Struct icu_datetime::neo_pattern::DateTimePattern

pub struct DateTimePattern { /* private fields */ }

A pattern for formatting a datetime in a calendar.

Most clients should use DateTimeFormatter instead of directly formatting with patterns.

There are two ways to make one of these:

1. From a custom pattern string: DateTimePattern::try_from_pattern_str
2. From a formatted datetime: FormattedNeoDateTime::pattern

Things you can do with one of these:

1. Use it to directly format a datetime via TypedDateTimeNames
2. Convert it to a string pattern via [Writeable]
3. Get the resolved components

📏 This item has a stack size of 32 bytes on the stable toolchain at release date.

Examples

Create a pattern from a custom string and compare it to one from data, then check the resolved components:

use icu::calendar::DateTime;
use icu::calendar::Gregorian;
use icu::datetime::neo::TypedNeoFormatter;
use icu::datetime::neo_marker::NeoYearMonthDayMarker;
use icu::datetime::neo_pattern::DateTimePattern;
use icu::datetime::neo_skeleton::NeoSkeletonLength;
use icu::datetime::options::components;
use icu::locale::locale;
use writeable::assert_writeable_eq;

// Create the pattern from a string:
let pattern_str = "d MMM y";
let custom_pattern =
    DateTimePattern::try_from_pattern_str(pattern_str).unwrap();
assert_writeable_eq!(custom_pattern, pattern_str);

// Load data that resolves to the same pattern:
let data_pattern =
    TypedNeoFormatter::<Gregorian, NeoYearMonthDayMarker>::try_new(
        &locale!("es-MX").into(),
        NeoSkeletonLength::Medium.into(),
    )
    .unwrap()
    // The pattern can depend on the datetime being formatted.
    // For this example, we'll choose the local Unix epoch.
    .format(&DateTime::local_unix_epoch().to_calendar(Gregorian))
    .pattern();
assert_writeable_eq!(data_pattern, pattern_str);
assert_eq!(custom_pattern, data_pattern);

// Check the resolved components:
let mut expected_components_bag = components::Bag::default();
expected_components_bag.year = Some(components::Year::Numeric);
expected_components_bag.month = Some(components::Month::Short);
expected_components_bag.day = Some(components::Day::NumericDayOfMonth);
let actual_components_bag = components::Bag::from(&data_pattern);
assert_eq!(actual_components_bag, expected_components_bag);

Implementations

impl DateTimePattern

pub fn try_from_pattern_str(pattern_str: &str) -> Result<Self, PatternError>

Creates a DateTimePattern from a pattern string.

For more details on the syntax, see UTS 35: https://unicode.org/reports/tr35/tr35-dates.html#Date_Format_Patterns

Trait Implementations

impl Debug for DateTimePattern

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

Formats the value using the given formatter.

impl Display for DateTimePattern

This trait is implemented for compatibility with fmt!. To create a string, [Writeable::write_to_string] is usually more efficient.

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

Formats the value using the given formatter.

impl From<&DateTimePattern> for Bag

fn from(value: &DateTimePattern) -> Self

Converts to this type from the input type.

impl FromStr for DateTimePattern

type Err = PatternError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

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

impl PartialEq for DateTimePattern

fn eq(&self, other: &Self) -> 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 Writeable for DateTimePattern

fn write_to<W: Write + ?Sized>(&self, sink: &mut W) -> Result

Writes a string to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to_parts, and discards any Part annotations.

fn write_to_parts<S>(&self, sink: &mut S) -> Result<(), Error>

where S: PartsWrite + ?Sized,

Write bytes and Part annotations to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to, and doesn’t produce any Part annotations.

fn writeable_length_hint(&self) -> LengthHint

Returns a hint for the number of UTF-8 bytes that will be written to the sink.

fn write_to_string(&self) -> Cow<'_, str>

Creates a new String with the data from this Writeable. Like ToString, but smaller and faster.

fn writeable_cmp_bytes(&self, other: &[u8]) -> Ordering

Compares the contents of this Writeable to the given bytes without allocating a String to hold the Writeable contents.

impl Eq for DateTimePattern