speedate

Fast and simple datetime, date, time and duration parsing for rust.

speedate is a lax† RFC 3339 date and time parser, in other words, it parses common ISO 8601 formats.

† - all relaxations of from RFC 3339 compliant with ISO 8601.

The following formats are supported:

• Date: YYYY-MM-DD
• Time: HH:MM:SS
• Time: HH:MM:SS.FFFFFF 1 to 6 digits are allowed
• Time: HH:MM
• Date time: YYYY-MM-DDTHH:MM:SS - all the above time formats are allowed for the time part
• Date time: YYYY-MM-DD HH:MM:SS - T, t, and _ are allowed as separators
• Date time: YYYY-MM-DDTHH:MM:SSZ - Z or z is allowed as timezone
• Date time: YYYY-MM-DDTHH:MM:SS+08:00- positive and negative timezone are allowed, as per ISO 8601, U+2212 minus − is allowed as well as ascii minus - (U+002D)
• Date time: YYYY-MM-DDTHH:MM:SS+0800 - the colon (:) in the timezone is optional
• Duration: PnYnMnDTnHnMnS - ISO 8601 duration format, see wikipedia for more details, W for weeks is also allowed
• Duration: HH:MM:SS - any of the above time formats are allowed to represent a duration
• Duration: D days, HH:MM:SS - time prefixed by X days, case-insensitive, spaces s and , are all optional
• Duration: D d, HH:MM:SS - time prefixed by X d, case-insensitive, spaces and , are optional
• Duration: ±... - all duration formats shown here can be prefixed with + or - to indicate positive and negative durations respectively

This will be the datetime parsing logic for pydantic-core.

Usage

use speedate::{DateTime, Date, Time};

fn main() {
    let dt = DateTime::parse_str("2022-01-01T12:13:14Z").unwrap();
    assert_eq!(
        dt,
        DateTime {
            date: Date {
                year: 2022,
                month: 1,
                day: 1,
            },
            time: Time {
                hour: 12,
                minute: 13,
                second: 14,
                microsecond: 0,
            },
            offset: Some(0),
        }
    );
    assert_eq!(dt.to_string(), "2022-01-01T12:13:14Z");
}

Performance

speedate is significantly faster than chrono's parse_from_rfc3339 and iso8601.

Micro-benchmarking from benches/main.rs:

test compare_dt_error_chrono   ... bench:         192 ns/iter (+/- 0)
test compare_dt_error_iso8601  ... bench:         462 ns/iter (+/- 4)
test compare_dt_error_speedate ... bench:          26 ns/iter (+/- 0)
test compare_dt_ok_chrono      ... bench:         250 ns/iter (+/- 1)
test compare_dt_ok_iso8601     ... bench:         323 ns/iter (+/- 1)
test compare_dt_ok_speedate    ... bench:          36 ns/iter (+/- 0)

Why not full iso8601?

ISO8601 has lots of allowed formats, see ijmacd.github.io/rfc3339-iso8601.

Most of these are unknown to most users, and not desired. This library aims to support the most common formats without introducing ambiguity.