Crate parse_duration[][src]

This crate provides a function parse for parsing strings into durations. The parser is based on the standard set by systemd.time, but extends it significantly. For example, negative numbers, decimals and exponents are allowed.

use parse_duration::parse;
use std::time::Duration;

// One hour less than a day
assert_eq!(parse("1 day -1 hour"), Ok(Duration::new(82_800, 0)));
// Using exponents
assert_eq!(parse("1.26e-1 days"), Ok(Duration::new(10_886, 400_000_000)));
// Extra things will be ignored
    parse("Duration: 1 hour, 15 minutes and 29 seconds"),
    Ok(Duration::new(4529, 0))


Generally, the accepted syntax is a sequence of [value] [unit] pairs, such as "15 days 20 seconds 100 milliseconds". Spaces are not needed as in "15days20seconds100milliseconds". Order doesn’t matter at all.

Characters other than alphanumeric (actually all word characters as defined by the regex crate) are ignored, other than the fact that they act as a word boundary. So ".:++++]][][[][15[]][seconds][]:}}}}" is the same as "15 seconds".

Any words with no corresponding value are ignored. So in "14 days seconds", "seconds" would be ignored.

Any value without a unit will produce an error, unless only that unit is passed (besides non-word characters). In that case, the value is interpreted as seconds. For example, ".:++++]][][[][15[]][][]:}}}}" would be interpreted as 15 seconds.

If the same unit is specified more than once, the sum of the values is used.

use parse_duration::parse;
use std::time::Duration;

    parse("15 days 20 seconds 100 milliseconds"),
    Ok(Duration::new(1_296_020, 100_000_000))
    Ok(Duration::new(1_296_020, 100_000_000))

assert_eq!(parse(".:++++]][][[][15[]][seconds][]:}}}}"), Ok(Duration::new(15, 0)));

assert_eq!(parse("14 days seconds"), Ok(Duration::new(1_209_600, 0)));

assert_eq!(parse(".:++++]][][[][15[]][][]:}}}}"), Ok(Duration::new(15, 0)));

assert_eq!(parse("10 seconds 20 seconds"), Ok(Duration::new(30, 0)));


The following units are accepted:

  • nanoseconds
  • microseconds
  • milliseconds
  • seconds
  • minutes
  • hours
  • days
  • weeks
  • months
  • years

Years are defined using the average over 400 years in the Gregorian calendar. As such, a year is equivalent to 365.2425 days. A month is defined as one twelfth of a year.

Abbreviations for each of these units are accepted. The general rule is that any initial segment of the full name is accepted as long as it’s not ambiguous. Additionally, the parser is generally case-insensitive. The exception to both these rules is that "m" (or "mi" or "min"…) is accepted for minutes and "M" (or "Mo" or "Mon"…) is accepted for months. Initial segments for other abbreviations ("nsecs", "usecs", "μsecs", "msecs", "secs", "mins", "hrs", "wks", "yrs") are also accepted.

use parse_duration::parse;
use std::time::Duration;

// Full names may be used
assert_eq!(parse("10 days 1 nanoseconds 15 years"), Ok(Duration::new(474_218_280, 1)));
// or very short names
assert_eq!(parse("10d1n15y"), Ok(Duration::new(474_218_280, 1)));


The values may be an integer, a decimal, or a mantissa with an exponent. They may be as large as desired as long as the final duration is less than 264 seconds.

Negatives are allowed, but the negative sign must be directly adjacent to the value: "-15 seconds", not "- 15 seconds". When using negative values, the sum must end up non-negative, since Durations are positive durations.

Decimals are accurate up to nanosecond precision. They will be rounded down to the nearest nanosecond if necessary.

use parse_duration::parse;
use std::time::Duration;

assert_eq!(parse("1 day -1 hour"), Ok(Duration::new(82_800, 0)));

assert_eq!(parse("1.84467e19 seconds"), Ok(Duration::new(18_446_700_000_000_000_000, 0)));
    parse("1.84467e28 nanoseconds"),
    Ok(Duration::new(18_446_700_000_000_000_000, 0))


The error enum has different variants for particular sorts of errors. See the documentation for the error enum for more information.

use parse_duration::parse;

let input = "1e100 seconds";

if let Err(parse::Error::OutOfBounds(_)) = parse(input) {
    println!("The input was too big");
} else {
    panic!("The input wasn't too big");


pub use parse::parse;



This module contains the parse function and the error enum.