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https://issues.apache.org/jira/browse/DERBY-4879?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Knut Anders Hatlen updated DERBY-4879:
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Attachment: ij.diff
Attaching a patch that reduces the lookahead in ij.jj from 2 to 1, thereby
enabling lookahead adequacy checking and silencing the warning. The following
grammar changes were needed to make it work with lookahead 1:
1) Remove the duplicate reference to FirstStatement in the grammar
2) Refactor the ConnectStatement rule so that it doesn't branch until after the
common prefix <CONNECT> has been seen
3) dynamicConnection/attributeList: Add a lookahead hint in attributeList to
avoid ambiguity when the attribute list is empty and followed by AS (as in
CONNECT '...' ATTRIBUTES AS C1, where a lookahead of 1 wouldn't be enough to
determine whether AS was a property name or a keyword)
4) Merge the rules for qualified and unqualified table names in
DescTableStatement
5) Factor out the common prefix <SHOW> in ShowStatement
6) Merge the rules IllegalStatementName and PrepareStatement into a single rule
with the common prefix <PREPARE> factored out
7) Merge the three rules JBMSPreparedStatementExec, F2KExecuteProcedure and
ExecuteStatement into a single rule, with the common prefix <EXECUTE> factored
out
> Lookahead warning from ij.jj
> ----------------------------
>
> Key: DERBY-4879
> URL: https://issues.apache.org/jira/browse/DERBY-4879
> Project: Derby
> Issue Type: Improvement
> Components: Tools
> Affects Versions: 10.7.1.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Priority: Minor
> Attachments: ij.diff
>
>
> When building with "ant -q", I see this warning when JavaCC processes ij.jj:
> [java] Warning: Lookahead adequacy checking not being performed since
> option LOOKAHEAD is more than 1. Set option FORCE_LA_CHECK to true to force
> checking.
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