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# Version

Library for handling version information and constraints

[![Build Status](https://travis-ci.org/phar-io/version.svg?branch=master)](https://travis-ci.org/phar-io/version)

## Installation

You can add this library as a local, per-project dependency to your project using [Composer](https://getcomposer.org/):

    composer require phar-io/version

If you only need this library during development, for instance to run your project's test suite, then you should add it as a development-time dependency:

    composer require --dev phar-io/version

## Version constraints

A Version constraint describes a range of versions or a discrete version number. The format of version numbers follows the schema of [semantic versioning](http://semver.org): `<major>.<minor>.<patch>`. A constraint might contain an operator that describes the range.

Beside the typical mathematical operators like `<=`, `>=`, there are two special operators:

*Caret operator*: `^1.0`
can be written as `>=1.0.0 <2.0.0` and read as »every Version within major version `1`«.

*Tilde operator*: `~1.0.0`
can be written as `>=1.0.0 <1.1.0` and read as »every version within minor version `1.1`. The behavior of tilde operator depends on whether a patch level version is provided or not. If no patch level is provided, tilde operator behaves like the caret operator: `~1.0` is identical to `^1.0`.

## Usage examples

Parsing version constraints and check discrete versions for compliance:

```php

use PharIo\Version\Version;
use PharIo\Version\VersionConstraintParser;

$parser = new VersionConstraintParser();
$caret_constraint = $parser->parse( '^7.0' );

$caret_constraint->complies( new Version( '7.0.17' ) ); // true
$caret_constraint->complies( new Version( '7.1.0' ) ); // true
$caret_constraint->complies( new Version( '6.4.34' ) ); // false

$tilde_constraint = $parser->parse( '~1.1.0' );

$tilde_constraint->complies( new Version( '1.1.4' ) ); // true
$tilde_constraint->complies( new Version( '1.2.0' ) ); // false
```

As of version 2.0.0, pre-release labels are supported and taken into account when comparing versions:

```php

$leftVersion = new PharIo\Version\Version('3.0.0-alpha.1');
$rightVersion = new PharIo\Version\Version('3.0.0-alpha.2');

$leftVersion->isGreaterThan($rightVersion); // false
$rightVersion->isGreaterThan($leftVersion); // true

```