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https://issues.apache.org/jira/browse/DAFFODIL-2692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17740305#comment-17740305
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Mike Beckerle commented on DAFFODIL-2692:
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See also DAFFODIL-2722 which is related, but not an exact duplicate.
> Add lengthKind 'valuePattern' which uses regex to match allowed data values
> ---------------------------------------------------------------------------
>
> Key: DAFFODIL-2692
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2692
> Project: Daffodil
> Issue Type: New Feature
> Components: Back End, Front End
> Affects Versions: 3.3.0
> Reporter: Mike Beckerle
> Priority: Major
>
> Existing dfdl:lengthKind 'pattern' uses the pattern to determine the length.
> No match means length 0.
> People want to use regular expression (or regex) matches differently from
> this. They want to specify the allowed data patterns, with no match meaning
> parse error.
> This should be added as a dfdlx experimental feature to develop experience
> with it.
> A few design issues: we need to decide if this pattern includes nil values in
> its syntax, or if those get added as allowed value patterns automatically. It
> is simpler if we define this to require that the regex pattern specify all
> possible data patterns that are accepted, whether they become nilled
> elements, or elements with values. That, however, requires one to redundantly
> express the dfdl:nilValue information.
> There may also be an interaction with properties like
> dfdl:emptyValueDelimiterPolicy and the empty representation. I.e., does the
> pattern have to allow for a zero-length successful match in order for the
> data to be zero-length?
>
>
>
>
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