Steve Lawrence created DAFFODIL-1917:
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             Summary: Support for new character classes
                 Key: DAFFODIL-1917
                 URL: https://issues.apache.org/jira/browse/DAFFODIL-1917
             Project: Daffodil
          Issue Type: New Feature
          Components: Back End, Front End, Middle "End"
            Reporter: Steve Lawrence
             Fix For: deferred


Daffodil v2.0 wishlist includes new character class entities LSP, LSP* and 
LSP+, which are the same as WSP except they do not match line endings. This is 
useful as currently it is impossible to match an empty line followed by a 
newline via something like %WSP*;%NL; due to the greediness of WSP* and the 
inability for our delimiter scanner to backtrack of forward lookahead.

Related, it might be useful to also add NL+ and NL* to match an unbounded 
number of newlines.

Additionally, it might be a good idea to cause an SDE if a character class that 
contains * or
+ is immediately followed by a character inside that character class. The 
reason being that such sequences will always fail without lookahead or 
backtracking, which probalby isn't worth implementing.

For security reasons, we should also implement a tunable to limit the number or 
repetitions of these character entities.



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