WordPress/wp-includes/html-api/class-wp-html-unsupported-exception.php
Bernhard Reiter 44629e6286 HTML-API: Introduce minimal HTML Processor.
This patch introduces the //first// of //many// iterations on the evolution of the HTML API, the HTML Processor, which is built in order to understand HTML structure including nesting, misnesting, and complicated semantic rules.

In the first iteration, the HTML Processor is arbitrarily limited to a minimal subset of functionality so that we can review it, ship it, test it, and collect feedback before moving forward. This means that this patch is more or less an extension to the Tag Processor query language, providing the ability not only to scan for a tag of a given name, but also to find an HTML element in a specific nesting path.

The HTML Processor also aborts any time it encounters:
 - a tag that isn't a `P`, `DIV`, `FIGURE`, `FIGCAPTION`, `IMG`, `STRONG`, `B`, `EM`, `I`, `A`, `BIG`, `CODE`, `FONT`, `SMALL`, `STRIKE`, `TT`, or `U` tag. this limit exists because many HTML elements require specific rules and we are trying to limit the number of rules introduced at once. this work is targeted at existing work in places like the image block.
 - certain misnesting constructs that evoke complicated resolution inside the HTML spec. where possible and where simple to do reliably, certain parse errors are handled. in most cases the HTML Processor aborts.

The structure of the HTML Processor is established in this patch. Further spec-compliance comes through filling out //more of the same// kind and nature of code as is found in this patch. Certain critical HTML algorithms are partially supported, and where support requires more than is present, the HTML Processor acknowledges this and refuses to operate.

In this patch are explorations for how to verify that new HTML support is fully added (instead of allowing for partial updates that leave some code paths non-compliant). Performance is hard to measure since support is so limited at the current time, but it should generally follow the performance of the Tag Processor somewhat close as the overhead is minimized as much as practical.

Props dmsnell, zieladam, costdev.
Fixes #58517.
Built from https://develop.svn.wordpress.org/trunk@56274


git-svn-id: http://core.svn.wordpress.org/trunk@55786 1a063a9b-81f0-0310-95a4-ce76da25c4cd
2023-07-20 13:43:25 +00:00

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PHP

<?php
/**
* HTML API: WP_HTML_Unsupported_Exception class
*
* @package WordPress
* @subpackage HTML-API
* @since 6.4.0
*/
/**
* Core class used by the HTML processor during HTML parsing
* for indicating that a given operation is unsupported.
*
* This class is designed for internal use by the HTML processor.
*
* The HTML API aims to operate in compliance with the HTML5
* specification, but does not implement the full specification.
* In cases where it lacks support it should not cause breakage
* or unexpected behavior. In the cases where it recognizes that
* it cannot proceed, this class is used to abort from any
* operation and signify that the given HTML cannot be processed.
*
* @since 6.4.0
*
* @access private
*
* @see WP_HTML_Processor
*/
class WP_HTML_Unsupported_Exception extends Exception {
}