Module icu_datetime::provider::skeleton

UTS 35 classical datetime skeletons.

Semantic skeletons (field sets) use classical skeletons for pattern matching in datagen.

See Skeleton and Bag for more information.

✨ Enabled with the datagen Cargo feature.

Implementation status

This is currently only a partial implementation of the UTS-35 skeleton matching algorithm.

Algorithm step	Status
Match skeleton fields according to a ranking	Implemented
Adjust the matched pattern to have certain widths	Implemented
Match date and times separately, and them combine them	Implemented
Use appendItems to fill in a pattern with missing fields	Not yet, and may not be fully implemented. See issue #586

Description

A components::Bag is a model of encoding information on how to format date and time by specifying a list of components the user wants to be visible in the formatted string and how each field should be displayed.

This model closely corresponds to ECMA402 API and allows for high level of customization compared to Length model.

Additionally, the bag contains an optional set of Preferences which represent user preferred adjustments that can be applied onto the pattern right before formatting.

Pattern Selection

The components::Bag is a way for the developer to describe which components should be included in in a datetime, and how they should be displayed. There is not a strict guarantee in how the final date will be displayed to the end user. The user’s preferences and locale information can override the developer preferences.

The fields in the components::Bag are matched against available patterns in the CLDR locale data. A best fit is found, and presented to the user. This means that in certain situations, and component combinations, fields will not have a match, or the match will have a different type of presentation for a given locale.

🚧 This code is considered unstable; it may change at any time, in breaking or non-breaking ways, including in SemVer minor releases. While the serde representation of data structs is guaranteed to be stable, their Rust representation might not be. Use with caution.

Modules

• components
  Types for specifying fields in a classical datetime skeleton.
• reference
  Reference Skeleton implementation for parsing.
• runtime
  Runtime Skeleton implementation for more efficient deserialization.

Structs

• PluralPattern
  A collection of plural variants of a pattern.

Enums

• BestSkeleton
  The best skeleton found, alongside information on how well it matches.
• PatternPlurals
  Either a Pattern single pattern or a PluralPattern collection of patterns when there are plural variants.
• SkeletonError
  These strings follow the recommendations for the serde::de::Unexpected::Other type. https://docs.serde.rs/serde/de/enum.Unexpected.html#variant.Other

Functions

• create_best_pattern_for_fields
  Given a set of fields (which represents a skeleton), try to create a best localized pattern
• get_best_available_format_pattern
  A partial implementation of the UTS 35 skeleton matching algorithm.