semver
======
Semantic version parsing and comparison.
[](https://travis-ci.org/rust-lang/semver)
[Documentation](http://doc.rust-lang.org/semver)
Semantic versioning (see http://semver.org/) is a set of rules for
assigning version numbers.
## SemVer and the Rust ecosystem
Rust itself follows the SemVer specification, as does its standard libraries. The two are
not tied together.
[Cargo](http://crates.io), Rust's package manager, uses SemVer to determine which versions of
packages you need installed.
## Installation
To use `semver`, add these lines to your `Cargo.toml`:
```toml
[dependencies]
semver = "*"
```
And this to your crate root:
```rust
extern crate semver;
```
## Versions
At its simplest, the `semver` crate allows you to construct `Version` objects using the `parse`
method:
```{rust}
use semver::Version;
assert!(Version::parse("1.2.3") == Ok(Version {
major: 1,
minor: 2,
patch: 3,
pre: vec!(),
build: vec!(),
}));
```
If you have multiple `Version`s, you can use the usual comparison operators to compare them:
```{rust}
use semver::Version;
assert!(Version::parse("1.2.3-alpha") != Version::parse("1.2.3-beta"));
assert!(Version::parse("1.2.3-alpha2") > Version::parse("1.2.0"));
```
## Requirements
The `semver` crate also provides the ability to compare requirements, which are more complex
comparisons.
For example, creating a requirement that only matches versions greater than or
equal to 1.0.0:
```{rust}
use semver::Version;
use semver::VersionReq;
let r = VersionReq::parse(">= 1.0.0").unwrap();
let v = Version::parse("1.0.0").unwrap();
assert!(r.to_string() == ">= 1.0.0".to_string());
assert!(r.matches(&v))
```
It also allows parsing of `~x.y.z` and `^x.y.z` requirements as defined at
https://www.npmjs.org/doc/misc/semver.html
**Tilde requirements** specify a minimal version with some updates:
```notrust
~1.2.3 := >=1.2.3 <1.3.0
~1.2 := >=1.2.0 <1.3.0
~1 := >=1.0.0 <2.0.0
```
**Caret requirements** allow SemVer compatible updates to a specified version,
`0.x` and `0.x+1` are not considered compatible, but `1.x` and `1.x+1` are.
`0.0.x` is not considered compatible with any other version.
Missing minor and patch versions are desugared to `0` but allow flexibility for that value.
```notrust
^1.2.3 := >=1.2.3 <2.0.0
^0.2.3 := >=0.2.3 <0.3.0
^0.0.3 := >=0.0.3 <0.0.4
^0.0 := >=0.0.0 <0.1.0
^0 := >=0.0.0 <1.0.0
```