tor-browser

rbnf.h (58565B)

---

// © 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 &quot;twenty-five thousand three hundred seventy-six&quot; or &quot;vingt-cinq mille trois
* cent soixante-seize&quot; or
* &quot;f&uuml;nfundzwanzigtausenddreihundertsechsundsiebzig&quot;), 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 &quot;one hundred twenty-three&quot;); ordinal, which
* appends an ordinal suffix to the end of a numeral (123 is &quot;123rd&quot;); 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[-&gt;&gt;];
* 30: thirty[-&gt;&gt;];
* 40: forty[-&gt;&gt;];
* 50: fifty[-&gt;&gt;];
* 60: sixty[-&gt;&gt;];
* 70: seventy[-&gt;&gt;];
* 80: eighty[-&gt;&gt;];
* 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 &quot;&gt;&gt;&quot; 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 &quot;&lt;&lt;&quot; was. Notice also that the meaning of
* &gt;&gt; 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 &lt;&lt;
* substitution, and the remainder is used to fill in the &gt;&gt; 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: &lt;&lt; million[ &gt;&gt;];
* 1,000,000,000: &lt;&lt; billion[ &gt;&gt;];
* 1,000,000,000,000: &lt;&lt; trillion[ &gt;&gt;];
* 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
* &quot;overflow rule&quot;, 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
* &gt;&gt; token here means &quot;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 &lt;&lt; token refers to
* the number's integral part, and the &gt;&gt; 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 '&amp;', 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 &gt; 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 &gt; 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: &lt;&lt; point &gt;&gt;;x,x: &lt;&lt; comma &gt;&gt;;" 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 &gt;&gt;;0,x: comma &gt;&gt;;" 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: &lt;&lt; point;x,0: &lt;&lt; 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 &lt; characters and the
*         rule does NOT also contain a &gt;&gt; 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: &lt;0&lt; seconds &gt;0&gt; 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 &lt;&lt; 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 &lt;&lt; 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;
   NFRule * initializeDefaultInfinityRule(UErrorCode &status);
   const NFRule * getDefaultInfinityRule() const;
   NFRule * initializeDefaultNaNRule(UErrorCode &status);
   const NFRule * getDefaultNaNRule() const;
   PluralFormat *createPluralFormat(UPluralType pluralType, const UnicodeString &pattern, UErrorCode& status) const;
   UnicodeString& adjustForCapitalizationContext(int32_t startPos, UnicodeString& currentResult, UErrorCode& status) const;
   UnicodeString& format(int64_t number, NFRuleSet *ruleSet, UnicodeString& toAppendTo, UErrorCode& status) const;
   void format(double number, NFRuleSet& rs, UnicodeString& toAppendTo, UErrorCode& status) const;

private:
   NFRuleSet **fRuleSets;
   UnicodeString* ruleSetDescriptions;
   int32_t numRuleSets;
   NFRuleSet *defaultRuleSet;
   Locale locale;
   RuleBasedCollator* collator;
   DecimalFormatSymbols* decimalFormatSymbols;
   NFRule *defaultInfinityRule;
   NFRule *defaultNaNRule;
   ERoundingMode fRoundingMode;
   UBool lenient;
   UnicodeString* lenientParseRules;
   LocalizationInfo* localizations;
   UnicodeString originalDescription;
   UBool capitalizationInfoSet;
   UBool capitalizationForUIListMenu;
   UBool capitalizationForStandAlone;
   BreakIterator* capitalizationBrkIter;
};

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

#if !UCONFIG_NO_COLLATION

inline UBool
RuleBasedNumberFormat::isLenient() const {
   return lenient;
}

#endif

inline NFRuleSet*
RuleBasedNumberFormat::getDefaultRuleSet() const {
   return defaultRuleSet;
}

U_NAMESPACE_END

/* U_HAVE_RBNF */
#endif

#endif /* U_SHOW_CPLUSPLUS_API */

/* RBNF_H */
#endif