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# HTML5-PHP
This is a **highly experimental** HTML5 Parser.
The need for an HTML5 parser in PHP is clear. This project initially
began with the seemingly abandoned `html5lib` project [original source](https://code.google.com/p/html5lib/source/checkout).
But after some initial refactoring work, we began a new parser.
- An HTML5 serializer [in progress; early alpha]
- Support for PHP namespace [done]
- Composer support [done]
- Event-based (SAX-like) parser [in progress]
- DOM tree builder [in progress]
- Interoperability with QueryPath [not started]
[![Build Status](https://travis-ci.org/Masterminds/html5-php.png?branch=master)](https://travis-ci.org/Masterminds/html5-php)
## Basic Usage
HTML5-PHP has a high-level API and a low-level API.
Here is how you use the high-level `HTML5` library API:
```php
<?php
// Assuming you installed from Composer:
require "vendor/autoload.php";
// An example HTML document:
$html = <<< 'HERE'
<html>
<head>
<title>TEST</title>
</head>
<body id='foo'>
<h1>Hello World</h1>
<p>This is a test of the HTML5 parser.</p>
</body>
</html>
HERE;
// Parse the document. $dom is a DOMDocument.
$dom = HTML5::loadHTML($html);
// Render it as HTML5:
print HTML5::saveHTML($dom);
// Or save it to a file:
HTML5::save($dom, 'out.html');
?>
```
The `$dom` created by the parser is a full `DOMDocument` object. And the
`save()` and `saveHTML()` methods will take any DOMDocument.
## The Low-Level API
This library provides the following low-level APIs that you can use to
create more customized HTML5 tools:
- An `InputStream` abstraction that can work with different kinds of
input source (not just files and strings).
- A SAX-like event-based parser that you can hook into for special kinds
of parsing.
- A flexible error-reporting mechanism that can be tuned to document
syntax checking.
- A DOM implementation that uses PHP's built-in DOM library.
The unit tests exercise each piece of the API, and every public function
is well-documented.
### Parser Design
The parser is designed as follows:
- The `InputStream` portion handles direct I/O.
- The `Scanner` handles scanning on behalf of the parser.
- The `Tokenizer` requests data off of the scanner, parses it, clasifies
it, and sends it to an `EventHandler`. It is a *recursive descent parser.*
- The `EventHandler` receives notifications and data for each specific
semantic event that occurs during tokenization.
- The `DOMBuilder` is an `EventHandler` that listens for tokenizing
events and builds a document tree (`DOMDocument`) based on the events.
### Serializer Design
The serializer takes a data structure (the `DOMDocument`) and transforms
it into a character representation -- an HTML5 document.
The serializer is broken into three parts:
- The `OutputRules` contain the rules to turn DOM elements into strings. The
rules used are configurable with the `OutputRules` being the default. An option
can be set by default or at call time to use a different ruleset that implements
`RulesInterface`.
- The `Traverser`, which is a special-purpose tree walker. It visits
each node node in the tree and uses the `OutputRules` to transform the node
into a string.
- The `Serializer` manages the `Traverser` and stores the resultant data
in the correct place.
The serializer (`save()`, `saveHTML()`) follows the
[section 8.9 of the HTML 5.0 spec](http://www.w3.org/TR/2012/CR-html5-20121217/syntax.html#serializing-html-fragments).
So tags are serialized according to these rules:
- A tag with children: <foo>CHILDREN</foo>
- A tag that cannot have content: <foo> (no closing tag)
- A tag that could have content, but doesn't: <foo></foo>
## Known Issues (Or, Things We Designed Against the Spec)
Please check the issue queue for a full list, but the following are
issues known issues that are not presently on the roadmap:
- Scripts: This parser does not contain a JavaScript or a CSS
interpreter. While one may be supplied, not all features will be
supported.
- Rentrance: The current parser is not re-entrant. (Thus you can't pause
the parser to modify the HTML string mid-parse.)
- Validation: The current tree builder is **not** a validating parser.
While it will correct some HTML, it does not check that the HTML
conforms to the standard. (Should you wish, you can build a validating
parser by extending DOMTree or building your own EventHandler
implementation.)
* There is limited support for insertion modes.
* Some autocorrection is done automatically.
* Per the spec, many legacy tags are admitted and correctly handled,
even though they are technically not part of HTML5.
- Processor Instructions: The HTML5 spec does not allow processor
instructions. We do. Since this is a server-side library, we think
this is useful. And that means, dear reader, that in some cases you
can parse the HTML from a mixed PHP/HTML document. This, however,
is an incidental feature, not a core feature.
- HTML manifests: Unsupported.
- PLAINTEXT: Unsupported.
- Adoption Agency Algorithm: Not yet implemented. (8.2.5.4.7)
## Thanks to...
We owe a huge debt of gratitude to the original authors of html5lib.
While not much of the orignal parser remains, we learned a lot from
reading the html5lib library. And some pieces remain here. In
particular, much of the UTF-8 and Unicode handling is derived from the
html5lib project.
## License
This software is released under the MIT license. The original html5lib
library was also released under the MIT license.
See LICENSE.txt
Certain files contain copyright assertions by specific individuals
involved with html5lib. Those have been retained where appropriate.
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