forked from GNUsocial/gnu-social
255 lines
8.6 KiB
Markdown
255 lines
8.6 KiB
Markdown
# HTML5-PHP
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HTML5 is a standards-compliant HTML5 parser and writer written entirely in PHP.
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It is stable and used in many production websites, and has
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well over [five million downloads](https://packagist.org/packages/masterminds/html5).
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HTML5 provides the following features.
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- An HTML5 serializer
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- Support for PHP namespaces
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- Composer support
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- Event-based (SAX-like) parser
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- A DOM tree builder
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- Interoperability with [QueryPath](https://github.com/technosophos/querypath)
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- Runs on **PHP** 5.3.0 or newer
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[](https://travis-ci.org/Masterminds/html5-php)
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[](https://packagist.org/packages/masterminds/html5)
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[](https://scrutinizer-ci.com/g/Masterminds/html5-php/?branch=master)
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[](https://scrutinizer-ci.com/g/Masterminds/html5-php/?branch=master)
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[](https://masterminds.github.io/stability/sustained.html)
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## Installation
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Install HTML5-PHP using [composer](http://getcomposer.org/).
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By adding the `masterminds/html5` dependency to your `composer.json` file:
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```json
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{
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"require" : {
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"masterminds/html5": "^2.0"
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},
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}
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```
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By invoking require command via composer executable:
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```bash
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composer require masterminds/html5
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```
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## Basic Usage
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HTML5-PHP has a high-level API and a low-level API.
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Here is how you use the high-level `HTML5` library API:
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```php
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<?php
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// Assuming you installed from Composer:
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require "vendor/autoload.php";
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use Masterminds\HTML5;
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// An example HTML document:
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$html = <<< 'HERE'
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<html>
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<head>
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<title>TEST</title>
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</head>
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<body id='foo'>
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<h1>Hello World</h1>
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<p>This is a test of the HTML5 parser.</p>
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</body>
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</html>
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HERE;
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// Parse the document. $dom is a DOMDocument.
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$html5 = new HTML5();
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$dom = $html5->loadHTML($html);
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// Render it as HTML5:
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print $html5->saveHTML($dom);
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// Or save it to a file:
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$html5->save($dom, 'out.html');
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```
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The `$dom` created by the parser is a full `DOMDocument` object. And the
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`save()` and `saveHTML()` methods will take any DOMDocument.
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### Options
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It is possible to pass in an array of configuration options when loading
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an HTML5 document.
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```php
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// An associative array of options
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$options = array(
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'option_name' => 'option_value',
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);
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// Provide the options to the constructor
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$html5 = new HTML5($options);
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$dom = $html5->loadHTML($html);
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```
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The following options are supported:
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* `encode_entities` (boolean): Indicates that the serializer should aggressively
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encode characters as entities. Without this, it only encodes the bare
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minimum.
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* `disable_html_ns` (boolean): Prevents the parser from automatically
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assigning the HTML5 namespace to the DOM document. This is for
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non-namespace aware DOM tools.
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* `target_document` (\DOMDocument): A DOM document that will be used as the
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destination for the parsed nodes.
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* `implicit_namespaces` (array): An assoc array of namespaces that should be
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used by the parser. Name is tag prefix, value is NS URI.
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## The Low-Level API
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This library provides the following low-level APIs that you can use to
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create more customized HTML5 tools:
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- A SAX-like event-based parser that you can hook into for special kinds
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of parsing.
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- A flexible error-reporting mechanism that can be tuned to document
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syntax checking.
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- A DOM implementation that uses PHP's built-in DOM library.
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The unit tests exercise each piece of the API, and every public function
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is well-documented.
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### Parser Design
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The parser is designed as follows:
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- The `Scanner` handles scanning on behalf of the parser.
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- The `Tokenizer` requests data off of the scanner, parses it, clasifies
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it, and sends it to an `EventHandler`. It is a *recursive descent parser.*
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- The `EventHandler` receives notifications and data for each specific
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semantic event that occurs during tokenization.
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- The `DOMBuilder` is an `EventHandler` that listens for tokenizing
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events and builds a document tree (`DOMDocument`) based on the events.
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### Serializer Design
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The serializer takes a data structure (the `DOMDocument`) and transforms
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it into a character representation -- an HTML5 document.
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The serializer is broken into three parts:
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- The `OutputRules` contain the rules to turn DOM elements into strings. The
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rules are an implementation of the interface `RulesInterface` allowing for
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different rule sets to be used.
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- The `Traverser`, which is a special-purpose tree walker. It visits
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each node node in the tree and uses the `OutputRules` to transform the node
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into a string.
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- `HTML5` manages the `Traverser` and stores the resultant data
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in the correct place.
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The serializer (`save()`, `saveHTML()`) follows the
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[section 8.9 of the HTML 5.0 spec](http://www.w3.org/TR/2012/CR-html5-20121217/syntax.html#serializing-html-fragments).
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So tags are serialized according to these rules:
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- A tag with children: <foo>CHILDREN</foo>
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- A tag that cannot have content: <foo> (no closing tag)
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- A tag that could have content, but doesn't: <foo></foo>
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## Known Issues (Or, Things We Designed Against the Spec)
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Please check the issue queue for a full list, but the following are
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issues known issues that are not presently on the roadmap:
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- Namespaces: HTML5 only [supports a selected list of namespaces](http://www.w3.org/TR/html5/infrastructure.html#namespaces)
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and they do not operate in the same way as XML namespaces. A `:` has no special
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meaning.
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By default the parser does not support XML style namespaces via `:`;
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to enable the XML namespaces see the [XML Namespaces section](#xml-namespaces)
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- Scripts: This parser does not contain a JavaScript or a CSS
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interpreter. While one may be supplied, not all features will be
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supported.
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- Rentrance: The current parser is not re-entrant. (Thus you can't pause
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the parser to modify the HTML string mid-parse.)
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- Validation: The current tree builder is **not** a validating parser.
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While it will correct some HTML, it does not check that the HTML
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conforms to the standard. (Should you wish, you can build a validating
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parser by extending DOMTree or building your own EventHandler
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implementation.)
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* There is limited support for insertion modes.
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* Some autocorrection is done automatically.
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* Per the spec, many legacy tags are admitted and correctly handled,
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even though they are technically not part of HTML5.
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- Attribute names and values: Due to the implementation details of the
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PHP implementation of DOM, attribute names that do not follow the
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XML 1.0 standard are not inserted into the DOM. (Effectively, they
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are ignored.) If you've got a clever fix for this, jump in!
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- Processor Instructions: The HTML5 spec does not allow processor
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instructions. We do. Since this is a server-side library, we think
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this is useful. And that means, dear reader, that in some cases you
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can parse the HTML from a mixed PHP/HTML document. This, however,
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is an incidental feature, not a core feature.
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- HTML manifests: Unsupported.
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- PLAINTEXT: Unsupported.
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- Adoption Agency Algorithm: Not yet implemented. (8.2.5.4.7)
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## XML Namespaces
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To use XML style namespaces you have to configure well the main `HTML5` instance.
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```php
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use Masterminds\HTML5;
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$html = new HTML5(array(
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"xmlNamespaces" => true
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));
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$dom = $html->loadHTML('<t:tag xmlns:t="http://www.example.com"/>');
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$dom->documentElement->namespaceURI; // http://www.example.com
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```
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You can also add some default prefixes that will not require the namespace declaration,
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but its elements will be namespaced.
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```php
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use Masterminds\HTML5;
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$html = new HTML5(array(
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"implicitNamespaces"=>array(
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"t"=>"http://www.example.com"
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)
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));
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$dom = $html->loadHTML('<t:tag/>');
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$dom->documentElement->namespaceURI; // http://www.example.com
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```
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## Thanks to...
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The dedicated (and patient) contributors of patches small and large,
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who have already made this library better.See the CREDITS file for
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a list of contributors.
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We owe a huge debt of gratitude to the original authors of html5lib.
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While not much of the original parser remains, we learned a lot from
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reading the html5lib library. And some pieces remain here. In
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particular, much of the UTF-8 and Unicode handling is derived from the
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html5lib project.
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## License
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This software is released under the MIT license. The original html5lib
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library was also released under the MIT license.
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See LICENSE.txt
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Certain files contain copyright assertions by specific individuals
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involved with html5lib. Those have been retained where appropriate.
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