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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).

//! Formatting date and time.
//!
//! This module is published as its own crate ([`icu_datetime`](https://docs.rs/icu_datetime/latest/icu_datetime/))
//! and as part of the [`icu`](https://docs.rs/icu/latest/icu/) crate. See the latter for more details on the ICU4X project.
//!
//! [`FixedCalendarDateTimeFormatter`] and [`DateTimeFormatter`] are the main types of the component. They accepts a set of arguments which
//! allow it to collect necessary data from the [data provider], and once instantiated, can be
//! used to quickly format any date and time provided. There are variants of these types that can format greater or fewer components.
//!
//! These formatters work with types from the [`calendar`] module, like [`Date`], [`DateTime`], and [`Time`],
//! and [`timezone::TimeZoneInfo`], however other types may be used provided they implement the traits from the [`input`] module.
//!
//! Each instance of a date-related formatter is associated with a particular [`Calendar`].
//! The "Typed" vs untyped formatter distinction is to help with this. For example, if you know at compile time that you
//! will only be formatting Gregorian dates, you can use [`FixedCalendarDateTimeFormatter<Gregorian>`](FixedCalendarDateTimeFormatter) and the
//! APIs will make sure that only Gregorian [`DateTime`]s are used with the calendar. On the other hand, if you want to be able to select
//! the calendar at runtime, you can use [`neo::DateTimeFormatter`] with the calendar specified in the locale, and use it with
//! [`DateTime<AnyCalendar>`](icu_calendar::DateTime) (see [`AnyCalendar`]). These formatters still require dates associated
//! with the appropriate calendar (though they will convert ISO dates to the calendar if provided), they just do not force the
//! programmer to pick the calendar at compile time.
//!
//!
//! # Examples
//!
//! ```
//! use icu::calendar::{DateTime, Gregorian};
//! use icu::datetime::fieldset::YMDT;
//! use icu::datetime::{DateTimeFormatter, FixedCalendarDateTimeFormatter};
//! use icu::locale::{locale, Locale};
//! use writeable::assert_try_writeable_eq;
//!
//! // You can work with a formatter that can select the calendar at runtime:
//! let locale = Locale::try_from_str("en-u-ca-gregory").unwrap();
//! let dtf = DateTimeFormatter::try_new(&locale.into(), YMDT::medium().hm())
//!     .expect("should successfully create DateTimeFormatter instance");
//!
//! // Or one that selects a calendar at compile time:
//! let typed_dtf = FixedCalendarDateTimeFormatter::<Gregorian, _>::try_new(
//!     &locale!("en").into(),
//!     YMDT::medium().hm(),
//! )
//! .expect(
//!     "should successfully create FixedCalendarDateTimeFormatter instance",
//! );
//!
//! let typed_date =
//!     DateTime::try_new_gregorian(2020, 9, 12, 12, 34, 28).unwrap();
//! // prefer using ISO dates with DateTimeFormatter
//! let date = typed_date.to_iso();
//!
//! let formatted_date = dtf.convert_and_format(&date);
//! let typed_formatted_date = typed_dtf.format(&typed_date);
//!
//! assert_try_writeable_eq!(formatted_date, "Sep 12, 2020, 12:34 PM");
//! assert_try_writeable_eq!(typed_formatted_date, "Sep 12, 2020, 12:34 PM");
//! ```
//!
//! [data provider]: icu_provider
//! [`ICU4X`]: ../icu/index.html
//! [`Length`]: options::length
//! [`DateTime`]: calendar::{DateTime}
//! [`Date`]: calendar::{Date}
//! [`Time`]: calendar::types::{Time}
//! [`Calendar`]: calendar::{Calendar}
//! [`AnyCalendar`]: calendar::any_calendar::{AnyCalendar}
//! [`timezone::TimeZoneInfo`]: icu::timezone::{TimeZoneInfo}

// https://github.com/unicode-org/icu4x/blob/main/documents/process/boilerplate.md#library-annotations
#![cfg_attr(not(any(test, feature = "std")), no_std)]
#![cfg_attr(
    not(test),
    deny(
        clippy::indexing_slicing,
        clippy::unwrap_used,
        clippy::expect_used,
        clippy::panic,
        clippy::exhaustive_structs,
        clippy::exhaustive_enums,
        missing_debug_implementations,
    )
)]
#![warn(missing_docs)]

extern crate alloc;

mod combo;
mod dynamic;
mod error;
mod external_loaders;
pub mod fields;
pub mod fieldset;
mod format;
pub mod input;
mod neo;
mod neo_marker;
pub mod neo_pattern;
#[cfg(feature = "serde")]
mod neo_serde;
pub mod neo_skeleton;
pub mod options;
pub mod provider;
pub(crate) mod raw;
pub mod scaffold;
pub(crate) mod size_test_macro;

pub use error::{DateTimeWriteError, MismatchedCalendarError};
pub use format::neo::{FormattedDateTimePattern, PatternLoadError, TypedDateTimeNames};

pub use neo::DateTimeFormatter;
pub use neo::FixedCalendarDateTimeFormatter;
pub use neo::FormattedNeoDateTime;
pub use neo_skeleton::NeoSkeletonLength;