Extended Backus-Naur Form - except-symbol

[Fabio Crisci]

Hello,

I was trying to translate HTML specification into a PEG grammar. XML uses a simple EBNF notation

http://www.w3.org/TR/REC-xml/#sec-notation

How would you translate the following?

CharData  // All text that is not markup constitutes the character data of the document.

  = [^<&]* - ([^<&]* "]]>" [^<&]*)

In other words I want to match an expression if it matches the first expression but not the second one.

Is it possible to do it in PEG or would it be a good idea to add the '-' symbol to PEG's grammar?

Thanks

Fabio

[David Majda]

Hi,

2013/1/15 Fabio Crisci <piu...@gmail.com>:

Matching an expression that matches A but not B is already possible
today with predicates:

rule = !B A

I don't think additional special syntax is needed.

--
David Majda
Entropy fighter
http://majda.cz/