    virtual UnicodeString& format(const number::impl::DecimalQuantity &number,

                                  UnicodeString& appendTo,

                                  FieldPosition& pos,

                                  UErrorCode& status) const override;

public:

  using NumberFormat::parse;

  /**

   * Parses the specified string, beginning at the specified position, according

   * to this formatter's rules.  This will match the string against all of the

   * formatter's public rule sets and return the value corresponding to the longest

   * parseable substring.  This function's behavior is affected by the lenient

   * parse mode.

   * @param text The string to parse

   * @param result the result of the parse, either a double or a long.

   * @param parsePosition On entry, contains the position of the first character

   * in "text" to examine.  On exit, has been updated to contain the position

   * of the first character in "text" that wasn't consumed by the parse.

   * @see #setLenient

   * @stable ICU 2.0

   */

  U_I18N_API virtual void parse(const UnicodeString& text,

                                Formattable& result,

                                ParsePosition& parsePosition) const override;

#if !UCONFIG_NO_COLLATION

  /**

   * Turns lenient parse mode on and off.

   *

   * When in lenient parse mode, the formatter uses a Collator for parsing the text.

   * Only primary differences are treated as significant.  This means that case

   * differences, accent differences, alternate spellings of the same letter

   * (e.g., ae and a-umlaut in German), ignorable characters, etc. are ignored in

   * matching the text.  In many cases, numerals will be accepted in place of words

   * or phrases as well.

   *

   * For example, all of the following will correctly parse as 255 in English in

   * lenient-parse mode:

   * <br>"two hundred fifty-five"

   * <br>"two hundred fifty five"

   * <br>"TWO HUNDRED FIFTY-FIVE"

   * <br>"twohundredfiftyfive"

   * <br>"2 hundred fifty-5"

   *

   * The Collator used is determined by the locale that was

   * passed to this object on construction.  The description passed to this object

   * on construction may supply additional collation rules that are appended to the

   * end of the default collator for the locale, enabling additional equivalences

   * (such as adding more ignorable characters or permitting spelled-out version of

   * symbols; see the demo program for examples).

   *

   * It's important to emphasize that even strict parsing is relatively lenient: it

   * will accept some text that it won't produce as output.  In English, for example,

   * it will correctly parse "two hundred zero" and "fifteen hundred".

   *

   * @param enabled If true, turns lenient-parse mode on; if false, turns it off.

   * @see RuleBasedCollator

   * @stable ICU 2.0

   */

  U_I18N_API virtual void setLenient(UBool enabled) override;

  /**

   * Returns true if lenient-parse mode is turned on.  Lenient parsing is off

   * by default.

   * @return true if lenient-parse mode is turned on.

   * @see #setLenient

   * @stable ICU 2.0

   */

  U_I18N_API virtual inline UBool isLenient() const override;

#endif

  /**

   * Override the default rule set to use.  If ruleSetName is null, reset

   * to the initial default rule set.  If the rule set is not a public rule set name,

   * U_ILLEGAL_ARGUMENT_ERROR is returned in status.

   * @param ruleSetName the name of the rule set, or null to reset the initial default.

   * @param status set to failure code when a problem occurs.

   * @stable ICU 2.6

   */

  U_I18N_API virtual void setDefaultRuleSet(const UnicodeString& ruleSetName, UErrorCode& status);

  /**

   * Return the name of the current default rule set.  If the current rule set is

   * not public, returns a bogus (and empty) UnicodeString.

   * @return the name of the current default rule set

   * @stable ICU 3.0

   */

  U_I18N_API virtual UnicodeString getDefaultRuleSetName() const;

  /**

   * Set a particular UDisplayContext value in the formatter, such as

   * UDISPCTX_CAPITALIZATION_FOR_STANDALONE. Note: For getContext, see

   * NumberFormat.

   * @param value The UDisplayContext value to set.

   * @param status Input/output status. If at entry this indicates a failure

   *               status, the function will do nothing; otherwise this will be

   *               updated with any new status from the function. 

   * @stable ICU 53

   */

  U_I18N_API virtual void setContext(UDisplayContext value, UErrorCode& status) override;

    /**

     * Get the rounding mode.

     * @return A rounding mode

     * @stable ICU 60

     */

    U_I18N_API virtual ERoundingMode getRoundingMode() const override;

    /**

     * Set the rounding mode.

     * @param roundingMode A rounding mode

     * @stable ICU 60

     */

    U_I18N_API virtual void setRoundingMode(ERoundingMode roundingMode) override;

public:

    /**

     * ICU "poor man's RTTI", returns a UClassID for this class.

     *

     * @stable ICU 2.8

     */

    U_I18N_API static UClassID getStaticClassID();

    /**

     * ICU "poor man's RTTI", returns a UClassID for the actual class.

     *

     * @stable ICU 2.8

     */

    U_I18N_API virtual UClassID getDynamicClassID() const override;

    /**

     * Sets the decimal format symbols, which is generally not changed

     * by the programmer or user. The formatter takes ownership of

     * symbolsToAdopt; the client must not delete it.

     *

     * @param symbolsToAdopt DecimalFormatSymbols to be adopted.

     * @stable ICU 49

     */

    U_I18N_API virtual void adoptDecimalFormatSymbols(DecimalFormatSymbols* symbolsToAdopt);

    /**

     * Sets the decimal format symbols, which is generally not changed

     * by the programmer or user. A clone of the symbols is created and

     * the symbols is _not_ adopted; the client is still responsible for

     * deleting it.

     *

     * @param symbols DecimalFormatSymbols.

     * @stable ICU 49

     */

    U_I18N_API virtual void setDecimalFormatSymbols(const DecimalFormatSymbols& symbols);

private:

    RuleBasedNumberFormat() = delete; // default constructor not implemented

    // this will ref the localizations if they are not nullptr

    // caller must deref to get adoption

    RuleBasedNumberFormat(const UnicodeString& description, LocalizationInfo* localizations,

              const Locale& locale, UParseError& perror, UErrorCode& status);

    void init(const UnicodeString& rules, LocalizationInfo* localizations, UParseError& perror, UErrorCode& status);

    void initCapitalizationContextInfo(const Locale& thelocale);

    void dispose();

    void stripWhitespace(UnicodeString& src);

    void initDefaultRuleSet();

    NFRuleSet* findRuleSet(const UnicodeString& name, UErrorCode& status) const;

    /* friend access */

    friend class NFSubstitution;

    friend class NFRule;

    friend class NFRuleSet;

    friend class FractionalPartSubstitution;

    inline NFRuleSet * getDefaultRuleSet() const;

    const RuleBasedCollator * getCollator() const;

    DecimalFormatSymbols * initializeDecimalFormatSymbols(UErrorCode &status);

    const DecimalFormatSymbols * getDecimalFormatSymbols() const;