traefik/vendor/github.com/Masterminds/semver/doc.go
2017-08-10 20:42:39 +02:00

115 lines
3.6 KiB
Go

/*
Package semver provides the ability to work with Semantic Versions (http://semver.org) in Go.
Specifically it provides the ability to:
* Parse semantic versions
* Sort semantic versions
* Check if a semantic version fits within a set of constraints
* Optionally work with a `v` prefix
Parsing Semantic Versions
To parse a semantic version use the `NewVersion` function. For example,
v, err := semver.NewVersion("1.2.3-beta.1+build345")
If there is an error the version wasn't parseable. The version object has methods
to get the parts of the version, compare it to other versions, convert the
version back into a string, and get the original string. For more details
please see the documentation at https://godoc.org/github.com/Masterminds/semver.
Sorting Semantic Versions
A set of versions can be sorted using the `sort` package from the standard library.
For example,
raw := []string{"1.2.3", "1.0", "1.3", "2", "0.4.2",}
vs := make([]*semver.Version, len(raw))
for i, r := range raw {
v, err := semver.NewVersion(r)
if err != nil {
t.Errorf("Error parsing version: %s", err)
}
vs[i] = v
}
sort.Sort(semver.Collection(vs))
Checking Version Constraints
Checking a version against version constraints is one of the most featureful
parts of the package.
c, err := semver.NewConstraint(">= 1.2.3")
if err != nil {
// Handle constraint not being parseable.
}
v, _ := semver.NewVersion("1.3")
if err != nil {
// Handle version not being parseable.
}
// Check if the version meets the constraints. The a variable will be true.
a := c.Check(v)
Basic Comparisons
There are two elements to the comparisons. First, a comparison string is a list
of comma separated and comparisons. These are then separated by || separated or
comparisons. For example, `">= 1.2, < 3.0.0 || >= 4.2.3"` is looking for a
comparison that's greater than or equal to 1.2 and less than 3.0.0 or is
greater than or equal to 4.2.3.
The basic comparisons are:
* `=`: equal (aliased to no operator)
* `!=`: not equal
* `>`: greater than
* `<`: less than
* `>=`: greater than or equal to
* `<=`: less than or equal to
Hyphen Range Comparisons
There are multiple methods to handle ranges and the first is hyphens ranges.
These look like:
* `1.2 - 1.4.5` which is equivalent to `>= 1.2, <= 1.4.5`
* `2.3.4 - 4.5` which is equivalent to `>= 2.3.4, <= 4.5`
Wildcards In Comparisons
The `x`, `X`, and `*` characters can be used as a wildcard character. This works
for all comparison operators. When used on the `=` operator it falls
back to the pack level comparison (see tilde below). For example,
* `1.2.x` is equivalent to `>= 1.2.0, < 1.3.0`
* `>= 1.2.x` is equivalent to `>= 1.2.0`
* `<= 2.x` is equivalent to `<= 3`
* `*` is equivalent to `>= 0.0.0`
Tilde Range Comparisons (Patch)
The tilde (`~`) comparison operator is for patch level ranges when a minor
version is specified and major level changes when the minor number is missing.
For example,
* `~1.2.3` is equivalent to `>= 1.2.3, < 1.3.0`
* `~1` is equivalent to `>= 1, < 2`
* `~2.3` is equivalent to `>= 2.3, < 2.4`
* `~1.2.x` is equivalent to `>= 1.2.0, < 1.3.0`
* `~1.x` is equivalent to `>= 1, < 2`
Caret Range Comparisons (Major)
The caret (`^`) comparison operator is for major level changes. This is useful
when comparisons of API versions as a major change is API breaking. For example,
* `^1.2.3` is equivalent to `>= 1.2.3, < 2.0.0`
* `^1.2.x` is equivalent to `>= 1.2.0, < 2.0.0`
* `^2.3` is equivalent to `>= 2.3, < 3`
* `^2.x` is equivalent to `>= 2.0.0, < 3`
*/
package semver