3 ms·

`$` does mean end of input in Java, unless you explicitly ask for multiline mode. In the latter case it means `(?=$|\n)` if also in Unix-lines mode, and the hor

by sjrd 2y ago

`$` does mean end of input in Java, unless you explicitly ask for multiline mode. In the latter case it means `(?=$|\n)` if also in Unix-lines mode, and the horrible `(?=$|(?<!\r)\n|[\r\u0085\u2028\u2029])` otherwise. I wrote a compiler from Java regex to JavaScript RegExp, in which you'll find that particular compilation scheme [1]. Edit: also quoting from [2]: > By default, the regular expressions ^ and $ ignore line terminators and only match at the beginning and the end, respectively, of the entire input sequence. If MULTILINE mode is activated then ^ matches at the beginning of input and after any line terminator except at the end of input. When in MULTILINE mode $ matches just before a line terminator or the end of the input sequence. [1] https://github.com/scala-js/scala-js/blob/eb160f1ef1137949994ba119d3a8d1e0754a09a4/javalib/src/main/scala/java/util/regex/PatternCompiler.scala#L1227 https://github.com/scala-js/scala-js/blob/eb160f1ef113794999... [2] https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pa...

sjrd 2y ago
OK it seems they changed the doc since. In the docs for JDK 21 we read instead [1]: > If MULTILINE mode is not activated, the regular expression ^ ignores line terminators and only matches at the beginning of the entire input sequence. The regular expression $ matches at the end of the entire input sequence, but also matches just before the last line terminator if this is not followed by any other input character. Other line terminators are ignored, including the last one if it is followed by other input characters. Looks like I have some code to fix. [1] https://docs.oracle.com/en%2Fjava%2Fjavase%2F21%2Fdocs%2Fapi%2F%2F/java.base/java/util/regex/Pattern.html https://docs.oracle.com/en%2Fjava%2Fjavase%2F21%2Fdocs%2Fapi...

by sjrd 2y ago

sjrd 2y ago

OK it seems they changed the doc since. In the docs for JDK 21 we read instead [1]: > If MULTILINE mode is not activated, the regular expression ^ ignores line terminators and only matches at the beginning of the entire input sequence. The regular expression $ matches at the end of the entire input sequence, but also matches just before the last line terminator if this is not followed by any other input character. Other line terminators are ignored, including the last one if it is followed by other input characters. Looks like I have some code to fix. [1] https://docs.oracle.com/en%2Fjava%2Fjavase%2F21%2Fdocs%2Fapi%2F%2F/java.base/java/util/regex/Pattern.html https://docs.oracle.com/en%2Fjava%2Fjavase%2F21%2Fdocs%2Fapi...