Struct icu_collator::CollatorOptions

#[non_exhaustive]
pub struct CollatorOptions {
    pub strength: Option<Strength>,
    pub alternate_handling: Option<AlternateHandling>,
    pub case_first: Option<CaseFirst>,
    pub max_variable: Option<MaxVariable>,
    pub case_level: Option<CaseLevel>,
    pub numeric: Option<Numeric>,
    pub backward_second_level: Option<BackwardSecondLevel>,
}

Options settable by the user of the API.

With the exception of reordering (BCP47 kr), options that can by implied by locale are also settable via CollatorOptions.

See the spec.

The setters take an Option so that None can be used to go back to default.

Options

Examples for using the different options below can be found in the crate-level docs.

ECMA-402 Sensitivity

ECMA-402 sensitivity maps to a combination of Strength and CaseLevel as follows:

sensitivity: "base"

Strength::Primary

sensitivity: "accent"

Strength::Secondary

sensitivity: "case"

Strength::Primary and CaseLevel::On

sensitivity: "variant"

Strength::Tertiary

Strength

This is the BCP47 key ks. The default is Strength::Tertiary.

Alternate Handling

This is the BCP47 key ka. Note that AlternateHandling::ShiftTrimmed and AlternateHandling::Blanked are unimplemented. The default is AlternateHandling::NonIgnorable, except for Thai, whose default is AlternateHandling::Shifted.

Case Level

See the spec. This is the BCP47 key kc. The default is CaseLevel::Off.

Case First

See the spec. This is the BCP47 key kf. Three possibilities: CaseFirst::Off (default, except for Danish and Maltese), CaseFirst::LowerFirst, and CaseFirst::UpperFirst (default for Danish and Maltese).

Backward second level

Compare the second level in backward order. This is the BCP47 key kb. kb is prohibited by ECMA-402. The default is BackwardSecondLevel::Off, except for Canadian French.

Numeric

This is the BCP47 key kn. When set to Numeric::On, any sequence of decimal digits (General_Category = Nd) is sorted at the primary level according to the numeric value. The default is Numeric::Off.

Unsupported BCP47 options

Reordering (BCP47 kr) currently cannot be set via the API and is implied by the locale of the collation. kr is prohibited by ECMA-402.

Normalization is always enabled and cannot be turned off. Therefore, there is no option corresponding to BCP47 kk. kk is prohibited by ECMA-402.

Hiragana quaternary handling is part of the strength for the Japanese tailoring. The BCP47 key kh is unsupported. kh is deprecated and prohibited by ECMA-402.

Variable top (BCP47 vt) is unsupported (use Max Variable instead). vt is deprecated and prohibited by ECMA-402.

ECMA-402 Usage

ECMA-402 usage: "search" is represented as -u-co-search as part of the locale in ICU4X. However, neither ECMA-402 nor ICU4X provides prefix matching or substring matching API surface. This makes the utility of search collations very narrow: With -u-co-search, Strength::Primary, and observing whether comparison output is core::cmp::Ordering::Equal (making no distinction between core::cmp::Ordering::Less and core::cmp::Ordering::Greater), it is possible to check if a set of human-readable strings contains a full-string fuzzy match of a user-entered string, where “fuzzy” means case-insensitive and accent-insensitive for scripts that have such concepts and something roughly similar for other scripts.

Due to the very limited utility, ICU4X data does not include search collations by default.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

strength: Option<Strength>

User-specified strength collation option.

alternate_handling: Option<AlternateHandling>

User-specified alternate handling collation option.

case_first: Option<CaseFirst>

User-specified case first collation option.

max_variable: Option<MaxVariable>

User-specified max variable collation option.

case_level: Option<CaseLevel>

User-specified case level collation option.

numeric: Option<Numeric>

User-specified numeric collation option.

backward_second_level: Option<BackwardSecondLevel>

User-specified backward second level collation option.

Implementations

impl CollatorOptions

pub const fn default() -> Self

Create a new CollatorOptions with the defaults.

Trait Implementations

impl Clone for CollatorOptions

fn clone(&self) -> CollatorOptions

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for CollatorOptions

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

Formats the value using the given formatter.

impl Default for CollatorOptions

fn default() -> CollatorOptions

Returns the “default value” for a type.

impl From<ResolvedCollatorOptions> for CollatorOptions

fn from(options: ResolvedCollatorOptions) -> CollatorOptions

Convenience conversion for copying the options from an existing collator into a new one (overriding any locale-provided defaults of the new one!).

impl Copy for CollatorOptions