The Plural Format is a formatter for Plural objects.

Required Header

#include <utils_i18n.h>

Overview

Plural Format supports the creation of internationalized messages with plural inflection. It is based on plural selection, i.e. the caller specifies messages for each plural case that can appear in the user's language and the Plural Format selects the appropriate message based on the number.

The Problem of Plural Forms in Internationalized Messages:

Different languages have different ways to inflect plurals. Creating internationalized messages that include plural forms is only feasible when the framework is able to handle plural forms of all languages correctly. In some languages, like Polish, one plural case applies to infinitely many intervals (e.g., the plural case applies to numbers ending with 2, 3, or 4 except those ending with 12, 13, or 14).

Plural Format deals with this by breaking the problem into two parts:

It uses Plural Rules that can define more complex conditions for a plural case than just a single interval. These plural rules define both what plural cases exist in a language, and to which numbers these cases apply.
It provides predefined plural rules for many languages. Thus, the programmer need not worry about the plural cases of a language and does not have to define the plural cases; they can simply use the predefined keywords. The whole plural formatting of messages can be done using localized patterns from resource bundles. For predefined plural rules, see the CLDR Language Plural Rules page at http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/language_plural_rules.html

Usage of Plural Format:

This discussion assumes that you use Plural Format with a predefined set of plural rules. You can create one using one of the constructors that takes a locale object. To specify the message pattern, you can either pass it to the constructor or set it explicitly using the i18n_plural_format_apply_pattern() function. The i18n_plural_format_format_* functions takes a number object and selects the message of the matching plural case. This message will be returned.

Patterns and Their Interpretation:

The pattern text defines the message output for each plural case of the specified locale. Syntax:

          pluralStyle = [offsetValue] (selector '{' message '}')+
          offsetValue = "offset:" number
          selector = explicitValue | keyword
          explicitValue = '=' number  // adjacent, no white space in between
          keyword = [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
          message: message = messageText (argument messageText)*
          argument = noneArg | simpleArg | complexArg
          complexArg = pluralArg | selectordinalArg
          noneArg = '{' argNameOrNumber '}'
          simpleArg = '{' argNameOrNumber ',' argType [',' argStyle] '}'
          pluralArg = '{' argNameOrNumber ',' "plural" ',' pluralStyle '}'
          selectordinalArg = '{' argNameOrNumber ',' "selectordinal" ',' pluralStyle '}'
          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

Examples:

          one{dog} other{dogs}                        // English plural format for dog
          one{pes} two{psa} few{psi} other{psov}      //Slovenian translation of dog in plural format

Pattern_White_Space between syntax elements is ignored, except between the {curly braces} and their sub-message, and between the '=' and the number of an explicitValue.

There are 6 predefined casekeyword in CLDR/ICU - 'zero', 'one', 'two', 'few', 'many' and 'other'. You always have to define a message text for the default plural case other which is contained in every rule set. If you do not specify a message text for a particular plural case, the message text of the plural case other gets assigned to this plural case.

When formatting, the input number is first matched against the explicitValue clauses. If there is no exact-number match, then a keyword is selected by calling the Plural Rules with the input number minus the offset. (The offset defaults to 0 if it is omitted from the pattern string.) If there is no clause with that keyword, then the "other" clauses is returned.

An unquoted pound sign (#) in the selected sub-message itself (i.e., outside of arguments nested in the sub-message) is replaced by the input number minus the offset. The number-minus-offset value is formatted using a Number Format for the Plural Format's locale.

Note: That argument is formatting without subtracting the offset! If you need a custom format and have a non-zero offset, then you need to pass the number-minus-offset value as a separate parameter.

Defining Custom Plural Rules:

If you need to use Plural Format with custom rules, you can create a Plural Rules object and pass it to Plural Format's constructor. If you also specify a locale in this constructor, this locale will be used to format the number in the message texts.

Functions
int	i18n_plural_format_create (i18n_plural_format_h *plural_format)
	Creates a new cardinal-number plural format object for the default locale.
int	i18n_plural_format_create_from_locale (const char locale, i18n_plural_format_h plural_format)
	Creates a new cardinal-number plural format object for a given locale.
int	i18n_plural_format_create_from_rules_pattern (i18n_plural_rules_h plural_rules, const char pattern, i18n_plural_format_h plural_format)
	Creates a new plural format object for a given set of rules, a pattern and a default locale.
int	i18n_plural_format_create_from_locale_type_pattern (const char locale, i18n_uplural_type_e type, const char pattern, i18n_plural_format_h *plural_format)
	Creates a new plural format object for a plural type, a pattern and a locale.
int	i18n_plural_format_create_from_locale_type (const char locale, i18n_uplural_type_e type, i18n_plural_format_h plural_format)
	Creates a new plural format object for the plural type.
int	i18n_plural_format_create_from_locale_pattern (const char locale, const char pattern, i18n_plural_format_h *plural_format)
	Creates a new cardinal-number plural format object for a given pattern string and locale.
int	i18n_plural_format_create_from_locale_rules_pattern (const char locale, i18n_plural_rules_h plural_rules, const char pattern, i18n_plural_format_h *plural_format)
	Creates a new plural format object for a given set of rules, a pattern and a locale.
int	i18n_plural_format_destroy (i18n_plural_format_h plural_format)
	Destroys the plural format object.
int	i18n_plural_format_clone (i18n_plural_format_h plural_format, i18n_format_h *clone)
	Creates a polymorphic clone of the given plural_format object.
int	i18n_plural_format_apply_pattern (i18n_plural_format_h plural_format, const char *pattern)
	Sets the pattern used by this plural format.
int	i18n_plural_format_format_int32 (i18n_plural_format_h plural_format, int32_t number, i18n_field_position_h field_position, int32_t append_to_size, i18n_uchar append_to, int32_t output_length)
	Formats a plural message for a given int32_t number.
int	i18n_plural_format_format_double (i18n_plural_format_h plural_format, double number, i18n_field_position_h field_position, int32_t append_to_size, i18n_uchar append_to, int32_t output_length)
	Formats a plural message for a given double number.
int	i18n_plural_format_format_formattable (i18n_plural_format_h plural_format, i18n_formattable_h formattable, i18n_field_position_h field_position, int32_t append_to_size, i18n_uchar append_to, int32_t output_length)
	Formats a plural message for a number taken from a i18n_formattable_h object.
int	i18n_plural_format_set_number_format (i18n_plural_format_h plural_format, i18n_unumber_format_h number_format)
	Sets the number format used by this formatter.
int	i18n_plural_format_to_pattern (i18n_plural_format_h plural_format, i18n_field_position_h field_position, int32_t append_to_size, i18n_uchar append_to, int32_t output_length)
	Returns the pattern from i18n_plural_format_apply_pattern() or i18n_plural_format_create_pattern().
Typedefs
typedef void *	i18n_plural_format_h
	An i18n_plural_format_h handle.

Typedef Documentation

typedef void* i18n_plural_format_h

An i18n_plural_format_h handle.

Use i18n_plural_format_* functions to operate on i18n_plural_format_h objects.

Since :: 5.0

Function Documentation

int i18n_plural_format_apply_pattern	(	i18n_plural_format_h	plural_format,
		const char *	pattern
	)

Sets the pattern used by this plural format.

The method parses the pattern and creates a map of format strings for the plural rules. Patterns and their interpretation are specified in the module overview.

Since :: 5.0

Parameters:

[in]	plural_format	The plural format object to set the pattern
[in]	pattern	The pattern to set in plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter

int i18n_plural_format_clone	(	i18n_plural_format_h	plural_format,
		i18n_format_h *	clone
	)

Creates a polymorphic clone of the given plural_format object.

Since :: 5.0

Remarks:: The clone object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	plural_format	The plural format object to be cloned
[out]	clone	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create ( i18n_plural_format_h * plural_format )

Creates a new cardinal-number plural format object for the default locale.

This locale will be used to get the set of plural rules and for standard number formatting.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[out] plural_format The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_locale	(	const char *	locale,
		i18n_plural_format_h *	plural_format
	)

Creates a new cardinal-number plural format object for a given locale.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	locale	The locale string containing language and country code
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_locale_pattern	(	const char *	locale,
		const char *	pattern,
		i18n_plural_format_h *	plural_format
	)

Creates a new cardinal-number plural format object for a given pattern string and locale.

The locale will be used to get the set of plural rules and for standard number formatting.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	locale	The locale string containing language and country code
[in]	pattern	The pattern for this plural format object
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_locale_rules_pattern	(	const char *	locale,
		i18n_plural_rules_h	plural_rules,
		const char *	pattern,
		i18n_plural_format_h *	plural_format
	)

Creates a new plural format object for a given set of rules, a pattern and a locale.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	locale	The locale string containing language and country code
[in]	plural_rules	Plural rules which defines the behavior of the plural format object
[in]	pattern	The pattern for this plural format object
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_locale_type	(	const char *	locale,
		i18n_uplural_type_e	type,
		i18n_plural_format_h *	plural_format
	)

Creates a new plural format object for the plural type.

The standard number formatting will be done using the given locale.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	locale	The locale string containing language and country code
[in]	type	The plural type
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_locale_type_pattern	(	const char *	locale,
		i18n_uplural_type_e	type,
		const char *	pattern,
		i18n_plural_format_h *	plural_format
	)

Creates a new plural format object for a plural type, a pattern and a locale.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	locale	The locale string containing language and country code
[in]	type	The plural type
[in]	pattern	The pattern for this plural format object
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_create_from_rules_pattern	(	i18n_plural_rules_h	plural_rules,
		const char *	pattern,
		i18n_plural_format_h *	plural_format
	)

Creates a new plural format object for a given set of rules, a pattern and a default locale.

Since :: 5.0

Remarks:: The created object should be released by the caller with the i18n_plural_format_destroy() function.

Parameters:

[in]	plural_rules	Plural rules which defines the behavior of the plural format object
[in]	pattern	The pattern for this plural format object
[out]	plural_format	The created plural format object

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_OUT_OF_MEMORY	Out of memory

int i18n_plural_format_destroy ( i18n_plural_format_h plural_format )

Destroys the plural format object.

Since :: 5.0

Parameters:

[in] plural_format The plural format object to destroy

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter

int i18n_plural_format_format_double	(	i18n_plural_format_h	plural_format,
		double	number,
		i18n_field_position_h	field_position,
		int32_t	append_to_size,
		i18n_uchar *	append_to,
		int32_t *	output_length
	)

Formats a plural message for a given double number.

Since :: 5.0

Parameters:

[in]	plural_format	The format object for which number will be formatted
[in]	number	Number to format
[in]	field_position	The i18n_field_position_h object
[in]	append_to_size	The size of the append_to buffer. If `append_to_size <= 0` then output string is not appended to the append_to buffer and I18N_ERROR_BUFFER_OVERFLOW is returned.
[in,out]	append_to	The buffer to which formatted string will be appended. Can be `NULL` if `append_to_size <= 0`. Otherwise must be `NULL` terminated.
[out]	output_length	The length of the output string, which is the string in append_to buffer with formatted string.

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_BUFFER_OVERFLOW	Buffer overflow

int i18n_plural_format_format_formattable	(	i18n_plural_format_h	plural_format,
		i18n_formattable_h	formattable,
		i18n_field_position_h	field_position,
		int32_t	append_to_size,
		i18n_uchar *	append_to,
		int32_t *	output_length
	)

Formats a plural message for a number taken from a i18n_formattable_h object.

Since :: 5.0

Parameters:

[in]	plural_format	The format object for which number will be formatted
[in]	formattable	The object containing a number for which the plural message should be formatted. The object must be of a numeric type.
[in]	field_position	The i18n_field_position_h object
[in]	append_to_size	The size of the append_to buffer. If `append_to_size <= 0` then output string is not appended to the append_to buffer and I18N_ERROR_BUFFER_OVERFLOW is returned.
[in,out]	append_to	The buffer to which formatted string will be appended. Can be `NULL` if `append_to_size <= 0`. Otherwise must be `NULL` terminated.
[out]	output_length	The length of the output string, which is the string in append_to buffer with formatted string.

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_BUFFER_OVERFLOW	Buffer overflow

int i18n_plural_format_format_int32	(	i18n_plural_format_h	plural_format,
		int32_t	number,
		i18n_field_position_h	field_position,
		int32_t	append_to_size,
		i18n_uchar *	append_to,
		int32_t *	output_length
	)

Formats a plural message for a given int32_t number.

Since :: 5.0

Parameters:

[in]	plural_format	The format object for which number will be formatted
[in]	number	Number to format
[in]	field_position	The i18n_field_position_h object
[in]	append_to_size	The size of the append_to buffer. If `append_to_size <= 0` then output string is not appended to the append_to buffer and I18N_ERROR_BUFFER_OVERFLOW is returned.
[in,out]	append_to	The buffer to which formatted string will be appended. Can be `NULL` if `append_to_size <= 0`. Otherwise must be `NULL` terminated.
[out]	output_length	The length of the output string, which is the string in append_to buffer with formatted string.

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_BUFFER_OVERFLOW	Buffer overflow

int i18n_plural_format_set_number_format	(	i18n_plural_format_h	plural_format,
		i18n_unumber_format_h	number_format
	)

Sets the number format used by this formatter.

You only need to call this if you want a different number format than the default formatter for the locale.

Since :: 5.0

Parameters:

[in]	plural_format	The format object to set
[in]	number_format	The number format to use

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter

int i18n_plural_format_to_pattern	(	i18n_plural_format_h	plural_format,
		i18n_field_position_h	field_position,
		int32_t	append_to_size,
		i18n_uchar *	append_to,
		int32_t *	output_length
	)

Returns the pattern from i18n_plural_format_apply_pattern() or i18n_plural_format_create_pattern().

Since :: 5.0

Parameters:

[in]	plural_format	The format object to get pattern from
[in]	field_position	The i18n_field_position_h object
[in]	append_to_size	The size of the append_to buffer. If `append_to_size <= 0` then output string is not appended to the append_to buffer and I18N_ERROR_BUFFER_OVERFLOW is returned.
[in,out]	append_to	The buffer to which formatted string will be appended. Can be `NULL` if `append_to_size <= 0`. Otherwise must be `NULL` terminated.
[out]	output_length	The length of the output string, which is the string in append_to buffer with formatted string.

Returns:: 0 on success, otherwise a negative error value

Return values:

I18N_ERROR_NONE	Successful
I18N_ERROR_INVALID_PARAMETER	Invalid function parameter
I18N_ERROR_BUFFER_OVERFLOW	Buffer overflow

Required Header

Overview

Functions

Typedefs

Typedef Documentation

Function Documentation