ICU 74.1 74.1
Data Structures | Public Types | Public Member Functions | Static Public Member Functions | Friends
icu::MessageFormat Class Reference

#include <msgfmt.h>

Inheritance diagram for icu::MessageFormat:
icu::Format icu::UObject icu::UMemory

Public Types

enum  EFormatNumber { kMaxFormat = 10 }
 Enum type for kMaxFormat. More...
 

Public Member Functions

 MessageFormat (const UnicodeString &pattern, UErrorCode &status)
 Constructs a new MessageFormat using the given pattern and the default locale. More...
 
 MessageFormat (const UnicodeString &pattern, const Locale &newLocale, UErrorCode &status)
 Constructs a new MessageFormat using the given pattern and locale. More...
 
 MessageFormat (const UnicodeString &pattern, const Locale &newLocale, UParseError &parseError, UErrorCode &status)
 Constructs a new MessageFormat using the given pattern and locale. More...
 
 MessageFormat (const MessageFormat &)
 Constructs a new MessageFormat from an existing one. More...
 
const MessageFormatoperator= (const MessageFormat &)
 Assignment operator. More...
 
virtual ~MessageFormat ()
 Destructor. More...
 
virtual MessageFormatclone () const override
 Clones this Format object polymorphically. More...
 
virtual bool operator== (const Format &other) const override
 Returns true if the given Format objects are semantically equal. More...
 
virtual void setLocale (const Locale &theLocale)
 Sets the locale to be used for creating argument Format objects. More...
 
virtual const LocalegetLocale (void) const
 Gets the locale used for creating argument Format objects. More...
 
virtual void applyPattern (const UnicodeString &pattern, UErrorCode &status)
 Applies the given pattern string to this message format. More...
 
virtual void applyPattern (const UnicodeString &pattern, UParseError &parseError, UErrorCode &status)
 Applies the given pattern string to this message format. More...
 
virtual void applyPattern (const UnicodeString &pattern, UMessagePatternApostropheMode aposMode, UParseError *parseError, UErrorCode &status)
 Sets the UMessagePatternApostropheMode and the pattern used by this message format. More...
 
UMessagePatternApostropheMode getApostropheMode () const
 
virtual UnicodeStringtoPattern (UnicodeString &appendTo) const
 Returns a pattern that can be used to recreate this object. More...
 
virtual void adoptFormats (Format **formatsToAdopt, int32_t count)
 Sets subformats. More...
 
virtual void setFormats (const Format **newFormats, int32_t cnt)
 Sets subformats. More...
 
virtual void adoptFormat (int32_t formatNumber, Format *formatToAdopt)
 Sets one subformat. More...
 
virtual void setFormat (int32_t formatNumber, const Format &format)
 Sets one subformat. More...
 
virtual StringEnumerationgetFormatNames (UErrorCode &status)
 Gets format names. More...
 
virtual FormatgetFormat (const UnicodeString &formatName, UErrorCode &status)
 Gets subformat pointer for given format name. More...
 
virtual void setFormat (const UnicodeString &formatName, const Format &format, UErrorCode &status)
 Sets one subformat for given format name. More...
 
virtual void adoptFormat (const UnicodeString &formatName, Format *formatToAdopt, UErrorCode &status)
 Sets one subformat for given format name. More...
 
virtual const Format ** getFormats (int32_t &count) const
 Gets an array of subformats of this object. More...
 
UnicodeStringformat (const Formattable *source, int32_t count, UnicodeString &appendTo, FieldPosition &ignore, UErrorCode &status) const
 Formats the given array of arguments into a user-readable string. More...
 
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const override
 Formats the given array of arguments into a user-readable string. More...
 
UnicodeStringformat (const UnicodeString *argumentNames, const Formattable *arguments, int32_t count, UnicodeString &appendTo, UErrorCode &status) const
 Formats the given array of arguments into a user-defined argument name array. More...
 
virtual Formattableparse (const UnicodeString &source, ParsePosition &pos, int32_t &count) const
 Parses the given string into an array of output arguments. More...
 
virtual Formattableparse (const UnicodeString &source, int32_t &count, UErrorCode &status) const
 Parses the given string into an array of output arguments. More...
 
virtual void parseObject (const UnicodeString &source, Formattable &result, ParsePosition &pos) const override
 Parses the given string into an array of output arguments stored within a single Formattable of type kArray. More...
 
UBool usesNamedArguments () const
 Returns true if this MessageFormat uses named arguments, and false otherwise. More...
 
int32_t getArgTypeCount () const
 This API is for ICU internal use only. More...
 
virtual UClassID getDynamicClassID (void) const override
 Returns a unique class ID POLYMORPHICALLY. More...
 
UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
 Formats an object to produce a string. More...
 
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const=0
 Format an object to produce a string. More...
 
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
 Format an object to produce a string. More...
 
- Public Member Functions inherited from icu::Format
virtual ~Format ()
 Destructor. More...
 
virtual bool operator== (const Format &other) const =0
 Return true if the given Format objects are semantically equal. More...
 
bool operator!= (const Format &other) const
 Return true if the given Format objects are not semantically equal. More...
 
virtual Formatclone () const =0
 Clone this object polymorphically. More...
 
UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, UErrorCode &status) const
 Formats an object to produce a string. More...
 
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPosition &pos, UErrorCode &status) const =0
 Format an object to produce a string. More...
 
virtual UnicodeStringformat (const Formattable &obj, UnicodeString &appendTo, FieldPositionIterator *posIter, UErrorCode &status) const
 Format an object to produce a string. More...
 
virtual void parseObject (const UnicodeString &source, Formattable &result, ParsePosition &parse_pos) const =0
 Parse a string to produce an object. More...
 
void parseObject (const UnicodeString &source, Formattable &result, UErrorCode &status) const
 Parses a string to produce an object. More...
 
Locale getLocale (ULocDataLocaleType type, UErrorCode &status) const
 Get the locale for this format object. More...
 
const char * getLocaleID (ULocDataLocaleType type, UErrorCode &status) const
 Get the locale for this format object. More...
 
- Public Member Functions inherited from icu::UObject
virtual ~UObject ()
 Destructor. More...
 
virtual UClassID getDynamicClassID () const
 ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class. More...
 

Static Public Member Functions

static UnicodeStringformat (const UnicodeString &pattern, const Formattable *arguments, int32_t count, UnicodeString &appendTo, UErrorCode &status)
 Formats the given array of arguments into a user-readable string using the given pattern. More...
 
static UnicodeString autoQuoteApostrophe (const UnicodeString &pattern, UErrorCode &status)
 Convert an 'apostrophe-friendly' pattern into a standard pattern. More...
 
static UClassID getStaticClassID (void)
 Return the class ID for this class. More...
 
static UBool equalFormats (const void *left, const void *right)
 Compares two Format objects. More...
 

Friends

class MessageFormatAdapter
 

Additional Inherited Members

- Protected Member Functions inherited from icu::Format
void setLocaleIDs (const char *valid, const char *actual)
 
 Format ()
 Default constructor for subclass use only. More...
 
 Format (const Format &)
 
Formatoperator= (const Format &)
 
- Static Protected Member Functions inherited from icu::Format
static void syntaxError (const UnicodeString &pattern, int32_t pos, UParseError &parseError)
 Simple function for initializing a UParseError from a UnicodeString. More...
 

Detailed Description

MessageFormat prepares strings for display to users, with optional arguments (variables/placeholders). The arguments can occur in any order, which is necessary for translation into languages with different grammars.

A MessageFormat is constructed from a pattern string with arguments in {curly braces} which will be replaced by formatted values.

MessageFormat differs from the other Format classes in that you create a MessageFormat object with one of its constructors (not with a createInstance style factory method). Factory methods aren't necessary because MessageFormat itself doesn't implement locale-specific behavior. Any locale-specific behavior is defined by the pattern that you provide and the subformats used for inserted arguments.

Arguments can be named (using identifiers) or numbered (using small ASCII-digit integers). Some of the API methods work only with argument numbers and throw an exception if the pattern has named arguments (see usesNamedArguments()).

An argument might not specify any format type. In this case, a numeric value is formatted with a default (for the locale) NumberFormat, and a date/time value is formatted with a default (for the locale) DateFormat.

An argument might specify a "simple" type for which the specified Format object is created, cached and used.

An argument might have a "complex" type with nested MessageFormat sub-patterns. During formatting, one of these sub-messages is selected according to the argument value and recursively formatted.

After construction, a custom Format object can be set for a top-level argument, overriding the default formatting and parsing behavior for that argument. However, custom formatting can be achieved more simply by writing a typeless argument in the pattern string and supplying it with a preformatted string value.

When formatting, MessageFormat takes a collection of argument values and writes an output string. The argument values may be passed as an array (when the pattern contains only numbered arguments) or as an array of names and and an array of arguments (which works for both named and numbered arguments).

Each argument is matched with one of the input values by array index or argument name and formatted according to its pattern specification (or using a custom Format object if one was set). A numbered pattern argument is matched with an argument name that contains that number as an ASCII-decimal-digit string (without leading zero).

Patterns and Their Interpretation

MessageFormat uses patterns of the following form:

message = messageText (argument messageText)*
argument = noneArg | simpleArg | complexArg
complexArg = choiceArg | pluralArg | selectArg | selectordinalArg

noneArg = '{' argNameOrNumber '}'
simpleArg = '{' argNameOrNumber ',' argType [',' argStyle] '}'
choiceArg = '{' argNameOrNumber ',' "choice" ',' choiceStyle '}'
pluralArg = '{' argNameOrNumber ',' "plural" ',' pluralStyle '}'
selectArg = '{' argNameOrNumber ',' "select" ',' selectStyle '}'
selectordinalArg = '{' argNameOrNumber ',' "selectordinal" ',' pluralStyle '}'

choiceStyle: see ChoiceFormat
pluralStyle: see PluralFormat
selectStyle: see SelectFormat

argNameOrNumber = argName | argNumber
argName = [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
argNumber = '0' | ('1'..'9' ('0'..'9')*)

argType = "number" | "date" | "time" | "spellout" | "ordinal" | "duration"
argStyle = "short" | "medium" | "long" | "full" | "integer" | "currency" | "percent" | argStyleText | "::" argSkeletonText

Recommendation: Use the real apostrophe (single quote) character ’ (U+2019) for human-readable text, and use the ASCII apostrophe ' (U+0027) only in program syntax, like quoting in MessageFormat. See the annotations for U+0027 Apostrophe in The Unicode Standard.

The choice argument type is deprecated. Use plural arguments for proper plural selection, and select arguments for simple selection among a fixed set of choices.

The argType and argStyle values are used to create a Format instance for the format element. The following table shows how the values map to Format instances. Combinations not shown in the table are illegal. Any argStyleText must be a valid pattern string for the Format subclass used.

argType argStyle resulting Format object
(none) null
number (none) NumberFormat.createInstance(getLocale(), status)
integer NumberFormat.createInstance(getLocale(), kNumberStyle, status)
currency NumberFormat.createCurrencyInstance(getLocale(), status)
percent NumberFormat.createPercentInstance(getLocale(), status)
argStyleText new DecimalFormat(argStyleText, new DecimalFormatSymbols(getLocale(), status), status)
argSkeletonText NumberFormatter::forSkeleton(argSkeletonText, status).locale(getLocale()).toFormat(status)
date (none) DateFormat.createDateInstance(kDefault, getLocale(), status)
short DateFormat.createDateInstance(kShort, getLocale(), status)
medium DateFormat.createDateInstance(kDefault, getLocale(), status)
long DateFormat.createDateInstance(kLong, getLocale(), status)
full DateFormat.createDateInstance(kFull, getLocale(), status)
argStyleText new SimpleDateFormat(argStyleText, getLocale(), status)
argSkeletonText DateFormat::createInstanceForSkeleton(argSkeletonText, getLocale(), status)
time (none) DateFormat.createTimeInstance(kDefault, getLocale(), status)
short DateFormat.createTimeInstance(kShort, getLocale(), status)
medium DateFormat.createTimeInstance(kDefault, getLocale(), status)
long DateFormat.createTimeInstance(kLong, getLocale(), status)
full DateFormat.createTimeInstance(kFull, getLocale(), status)
argStyleText new SimpleDateFormat(argStyleText, getLocale(), status)
spellout argStyleText (optional) new RuleBasedNumberFormat(URBNF_SPELLOUT, getLocale(), status)
    .setDefaultRuleset(argStyleText, status);
ordinal argStyleText (optional) new RuleBasedNumberFormat(URBNF_ORDINAL, getLocale(), status)
    .setDefaultRuleset(argStyleText, status);
duration argStyleText (optional) new RuleBasedNumberFormat(URBNF_DURATION, getLocale(), status)
    .setDefaultRuleset(argStyleText, status);

Argument formatting

Arguments are formatted according to their type, using the default ICU formatters for those types, unless otherwise specified.

There are also several ways to control the formatting.

We recommend you use default styles, predefined style values, skeletons, or preformatted values, but not pattern strings or custom format objects.

For more details, see the ICU User Guide.

Usage Information

Here are some examples of usage: Example 1:

GregorianCalendar cal(success);
Formattable arguments[] = {
7L,
Formattable( (Date) cal.getTime(success), Formattable::kIsDate),
"a disturbance in the Force"
};
"At {1,time,::jmm} on {1,date,::dMMMM}, there was {2} on planet {0,number}.",
arguments, 3, result, success );
cout << "result: " << result << endl;
//<output>: At 4:34 PM on March 23, there was a disturbance
// in the Force on planet 7.
Formattable objects can be passed to the Format class or its subclasses for formatting.
Definition: fmtable.h:64
Concrete class which provides the standard calendar used by most of the world.
Definition: gregocal.h:153
UnicodeString & format(const Formattable *source, int32_t count, UnicodeString &appendTo, FieldPosition &ignore, UErrorCode &status) const
Formats the given array of arguments into a user-readable string.
UnicodeString is a string class that stores Unicode characters directly and provides similar function...
Definition: unistr.h:296
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition: utypes.h:415
@ U_ZERO_ERROR
No error, no warning.
Definition: utypes.h:449

Typically, the message format will come from resources, and the arguments will be dynamically set at runtime.

Example 2:

 
success = U_ZERO_ERROR;
Formattable testArgs[] = {3L, "MyDisk"};
"The disk \"{1}\" contains {0} file(s).", success );
FieldPosition fpos = 0;
cout << "format: " << form.format(testArgs, 2, string, fpos, success ) << endl;
// output, with different testArgs:
// output: The disk "MyDisk" contains 0 file(s).
// output: The disk "MyDisk" contains 1 file(s).
// output: The disk "MyDisk" contains 1,273 file(s).
FieldPosition is a simple class used by Format and its subclasses to identify fields in formatted out...
Definition: fieldpos.h:110

For messages that include plural forms, you can use a plural argument:

success = U_ZERO_ERROR;
"{num_files, plural, "
"=0{There are no files on disk \"{disk_name}\".}"
"=1{There is one file on disk \"{disk_name}\".}"
"other{There are # files on disk \"{disk_name}\".}}",
Locale("en"),
success);
FieldPosition fpos = 0;
Formattable testArgs[] = {0L, "MyDisk"};
UnicodeString testArgsNames[] = {"num_files", "disk_name"};
UnicodeString result;
cout << msgFmt.format(testArgs, testArgsNames, 2, result, fpos, 0, success);
testArgs[0] = 3L;
cout << msgFmt.format(testArgs, testArgsNames, 2, result, fpos, 0, success);
A Locale object represents a specific geographical, political, or cultural region.
Definition: locid.h:195
output: There are no files on disk "MyDisk". There are 3 files on "MyDisk".

See PluralFormat and PluralRules for details.

Synchronization

MessageFormats are not synchronized. It is recommended to create separate format instances for each thread. If multiple threads access a format concurrently, it must be synchronized externally.

Stable:
ICU 2.0

Definition at line 345 of file msgfmt.h.

Member Enumeration Documentation

◆ EFormatNumber

Enum type for kMaxFormat.

Obsolete:
ICU 3.0. The 10-argument limit was removed as of ICU 2.6, rendering this enum type obsolete.
Enumerator
kMaxFormat 

The maximum number of arguments.

Obsolete:
ICU 3.0. The 10-argument limit was removed as of ICU 2.6, rendering this constant obsolete.

Definition at line 353 of file msgfmt.h.

Constructor & Destructor Documentation

◆ MessageFormat() [1/4]

icu::MessageFormat::MessageFormat ( const UnicodeString pattern,
UErrorCode status 
)

Constructs a new MessageFormat using the given pattern and the default locale.

Parameters
patternPattern used to construct object.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0

◆ MessageFormat() [2/4]

icu::MessageFormat::MessageFormat ( const UnicodeString pattern,
const Locale newLocale,
UErrorCode status 
)

Constructs a new MessageFormat using the given pattern and locale.

Parameters
patternPattern used to construct object.
newLocaleThe locale to use for formatting dates and numbers.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0

◆ MessageFormat() [3/4]

icu::MessageFormat::MessageFormat ( const UnicodeString pattern,
const Locale newLocale,
UParseError parseError,
UErrorCode status 
)

Constructs a new MessageFormat using the given pattern and locale.

Parameters
patternPattern used to construct object.
newLocaleThe locale to use for formatting dates and numbers.
parseErrorStruct to receive information on the position of an error within the pattern.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0

◆ MessageFormat() [4/4]

icu::MessageFormat::MessageFormat ( const MessageFormat )

Constructs a new MessageFormat from an existing one.

Stable:
ICU 2.0

◆ ~MessageFormat()

virtual icu::MessageFormat::~MessageFormat ( )
virtual

Destructor.

Stable:
ICU 2.0

Member Function Documentation

◆ adoptFormat() [1/2]

virtual void icu::MessageFormat::adoptFormat ( const UnicodeString formatName,
Format formatToAdopt,
UErrorCode status 
)
virtual

Sets one subformat for given format name.

See the class description about format name. This function supports both named and numbered arguments– if numbered, the formatName is the corresponding UnicodeStrings (e.g. "0", "1", "2"...). If there is no matched formatName or wrong type, the item will be ignored. The caller should not delete the Format object after this call.

Parameters
formatNameName of the subformat.
formatToAdoptFormat to be adopted.
statusoutput param set to success/failure code.
Stable:
ICU 4.0

◆ adoptFormat() [2/2]

virtual void icu::MessageFormat::adoptFormat ( int32_t  formatNumber,
Format formatToAdopt 
)
virtual

Sets one subformat.

See the class description about format numbering. The caller should not delete the Format object after this call. If the number is over the number of formats already set, the item will be deleted and ignored.

If this format uses named arguments, the new format is discarded and this format remains unchanged.

Stable:
ICU 2.0
Parameters
formatNumberindex of the subformat.
formatToAdoptthe format to be adopted.

◆ adoptFormats()

virtual void icu::MessageFormat::adoptFormats ( Format **  formatsToAdopt,
int32_t  count 
)
virtual

Sets subformats.

See the class description about format numbering. The caller should not delete the Format objects after this call. The array formatsToAdopt is not itself adopted. Its ownership is retained by the caller. If the call fails because memory cannot be allocated, then the formats will be deleted by this method, and this object will remain unchanged.

If this format uses named arguments, the new formats are discarded and this format remains unchanged.

Stable:
ICU 2.0
Parameters
formatsToAdoptthe format to be adopted.
countthe size of the array.

◆ applyPattern() [1/3]

virtual void icu::MessageFormat::applyPattern ( const UnicodeString pattern,
UErrorCode status 
)
virtual

Applies the given pattern string to this message format.

Parameters
patternThe pattern to be applied.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0

◆ applyPattern() [2/3]

virtual void icu::MessageFormat::applyPattern ( const UnicodeString pattern,
UMessagePatternApostropheMode  aposMode,
UParseError parseError,
UErrorCode status 
)
virtual

Sets the UMessagePatternApostropheMode and the pattern used by this message format.

Parses the pattern and caches Format objects for simple argument types. Patterns and their interpretation are specified in the class description.

This method is best used only once on a given object to avoid confusion about the mode, and after constructing the object with an empty pattern string to minimize overhead.

Parameters
patternThe pattern to be applied.
aposModeThe new apostrophe mode.
parseErrorStruct to receive information on the position of an error within the pattern. Can be nullptr.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 4.8

◆ applyPattern() [3/3]

virtual void icu::MessageFormat::applyPattern ( const UnicodeString pattern,
UParseError parseError,
UErrorCode status 
)
virtual

Applies the given pattern string to this message format.

Parameters
patternThe pattern to be applied.
parseErrorStruct to receive information on the position of an error within the pattern.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Stable:
ICU 2.0

◆ autoQuoteApostrophe()

static UnicodeString icu::MessageFormat::autoQuoteApostrophe ( const UnicodeString pattern,
UErrorCode status 
)
static

Convert an 'apostrophe-friendly' pattern into a standard pattern.

Standard patterns treat all apostrophes as quotes, which is problematic in some languages, e.g. French, where apostrophe is commonly used. This utility assumes that only an unpaired apostrophe immediately before a brace is a true quote. Other unpaired apostrophes are paired, and the resulting standard pattern string is returned.

Note it is not guaranteed that the returned pattern is indeed a valid pattern. The only effect is to convert between patterns having different quoting semantics.

Parameters
patternthe 'apostrophe-friendly' patttern to convert
statusInput/output error code. If the pattern cannot be parsed, the failure code is set.
Returns
the standard equivalent of the original pattern
Stable:
ICU 3.4

◆ clone()

virtual MessageFormat * icu::MessageFormat::clone ( ) const
overridevirtual

Clones this Format object polymorphically.

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

Stable:
ICU 2.0

Implements icu::Format.

◆ equalFormats()

static UBool icu::MessageFormat::equalFormats ( const void *  left,
const void *  right 
)
static

Compares two Format objects.

This is used for constructing the hash tables.

Parameters
leftpointer to a Format object. Must not be nullptr.
rightpointer to a Format object. Must not be nullptr.
Returns
whether the two objects are the same
Internal:
Do not use. This API is for internal use only.

◆ format() [1/7]

virtual UnicodeString & icu::MessageFormat::format ( const Formattable obj,
UnicodeString appendTo,
FieldPosition pos,
UErrorCode status 
) const
overridevirtual

Formats the given array of arguments into a user-readable string.

The array must be stored within a single Formattable object of type kArray. If the Formattable object type is not of type kArray, then returns a failing UErrorCode.

If this format uses named arguments, appendTo is unchanged and status is set to U_ILLEGAL_ARGUMENT_ERROR.

Parameters
objA Formattable of type kArray containing arguments to be formatted.
appendToOutput parameter to receive result. Result is appended to existing contents.
posOn input: an alignment field, if desired. On output: the offsets of the alignment field.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Implements icu::Format.

◆ format() [2/7]

virtual UnicodeString & icu::Format::format ( const Formattable obj,
UnicodeString appendTo,
FieldPosition pos,
UErrorCode status 
) const
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
objThe object to format.
appendToOutput parameter to receive result. Result is appended to existing contents.
posOn input: an alignment field, if desired. On output: the offsets of the alignment field.
statusOutput param filled with success/failure status.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

Implements icu::Format.

◆ format() [3/7]

virtual UnicodeString & icu::Format::format ( const Formattable obj,
UnicodeString appendTo,
FieldPositionIterator posIter,
UErrorCode status 
) const
virtual

Format an object to produce a string.

Subclasses should override this method. 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
objThe object to format.
appendToOutput parameter to receive result. Result is appended to existing contents.
posIterOn return, can be used to iterate over positions of fields generated by this format call.
statusOutput param filled with success/failure status.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 4.4

Reimplemented from icu::Format.

◆ format() [4/7]

UnicodeString & icu::Format::format ( const Formattable obj,
UnicodeString appendTo,
UErrorCode status 
) const

Formats an object to produce a string.

Parameters
objThe object to format.
appendToOutput parameter to receive result. Result is appended to existing contents.
statusOutput parameter filled in with success or failure status.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

◆ format() [5/7]

UnicodeString & icu::MessageFormat::format ( const Formattable source,
int32_t  count,
UnicodeString appendTo,
FieldPosition ignore,
UErrorCode status 
) const

Formats the given array of arguments into a user-readable string.

Does not take ownership of the Formattable* array or its contents.

If this format uses named arguments, appendTo is unchanged and status is set to U_ILLEGAL_ARGUMENT_ERROR.

Parameters
sourceAn array of objects to be formatted.
countThe number of elements of 'source'.
appendToOutput parameter to receive result. Result is appended to existing contents.
ignoreNot used; inherited from base class API.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

◆ format() [6/7]

static UnicodeString & icu::MessageFormat::format ( const UnicodeString pattern,
const Formattable arguments,
int32_t  count,
UnicodeString appendTo,
UErrorCode status 
)
static

Formats the given array of arguments into a user-readable string using the given pattern.

If this format uses named arguments, appendTo is unchanged and status is set to U_ILLEGAL_ARGUMENT_ERROR.

Parameters
patternThe pattern.
argumentsAn array of objects to be formatted.
countThe number of elements of 'source'.
appendToOutput parameter to receive result. Result is appended to existing contents.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

◆ format() [7/7]

UnicodeString & icu::MessageFormat::format ( const UnicodeString argumentNames,
const Formattable arguments,
int32_t  count,
UnicodeString appendTo,
UErrorCode status 
) const

Formats the given array of arguments into a user-defined argument name array.

This function supports both named and numbered arguments– if numbered, the formatName is the corresponding UnicodeStrings (e.g. "0", "1", "2"...).

Parameters
argumentNamesargument name array
argumentsAn array of objects to be formatted.
countThe number of elements of 'argumentNames' and arguments. The number of argumentNames and arguments must be the same.
appendToOutput parameter to receive result. Result is appended to existing contents.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 4.0

◆ getApostropheMode()

UMessagePatternApostropheMode icu::MessageFormat::getApostropheMode ( ) const
inline
Returns
this instance's UMessagePatternApostropheMode.
Stable:
ICU 4.8

Definition at line 500 of file msgfmt.h.

◆ getArgTypeCount()

int32_t icu::MessageFormat::getArgTypeCount ( ) const

This API is for ICU internal use only.

Please do not use it.

Returns argument types count in the parsed pattern. Used to distinguish pattern "{0} d" and "d".

Returns
The number of formattable types in the pattern
Internal:
Do not use. This API is for internal use only.

◆ getDynamicClassID()

virtual UClassID icu::MessageFormat::getDynamicClassID ( void  ) const
overridevirtual

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

Reimplemented from icu::UObject.

◆ getFormat()

virtual Format * icu::MessageFormat::getFormat ( const UnicodeString formatName,
UErrorCode status 
)
virtual

Gets subformat pointer for given format name.

This function supports both named and numbered arguments. If numbered, the formatName is the corresponding UnicodeStrings (e.g. "0", "1", "2"...). The returned Format object should not be deleted by the caller, nor should the pointer of other object . The pointer and its contents remain valid only until the next call to any method of this class is made with this object.

Parameters
formatNamethe name or number specifying a format
statusoutput param set to success/failure code.
Stable:
ICU 4.0

◆ getFormatNames()

virtual StringEnumeration * icu::MessageFormat::getFormatNames ( UErrorCode status)
virtual

Gets format names.

This function returns formatNames in StringEnumerations which can be used with getFormat() and setFormat() to export formattable array from current MessageFormat to another. It is the caller's responsibility to delete the returned formatNames.

Parameters
statusoutput param set to success/failure code.
Stable:
ICU 4.0

◆ getFormats()

virtual const Format ** icu::MessageFormat::getFormats ( int32_t &  count) const
virtual

Gets an array of subformats of this object.

The returned array should not be deleted by the caller, nor should the pointers within the array. The array and its contents remain valid only until the next call to this format. See the class description about format numbering.

Parameters
countoutput parameter to receive the size of the array
Returns
an array of count Format* objects, or nullptr if out of memory. Any or all of the array elements may be nullptr.
Stable:
ICU 2.0

◆ getLocale()

virtual const Locale & icu::MessageFormat::getLocale ( void  ) const
virtual

Gets the locale used for creating argument Format objects.

format information.

Returns
the locale of the object.
Stable:
ICU 2.0

◆ getStaticClassID()

static UClassID icu::MessageFormat::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

◆ operator=()

const MessageFormat & icu::MessageFormat::operator= ( const MessageFormat )

Assignment operator.

Stable:
ICU 2.0

◆ operator==()

virtual bool icu::MessageFormat::operator== ( const Format other) const
overridevirtual

Returns true if the given Format objects are semantically equal.

Objects of different subclasses are considered unequal.

Parameters
otherthe object to be compared with.
Returns
true if the given Format objects are semantically equal.
Stable:
ICU 2.0

Implements icu::Format.

◆ parse() [1/2]

virtual Formattable * icu::MessageFormat::parse ( const UnicodeString source,
int32_t &  count,
UErrorCode status 
) const
virtual

Parses the given string into an array of output arguments.

If this format uses named arguments, status is set to U_ARGUMENT_TYPE_MISMATCH.

Parameters
sourceString to be parsed.
countOutput param to receive size of returned array.
statusInput/output error code. If the pattern cannot be parsed, set to failure code.
Returns
an array of parsed arguments. The caller owns both the array and its contents. Returns nullptr if status is not U_ZERO_ERROR.
Stable:
ICU 2.0

◆ parse() [2/2]

virtual Formattable * icu::MessageFormat::parse ( const UnicodeString source,
ParsePosition pos,
int32_t &  count 
) const
virtual

Parses the given string into an array of output arguments.

Parameters
sourceString to be parsed.
posOn input, starting position for parse. On output, final position after parse. Unchanged if parse fails.
countOutput parameter to receive the number of arguments parsed.
Returns
an array of parsed arguments. The caller owns both the array and its contents.
Stable:
ICU 2.0

◆ parseObject()

virtual void icu::MessageFormat::parseObject ( const UnicodeString source,
Formattable result,
ParsePosition pos 
) const
overridevirtual

Parses the given string into an array of output arguments stored within a single Formattable of type kArray.

Parameters
sourceThe string to be parsed into an object.
resultFormattable to be set to the parse result. If parse fails, return contents are undefined.
posOn input, starting position for parse. On output, final position after parse. Unchanged if parse fails.
Stable:
ICU 2.0

Implements icu::Format.

◆ setFormat() [1/2]

virtual void icu::MessageFormat::setFormat ( const UnicodeString formatName,
const Format format,
UErrorCode status 
)
virtual

Sets one subformat for given format name.

See the class description about format name. This function supports both named and numbered arguments– if numbered, the formatName is the corresponding UnicodeStrings (e.g. "0", "1", "2"...). If there is no matched formatName or wrong type, the item will be ignored.

Parameters
formatNameName of the subformat.
formatthe format to be set.
statusoutput param set to success/failure code.
Stable:
ICU 4.0

◆ setFormat() [2/2]

virtual void icu::MessageFormat::setFormat ( int32_t  formatNumber,
const Format format 
)
virtual

Sets one subformat.

See the class description about format numbering. If the number is over the number of formats already set, the item will be ignored.

Parameters
formatNumberindex of the subformat.
formatthe format to be set.
Stable:
ICU 2.0

◆ setFormats()

virtual void icu::MessageFormat::setFormats ( const Format **  newFormats,
int32_t  cnt 
)
virtual

Sets subformats.

See the class description about format numbering. Each item in the array is cloned into the internal array. If the call fails because memory cannot be allocated, then this object will remain unchanged.

If this format uses named arguments, the new formats are discarded and this format remains unchanged.

Stable:
ICU 2.0
Parameters
newFormatsthe new format to be set.
cntthe size of the array.

◆ setLocale()

virtual void icu::MessageFormat::setLocale ( const Locale theLocale)
virtual

Sets the locale to be used for creating argument Format objects.

Parameters
theLocalethe new locale value to be set.
Stable:
ICU 2.0

◆ toPattern()

virtual UnicodeString & icu::MessageFormat::toPattern ( UnicodeString appendTo) const
virtual

Returns a pattern that can be used to recreate this object.

Parameters
appendToOutput parameter to receive the pattern. Result is appended to existing contents.
Returns
Reference to 'appendTo' parameter.
Stable:
ICU 2.0

◆ usesNamedArguments()

UBool icu::MessageFormat::usesNamedArguments ( ) const

Returns true if this MessageFormat uses named arguments, and false otherwise.

See class description.

Returns
true if named arguments are used.
Stable:
ICU 4.0

Friends And Related Function Documentation

◆ MessageFormatAdapter

friend class MessageFormatAdapter
friend

Definition at line 1107 of file msgfmt.h.


The documentation for this class was generated from the following file: