set page context in Handler

[splitbrain]

Under some circumstances it is useful to know if the current parsing process is running in a page context or not.

One of the examples is the struct plugin's use of the PARSER_HANDLER_DONE event to automatically inject its own output instruction. Currently this instruction is injected in each and every processing and only on rendering is decided if there is anything to output.

This patch injects a page hint into the Handler when the handler was created from our p_wiki_xhtml() method (and only then). Plugins can use the getPage() method to check the context if needed.

Note: currently p_wiki_xhtml() also modifies the global $ID variable which might also used as context hint (but will also be set during on-the-fly renders, eg. the preview intro text).

It would probably be a good idea to check if it would be better when all handle methods rely on getPage() instead of global $ID instead. This would be a major change in parsing though and needs serious testing while this addition has basically no consequences currently.

[lpaulsen93]

So getPage() will return null in any other context and the page name/ID in case of normal rendering?

[splitbrain]

Yes, that's the idea.

[ssahara]

1. it may be possible to instantiate handler with $page argument in p_get_instructions(); $handler = new Doku_Handler($id) ?
2. Doku_Handler has already $status[] property and setStatus() / getStatus() methods, and the new $page property could be simply $status['page'] ?

[michitux]

Is there any reason why the id is not passed on in line 181 in p_cached_instructions, which should be the place where the parser is usually called for a page?

[Edit] Iirc there are also cases where p_cached_instructions is called without id, and then the id is also missing in the instruction cache event. This is why I added code to some plugins that handle the instruction cache event to check if the file is inside the pages directory and if yes, recover the id from the file's path. I cannot say if this is actually happening but it might not hurt to add similar code directly in p_cached_instructions to ensure that the id is always passed to the handler as otherwise the cache might be created somewhere where the id is not set (e.g., in some plugin) and then you have the wrong instructions in the cache.

[Klap-in]

I have not yet looked in the details, but this looks like an other application of this: lpaulsen93/dokuwiki-plugin-odt#260