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https://issues.apache.org/jira/browse/LANG-846?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13634980#comment-13634980
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Henri Yandell commented on LANG-846:
------------------------------------
Thanks Dmitry :)
svn ci -m "Adding Dmitry Katsubo's patch from LANG-846, providing
CharSequenceUtils.regionMatches with a proper green implementation instead of
inefficiently converting to Strings"
Sending src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
Sending
src/test/java/org/apache/commons/lang3/StringUtilsStartsEndsWithTest.java
Transmitting file data ..
Committed revision 1469220.
> StringUtils.equals() / CharSequenceUtils.regionMatches() assumes that
> CharSequence.toString() implementation is effective
> -------------------------------------------------------------------------------------------------------------------------
>
> Key: LANG-846
> URL: https://issues.apache.org/jira/browse/LANG-846
> Project: Commons Lang
> Issue Type: Improvement
> Components: lang.*
> Affects Versions: 3.1
> Reporter: Dmitry Katsubo
> Priority: Minor
> Fix For: 3.2
>
> Attachments: CharSequenceUtils.patch
>
>
> In my case I have {{CharSequence}} that implements a "lazy" string which is
> stored on disk, and although {{toString()}} implementation is valid, it is
> very expensive plus can potentially cause OOM.
> Thus {{CharSequenceUtils.regionMatches()}} should really do char-by-char
> comparison, leaving the optimization to underlying {{CharSequence}}
> implementation.
> Maybe {{CharSequenceUtils.regionMatches()}} could check that passed
> {{CharSequence}} is standard implementation (like {{StringBuilder}},
> {{StringBuffer}}) that has "effective" {{toString()}} implementation, but
> this implementation ends up with creating new {{String}} object and thus
> duplicating the character buffer. So we have classical speed/memory trade-off.
> P.S. [Line 192 of
> CharSequenceUtils()|http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java?revision=1199894&view=markup#l192]
> reads
> {{TODO: Implement rather than convert to String}}
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