hourglass

Timezone-aware datetime library for the Rust programming language (doc)

hourglass provides support for timezone, datetime arithmetic and take care of subtleties related to time handling, like leap seconds.

Usage

Add the following in your Cargo.toml:

[dependencies]
hourglass = "0.*"

And put this in your crate root:

extern crate hourglass;

Overview

Timezone

Because a datetime without a timezone is ambiguous and error-prone, hourglass only exposes a Datetime that is timezone-aware. The creation of a Timezone is the entry point of the API. hourglass provides several way of creating a Timezone:

use hourglass::Timezone;

let utc = Timezone::utc();
let local = Timezone::local().unwrap();
let paris = Timezone::new("Europe/Paris").unwrap();
let fixed = Timezone::fixed(-5 * 3600);

A Datetime is created for a specific timezone and can be projected in another timezone:

use hourglass::Timezone;

let utc = Timezone::utc();
let paris = Timezone::new("Europe/Paris").unwrap();

// Create a `Datetime` corresponding to midnight in Paris timezone...
let t = paris.datetime(2015, 12, 25, 0, 0, 0, 0).unwrap();
// ... and project it into UTC timezone.
let t_utc = t.project(&utc);
assert_eq!(t_utc.date(), (2015, 12, 24));
assert_eq!(t_utc.time(), (23, 0, 0, 0));

Arithmetic

Datetime arithmetic is performed with a Deltatime. Several granularities are available when handling Deltatime and will yield different results:

use hourglass::{Timezone, Deltatime};

let utc = Timezone::utc();
let t = utc.datetime(2015, 6, 30, 0, 0, 0, 0).unwrap();
let t_plus_1_day = t + Deltatime::days(1);
let t_plus_86400_sec = t + Deltatime::seconds(86400);

assert_eq!(t_plus_1_day.date(), (2015, 7, 1));
// One leap second was inserted this day.
assert_eq!(t_plus_86400_sec.date(), (2015, 6, 30));
assert_eq!(t_plus_86400_sec.time(), (23, 59, 60, 0));

Two Datetime can also be compared:

use hourglass::{Timezone, Deltatime};

let utc = Timezone::utc();
let t0 = utc.datetime(2015, 6, 30, 0, 0, 0, 0).unwrap();
let t1 = utc.datetime(2015, 7, 1, 0, 0, 0, 0).unwrap();

assert_eq!(t0 < t1, true);
assert_eq!(t0 >= t1, false);
assert_eq!(t1 == t1, true);
assert_eq!(t1 - t0, Deltatime::seconds(86401));

Iterators

hourglass also provides the Every iterator for scheduling a loop body execution at regular time interval:

use hourglass::{Timezone, Deltatime, Timespec, Every};

let paris = Timezone::new("Europe/Paris").unwrap();
let until = Timespec::now() + Deltatime::seconds(5);

for t in Every::until(Deltatime::seconds(1), until) {
    println!("it is {} in Paris", t.to_datetime(&paris).format("%H:%M:%S").unwrap());
}

The Range iterator can be used to iterate over a range of Timespec:

use hourglass::{Deltatime, Timespec, Range};

let now = Timespec::now();
let then = now + Deltatime::minutes(1);

for t in Range::new(now, then, Deltatime::seconds(1)) {
    println!("tick {}", t.seconds());
}