---
Hoa is a modular, extensible and
structured set of PHP libraries.
Moreover, Hoa aims at being a bridge between industrial and research worlds.
# Hoa\Visitor
[](https://webchat.freenode.net/?channels=#hoaproject)
[](https://gitter.im/hoaproject/central)
[](https://central.hoa-project.net/Documentation/Library/Visitor)
[](https://waffle.io/hoaproject/visitor)
This library provides interfaces to apply the visitor pattern.
[Learn more](https://central.hoa-project.net/Documentation/Library/Visitor).
## Installation
With [Composer](https://getcomposer.org/), to include this library into
your dependencies, you need to
require [`hoa/visitor`](https://packagist.org/packages/hoa/visitor):
```sh
$ composer require hoa/visitor '~2.0'
```
For more installation procedures, please read [the Source
page](https://hoa-project.net/Source.html).
## Testing
Before running the test suites, the development dependencies must be installed:
```sh
$ composer install
```
Then, to run all the test suites:
```sh
$ vendor/bin/hoa test:run
```
For more information, please read the [contributor
guide](https://hoa-project.net/Literature/Contributor/Guide.html).
## Quick usage
We propose to explain the basis of this library. We have two entities: an
element to visit and a visitor, for example a node of a tree and a dumper. The
element to visit will implement the `Hoa\Visitor\Element` interface and the
visitor will implement the `Hoa\Visitor\Visit` interface. The first one will ask
to implement the `accept` method in order to define what data it holds will be
visited. The second one will ask to implement the `visit` method which will
contain the visitor computations. We will find several examples in Hoa
libraries.
## Documentation
The
[hack book of `Hoa\Visitor`](https://central.hoa-project.net/Documentation/Library/Visitor)
contains detailed information about how to use this library and how it works.
To generate the documentation locally, execute the following commands:
```sh
$ composer require --dev hoa/devtools
$ vendor/bin/hoa devtools:documentation --open
```
More documentation can be found on the project's website:
[hoa-project.net](https://hoa-project.net/).
## Getting help
There are mainly two ways to get help:
* On the [`#hoaproject`](https://webchat.freenode.net/?channels=#hoaproject)
IRC channel,
* On the forum at [users.hoa-project.net](https://users.hoa-project.net).
## Contribution
Do you want to contribute? Thanks! A detailed [contributor
guide](https://hoa-project.net/Literature/Contributor/Guide.html) explains
everything you need to know.
## License
Hoa is under the New BSD License (BSD-3-Clause). Please, see
[`LICENSE`](https://hoa-project.net/LICENSE) for details.