[dokuwiki] Re: plugin: recursive syntax substitution


On 18 Mar 2009, at 11:57, Andreas Wagner wrote:


Hi all,
in further developing a plugin [1] for interaction with wikindx [2], I am trying to draw more resources from the remote database than just resource titles. Quotes is what I'm at - and in wikindx, quotes (and probably other entries (notes, musings, ...) can contain references to other resources. I can successfully s/wikindx-syntax/ dw-my_plugin-syntax in the generated string, but then the plugin would have to start over and also resolve the dw-my_plugin-syntax term. I have tried mode type 'substitution' and 'container' for the plugin with both of them also in the AllowedTypes array. But I think the recursion just isn't triggered.
Syntax plugins don't have a mechanism for feeding back changes to the parser for it to process those changes. You can instantiate another parser, however that is an expensive operation. If you expect to need to process several "snippets" in the course of a wiki page, your plugin could instantiate and save a parser and then resuse that parser for subsequent snippets.
See inc/parserutils.php in particular p_get_instructions() for details on parsing wiki text into instructions.
To hand the converted instruction list back to your original parser you can look at the call rewriters in inc/parser/handler.php or simply iterate over the list and call _addCall() for each. You will probably have to make some adjustments to the "pos" field. Alternatively, you could piggy back on the nest call rewriter.
There maybe hidden gotchas in this method. E.g. the instructions created for a wiki page are used by at least two renderers, metadata and xhtml. The xhtml renderer could be a plugin.
You may also want to look into using an action plugin to handle PARSER_WIKITEXT_PREPROCESS. It could look for your syntax and do the substitutions of the converted syntax before the wikitext is handed to the parser removing the need for all the above fancy shenanigans in a syntax plugin - a syntax plugin wouldn't be necessary at all. 

- Chris

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