I think your approach will be worth following, but I have not seem something like this until now.

The big difference between your proposal and the existing modules, if I understand you correctly, is that you want to create (e.g., with this "tagblock" syntax) a special-purpose regex-based parser that ignores nearly all of the document and just dives into the parts that match the input specification. This could of course be faster than a full parse of the whole document tree.

The main point here is: what will be the grammar for your input specification syntax? If you could post some proposal for it in a more formal notation (e.g., BNF), it would be interesting to work on this problem.

From a performance point, the result of the compiled specification syntax should most surely not be one big regex (a lot of alternation etc. will make it slow, and the "Little Engine that couldn't" problems looms, too), but a closure that performs the needed logical tests in concert with the generated regexes.

The main point here is of course that using your approach people that would not be able to use regexes at all will be able to do some quite sophisticated regex matching. Maybe this warrants some search, too - any "user friendly" regex specification packages out there?

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com

In reply to RE: A grammar for HTML matching by clemburg
in thread A grammar for HTML matching by mcelrath

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