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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-6075) Use modern collections in impl/sql/compile
Date Thu, 21 Feb 2013 10:48:20 GMT

     [ https://issues.apache.org/jira/browse/DERBY-6075?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-6075:
--------------------------------------

    Attachment: d6075-4a-parameterList.diff

The attached 4a patch changes the signatures of CompilerContext.setParameterList(Vector),
CompilerContext.getParameterList() and ResultColumnList.bindExpressions(FromList, SubqueryList,
Vector), and of overriding methods, so that they use List instead of Vector. It also changes
signatures of methods called from these methods, as they must also accept List.

Most of the affected code already used the List interface methods. Only a single call to Vector.copyInto()
had to be changed to List.toArray(). I also took the opportunity to change a few occurrences
of size() == 0 to isEmpty().

The patch does not change the actual type of the objects passed to these methods. They are
still of type java.util.Vector.

All the regression tests passed.
                
> Use modern collections in impl/sql/compile
> ------------------------------------------
>
>                 Key: DERBY-6075
>                 URL: https://issues.apache.org/jira/browse/DERBY-6075
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.10.0.0
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>            Priority: Minor
>         Attachments: d6075-1a-CollectNodesVisitor.diff, d6075-2a-bindExpression.diff,
d6075-3a-javadoc.diff, d6075-4a-parameterList.diff
>
>
> The code in the org.apache.derby.impl.sql.compile package predates the Java Collections
Framework and uses old-style collections like java.util.Vector and java.util.Hashtable. Since
the old-style collection classes are used in many method signatures, it's difficult to use
modern collection classes when adding new code.
> I suggest we switch to using interfaces (like java.util.List and java.util.Map) instead
of specific classes in the signatures, so that we have more flexibility in choosing the right
collection class for the job.
> Only changing the signatures would allow us to continue using Vector and Hashtable, since
they implement the interfaces. However, I think it would be good to switch to ArrayList and
HashMap in a second step. The instances in impl/sql/compile are not shared between threads,
so we don't need the synchronization provided by the old-style classes. Switching to unsynchronized
classes may make compilation slightly faster.

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