The reason is (fairly) simple. The cause is that \digit is used as a replacement token.
So the code in org.apache.tools.ant.util.regex.(JakartaOro|Jdk14Regexp|JakartaRegexp)Regexp #substitute check if a \ appears in the string and if so if the next character is a digit, if so it then does the subs (for oro and 14 this means placing a $digit in the character stream). If the following character is not a digit, it gets put in the stream, in other words the backslash is dropped. As \ is also an escape character for the oro/14/jakarata matcher function it needs to be excaped again. You need to place two in the output stream so you need 2 * 2 * 2 or 8 backslashs. 7 backslashs work if the last backslash is the last character in the replacement string, in which change the code commented by /* XXX - should throw an exception instead? */ comes into play. I am not to sure if this (dropping the \ character if it is not followed by a digit) is correct behaviour, however it has been in ant for a while, so needs to be maintained for BC reasons. Peter. On Thursday 04 September 2003 18:29, Rutger Hofman wrote: > Why do I have to quadruplate the backslash? Why in replace and > not in regexp? > I would expect, to replace '\' with '\\': > regexp="\\" replace="\\\\" (2 and 4) > or if I must quadruplate, then I would expect > regexp="\\\\" replace="\\\\\\\\" (4 and 8) > > It is like none of these. Specifying 8 '\' in replace also > gives the correct result. So, 2 and 8 is OK, as is 2 and 7. > However, 4 and 8 gives a failure to match the pattern: > 4 apparently matches 2 '\' in the input string. > > (In fact, I would not have been surprised if the seventh > backslash would have escaped the following end-quote, but ant > life seems not so simple.) > > Greetz, > > Rutger Hofman > VU Amsterdam > > Inger, Matthew wrote:> Backslashes should be in increments of two if you're > > > actually trying to represent the backslash character. > > So, you should probably have 8 backslashes. > > > > ---------------- > > Matthew Inger [EMAIL PROTECTED] > > Software Developer > > Synygy, Inc > > 610-664-7433 x 7770 > > "Man who jump off cliff, leap to conclusions." - Confucious > > > > > > -----Original Message----- > > From: Rutger Hofman [mailto:[EMAIL PROTECTED] > > Sent: Thursday, September 04, 2003 12:13 PM > > To: [EMAIL PROTECTED] > > Subject: [Ant-contrib-developers] propertyregex: '\' within patterns > > > > > > Another question about propertyregex. > > > > I want to basically set property p-out from replacing > > "\" with "\\" in some property, p-in. Now, '\' is of > > course escape character, so I must replace it. I would > > presume that regexp="\\" and replace="\\\\" would do > > the job. > > > > However, I must do: > > > > <propertyregex > > property="p-out" > > input="${p-in}" > > regexp="\\" > > replace="\\\\\\\" > > global="true" /> > > > > This is, yes, seven(!) backslashes in replace, > > where I would expect four. > > > > Other numbers of backslashes in replace lead to > > > > java.lang.StringIndexOutOfBoundsException: String index out of range: 3 > > at java.lang.String.charAt(String.java:460) > > at java.util.regex.Matcher.appendReplacement(Matcher.java:544) > > > > or other errors. > > > > Any clue? Is this going to be required (and documented) behaviour, > > or is it a bug? > > If you want, I can spend some time to hunt down the bug (if my professor > > allows it :-) > > > > Rutger > > > > > > > > > > ------------------------------------------------------- > > This sf.net email is sponsored by:ThinkGeek > > Welcome to geek heaven. > > http://thinkgeek.com/sf > > _______________________________________________ > > Ant-contrib-developers mailing list > > [EMAIL PROTECTED] > > https://lists.sourceforge.net/lists/listinfo/ant-contrib-developers > > ------------------------------------------------------- > This sf.net email is sponsored by:ThinkGeek > Welcome to geek heaven. > http://thinkgeek.com/sf > _______________________________________________ > Ant-contrib-developers mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/ant-contrib-developers --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
