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Posted to notifications@groovy.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2017/07/27 11:57:02 UTC
[jira] [Commented] (GROOVY-8271) Take/TakeRight methods on iterator
needlessly calls hasNext for one too many elements
[ https://issues.apache.org/jira/browse/GROOVY-8271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16103101#comment-16103101 ]
ASF GitHub Bot commented on GROOVY-8271:
----------------------------------------
GitHub user MartyNeal opened a pull request:
https://github.com/apache/groovy/pull/578
Call iterators hasNext as last when simpler checks can be done first
Addresses https://issues.apache.org/jira/browse/GROOVY-8271
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/MartyNeal/groovy GROOVY-8271
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/groovy/pull/578.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #578
----
commit 16528d3b443d3c8c838c2b862e658285d211cf69
Author: Marty Neal <ma...@oracle.com>
Date: 2017-07-27T11:52:25Z
Call iterators hasNext as late as possible where simpler checks can be done first
----
> Take/TakeRight methods on iterator needlessly calls hasNext for one too many elements
> -------------------------------------------------------------------------------------
>
> Key: GROOVY-8271
> URL: https://issues.apache.org/jira/browse/GROOVY-8271
> Project: Groovy
> Issue Type: Bug
> Components: groovy-jdk
> Affects Versions: 2.4.12
> Reporter: Marty Neal
> Priority: Minor
>
> I expect the {{TakeIterator}} to only call the {{hasNext()}} method for the delegate a maximum of {{N}} times where {{N}} is the number of elements to take. If the iterator represents some expensive operations, or an unexhausted infinite stream that has exactly {{N}} elements available, the {{TakeIterator}} will block waiting for the {{Nth+1}} element only to return {{N}} of them.
> In short, change the {{TakeIterator}}'s {{hasNext}} function from
> {{return delegate.hasNext() && num > 0;}}
> to
> {{return num > 0 && delegate.hasNext();}}
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