Crate hifitime

Expand description

hifitime

Precise date and time handling in Rust built on top of std::time::Duration. The Epoch used is TAI Epoch of 01 Jan 1900 at midnight, but that should not matter in day-to-day use of this library.

Features

Leap seconds (as announced by the IETF on a yearly basis)
Julian dates and Modified Julian dates
UTC representation with ISO8601 formatting (and parsing in that format)
Allows building custom TimeSystem (e.g. Julian days)
Simple to use Offsets to represent fixed or time-varying UTC offsets (e.g. for very high speed reference frames)
Clock drift via oscillator stability for simulation of time measuring hardware (via the simulation feature)
A canonical time struct (Instant) defined as the NTP specifications. Supports arithmetic operations between Instant and std::time::Duration

Almost all examples are validated with external references, as detailed on a test-by-test basis.

Each time computing library may decide when the extra leap second exists as explained in the IETF leap second reference. To ease computation, hifitime decides that second is the 60th of a UTC date, if such exists. Note that this second exists at a different time than defined on NASA HEASARC. That tool is used for validation of Julian dates. As an example of how this is handled, check the Julian day computations for 2015-06-30 23:59:59, 2015-06-30 23:59:60 and 2015-07-01 00:00:00.

Does not include

Dates only, or times only (i.e. handles only the combination of both), but the Datetime::{at_midnight, at_noon} help
Custom formatting of date time objects
An initializer from machine time

Usage

Put this in your Cargo.toml:

[dependencies]
hifitime = "0.1.5"

And add the following to your crate root:

extern crate hifitime;

Examples:

use hifitime::datetime::{Datetime, TimeSystem};
use hifitime::instant::Duration;
use hifitime::julian::ModifiedJulian;

let santa = Datetime::new(2017, 12, 25, 01, 02, 14, 0).expect("Xmas failed");

assert_eq!(
    santa.into_instant() + Duration::new(3600, 0),
    Datetime::new(2017, 12, 25, 02, 02, 14, 0)
        .expect("Xmas failed")
        .into_instant(),
    "Could not add one hour to Christmas"
);
assert_eq!(format!("{}", santa), "2017-12-25T01:02:14+00:00");
assert_eq!(
    ModifiedJulian::from_instant(santa.into_instant()).days,
    58112.043217592596
);
assert_eq!(
    ModifiedJulian::from_instant(santa.into_instant()).julian_days(),
    2458112.5432175924
);

Modules

datetime

The datetime module supports conversions between seconds past TAI epoch and a Datetime struct. The main advantage (and challenge) is the inherent support for leap seconds. Refer to module documentation for leap second implementation details.

durations

The durations module provides helpers for initializing an std::time::Duration.

instant

The instant module is built on top of std::time::Duration. It is the basis of almost all computations in this library. It is the only common denominator allowing for conversions between Time Systems.

julian

The julian module supports (Modified) Julian Days, which are heavily used in astronomy and its engineering friends.

Enums

Errors

Errors handles all oddities which may occur in this library.

Constants

DAYS_PER_YEAR

DAYS_PER_YEAR corresponds to the number of days per year in the Julian calendar.

J1900_OFFSET

J1900_OFFSET determines the offset in julian days between 01 Jan 1900 at midnight and the Modified Julian Day at 17 November 1858. NOTE: Julian days “start” at noon so that astronomical observations throughout the night happen at the same Julian day. Note however that the Modified Julian Date (MJD) starts at midnight, not noon, cf. http://tycho.usno.navy.mil/mjd.html.

J2000_OFFSET

J2000_OFFSET determines the offset in julian days between 01 Jan 2000 at noon and the Modified Julian Day at 17 November 1858.

SECONDS_PER_DAY

SECONDS_PER_DAY defines the number of seconds per day.

SECONDS_PER_HOUR

SECONDS_PER_HOUR defines the number of seconds per hour.

SECONDS_PER_MINUTE

SECONDS_PER_MINUTE defines the number of seconds per minute.

SECONDS_PER_TROPICAL_YEAR

SECONDS_PER_TROPICAL_YEAR corresponds to the number of seconds per tropical year, as defined in tyear_c.c in NAIF SPICE.

Traits

TimeSystem

A TimeSystem enables the creation of system for measuring spans of time, such as UTC or Julian days.