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https://issues.apache.org/jira/browse/CALCITE-4238?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17202970#comment-17202970
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Danny Chen commented on CALCITE-4238:
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The PR looks good. Except that i think we should change the file name
`default_parser` to `default_config` because it is not really a "parser".
> Create a default parser configuration, to reduce redundant information in
> sub-parsers
> -------------------------------------------------------------------------------------
>
> Key: CALCITE-4238
> URL: https://issues.apache.org/jira/browse/CALCITE-4238
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Julian Hyde
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.26.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Create a default parser configuration, to reduce redundant information in
> sub-parsers. In particular, each sub-project parser would not need its own
> list of non-reserved keywords (currently the list is over 250 keywords, and
> the list is identical in each sub-parser).
> Since CALCITE-2405 each sub-parser has its own list of non-reserved keywords.
> This is good, because it allows the sub-parser to make keywords non-reserved
> (e.g. in DRILL-1065 Drill wanted {{EXEC}} [to be
> non-reserved|https://issues.apache.org/jira/browse/DRILL-1065?focusedCommentId=14903669&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14903669])
> but it still requires each parser to have a list of non-reserved keywords
> (see e.g. [the list in Babel
> parser|https://github.com/apache/calcite/blob/eb4011bb4b9d962c2f8e6767cbee8c23435ef939/babel/src/main/codegen/config.fmpp#L37]).
> And if we add a keyword to Calcite, we almost always have to modify the list
> in each sub-parser.
> This proposal would move the list of default non-reserved keywords to a
> shared config file. This would reduce the amount of code in sub-parsers, and
> remove the need to edit them when we add a keyword to the base parser.
> Also, we would not need to modify each sub-parser each time we add a markup
> variable (e.g. when we added {{binaryOperatorsTokens}} and
> {{extraBinaryExpressions}} in CALCITE-2843).
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