Struct LanguageTag

pub struct LanguageTag { /* private fields */ }

A language tag as described in RFC 5646.

Language tags are used to help identify languages, whether spoken, written, signed, or otherwise signaled, for the purpose of communication. This includes constructed and artificial languages but excludes languages not intended primarily for human communication, such as programming languages.

Implementations

impl LanguageTag

pub fn as_str(&self) -> &str

Return the serialization of this language tag.

This is fast since that serialization is already stored in the LanguageTag struct.

pub fn into_string(self) -> String

Return the serialization of this language tag.

This consumes the LanguageTag and takes ownership of the String stored in it.

pub fn primary_language(&self) -> &str

Return the primary language subtag.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.primary_language(), "zh");

pub fn extended_language(&self) -> Option<&str>

Return the extended language subtags.

Valid language tags have at most one extended language.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.extended_language(), Some("cmn"));

pub fn extended_language_subtags(&self) -> impl Iterator<Item = &str>

Iterate on the extended language subtags.

Valid language tags have at most one extended language.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.extended_language_subtags().collect::<Vec<_>>(), vec!["cmn"]);

pub fn full_language(&self) -> &str

Return the primary language subtag and its extended language subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.full_language(), "zh-cmn");

pub fn script(&self) -> Option<&str>

Return the script subtag.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.script(), Some("Hans"));

pub fn region(&self) -> Option<&str>

Return the region subtag.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-cmn-Hans-CN").unwrap();
assert_eq!(language_tag.region(), Some("CN"));

pub fn variant(&self) -> Option<&str>

Return the variant subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-Latn-TW-pinyin").unwrap();
assert_eq!(language_tag.variant(), Some("pinyin"));

pub fn variant_subtags(&self) -> impl Iterator<Item = &str>

Iterate on the variant subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("zh-Latn-TW-pinyin").unwrap();
assert_eq!(language_tag.variant_subtags().collect::<Vec<_>>(), vec!["pinyin"]);

pub fn extension(&self) -> Option<&str>

Return the extension subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("de-DE-u-co-phonebk").unwrap();
assert_eq!(language_tag.extension(), Some("u-co-phonebk"));

pub fn extension_subtags(&self) -> impl Iterator<Item = (char, &str)>

Iterate on the extension subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("de-DE-u-co-phonebk").unwrap();
assert_eq!(language_tag.extension_subtags().collect::<Vec<_>>(), vec![('u', "co-phonebk")]);

pub fn private_use(&self) -> Option<&str>

Return the private use subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("de-x-foo-bar").unwrap();
assert_eq!(language_tag.private_use(), Some("x-foo-bar"));

pub fn private_use_subtags(&self) -> impl Iterator<Item = &str>

Iterate on the private use subtags.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("de-x-foo-bar").unwrap();
assert_eq!(language_tag.private_use_subtags().collect::<Vec<_>>(), vec!["foo", "bar"]);

pub fn parse(input: &str) -> Result<Self, ParseError>

Create a LanguageTag from its serialization.

This parser accepts the language tags that are “well-formed” according to RFC 5646. Full validation could be done with the validate method.

use language_tags::LanguageTag;

let language_tag = LanguageTag::parse("en-us").unwrap();
assert_eq!(language_tag.into_string(), "en-US")

Errors

If the language tag is not “well-formed” a ParseError variant will be returned.

pub fn validate(&self) -> Result<(), ValidationError>

Check if the language tag is “valid” according to RFC 5646.

It applies the following steps:

• grandfathereds and private use tags are valid
• There should be no more than one extended language subtag (c.f. errata 5457).
• Primary language, extended language, script, region and variants should appear in the IANA Language Subtag Registry.
• Extended language and variants should have a correct prefix as set in the IANA Language Subtag Registry.
• There should be no duplicate variant and singleton (extension) subtags.

Errors

If the language tag is not “valid” a ValidationError variant will be returned.

pub fn is_valid(&self) -> bool

Check if the language tag is valid according to RFC 5646.

pub fn canonicalize(&self) -> Result<LanguageTag, ValidationError>

Returns the canonical version of the language tag following RFC 5646 4.5.

It currently applies the following steps:

• Grandfathered tags are replaced with the canonical version if possible.
• Redundant tags are replaced with the canonical version if possible.
• Extension languages are promoted to primary language.
• Deprecated languages, scripts, regions and variants are replaced with modern equivalents.
• Suppress-Script is applied to remove default script for a language (e.g. “en-Latn” is canonicalized as “en”).
• Variants are deduplicated

Errors

If there is not a unique way to canonicalize the language tag a ValidationError variant will be returned.

pub fn matches(&self, other: &LanguageTag) -> bool

Matches language tags. The first language acts as a language range, the second one is used as a normal language tag. None fields in the language range are ignored. If the language tag has more extlangs than the range these extlangs are ignored. Matches are case-insensitive.

For example the range en-GB matches only en-GB and en-Arab-GB but not en. The range en matches all language tags starting with en including en, en-GB, en-Arab and en-Arab-GB.

Panics

If the language range has extensions or private use tags.

Examples

use language_tags::LanguageTag;

let range_italian = LanguageTag::parse("it").unwrap();
let tag_german = LanguageTag::parse("de").unwrap();
let tag_italian_switzerland = LanguageTag::parse("it-CH").unwrap();
assert!(!range_italian.matches(&tag_german));
assert!(range_italian.matches(&tag_italian_switzerland));

let range_spanish_brazil = LanguageTag::parse("es-BR").unwrap();
let tag_spanish = LanguageTag::parse("es").unwrap();
assert!(!range_spanish_brazil.matches(&tag_spanish));

pub fn is_language_range(&self) -> bool

Checks if it is a language range, meaning that there are no extension and privateuse tags.

Trait Implementations

impl Clone for LanguageTag

fn clone(&self) -> LanguageTag

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LanguageTag

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for LanguageTag

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl FromStr for LanguageTag

type Err = ParseError

The associated error which can be returned from parsing.

fn from_str(input: &str) -> Result<Self, ParseError>

Parses a string s to return a value of this type.

impl Hash for LanguageTag

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for LanguageTag

fn eq(&self, other: &LanguageTag) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for LanguageTag

impl StructuralPartialEq for LanguageTag