Type representing argument and return values for custom functions. More...

#include <messageformat2_function_registry.h>

Inheritance diagram for icu::message2::FunctionValue:

Public Member Functions
virtual U_I18N_API UnicodeString	formatToString (UErrorCode &status) const
	Returns the string representation of this value.
virtual U_I18N_API const Formattable &	unwrap () const
	Returns the Formattable operand that was used to construct this value.
virtual U_I18N_API const FunctionOptions &	getResolvedOptions () const
	Returns a reference to the resolved options for this value.
virtual U_I18N_API UMFDirectionality	getDirection () const
	Returns the directionality of this value, i.e.
virtual U_I18N_API UMFBidiOption	getDirectionAnnotation () const
	Returns the directionality that this value was annotated with.
virtual U_I18N_API UBool	isSelectable () const
	Returns true if this value supports selection.
virtual U_I18N_API UBool	isNullOperand () const
	Returns true if this value represents a null operand, that is, the absence of an argument.
virtual U_I18N_API void	selectKeys (const UnicodeString keys, int32_t keysLen, int32_t prefs, int32_t &prefsLen, UErrorCode &status) const
	Compares this value to an array of keys, and returns an array of matching keys sorted by preference.
virtual U_I18N_API const FunctionName &	getFunctionName () const
	Returns the name of the function that constructed this value.
virtual U_I18N_API const UnicodeString &	getFallback () const
	Returns a fallback string that can be used as output if processing this function results in an error.
virtual U_I18N_API	~FunctionValue ()
	Destructor.
Public Member Functions inherited from icu::UObject
virtual	~UObject ()
	Destructor.
virtual UClassID	getDynamicClassID () const
	ICU4C "poor man's RTTI", returns a UClassID for the actual ICU class.

Protected Attributes
Formattable	innerValue
	Computed result of the function invocation that returned this FunctionValue.
FunctionOptions	opts
	Resolved options attached to this value.
FunctionName	functionName
	The name of the function that constructed this FunctionValue.
UnicodeString	fallback
	Fallback string that can be used if a later function encounters an error when processing this FunctionValue.
Locale	locale
	Locale from u:locale option.
UMFDirectionality	dir = U_MF_DIRECTIONALITY_UNKNOWN
	Directionality of formatted result.
UMFBidiOption	inputDir = U_MF_BIDI_OPTION_INHERIT
	Input directionality from u:dir option.

Friends
class	FunctionOptions

Detailed Description

Type representing argument and return values for custom functions.

It encapsulates an operand and resolved options, and can be extended with additional state. Adding a new custom function requires adding a new class that implements this interface.

FunctionValues are assumed to be immutable (the call() method on Function takes a const FunctionValue&, and the formatToString() and selectKeys() methods are const.) Feedback on whether internal mutable state in classes implementing FunctionValue is welcomed during the Technology Preview period.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 368 of file messageformat2_function_registry.h.

Constructor & Destructor Documentation

◆ ~FunctionValue()

virtual U_I18N_API icu::message2::FunctionValue::~FunctionValue ( )

virtual

Destructor.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

References U_I18N_API.

Member Function Documentation

◆ formatToString()

virtual U_I18N_API UnicodeString icu::message2::FunctionValue::formatToString ( UErrorCode & status ) const

inlinevirtual

Returns the string representation of this value.

The default method signals an error. Must be overridden by classes implementing values that support formatting.

Parameters

status Input/output error code

Returns: A string.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 381 of file messageformat2_function_registry.h.

References U_I18N_API, U_MF_FORMATTING_ERROR, and U_SUCCESS.

◆ getDirection()

virtual U_I18N_API UMFDirectionality icu::message2::FunctionValue::getDirection ( ) const

inlinevirtual

Returns the directionality of this value, i.e.

the directionality that its formatted result should have.

Returns: A UBiDiDirection indicating the directionality that the formatted result of this value should have.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 417 of file messageformat2_function_registry.h.

References dir, and U_I18N_API.

◆ getDirectionAnnotation()

virtual U_I18N_API UMFBidiOption icu::message2::FunctionValue::getDirectionAnnotation ( ) const

inlinevirtual

Returns the directionality that this value was annotated with.

This is distinct from the directionality of the formatted text. See the description of the "Default Bidi Strategy", https://github.com/unicode-org/message-format-wg/blob/main/spec/formatting.md#handling-bidirectional-text for further context.

Returns: A UMFBidiOption indicating the directionality that this value was annotated with.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 432 of file messageformat2_function_registry.h.

References inputDir, and U_I18N_API.

◆ getFallback()

virtual U_I18N_API const UnicodeString & icu::message2::FunctionValue::getFallback ( ) const

inlinevirtual

Returns a fallback string that can be used as output if processing this function results in an error.

Returns: A string determined by the creator of this FunctionValue.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 512 of file messageformat2_function_registry.h.

References fallback, and U_I18N_API.

◆ getFunctionName()

virtual U_I18N_API const FunctionName & icu::message2::FunctionValue::getFunctionName ( ) const

inlinevirtual

Returns the name of the function that constructed this value.

Returns: A string representing a function name. The string does not include a leading ':'.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 502 of file messageformat2_function_registry.h.

References functionName, and U_I18N_API.

◆ getResolvedOptions()

virtual U_I18N_API const FunctionOptions & icu::message2::FunctionValue::getResolvedOptions ( ) const

inlinevirtual

Returns a reference to the resolved options for this value.

Returns: A reference to the resolved options for this value.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 406 of file messageformat2_function_registry.h.

References opts, and U_I18N_API.

◆ isNullOperand()

virtual U_I18N_API UBool icu::message2::FunctionValue::isNullOperand ( ) const

inlinevirtual

Returns true if this value represents a null operand, that is, the absence of an argument.

This method should not be overridden. It can be called in order to check whether the argument is present. Some functions may be nullary (they may work with no arguments).

Returns: True iff this value represents an absent operand.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 459 of file messageformat2_function_registry.h.

References U_I18N_API.

◆ isSelectable()

virtual U_I18N_API UBool icu::message2::FunctionValue::isSelectable ( ) const

inlinevirtual

Returns true if this value supports selection.

The default method returns false. The method must be overridden for values that support selection.

Returns: True iff this value supports selection.

Internal: Do not use. This API is for internal use only. ICU 79 technology preview

Deprecated: This API is for technology preview only.

Definition at line 443 of file messageformat2_function_registry.h.

References U_I18N_API.

◆ selectKeys()

virtual U_I18N_API void icu::message2::FunctionValue::selectKeys	(	const UnicodeString *	keys,
		int32_t	keysLen,
		int32_t *	prefs,
		int32_t &	prefsLen,
		UErrorCode &	status ) const

inlinevirtual

Compares this value to an array of keys, and returns an array of matching keys sorted by preference.

The default implementation of this method signals an error. It should be overridden for value classes that support selection.

Parameters

keys	An array of strings to compare to the input.
keysLen	The length of keys.
prefs	An array of indices into keys. The initial contents of the array is undefined. selectKey() should set the contents of prefs to a subset of the indices in keys, with the best match placed at the lowest index in prefs.
prefsLen	A reference that selectKey() should set to the length of prefs, which must be less than or equal to keysLen.
status	Input/output error code.