A class that formats numbers according to a set of rules. This number formatter is * typically used for spelling out numeric values in words (e.g., 25,3476 as * "twenty-five thousand three hundred seventy-six" or "vingt-cinq mille trois * cents soixante-seize" or * "fünfundzwanzigtausenddreihundertsechsundsiebzig"), but can also be used for * other complicated formatting tasks, such as formatting a number of seconds as hours, * minutes and seconds (e.g., 3,730 as "1:02:10").
* *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 * duration, which shows a duration in seconds as hours, minutes, and seconds (123 is * "2:03"). The client can also define more specialized RuleBasedNumberFormats * by supplying programmer-defined rule sets.
* *The behavior of a RuleBasedNumberFormat is specified by a textual description * that is either passed to the constructor as a String or loaded from a resource * bundle. In its simplest form, the description consists of a semicolon-delimited list of rules. * 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:
* *zero; one; two; three; four; five; six; seven; eight; nine; * ten; eleven; twelve; thirteen; fourteen; fifteen; sixteen; seventeen; eighteen; nineteen;* *
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:
* *20: twenty[->>]; * 30: thirty[->>]; * 40: forty[->>]; * 50: fifty[->>]; * 60: sixty[->>]; * 70: seventy[->>]; * 80: eighty[->>]; * 90: ninety[->>];* *
In these rules, the base value 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 * ">>" token is called a substitution and tells the fomatter 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 "twenty-four," not "twenty four").
* *For even larger numbers, we can actually look up several parts of the number in the * list:
* *100: << hundred[ >>];* *
The "<<" represents a new kind of substitution. The << 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 divisor, * 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.
* *This rule covers values up to 999, at which point we add another rule:
* *1000: << thousand[ >>];* *
Again, 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:
* *1,000,000: << million[ >>]; * 1,000,000,000: << billion[ >>]; * 1,000,000,000,000: << trillion[ >>]; * 1,000,000,000,000,000: OUT OF RANGE!;* *
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.
* *To see how these rules actually work in practice, consider the following example: * Formatting 25,430 with this rule set would work like this:
* *| * | << thousand >> | *[the rule whose base value is 1,000 is applicable to 25,340] | *
| * | twenty->> thousand >> | *[25,340 over 1,000 is 25. The rule for 20 applies.] | *
| * | twenty-five thousand >> | *[25 mod 10 is 5. The rule for 5 is "five." | *
| * | twenty-five thousand << hundred >> | *[25,340 mod 1,000 is 340. The rule for 100 applies.] | *
| * | twenty-five thousand three hundred >> | *[340 over 100 is 3. The rule for 3 is "three."] | *
| * | twenty-five thousand three hundred forty | *[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.] | *
The above syntax suffices only to format positive integers. To format negative numbers, * we add a special rule:
* *-x: minus >>;* *
This is called a negative-number rule, and is identified by "-x" * 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."
* *We also add a special rule called a fraction rule for numbers with fractional * parts:
* *x.x: << point >>;* *
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 "one hundred twenty-three point four five six").
* *To see how this rule syntax is applied to various languages, examine the resource data.
* *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:
* *The description of a RuleBasedNumberFormat's behavior consists of one or more rule * sets. Each rule set consists of a name, a colon, and a list of rules. A rule * set name must begin with a % sign. Rule sets with names that begin with a single % sign * are public: the caller can specify that they be used to format and parse numbers. * Rule sets with names that begin with %% are private: they exist only for the use * of other rule sets. If a formatter only has one rule set, the name may be omitted.
* *The user can also specify a special "rule set" named %%lenient-parse. * The body of %%lenient-parse isn't a set of number-formatting rules, but a RuleBasedCollator * description which is used to define equivalences for lenient parsing. For more information * on the syntax, see RuleBasedCollator. For more information on lenient parsing, * see setLenientParse().
* *The body of a rule set consists of an ordered, semicolon-delimited list of rules. * Internally, every rule has a base value, a divisor, rule text, and zero, one, or two substitutions. * These parameters are controlled by the description syntax, which consists of a rule * descriptor, a colon, and a rule body.
* *A rule descriptor can take one of the following forms (text in italics is the * name of a token):
* *| * | bv: | *bv specifies the rule's base value. bv is a decimal * number expressed using ASCII digits. bv 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. | *
| * | bv/rad: | *bv specifies the rule's base value. The rule's divisor is the * highest power of rad less than or equal to the base value. | *
| * | bv>: | *bv 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. | *
| * | bv/rad>: | *bv specifies the rule's base value. To calculate the divisor, * let the radix be rad, 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. | *
| * | -x: | *The rule is a negative-number rule. | *
| * | x.x: | *The rule is an improper fraction rule. | *
| * | 0.x: | *The rule is a proper fraction rule. | *
| * | x.0: | *The rule is a master rule. | *
| * | nothing | *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. | *
A rule set may be either a regular rule set or a fraction rule set, 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.
* *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: * *
If the rule set is a fraction rule set, do the following: * *
A rule's body consists of a string of characters terminated by a semicolon. The rule * may include zero, one, or two substitution tokens, 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.
* *A substitution token begins and ends with a token character. The token * character and the context together specify a mathematical operation to be performed on the * number being formatted. An optional substitution descriptor 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.
* *The meanings of the substitution token characters are as follows:
* *| * | >> | *in normal rule | *Divide the number by the rule's divisor and format the remainder | *
| * | * | in negative-number rule | *Find the absolute value of the number and format the result | *
| * | * | in fraction or master rule | *Isolate the number's fractional part and format it. | *
| * | * | in rule in fraction rule set | *Not allowed. | *
| * | >>> | *in normal rule | *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. | *
| * | * | in all other rules | *Not allowed. | *
| * | << | *in normal rule | *Divide the number by the rule's divisor and format the quotient | *
| * | * | in negative-number rule | *Not allowed. | *
| * | * | in fraction or master rule | *Isolate the number's integral part and format it. | *
| * | * | in rule in fraction rule set | *Multiply the number by the rule's base value and format the result. | *
| * | == | *in all rule sets | *Format the number unchanged | *
| * | [] | *in normal rule | *Omit the optional text if the number is an even multiple of the rule's divisor | *
| * | * | in negative-number rule | *Not allowed. | *
| * | * | in improper-fraction rule | *Omit the optional text if the number is between 0 and 1 (same as specifying both an * x.x rule and a 0.x rule) | *
| * | * | in master rule | *Omit the optional text if the number is an integer (same as specifying both an x.x * rule and an x.0 rule) | *
| * | * | in proper-fraction rule | *Not allowed. | *
| * | * | in rule in fraction rule set | *Omit the optional text if multiplying the number by the rule's base value yields 1. | *
The substitution descriptor (i.e., the text between the token characters) may take one * of three forms:
* *| * | a rule set name | *Perform the mathematical operation on the number, and format the result using the * named rule set. | *
| * | a DecimalFormat pattern | *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 #. | *
| * | nothing | *Perform the mathematical operation on the number, and format the result using the rule
* set containing the current rule, except:
|
*
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.
* *See the resource data and the demo program for annotated examples of real rule sets * using these features.
* * @author Richard Gillam * @see NumberFormat * @see DecimalFormat * @draft */ /** Tags for the predefined rulesets. */ enum URBNFRuleSetTag { URBNF_SPELLOUT, URBNF_ORDINAL, URBNF_DURATION, URBNF_COUNT }; class U_I18N_API RuleBasedNumberFormat : public NumberFormat { public: //----------------------------------------------------------------------- // constructors //----------------------------------------------------------------------- /** * 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. * @draft */ RuleBasedNumberFormat(const UnicodeString& rules, const Locale& locale, UParseError& perror, UErrorCode& status); /** * Creates a RuleBasedNumberFormat from a predefined ruleset. The selector * code choosed 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 three 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"), * and URBNF_DURATION, which formats a duration in seconds as hours, minutes, and seconds. * @param locale The locale for the formatter. * @param status The status indicating whether the constructor succeeded. * @draft */ RuleBasedNumberFormat(URBNFRuleSetTag tag, const Locale& locale, UErrorCode& status); //----------------------------------------------------------------------- // boilerplate //----------------------------------------------------------------------- /** * Copy constructor */ RuleBasedNumberFormat(const RuleBasedNumberFormat& rhs); /** * Assignment operator */ RuleBasedNumberFormat& operator=(const RuleBasedNumberFormat& rhs); /** * Release memory allocated for a RuleBasedNumberFormat when you are finished with it. */ virtual ~RuleBasedNumberFormat(); /** * Clone this object polymorphically. The caller is responsible * for deleting the result when done. */ virtual Format* clone(void) const; /** * Return true if the given Format objects are semantically equal. * Objects of different subclasses are considered unequal. */ virtual UBool operator==(const Format& other) const; //----------------------------------------------------------------------- // public API functions //----------------------------------------------------------------------- /** * @return the rules that were provided to the RuleBasedNumberFormat. * @return the result String that was passed in * @draft */ virtual UnicodeString getRules() 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. * @draft */ virtual UnicodeString getRuleSetName(int32_t index) const; /** * Return the number of public rule set names. * @return the number of public rule set names. * @draft */ virtual int32_t getNumberOfRuleSetNames() const; /** * 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. * @draft */ virtual UnicodeString& format(int32_t number, UnicodeString& toAppendTo, FieldPosition& pos) const; /** * 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. * @draft */ virtual UnicodeString& format(double number, UnicodeString& toAppendTo, FieldPosition& pos) const; /** * Formats the specified number using the default 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. * @draft */ virtual UnicodeString& format(int32_t number, const UnicodeString& ruleSetName, UnicodeString& toAppendTo, FieldPosition& pos, UErrorCode& status) const; /** * Formats the specified number using the default 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. * @draft */ virtual UnicodeString& format(double number, const UnicodeString& ruleSetName, UnicodeString& toAppendTo, FieldPosition& pos, UErrorCode& status) const; /** * Formats the specified number using the default ruleset. * @param obj The number to format. * @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. * @draft */ virtual UnicodeString& format(const Formattable& obj, UnicodeString& toAppendTo, FieldPosition& pos, UErrorCode& status) const; /** * Redeclared Format method. * @stable */ UnicodeString& format(const Formattable& obj, UnicodeString& result, UErrorCode& status) const; /** * Redeclared NumberFormat method. * @stable */ UnicodeString& format(double number, UnicodeString& output) const; /** * Redeclared NumberFormat method. * @stable */ UnicodeString& format(int32_t number, UnicodeString& output) const; /** * Parses the specfied 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 #setLenientParseMode * @draft */ virtual void parse(const UnicodeString& text, Formattable& result, ParsePosition& parsePosition) const; /** * Redeclared Format method. * @stable */ virtual inline void parse(const UnicodeString& text, Formattable& result, UErrorCode& status) const; /** * 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: *