This patch adds support to process the BUTTON element. This requires adding some additional semantic rules to handle situations where a BUTTON element is already in scope.
Also included is a fixup to enforce that `WP_HTML_Processor::next_tag()` never returns for a tag closer. This is useful with the Tag Processor, but not for the HTML Processor. There were tests relying on this behavior to assert that internal processes were working as they should, but those tests have been updated to use the semi-private `step()` function, which does stop on tag closers.
This patch is one in a series of changes to expand support within the HTML API, moving gradually to allow for more focused changes that are easier to review and test. The HTML Processor is a work in progress with a certain set of features slated to be ready and tested by 6.4.0, but it will only contain partial support of the HTML5 specification even after that. Whenever it cannot positively recognize and process its input it bails, and certain function stubs and logical stubs exist to structure future expansions of support.
Props dmsnell.
Fixes#58961.
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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