http://dev.clojure.org/jira This file is an XML representation of an issue en-us 4.4 649 25-07-2011 http://dev.clojure.org/jira/browse/CLJ-753 Clojure <p><a href="https://groups.google.com/d/topic/clojure/wDO1u7wRmDQ/discussion">Originally reported by Takahiro Hozumi</a></p> <p>With a function as the "replacement" argument, clojure.string/replace-first returns nil if there is no match, instead of returning the original string unchanged.</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">user=&gt; (use 'clojure.string) nil user=&gt; (replace-first <span class="code-quote">"abcdef"</span> <span class="code-quote">"ghi"</span> <span class="code-quote">"jkl"</span>) <span class="code-quote">"abcdef"</span> user=&gt; (replace-first <span class="code-quote">"abcdef"</span> #<span class="code-quote">"ghi"</span> <span class="code-quote">"jkl"</span>) <span class="code-quote">"abcdef"</span> user=&gt; (replace-first <span class="code-quote">"abcdef"</span> #<span class="code-quote">"ghi"</span> (fn [a] <span class="code-quote">"jkl"</span>)) nil</pre> </div></div> CLJ-753

clojure.string/replace-first returns nil with replacement fn when regex doesn't match

Defect Minor Closed Completed Stuart Sierra Stuart Sierra Fri, 11 Mar 2011 07:54:15 -0600 Fri, 1 Mar 2013 12:47:01 -0600 Fri, 24 Aug 2012 07:41:03 -0500 Approved Backlog 2 2 <p>This is my patch for this issue. I have a CA signed. Any suggestions and i can try again. Federico</p> <p>Same fix as Frederico's patch, but also removes unnecessary allocation of a StringBuffer when there is no match, for both replace and replace first.</p> <p>Same again, but with docstring typo fixes too.</p> <p>You should use StringBuilder instead of StringBuffer.</p> <p><a href="http://stackoverflow.com/questions/355089/stringbuilder-and-stringbuffer-in-java">http://stackoverflow.com/questions/355089/stringbuilder-and-stringbuffer-in-java</a></p> <p>Yup, that's what I thought, but it turns out it doesn't work because java's Matcher/appendReplacement requires a StringBuffer, unfortunately.</p> <p>I've tested Chris's clojure-string-with-no-match-returns-original-2.patch against latest github Clojure as of this morning, and the tests pass. Cool that he found a straightforward performance improvement for the no match case. The code appears correct. I also verified that for the reason Chris mentions, StringBuilder will not work as a replacement for StringBuffer. At least there will never be any contention on the locks implementing the StringBuffer synchronization the way they are used here.</p> <p>Vetted &amp; moved to Approved Backlog.</p> <p><a href="http://dev.clojure.org/jira/browse/CLJ-870" title="clojure.string/replace behaves unexpectedly when \ or $ are part of the result string"><del>CLJ-870</del></a> has an attached proposed combined patch for this issue and that one.</p> <p>This issue should now be corrected with the patch, attached to <a href="http://dev.clojure.org/jira/browse/CLJ-870" title="clojure.string/replace behaves unexpectedly when \ or $ are part of the result string"><del>CLJ-870</del></a>, that was applied on Aug 18, 2012.</p> <p><a href="http://dev.clojure.org/jira/browse/CLJ-753" title="clojure.string/replace-first returns nil with replacement fn when regex doesn&#39;t match"><del>CLJ-753</del></a> patch applied for <a href="http://dev.clojure.org/jira/browse/CLJ-870" title="clojure.string/replace behaves unexpectedly when \ or $ are part of the result string"><del>CLJ-870</del></a> addresses this one, too, applied Aug 18, 2012 </p> Approval Vetted Global Rank Patch Code and Test