Enum icu_datetime::fields::FieldSymbol

pub enum FieldSymbol {
    Era,
    Year(Year),
    Month(Month),
    Week(Week),
    Day(Day),
    Weekday(Weekday),
    DayPeriod(DayPeriod),
    Hour(Hour),
    Minute,
    Second(Second),
    TimeZone(TimeZone),
}

A field symbol for a date formatting pattern. Field symbols are a more granular distinction for a pattern field within the category of a field type. Examples of field types are: Year, Month, Hour. Within the Hour field type, examples of field symbols are: Hour::H12, Hour::H24. Each field symbol is represented within the date formatting pattern string by a distinct character from the set of A..Z and a..z.

Variants

Era

Era name.

Year(Year)

Year number or year name.

Month(Month)

Month number or month name.

Week(Week)

Week number or week name.

Day(Day)

Day number relative to a time period longer than a week (ex: month, year).

Weekday(Weekday)

Day number or day name relative to a week.

DayPeriod(DayPeriod)

Name of a period within a day.

Hour(Hour)

Hour number within a day, possibly with day period.

Minute

Minute number within an hour.

Second(Second)

Seconds number within a minute, including fractional seconds, or milliseconds within a day.

TimeZone(TimeZone)

Time zone as a name, a zone ID, or a ISO 8601 numerical offset.

Implementations

impl FieldSymbol

pub(crate) fn idx(&self) -> u8

Symbols are necessary components of Pattern struct which uses efficient byte serialization and deserialization via zerovec.

The FieldSymbol impl provides non-public methods that can be used to efficiently convert between u8 and the symbol variant.

The serialization model packages the variant in one byte.

1. The top four bits are used to determine the type of the field using that type’s idx()/from_idx() for the mapping. (Examples: Year, Month, Hour)

2. The bottom four bits are used to determine the symbol of the type. (Examples: Year::Calendar, Hour::H11)

Diagram

┌─┬─┬─┬─┬─┬─┬─┬─┐
├─┴─┴─┴─┼─┴─┴─┴─┤
│ Type  │Symbol │
└───────┴───────┘

Optimization

This model is optimized to package data efficiently when FieldSymbol is used as a variant of PatternItem. See the documentation of PatternItemULE for details on how it is composed.

Constraints

This model limits the available number of possible types and symbols to 16 each.

pub(crate) fn from_idx(idx: u8) -> Result<Self, SymbolError>

impl FieldSymbol

fn get_canonical_order(&self) -> u8

Skeletons are a Vec, and represent the Fields that can be used to match to a specific pattern. The order of the Vec does not affect the Pattern that is output. However, it’s more performant when matching these fields, and it’s more deterministic when serializing them to present them in a consistent order.

This ordering is taken by the order of the fields listed in the [UTS 35 Date Field Symbol Table] (https://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table), and are generally ordered most significant to least significant.

Trait Implementations

impl AsULE for FieldSymbol

type ULE = FieldSymbolULE

The ULE type corresponding to Self.

fn to_unaligned(self) -> Self::ULE

Converts from Self to Self::ULE.

fn from_unaligned(unaligned: Self::ULE) -> Self

Converts from Self::ULE to Self.

impl Clone for FieldSymbol

fn clone(&self) -> FieldSymbol

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for FieldSymbol

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

Formats the value using the given formatter.

impl From<Day> for FieldSymbol

fn from(input: Day) -> Self

Converts to this type from the input type.

impl From<DayPeriod> for FieldSymbol

fn from(input: DayPeriod) -> Self

Converts to this type from the input type.

impl From<FieldSymbol> for char

fn from(symbol: FieldSymbol) -> Self

Converts to this type from the input type.

impl From<Hour> for FieldSymbol

fn from(input: Hour) -> Self

Converts to this type from the input type.

impl From<Month> for FieldSymbol

fn from(input: Month) -> Self

Converts to this type from the input type.

impl From<Second> for FieldSymbol

fn from(input: Second) -> Self

Converts to this type from the input type.

impl From<TimeZone> for FieldSymbol

fn from(input: TimeZone) -> Self

Converts to this type from the input type.

impl From<Week> for FieldSymbol

fn from(input: Week) -> Self

Converts to this type from the input type.

impl From<Weekday> for FieldSymbol

fn from(input: Weekday) -> Self

Converts to this type from the input type.

impl From<Year> for FieldSymbol

fn from(input: Year) -> Self

Converts to this type from the input type.

impl Ord for FieldSymbol

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for FieldSymbol

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl PartialOrd for FieldSymbol

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

This method tests less than (for self and other) and is used by the < operator.

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

This method tests less than or equal to (for self and other) and is used by the <= operator.

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

This method tests greater than (for self and other) and is used by the > operator.

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

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl TryFrom<char> for FieldSymbol

type Error = SymbolError

The type returned in the event of a conversion error.

fn try_from(ch: char) -> Result<Self, Self::Error>

Performs the conversion.

impl Copy for FieldSymbol

impl Eq for FieldSymbol

impl StructuralPartialEq for FieldSymbol