SemVer

Semantic version parsing and comparison (semver). The implementation of this crate is based on the node-semver npm package. The tests are taken directly from node-semver's repo. This should make this crate as good at parsing semver expressions as the node package manager.

Installation

Add this to your [dependencies] section in Cargo.toml:

semver_rs = "0.1"

Usage

Comparing two versions:

use semver_rs::Version;

// by constructing version instances manually
let ver1 = Version::new("2.0.0").parse()?;
let ver2 = Version::new("1.2.3").parse()?;

assert!(ver1 > ver2);

// by using the exported helper function
use semver_rs::compare;
use std::cmp::Ordering;

assert!(compare("2.0.0", "1.2.3", None)? == Ordering::Greater);

Checking whether a version is in a range

use semver_rs::{Range, Version};

// by constructing version instances manually
let range = Range::new(">=1.2.3").parse()?;
let ver = Version::new("1.2.4").parse()?;

assert!(range.test(&ver));

// by using the exported helper function
use semver_rs::satisfies;

assert!(satisfies("1.2.4", ">=1.2.4", None)?);

Parsing with specific options

use semver_rs::{Version, Range, Options};

let opts = Options::builder().loose(true).include_prerelease(true).build();
let range = Range::new(">=1.2.3").with_options(opts.clone()).parse()?;
let ver = Version::new("1.2.4-pre1").with_options(opts.clone()).parse()?;

assert!(range.test(&ver));

Comparisons and considerations with other crates

At the time of writing this README there's only one other crate in the Rust ecosystem capable of parsing semver - steveklabnik/semver. While this crate is being used in cargo and is clearly doing its job there very well, while comparing arbitrary semver strings from a number of NPM packages I found it unable to parse a lot of them. Since its implementation of semver was vastly different from NPM's I decided to base this crate on NPM's package in the hopes of making it easier to keep up with any updates in the future. I kept the implementation as close as possible so the code structure and the way input is parsed should be very similar.

One trade-off this implementation had to make was a tiny bit of performance. Since the parsing is based heavily on Regex it's a little bit slower. There are still a lot of string allocations that can be eliminated, especially in parsing Ranges and Versions with prereleases.

In the bench directory I have compiled series of tests. They can all be ran with $ cd bench && bash gen.sh. This shell script basically collects some ranges from random npm packages and compares the results for the three implementations - semver_node, semver_rs and steveklabnik/semver. From the table bellow the results can be observed.

Basically semver_rs is faster than semver_node and slower than steveklabnik/semver. It's also as accurate in parsing as semver_node, while steveklabnik/semver couldn't handle 9 of the ranges.

Goals and the future

This initial release aims at bringing this package out in the public and also as a baseline in terms of performance. From now on performance can be improved upon by keeping compatibility at the absolute maximum. In general the parsing algorithm itself is not optimal at a lot of places. There's also a lot of needless string and vector allocations at the moment which are leftovers from the prototyping phase of the package, that can be addressed gradually.