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https://issues.apache.org/jira/browse/IMPALA-7818?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16691545#comment-16691545
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ASF subversion and git services commented on IMPALA-7818:
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Commit 8dfbe3c82d4acfae60d58636af041ac13708ef1e in impala's branch
refs/heads/branch-3.1.0 from [~paul-rogers]
[ https://git-wip-us.apache.org/repos/asf?p=impala.git;h=8dfbe3c ]
IMPALA-7818: Standardize use of Expr predicates
The Expr node provide two kinds of queries about node categories:
predicates and isMumble() functions. This change standardizes two
existing methods to use predicates instead.
First, the existing isLiteral() method is replaced by a new
IS_LITERAL predicate.
The key purpose is to clean up the confusing use of the existing
isNullLiteral() method, which actually is a check for either a null
literal or a cast of a null. To make this clearer, replaced this
method with a new IS_NULL_VALUE() predicate.
Added a new IS_NULL_LITERAL predicate for the case when a node must be
exactly the NULL literal, not a cast to NULL. Replaced instances of
foo instanceof NullLiteral with a use of the new IS_NULL_LITERAL
predicate. (This revealed bugs which will be addressed separately.)
Added an IS_NON_NULL_LITERAL to replace the two-method idiom used in
several places.
Tests: No functional change. Reran all tests to ensure nothing changed.
Change-Id: I09a089c0f2484246e5c6444b78990fa9260c036a
Reviewed-on: http://gerrit.cloudera.org:8080/11887
Reviewed-by: Impala Public Jenkins <[email protected]>
Tested-by: Impala Public Jenkins <[email protected]>
> Standardize use of Expr predicates
> ----------------------------------
>
> Key: IMPALA-7818
> URL: https://issues.apache.org/jira/browse/IMPALA-7818
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Affects Versions: Impala 3.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Minor
>
> The {{Expr}} (expression) class in the frontend has many handy predicates
> such as {{IS_BINARY_PREDICATE}} and so on. (Note the confusing terminology:
> there are subclasses of {{Expr}} which are SQL predicates. The predicates
> discussed here are those based on the Guava {{Predicate}} class.)
> The class also has predicate-like methods: {{isLiteral()}} and
> {{isNullLiteral()}}. As it has evolved, {{isNullLiteral()}} checks not only
> for a null literal, but also a cast of a null to some type. These functions
> are in the base class, but do their work by checking the type of the
> expression.
> It would be cleaner to make these methods into predicates with names that
> follow their function: {{IS_LITERAL}}, and {{IS_NULL_VALUE}}.
> Further, there are a few places in the code that check for a non-null literal
> using an and of conditions, This would be cleaner using a new
> {{IS_NON_NULL_LITERAL}} predicate.
> These changes put us in position to add new predicates as a result of work in
> the pipeline; this refactoring is done as a separate change to keep the other
> commit smaller.
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