https://ask.clojure.org/index.php/activity/clojure/regex https://ask.clojure.org/index.php/13894/could-re-pattern-be-extended-to-allow-flags?show=13897#a13897 <p>Logged as <a rel="nofollow" href="https://clojure.atlassian.net/browse/CLJ-2854">https://clojure.atlassian.net/browse/CLJ-2854</a></p> Regex https://ask.clojure.org/index.php/13894/could-re-pattern-be-extended-to-allow-flags?show=13897#a13897 Wed, 22 May 2024 19:20:39 +0000 https://ask.clojure.org/index.php/9740/off-one-error-nth-java-util-regex-matcher-instance-index-found?show=9740#q9740 <pre><code>(def matcher (doto (re-matcher #"(\d{2})\/(\d{2})\/(\d{4})" "12/02/1975 ") (.find))) (.groupCount matcher) ;; 3 (.group matcher 3) ;; "1975" (nth matcher 3) ;; "1975" (nth matcher 3 nil) ;; nil, but "1975" expected </code></pre> <p>seems like a bug in <code>(nth &lt;matcher-instance&gt; &lt;index&gt; &lt;not-found&gt;)</code> implementation for <code>Matcher</code>.</p> <ul> <li>from the docs of <a rel="nofollow" href="https://docs.oracle.com/javase/7/docs/api/java/util/regex/Matcher.html#groupCount()">.groupCount</a>: "Group zero denotes the entire pattern by convention. It is not included in this count."</li> <li>the check in <a rel="nofollow" href="https://github.com/clojure/clojure/blob/d07ef175c700329f7afbef8770332b6247a34a49/src/jvm/clojure/lang/RT.java#L968">RT.java</a> in the <code>nth</code> implementation checks to make sure <code>n &lt; m.groupCount()</code></li> <li>the check should be for <code>n &lt;= m.groupCount()</code></li> </ul> Regex https://ask.clojure.org/index.php/9740/off-one-error-nth-java-util-regex-matcher-instance-index-found?show=9740#q9740 Mon, 18 Jan 2021 16:10:49 +0000