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
Offset
s 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 betweenInstant
andstd::time::Duration
Almost all examples are validated with external references, as detailed on a test-by-test basis.
Leap second support
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
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
module provides helpers for initializing an std::time::Duration
.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
module supports (Modified) Julian Days, which are heavily used in astronomy
and its engineering friends.Enums
Constants
DAYS_PER_YEAR
corresponds to the number of days per year in the Julian calendar.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
determines the offset in julian days between 01 Jan 2000 at noon and the
Modified Julian Day at 17 November 1858.SECONDS_PER_DAY
defines the number of seconds per day.SECONDS_PER_HOUR
defines the number of seconds per hour.SECONDS_PER_MINUTE
defines the number of seconds per minute.SECONDS_PER_TROPICAL_YEAR
corresponds to the number of seconds per tropical year, as defined in tyear_c.c
in NAIF SPICE.Traits
TimeSystem
enables the creation of system for measuring spans of time, such as UTC or Julian
days.