How to make HTML5 work with DOMDocument?
I'm attempting to parse HTML code with DOMDocument, do stuff like changes to it, then assemble it back to a string which I send to the output.
But there a few issues regarding parsing, meaning that what I send to DOMDocument does not always come back in the same form :)
Here's a list:
using ->loadHTML:
preserveWhitespace and formatOutput settings (loosing whitespaces on preformatted text) <header> , <footer> etc. But they can be supressed, so I can live with this. <link ... /> element (with a self-closing tag), after parsing/saveHTML the output will be <link .. > using ->loadXML:
> from <style> or <script> tags: body > div becomes body > div body > div <meta ... /> becomes <meta...></meta> ; but this can be fixed with an regex. I didn't try HTML5lib but I'd prefer DOMDocument instead of a custom parser for performance reasons
Update:
So like the Honeymonster mentioned using CDATA fixes the main problem with loadXML.
Is there any way I could prevent self closing of all empty HTML tags besides a certain set, without using regex?
Right now I have:
$html = $dom->saveXML($node);
$html = preg_replace_callback('#<(w+)([^>]*)s*/>#s', function($matches){
// ignore only these tags
$xhtml_tags = array('br', 'hr', 'input', 'frame', 'img', 'area', 'link', 'col', 'base', 'basefont', 'param' ,'meta');
// if a element that is not in the above list is empty,
// it should close like `<element></element>` (for eg. empty `<title>`)
return in_array($matches[1], $xhtml_tags) ? "<{$matches[1]}{$matches[2]} />" : "<{$matches[1]}{$matches[2]}></{$matches[1]}>";
}, $html);
which works but it will also do the replacements in the CDATA content, which I don't want...
Unfortunately, or possibly fortunately, domdocument is designed to not try to preserve formatting from the original document. This is to make the parser's internal state easier to manage by keeping all elements the same style. Afaik most parsers will create a tree representation in memory and not worry about the textual formatting until the user requests such. This is why your self closed tags are output with separate closing tags. The good news is that it doesn't matter.
As to style tags and script tags getting <> converted to <> , you may be able to avoid the conversion by surrounding the contents of the element in question with the recommended cdata tags thusly:
<style>
/*<![CDATA[*/
body > div {
width: 50%;
}
/*]]>*/
</style>
The comment /* */ around the cdata declarations are to allow for broken clients which don't know about cdata sections and instead treat the declarations as CSS code. If you're using the document internally only then you may omit the /* */ comment surrounds and have the cdata declaration only. You may encounter issues with the aforementioned broken clients if you manipulate the document and then send it to the browser without checking to ensure the /* */ comments are retained; I am unsure whether domdocument will retain these or not.
Use html5lib. It can parse html5 and produce a DOMDocument. Example:
require_once '/path/to/HTML5/Parser.php';
$dom = HTML5_Parser::parse('<html><body>...');
Documentation
If you want to support HTML5, do not touch DOMDocument at all.
Currently the best option seems to be https://github.com/Masterminds/html5-php
Previously the best option was https://github.com/html5lib/html5lib-php but as the description says, it's "currently unmaintained". And this has been status for since October 2011 so I'm not holding my breath anymore.
I haven't used html5-php in production so I cannot provide any real world experiences about that. I've used html5lib-php in production and I would say that it's parsing well formed documents correctly but it has unexpected errors with some simple syntax errors. On the other hand, it seems to implement adoption agency algorithm and some other weird corner cases correctly. If html5lib-php were still maintained, I'd still prefer it. However, as things currently stand, I'd prefer using html5-php and possibly help fixing remaining bugs there.