path: root/third_party/rust/time/src/lib.rs

//! # Feature flags
//!
//! This crate exposes a number of features. These can be enabled or disabled as shown
//! [in Cargo's documentation](https://doc.rust-lang.org/cargo/reference/features.html). Features
//! are _disabled_ by default unless otherwise noted.
//!
//! Reliance on a given feature is always indicated alongside the item definition.
//!
//! - `std` (_enabled by default, implicitly enables `alloc`_)
//!
//!   This enables a number of features that depend on the standard library.
//!
//! - `alloc` (_enabled by default via `std`_)
//!
//!   Enables a number of features that require the ability to dynamically allocate memory.
//!
//! - `macros`
//!
//!   Enables macros that provide compile-time verification of values and intuitive syntax.
//!
//! - `formatting` (_implicitly enables `std`_)
//!
//!   Enables formatting of most structs.
//!
//! - `parsing`
//!
//!   Enables parsing of most structs.
//!
//! - `local-offset` (_implicitly enables `std`_)
//!
//!   This feature enables a number of methods that allow obtaining the system's UTC offset.
//!
//! - `large-dates`
//!
//!   By default, only years within the ±9999 range (inclusive) are supported. If you need support
//!   for years outside this range, consider enabling this feature; the supported range will be
//!   increased to ±999,999.
//!
//!   Note that enabling this feature has some costs, as it means forgoing some optimizations.
//!   Ambiguities may be introduced when parsing that would not otherwise exist.
//!
//! - `serde`
//!
//!   Enables [serde](https://docs.rs/serde) support for all types except [`Instant`].
//!
//! - `serde-human-readable` (_implicitly enables `serde`, `formatting`, and `parsing`_)
//!
//!   Allows serde representations to use a human-readable format. This is determined by the
//!   serializer, not the user. If this feature is not enabled or if the serializer requests a
//!   non-human-readable format, a format optimized for binary representation will be used.
//!
//!   Libraries should never enable this feature, as the decision of what format to use should be up
//!   to the user.
//!
//! - `serde-well-known` (_implicitly enables `serde-human-readable`_)
//!
//!   _This feature flag is deprecated and will be removed in a future breaking release. Use the
//!   `serde-human-readable` feature instead._
//!
//!   Enables support for serializing and deserializing well-known formats using serde's
//!   [`#[with]` attribute](https://serde.rs/field-attrs.html#with).
//!
//! - `rand`
//!
//!   Enables [rand](https://docs.rs/rand) support for all types.
//!
//! - `quickcheck` (_implicitly enables `alloc`_)
//!
//!   Enables [quickcheck](https://docs.rs/quickcheck) support for all types except [`Instant`].
//!
//! - `wasm-bindgen`
//!
//!   Enables [wasm-bindgen](https://github.com/rustwasm/wasm-bindgen) support for converting
//!   [JavaScript dates](https://rustwasm.github.io/wasm-bindgen/api/js_sys/struct.Date.html), as
//!   well as obtaining the UTC offset from JavaScript.

#![doc(html_playground_url = "https://play.rust-lang.org")]
#![cfg_attr(__time_03_docs, feature(doc_auto_cfg, doc_notable_trait))]
#![cfg_attr(coverage_nightly, feature(no_coverage))]
#![cfg_attr(not(feature = "std"), no_std)]
#![deny(
    anonymous_parameters,
    clippy::all,
    clippy::alloc_instead_of_core,
    clippy::explicit_auto_deref,
    clippy::obfuscated_if_else,
    clippy::std_instead_of_core,
    clippy::undocumented_unsafe_blocks,
    illegal_floating_point_literal_pattern,
    late_bound_lifetime_arguments,
    path_statements,
    patterns_in_fns_without_body,
    rust_2018_idioms,
    trivial_casts,
    trivial_numeric_casts,
    unreachable_pub,
    unsafe_op_in_unsafe_fn,
    unused_extern_crates,
    rustdoc::broken_intra_doc_links,
    rustdoc::private_intra_doc_links
)]
#![warn(
    clippy::dbg_macro,
    clippy::decimal_literal_representation,
    clippy::get_unwrap,
    clippy::missing_docs_in_private_items,
    clippy::nursery,
    clippy::print_stdout,
    clippy::todo,
    clippy::unimplemented,
    clippy::uninlined_format_args,
    clippy::unnested_or_patterns,
    clippy::unwrap_in_result,
    clippy::unwrap_used,
    clippy::use_debug,
    deprecated_in_future,
    missing_copy_implementations,
    missing_debug_implementations,
    unused_qualifications,
    variant_size_differences
)]
#![allow(
    clippy::redundant_pub_crate, // suggests bad style
    clippy::option_if_let_else, // suggests terrible code
    clippy::unused_peekable, // temporary due to bug: remove when Rust 1.66 is released
    clippy::std_instead_of_core, // temporary due to bug: remove when Rust 1.66 is released
)]
#![doc(html_favicon_url = "https://avatars0.githubusercontent.com/u/55999857")]
#![doc(html_logo_url = "https://avatars0.githubusercontent.com/u/55999857")]
#![doc(test(attr(deny(warnings))))]

#[allow(unused_extern_crates)]
#[cfg(feature = "alloc")]
extern crate alloc;

// TODO(jhpratt) remove this after a while
#[cfg(unsound_local_offset)]
compile_error!(
    "The `unsound_local_offset` flag was removed in time 0.3.18. If you need this functionality, \
     see the `time::util::local_offset::set_soundness` function."
);

// region: macros
/// Helper macro for easily implementing `OpAssign`.
macro_rules! __impl_assign {
    ($sym:tt $op:ident $fn:ident $target:ty : $($(#[$attr:meta])* $t:ty),+) => {$(
        #[allow(unused_qualifications)]
        $(#[$attr])*
        impl core::ops::$op<$t> for $target {
            fn $fn(&mut self, rhs: $t) {
                *self = *self $sym rhs;
            }
        }
    )+};
}

/// Implement `AddAssign` for the provided types.
macro_rules! impl_add_assign {
    ($target:ty : $($(#[$attr:meta])* $t:ty),+ $(,)?) => {
        __impl_assign!(+ AddAssign add_assign $target : $($(#[$attr])* $t),+);
    };
}

/// Implement `SubAssign` for the provided types.
macro_rules! impl_sub_assign {
    ($target:ty : $($(#[$attr:meta])* $t:ty),+ $(,)?) => {
        __impl_assign!(- SubAssign sub_assign $target : $($(#[$attr])* $t),+);
    };
}

/// Implement `MulAssign` for the provided types.
macro_rules! impl_mul_assign {
    ($target:ty : $($(#[$attr:meta])* $t:ty),+ $(,)?) => {
        __impl_assign!(* MulAssign mul_assign $target : $($(#[$attr])* $t),+);
    };
}

/// Implement `DivAssign` for the provided types.
macro_rules! impl_div_assign {
    ($target:ty : $($(#[$attr:meta])* $t:ty),+ $(,)?) => {
        __impl_assign!(/ DivAssign div_assign $target : $($(#[$attr])* $t),+);
    };
}

/// Division of integers, rounding the resulting value towards negative infinity.
macro_rules! div_floor {
    ($a:expr, $b:expr) => {{
        let _a = $a;
        let _b = $b;

        let (_quotient, _remainder) = (_a / _b, _a % _b);

        if (_remainder > 0 && _b < 0) || (_remainder < 0 && _b > 0) {
            _quotient - 1
        } else {
            _quotient
        }
    }};
}

/// Cascade an out-of-bounds value.
macro_rules! cascade {
    (@ordinal ordinal) => {};
    (@year year) => {};

    // Cascade an out-of-bounds value from "from" to "to".
    ($from:ident in $min:literal.. $max:expr => $to:tt) => {
        #[allow(unused_comparisons, unused_assignments)]
        let min = $min;
        let max = $max;
        if $from >= max {
            $from -= max - min;
            $to += 1;
        } else if $from < min {
            $from += max - min;
            $to -= 1;
        }
    };

    // Special case the ordinal-to-year cascade, as it has different behavior.
    ($ordinal:ident => $year:ident) => {
        // We need to actually capture the idents. Without this, macro hygiene causes errors.
        cascade!(@ordinal $ordinal);
        cascade!(@year $year);
        #[allow(unused_assignments)]
        if $ordinal > crate::util::days_in_year($year) as i16 {
            $ordinal -= crate::util::days_in_year($year) as i16;
            $year += 1;
        } else if $ordinal < 1 {
            $year -= 1;
            $ordinal += crate::util::days_in_year($year) as i16;
        }
    };
}

/// Returns `Err(error::ComponentRange)` if the value is not in range.
macro_rules! ensure_value_in_range {
    ($value:ident in $start:expr => $end:expr) => {{
        let _start = $start;
        let _end = $end;
        #[allow(trivial_numeric_casts, unused_comparisons)]
        if $value < _start || $value > _end {
            return Err(crate::error::ComponentRange {
                name: stringify!($value),
                minimum: _start as _,
                maximum: _end as _,
                value: $value as _,
                conditional_range: false,
            });
        }
    }};

    ($value:ident conditionally in $start:expr => $end:expr) => {{
        let _start = $start;
        let _end = $end;
        #[allow(trivial_numeric_casts, unused_comparisons)]
        if $value < _start || $value > _end {
            return Err(crate::error::ComponentRange {
                name: stringify!($value),
                minimum: _start as _,
                maximum: _end as _,
                value: $value as _,
                conditional_range: true,
            });
        }
    }};
}

/// Try to unwrap an expression, returning if not possible.
///
/// This is similar to the `?` operator, but does not perform `.into()`. Because of this, it is
/// usable in `const` contexts.
macro_rules! const_try {
    ($e:expr) => {
        match $e {
            Ok(value) => value,
            Err(error) => return Err(error),
        }
    };
}

/// Try to unwrap an expression, returning if not possible.
///
/// This is similar to the `?` operator, but is usable in `const` contexts.
macro_rules! const_try_opt {
    ($e:expr) => {
        match $e {
            Some(value) => value,
            None => return None,
        }
    };
}

/// Try to unwrap an expression, panicking if not possible.
///
/// This is similar to `$e.expect($message)`, but is usable in `const` contexts.
macro_rules! expect_opt {
    ($e:expr, $message:literal) => {
        match $e {
            Some(value) => value,
            None => crate::expect_failed($message),
        }
    };
}

/// `unreachable!()`, but better.
macro_rules! bug {
    () => { compile_error!("provide an error message to help fix a possible bug") };
    ($descr:literal $($rest:tt)?) => {
        panic!(concat!("internal error: ", $descr) $($rest)?)
    }
}
// endregion macros

mod date;
mod date_time;
mod duration;
pub mod error;
pub mod ext;
#[cfg(any(feature = "formatting", feature = "parsing"))]
pub mod format_description;
#[cfg(feature = "formatting")]
pub mod formatting;
#[cfg(feature = "std")]
mod instant;
#[cfg(feature = "macros")]
pub mod macros;
mod month;
mod offset_date_time;
#[cfg(feature = "parsing")]
pub mod parsing;
mod primitive_date_time;
#[cfg(feature = "quickcheck")]
mod quickcheck;
#[cfg(feature = "rand")]
mod rand;
#[cfg(feature = "serde")]
#[allow(missing_copy_implementations, missing_debug_implementations)]
pub mod serde;
mod sys;
#[cfg(test)]
mod tests;
mod time;
mod utc_offset;
pub mod util;
mod weekday;

// Not public yet.
use time_core::convert;

pub use crate::date::Date;
use crate::date_time::DateTime;
pub use crate::duration::Duration;
pub use crate::error::Error;
#[cfg(feature = "std")]
pub use crate::instant::Instant;
pub use crate::month::Month;
pub use crate::offset_date_time::OffsetDateTime;
pub use crate::primitive_date_time::PrimitiveDateTime;
pub use crate::time::Time;
pub use crate::utc_offset::UtcOffset;
pub use crate::weekday::Weekday;

/// An alias for [`std::result::Result`] with a generic error from the time crate.
pub type Result<T> = core::result::Result<T, Error>;

/// This is a separate function to reduce the code size of `expect_opt!`.
#[inline(never)]
#[cold]
#[track_caller]
const fn expect_failed(message: &str) -> ! {
    panic!("{}", message)
}