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Format Class Reference

Base class for all formats. More...

#include <format.h>

Inheritance diagram for Format:

DateFormat MessageFormat NumberFormat SimpleDateFormat ChoiceFormat DecimalFormat RuleBasedNumberFormat

Public Member Functions

virtual UBool operator== (const Format &other) const=0
 Return true if the given Format objects are semantically equal.

UBool operator!= (const Format &other) const
 Return true if the given Format objects are not semantically equal.

virtual Format * clone () const=0
 Clone this object polymorphically.

UnicodeStringformat (const Formattable &obj, UnicodeString &result, UErrorCode &status) const
 Formats an object to produce a string.

virtual UnicodeStringformat (const Formattable &obj, UnicodeString &toAppendTo, FieldPosition &pos, UErrorCode &status) const=0
 Format an object to produce a string.

virtual void parseObject (const UnicodeString &source, Formattable &result, ParsePosition &parse_pos) const=0
 Parse a string to produce an object.

void parseObject (const UnicodeString &source, Formattable &result, UErrorCode &status) const
 Parses a string to produce an object.

virtual UClassID getDynamicClassID () const=0
 Returns a unique class ID POLYMORPHICALLY.


Protected Member Functions

 Format ()
 Default constructor for subclass use only.

 Format (const Format &)
 

Format & operator= (const Format &)
 

void syntaxError (const UnicodeString &pattern, int32_t pos, UParseError &parseError)

Detailed Description

Base class for all formats.

This is an abstract base class which specifies the protocol for classes which convert other objects or values, such as numeric values and dates, and their string representations. In some cases these representations may be localized or contain localized characters or strings. For example, a numeric formatter such as DecimalFormat may convert a numeric value such as 12345 to the string "$12,345". It may also parse the string back into a numeric value. A date and time formatter like SimpleDateFormat may represent a specific date, encoded numerically, as a string such as "Wednesday, February 26, 1997 AD".

Many of the concrete subclasses of Format employ the notion of a pattern. A pattern is a string representation of the rules which govern the interconversion between values and strings. For example, a DecimalFormat object may be associated with the pattern "$#,##0.00;($#,##0.00)", which is a common US English format for currency values, yielding strings such as "$1,234.45" for 1234.45, and "($987.65)" for 987.6543. The specific syntax of a pattern is defined by each subclass.

Even though many subclasses use patterns, the notion of a pattern is not inherent to Format classes in general, and is not part of the explicit base class protocol.

Two complex formatting classes bear mentioning. These are MessageFormat and ChoiceFormat. ChoiceFormat is a subclass of NumberFormat which allows the user to format different number ranges as strings. For instance, 0 may be represented as "no files", 1 as "one file", and any number greater than 1 as "many files". MessageFormat is a formatter which utilizes other Format objects to format a string containing with multiple values. For instance, A MessageFormat object might produce the string "There are no files on the disk MyDisk on February 27, 1997." given the arguments 0, "MyDisk", and the date value of 2/27/97. See the ChoiceFormat and MessageFormat headers for further information.

If formatting is unsuccessful, a failing UErrorCode is returned when the Format cannot format the type of object, otherwise if there is something illformed about the the Unicode replacement character 0xFFFD is returned.

If there is no match when parsing, a parse failure UErrorCode is retured for methods which take no ParsePosition. For the method that takes a ParsePosition, the index parameter is left unchanged.

[Subclassing.] All base classes that provide static functions that create objects for Locales must implement the following static:

 
       public static const Locale* getAvailableLocales(long&)
 


Constructor & Destructor Documentation

Format::Format   [protected]
 

Default constructor for subclass use only.

Does nothing.


Member Function Documentation

virtual Format* Format::clone   const [pure virtual]
 

Clone this object polymorphically.

The caller is responsible for deleting the result when done.

Implemented in ChoiceFormat, DecimalFormat, MessageFormat, RuleBasedNumberFormat, and SimpleDateFormat.

virtual UnicodeString& Format::format const Formattable   obj,
UnicodeString   toAppendTo,
FieldPosition   pos,
UErrorCode   status
const [pure virtual]
 

Format an object to produce a string.

This is a pure virtual method which subclasses must implement. This method allows polymorphic formatting of Formattable objects. If a subclass of Format receives a Formattable object type it doesn't handle (e.g., if a numeric Formattable is passed to a DateFormat object) then it returns a failing UErrorCode.

Parameters:
obj The object to format.
toAppendTo Where the text is to be appended.
pos On input: an alignment field, if desired. On output: the offsets of the alignment field.
status Output param filled with success/failure status.
Returns:
The value passed in as toAppendTo (this allows chaining, as with UnicodeString::append())

Implemented in ChoiceFormat, DateFormat, DecimalFormat, MessageFormat, NumberFormat, RuleBasedNumberFormat, and SimpleDateFormat.

UnicodeString& Format::format const Formattable   obj,
UnicodeString   result,
UErrorCode   status
const
 

Formats an object to produce a string.

Parameters:
obj The object to format.
result Output parameter which will be filled in with the formatted string.
status Output parameter filled in with success or failure status.
Returns:
Reference to 'result' parameter.

Reimplemented in ChoiceFormat, DateFormat, DecimalFormat, MessageFormat, NumberFormat, RuleBasedNumberFormat, and SimpleDateFormat.

virtual UClassID Format::getDynamicClassID   const [pure virtual]
 

Returns a unique class ID POLYMORPHICALLY.

Pure virtual method. 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.

Concrete subclasses of Format must implement getDynamicClassID() and also a static method and data member:

static UClassID getStaticClassID() { return (UClassID) } static char fgClassID;

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.

Implemented in ChoiceFormat, DecimalFormat, MessageFormat, NumberFormat, RuleBasedNumberFormat, and SimpleDateFormat.

UBool Format::operator!= const Format &    other const [inline]
 

Return true if the given Format objects are not semantically equal.

virtual UBool Format::operator== const Format &    other const [pure virtual]
 

Return true if the given Format objects are semantically equal.

Objects of different subclasses are considered unequal.

Implemented in ChoiceFormat, DateFormat, DecimalFormat, MessageFormat, NumberFormat, RuleBasedNumberFormat, and SimpleDateFormat.

void Format::parseObject const UnicodeString   source,
Formattable   result,
UErrorCode   status
const
 

Parses a string to produce an object.

This is a convenience method which calls the pure virtual parseObject() method, and returns a failure UErrorCode if the ParsePosition indicates failure.

Parameters:
source The string to be parsed into an object.
result Formattable to be set to the parse result. If parse fails, return contents are undefined.
status Output param to be filled with success/failure result code.

virtual void Format::parseObject const UnicodeString   source,
Formattable   result,
ParsePosition   parse_pos
const [pure virtual]
 

Parse a string to produce an object.

This is a pure virtual method which subclasses must implement. This method allows polymorphic parsing of strings into Formattable objects.

Before calling, set parse_pos.index to the offset you want to start parsing at in the source. After calling, parse_pos.index is the end of the text you parsed. If error occurs, index is unchanged.

When parsing, leading whitespace is discarded (with successful parse), while trailing whitespace is left as is.

Example:

Parsing "_12_xy" (where _ represents a space) for a number, with index == 0 will result in the number 12, with parse_pos.index updated to 3 (just before the second space). Parsing a second time will result in a failing UErrorCode since "xy" is not a number, and leave index at 3.

Subclasses will typically supply specific parse methods that return different types of values. Since methods can't overload on return types, these will typically be named "parse", while this polymorphic method will always be called parseObject. Any parse method that does not take a parse_pos should set status to an error value when no text in the required format is at the start position.

Parameters:
source The string to be parsed into an object.
result Formattable to be set to the parse result. If parse fails, return contents are undefined.
parse_pos The position to start parsing at. Upon return this param is set to the position after the last character successfully parsed. If the source is not parsed successfully, this param will remain unchanged.

Implemented in DateFormat, MessageFormat, and NumberFormat.


The documentation for this class was generated from the following file:
Generated on Fri Mar 7 20:02:47 2003 for ICU 2.1 by doxygen1.3-rc3