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https://issues.apache.org/jira/browse/DAFFODIL-2512?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Lawrence updated DAFFODIL-2512:
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Summary: Unordered sequences with initiated content or discriminators does
not parse correctly (was: Unordered sequences with initiated content or
discriminatores does not parse correctly)
> Unordered sequences with initiated content or discriminators does not parse
> correctly
> -------------------------------------------------------------------------------------
>
> Key: DAFFODIL-2512
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2512
> Project: Daffodil
> Issue Type: Bug
> Components: Back End
> Reporter: Steve Lawrence
> Priority: Critical
>
> Parsing of unordered sequences uses the ChoiceParser to handle parsing the
> different alternatives. This causes issues because the SequenceParser that
> orchestrates the ChoiceParser needs to know why a ChoiceParser fails and
> react differently. If the ChoiceParser fails because all branches
> speculatively failed, then we need to simply ignore the failure and it
> signifies the end of the sequence. But if the ChoiceParser fails because a
> discriminated branch failed, then it signifies the unordered seuence failed,
> and the error must propogate upwards.
> This suggests that we cannot use the ChoiceParser when parsing an unordred
> sequence because we cannot know the reason for failure once it completes–all
> we know is it failed. Instead, the SequenceParser must create and manage
> points of uncertainty attempt to parse each branch of the unordered sequence
> individually, much like the ChoiceParser does. This way, it can know if a
> branch was discriminated and failed, or if all branches were tried and they
> all failed, and react appropriately.
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