Vendor things

third-party/vendor/semver/README.md

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+semver
+======
+
+Semantic version parsing and comparison.
+
+[![Build Status](https://api.travis-ci.org/steveklabnik/semver.svg?branch=master)](https://travis-ci.org/steveklabnik/semver)
+
+[Documentation](https://steveklabnik.github.io/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](https://crates.io), Rust's package manager, uses SemVer to determine which versions of
+packages you need installed.
+
+## Installation
+
+To use `semver`, add this to your `[dependencies]` section:
+
+```toml
+semver = "0.7.0"
+```
+
+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
+```