ChoiceFormat Class Reference

ChoiceFormat converts between ranges of numeric values and string names for those ranges. More...

#include <choicfmt.h>

Inheritance diagram for ChoiceFormat:
NumberFormat Format UObject UMemory

Public Member Functions

 ChoiceFormat (const UnicodeString &pattern, UErrorCode &status)
 Construct a new ChoiceFormat with the limits and the corresponding formats based on the pattern.
 ChoiceFormat (const double *limits, const UnicodeString *formats, int32_t count)
 Construct a new ChoiceFormat with the given limits and formats.
 ChoiceFormat (const double *limits, const UBool *closures, const UnicodeString *formats, int32_t count)
 Construct a new ChoiceFormat with the given limits and formats.
 ChoiceFormat (const ChoiceFormat &that)
 Copy constructor.
const ChoiceFormatoperator= (const ChoiceFormat &that)
 Assignment operator.
virtual ~ChoiceFormat ()
 Destructor.
virtual Formatclone (void) const
 Clone this Format object polymorphically.
virtual UBool operator== (const Format &other) const
 Return true if the given Format objects are semantically equal.
virtual void applyPattern (const UnicodeString &pattern, UErrorCode &status)
 Sets the pattern.
virtual void applyPattern (const UnicodeString &pattern, UParseError &parseError, UErrorCode &status)
 Sets the pattern.
virtual UnicodeStringtoPattern (UnicodeString &pattern) const
 Gets the pattern.
virtual void setChoices (const double *limitsToCopy, const UnicodeString *formatsToCopy, int32_t count)
 Set the choices to be used in formatting.
virtual void setChoices (const double *limits, const UBool *closures, const UnicodeString *formats, int32_t count)
 Set the choices to be used in formatting.
virtual const double * getLimits (int32_t &count) const
 Get the limits passed in the constructor.
virtual const UBoolgetClosures (int32_t &count) const
 Get the limit booleans passed in the constructor.
virtual const UnicodeStringgetFormats (int32_t &count) const
 Get the formats passed in the constructor.
virtual UnicodeStringformat (double number, UnicodeString &appendTo, FieldPosition &pos) const
 Format a double or long number using this object's choices.
virtual UnicodeStringformat (int32_t number, UnicodeString &appendTo, FieldPosition &pos) const
 Format a int_32t number using this object's choices.
virtual UnicodeStringformat (int64_t number, UnicodeString &appendTo, FieldPosition &pos) const
 Format an int64_t number using this object's choices.
virtual UnicodeStringformat (const Formattable *objs, int32_t cnt, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &success) const
 Format an array of objects using this object's choices.
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const
 Format an object using this object's choices.
UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
 Redeclared NumberFormat method.
UnicodeStringformat (double number, UnicodeString &appendTo) const
 Redeclared NumberFormat method.
UnicodeStringformat (int32_t number, UnicodeString &appendTo) const
 Redeclared NumberFormat method.
virtual void parse (const UnicodeString &text, Formattable &result, ParsePosition &parsePosition) const
 Return a long if possible (e.g.
virtual void parse (const UnicodeString &text, Formattable &result, UErrorCode &status) const
 Return a long if possible (e.g.
virtual UClassID getDynamicClassID (void) const
 Returns a unique class ID POLYMORPHICALLY.

Static Public Member Functions

static UClassID getStaticClassID (void)
 Return the class ID for this class.

Friends

class MessageFormat

Detailed Description

ChoiceFormat converts between ranges of numeric values and string names for those ranges.

A ChoiceFormat splits the real number line -Inf to +Inf into two or more contiguous ranges. Each range is mapped to a string. ChoiceFormat is generally used in a MessageFormat for displaying grammatically correct plurals such as "There are 2 files."

There are two methods of defining a ChoiceFormat; both are equivalent. The first is by using a string pattern. This is the preferred method in most cases. The second method is through direct specification of the arrays that make up the ChoiceFormat.

Patterns

In most cases, the preferred way to define a ChoiceFormat is with a pattern. Here is an example of a ChoiceFormat pattern:

    0≤are no files|1≤is one file|1<are many files

or equivalently,

    0#are no files|1#is one file|1<are many files

The pattern consists of a number or range specifiers separated by vertical bars '|' (U+007C). There is no vertical bar after the last range. Each range specifier is of the form:

Number Separator String

Number is a floating point number that can be parsed by a default NumberFormat for the US locale. It gives the lower limit of this range. The lower limit is either inclusive or exclusive, depending on the separator. The upper limit is given by the lower limit of the next range. The Unicode infinity sign ∞ (U+221E) is recognized for positive infinity. It may be preceded by '-' (U+002D) to indicate negative infinity.

String is the format string for this range, with special characters enclosed in single quotes ('The # sign'). Single quotes themselves are indicated by two single quotes in a row ('o''clock').

Separator is one of the following single characters:

See below for more information about closures.

Arrays

A ChoiceFormat defining n intervals (n >= 2) is specified by three arrays of n items:

Formatting and Parsing

During formatting, a number is converted to a string. ChoiceFormat accomplishes this by mapping the number to an interval using the following rule. Given a number X and and index value j in the range 0..n-1, where n is the number of ranges:

X matches j if and only if limit[j] <= X < limit[j+1]

(This assumes that all closures are FALSE. If some closures are TRUE then the relations must be changed to <= or < as appropriate.) If there is no match, then either the first or last index is used, depending on whether the number is too low or too high. Once a number is mapped to an interval j, the string formats[j] is output.

During parsing, a string is converted to a number. ChoiceFormat finds the element formats[j] equal to the string, and returns limits[j] as the parsed value.

Notes

The first limit value does not define a range boundary. For example, in the pattern "1.0#a|2.0#b", the intervals are [-Inf, 2.0) and [2.0, +Inf]. It appears that the first interval should be [1.0, 2.0). However, since all values that are too small are mapped to range zero, the first interval is effectively [-Inf, 2.0). However, the first limit value is used during formatting. In this example, parse("a") returns 1.0.

There are no gaps between intervals and the entire number line is covered. A ChoiceFormat maps all possible double values to a finite set of intervals.

The non-number NaN is mapped to interval zero during formatting.

Examples

Here is an example of two arrays that map the number 1..7 to the English day of the week abbreviations Sun..Sat. No closures array is given; this is the same as specifying all closures to be FALSE.

    {1,2,3,4,5,6,7},
     {"Sun","Mon","Tue","Wed","Thur","Fri","Sat"}

Here is an example that maps the ranges [-Inf, 1), [1, 1], and (1, +Inf] to three strings. That is, the number line is split into three ranges: x < 1.0, x = 1.0, and x > 1.0.

    {0, 1, 1},
     {FALSE, FALSE, TRUE},
     {"no files", "one file", "many files"}

Here is a simple example that shows formatting and parsing:

   #include <unicode/choicfmt.h>
   #include <unicode/unistr.h>
   #include <iostream.h>
   
   int main(int argc, char *argv[]) {
       double limits[] = {1,2,3,4,5,6,7};
       UnicodeString monthNames[] = {
           "Sun","Mon","Tue","Wed","Thu","Fri","Sat"};
       ChoiceFormat fmt(limits, monthNames, 7);
       UnicodeString str;
       char buf[256];
       for (double x = 1.0; x <= 8.0; x += 1.0) {
           fmt.format(x, str);
           str.extract(0, str.length(), buf, 256, "");
           str.truncate(0);
           cout << x << " -> "
                << buf << endl;
       }
       cout << endl;
       return 0;
   }

Here is a more complex example using a ChoiceFormat constructed from a pattern together with a MessageFormat.

   #include <unicode/choicfmt.h>
   #include <unicode/msgfmt.h>
   #include <unicode/unistr.h>
   #include <iostream.h>
 
   int main(int argc, char *argv[]) {
       UErrorCode status = U_ZERO_ERROR;
       double filelimits[] = {0,1,2};
       UnicodeString filepart[] =
           {"are no files","is one file","are {0} files"};
       ChoiceFormat* fileform = new ChoiceFormat(filelimits, filepart, 3 );
       Format* testFormats[] =
           {fileform, NULL, NumberFormat::createInstance(status)};
       MessageFormat pattform("There {0} on {1}", status );
       pattform.adoptFormats(testFormats, 3);
       Formattable testArgs[] = {0L, "Disk A"};
       FieldPosition fp(0);
       UnicodeString str;
       char buf[256];
       for (int32_t i = 0; i < 4; ++i) {
           Formattable fInt(i);
           testArgs[0] = fInt;
           pattform.format(testArgs, 2, str, fp, status );
           str.extract(0, str.length(), buf, "");
           str.truncate(0);
           cout << "Output for i=" << i << " : " << buf << endl;
       }
       cout << endl;
       return 0;
   }

User subclasses are not supported. While clients may write subclasses, such code will not necessarily work and will not be guaranteed to work stably from release to release.

Definition at line 259 of file choicfmt.h.


Constructor & Destructor Documentation

ChoiceFormat::ChoiceFormat ( const UnicodeString pattern,
UErrorCode status 
)

Construct a new ChoiceFormat with the limits and the corresponding formats based on the pattern.

Parameters:
pattern Pattern used to construct object.
status Output param to receive success code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0
ChoiceFormat::ChoiceFormat ( const double *  limits,
const UnicodeString formats,
int32_t  count 
)

Construct a new ChoiceFormat with the given limits and formats.

Copy the limits and formats instead of adopting them.

Parameters:
limits Array of limit values.
formats Array of formats.
count Size of 'limits' and 'formats' arrays.
Stable:
ICU 2.0
ChoiceFormat::ChoiceFormat ( const double *  limits,
const UBool closures,
const UnicodeString formats,
int32_t  count 
)

Construct a new ChoiceFormat with the given limits and formats.

Copy the limits and formats (instead of adopting them). By default, each limit in the array specifies the inclusive lower bound of its range, and the exclusive upper bound of the previous range. However, if the isLimitOpen element corresponding to a limit is TRUE, then the limit is the exclusive lower bound of its range, and the inclusive upper bound of the previous range.

Parameters:
limits Array of limit values
closures Array of booleans specifying whether each element of 'limits' is open or closed. If FALSE, then the corresponding limit is a member of the range above it. If TRUE, then the limit belongs to the range below it.
formats Array of formats
count Size of 'limits', 'closures', and 'formats' arrays
Stable:
ICU 2.4
ChoiceFormat::ChoiceFormat ( const ChoiceFormat that  ) 

Copy constructor.

Parameters:
that ChoiceFormat object to be copied from
Stable:
ICU 2.0
virtual ChoiceFormat::~ChoiceFormat (  )  [virtual]

Destructor.

Stable:
ICU 2.0

Member Function Documentation

virtual void ChoiceFormat::applyPattern ( const UnicodeString pattern,
UParseError parseError,
UErrorCode status 
) [virtual]

Sets the pattern.

Parameters:
pattern The pattern to be applied.
parseError Struct to recieve information on position of error if an error is encountered
status Output param set to success/failure code on exit. If the pattern is invalid, this will be set to a failure result.
Stable:
ICU 2.0
virtual void ChoiceFormat::applyPattern ( const UnicodeString pattern,
UErrorCode status 
) [virtual]

Sets the pattern.

Parameters:
pattern The pattern to be applied.
status Output param set to success/failure code on exit. If the pattern is invalid, this will be set to a failure result.
Stable:
ICU 2.0
virtual Format* ChoiceFormat::clone ( void   )  const [virtual]

Clone this Format object polymorphically.

The caller owns the result and should delete it when done.

Returns:
a copy of this object
Stable:
ICU 2.0

Implements Format.

UnicodeString & ChoiceFormat::format ( int32_t  number,
UnicodeString appendTo 
) const [inline]

Redeclared NumberFormat method.

Format a long number. These methods call the NumberFormat pure virtual format() methods with the default FieldPosition.

Parameters:
number The value to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

Definition at line 737 of file choicfmt.h.

References format().

UnicodeString & ChoiceFormat::format ( double  number,
UnicodeString appendTo 
) const [inline]

Redeclared NumberFormat method.

Format a double number. These methods call the NumberFormat pure virtual format() methods with the default FieldPosition.

Parameters:
number The value to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

Definition at line 731 of file choicfmt.h.

References format().

UnicodeString & ChoiceFormat::format ( const Formattable obj,
UnicodeString appendTo,
UErrorCode status 
) const [inline]

Redeclared NumberFormat method.

Parameters:
obj The object to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
status Output param set to success/failure code on exit.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

Definition at line 722 of file choicfmt.h.

References format().

virtual UnicodeString& ChoiceFormat::format ( const Formattable obj,
UnicodeString appendTo,
FieldPosition pos,
UErrorCode status 
) const [virtual]

Format an object using this object's choices.

Parameters:
obj The object to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
status Output param set to success/failure code on exit.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

virtual UnicodeString& ChoiceFormat::format ( const Formattable objs,
int32_t  cnt,
UnicodeString appendTo,
FieldPosition pos,
UErrorCode success 
) const [virtual]

Format an array of objects using this object's choices.

Parameters:
objs The array of objects to be formatted.
cnt The size of objs.
appendTo Output parameter to receive result. Result is appended to existing contents.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
success Output param set to success/failure code on exit.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0
virtual UnicodeString& ChoiceFormat::format ( int64_t  number,
UnicodeString appendTo,
FieldPosition pos 
) const [virtual]

Format an int64_t number using this object's choices.

Parameters:
number The value to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.8

Reimplemented from NumberFormat.

virtual UnicodeString& ChoiceFormat::format ( int32_t  number,
UnicodeString appendTo,
FieldPosition pos 
) const [virtual]

Format a int_32t number using this object's choices.

Parameters:
number The value to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Implements NumberFormat.

virtual UnicodeString& ChoiceFormat::format ( double  number,
UnicodeString appendTo,
FieldPosition pos 
) const [virtual]

Format a double or long number using this object's choices.

Parameters:
number The value to be formatted.
appendTo Output parameter to receive result. Result is appended to existing contents.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
Returns:
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Implements NumberFormat.

Referenced by format().

virtual const UBool* ChoiceFormat::getClosures ( int32_t &  count  )  const [virtual]

Get the limit booleans passed in the constructor.

The caller must not delete the result.

Parameters:
count The size of the arrays
Returns:
the closures
Stable:
ICU 2.4
virtual UClassID ChoiceFormat::getDynamicClassID ( void   )  const [virtual]

Returns a unique class ID POLYMORPHICALLY.

Pure virtual override. This method is to implement a simple version of RTTI, since not all C++ compilers support genuine RTTI. Polymorphic operator==() and clone() methods call this method.

Returns:
The class ID for this object. All objects of a given class have the same class ID. Objects of other classes have different class IDs.
Stable:
ICU 2.0

Implements NumberFormat.

virtual const UnicodeString* ChoiceFormat::getFormats ( int32_t &  count  )  const [virtual]

Get the formats passed in the constructor.

Parameters:
count The size of the arrays
Returns:
the formats.
Stable:
ICU 2.0
virtual const double* ChoiceFormat::getLimits ( int32_t &  count  )  const [virtual]

Get the limits passed in the constructor.

Parameters:
count The size of the limits arrays
Returns:
the limits.
Stable:
ICU 2.0
static UClassID ChoiceFormat::getStaticClassID ( void   )  [static]

Return the class ID for this class.

This is useful only for comparing to a return value from getDynamicClassID(). For example:

 .       Base* polymorphic_pointer = createPolymorphicObject();
 .       if (polymorphic_pointer->getDynamicClassID() ==
 .           Derived::getStaticClassID()) ...
 
Returns:
The class ID for all objects of this class.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

const ChoiceFormat& ChoiceFormat::operator= ( const ChoiceFormat that  ) 

Assignment operator.

Parameters:
that ChoiceFormat object to be copied
Stable:
ICU 2.0

Reimplemented from NumberFormat.

virtual UBool ChoiceFormat::operator== ( const Format other  )  const [virtual]

Return true if the given Format objects are semantically equal.

Objects of different subclasses are considered unequal.

Parameters:
other ChoiceFormat object to be compared
Returns:
true if other is the same as this.
Stable:
ICU 2.0

Reimplemented from NumberFormat.

virtual void ChoiceFormat::parse ( const UnicodeString text,
Formattable result,
UErrorCode status 
) const [virtual]

Return a long if possible (e.g.

within range LONG_MAX, LONG_MAX], and with no decimals), otherwise a double. If IntegerOnly is set, will stop at a decimal point (or equivalent; e.g. for rational numbers "1 2/3", will stop after the 1).

If no object can be parsed, parsePosition is unchanged, and NULL is returned.

Parameters:
text The text to be parsed.
result Formattable to be set to the parse result. If parse fails, return contents are undefined.
status Output param with the formatted string.
See also:
NumberFormat::isParseIntegerOnly
Stable:
ICU 2.0

Reimplemented from NumberFormat.

virtual void ChoiceFormat::parse ( const UnicodeString text,
Formattable result,
ParsePosition parsePosition 
) const [virtual]

Return a long if possible (e.g.

within range LONG_MAX, LONG_MAX], and with no decimals), otherwise a double. If IntegerOnly is set, will stop at a decimal point (or equivalent; e.g. for rational numbers "1 2/3", will stop after the 1).

If no object can be parsed, parsePosition is unchanged, and NULL is returned.

Parameters:
text The text to be parsed.
result Formattable to be set to the parse result. If parse fails, return contents are undefined.
parsePosition The position to start parsing at on input. On output, moved to after the last successfully parse character. On parse failure, does not change.
See also:
NumberFormat::isParseIntegerOnly
Stable:
ICU 2.0

Implements NumberFormat.

virtual void ChoiceFormat::setChoices ( const double *  limits,
const UBool closures,
const UnicodeString formats,
int32_t  count 
) [virtual]

Set the choices to be used in formatting.

See class description for documenatation of the limits, closures, and formats arrays.

Parameters:
limits Array of limits
closures Array of limit booleans
formats Array of format string
count The size of the above arrays
Stable:
ICU 2.4
virtual void ChoiceFormat::setChoices ( const double *  limitsToCopy,
const UnicodeString formatsToCopy,
int32_t  count 
) [virtual]

Set the choices to be used in formatting.

Parameters:
limitsToCopy Contains the top value that you want parsed with that format,and should be in ascending sorted order. When formatting X, the choice will be the i, where limit[i] <= X < limit[i+1].
formatsToCopy The format strings you want to use for each limit.
count The size of the above arrays.
Stable:
ICU 2.0
virtual UnicodeString& ChoiceFormat::toPattern ( UnicodeString pattern  )  const [virtual]

Gets the pattern.

Parameters:
pattern Output param which will recieve the pattern Previous contents are deleted.
Returns:
A reference to 'pattern'
Stable:
ICU 2.0

The documentation for this class was generated from the following file:
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Friends Defines

Generated on Sat Jan 23 15:17:42 2010 for ICU 4.3.4 by  doxygen 1.6.1