Hi,
Can we close this JIRA as 'non-bug difference, won't fix'?
I agree with Anton the issue is RI bug. In JDK 1.5 it allows one reference more
than expected. May be the initial groups number is 1 instead 0. Therefore it
doesn't correctly execute check-up of the back reference '\1' at regular
expression parsing.
Regards,
Nellya.
>From "Anton Ivanov (JIRA)" <[EMAIL PROTECTED]>
Subject [jira] Commented: (HARMONY-1149) [classlib][util] unexpected
PatternSyntaxException for String.replaceFirst()/replaceAll()
Date Fri, 11 Aug 2006 08:50:14 GMT
[
http://issues.apache.org/jira/browse/HARMONY-1149?page=comments#action_12427473
<http://issues.apache.org/jira/browse/HARMONY-1149?page=comments%23action_12427473%20>
]
Anton Ivanov commented on HARMONY-1149:
---------------------------------------
As you can see the problem arose while compiling regular expression "\\1" in
the Pattern class.
1. To minimize the example you can write:
import java.util.regex.*;
public class test {
public static void main (String [] args) {
String str_re = "\\1";
try {
Pattern.compile(str_re);
} catch (Exception e) {
System.out.println("unexpected exception: " + e);
}
}
}
2. As it is written in the API documentation for Pattern class "...сapturing
groups are numbered
by counting their opening parentheses from left to right..." and "...capturing
groups are
so named because, during a match, each subsequence of the input sequence that
matches such
a group is saved. The captured subsequence may be used later in the expression,
via a back
reference, and may also be retrieved from the matcher once the match operation
is complete..."
In the pattern "\\1" we have no yet group number 1 while compiling it, so
backreference to
the first group \1 is invalid.
So we throw an exception.
You can try to compile "\\2" string on RI and you will see the same situaution
as for "\\1"
on Harmony.
3. Another question is what backreference \1 should match while no such group
in the pattern
yet exists?
For example if you write following on RI
Pattern pat = Pattern.compile("\\1(c)");
Matcher mat = pat.matcher("cc");
if (mat.matches()) {
System.out.println("matches");
} else {
System.out.println("not matches");
}
There will be the output "not matches"
But if you change the first string to
Pattern pat = Pattern.compile("(c)\\1");
Then the output will be "matches".
So backrefences to groups that do not yet exist are not processed as it may be
expected.
And again
Pattern.compile("\\2(a)(b)");
will cause an exception.
I beleave this is a RI bug, not Harmony.
> [classlib][util] unexpected PatternSyntaxException for
> String.replaceFirst()/replaceAll()
> -----------------------------------------------------------------------------------------
>
> Key: HARMONY-1149
> URL: http://issues.apache.org/jira/browse/HARMONY-1149
> Project: Harmony
> Issue Type: Bug
> Components: Classlib
> Reporter: Vladimir Ivanov
> Attachments: StringTest.patch
>
>
> The Harmony methods String.replaceFirst(String regex, String replacement) and
> String.replaceAll(String
regex, String replacement) throws PatternSyntaxException on Harmony and works
silently on
RI.
> =================== test.java ======================
> import java.util.regex.*;
> public class test {
> public static void main (String [] args) {
> String str_re = "\\1";
> try {
> System.out.println("replaceFirst = " + "abc".replaceFirst(str_re,
> "x"));
> } catch (Exception e) {
> System.out.println("unexpected exception: " + e);
> }
> try {
> System.out.println("replaceAll = " + "abc".replaceAll(str_re,
> "x"));
> } catch (Exception e) {
> System.out.println("unexpected exception: " + e);
> e.printStackTrace();
> }
> }
> }
> ================================================
> Output:
> C:\tmp\tmp17>C:\jrockit-jdk1.5.0-windows-ia32\bin\java.exe -cp . -showversion
> test
> java version "1.5.0"
> Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
> BEA WebLogic JRockit(R) (build dra-38972-20041208-2001-win-ia32, R25.0.0-75,
> GC: System
optimized over throughput (initial strategy singleparpar))
> replaceFirst = abc
> replaceAll = abc
> C:\tmp\tmp17>C:\harmony\classlib1.5\deploy\jdk\jre\bin\java.exe -cp .
> -showversion
test
> java version 1.5 (subset)
> (c) Copyright 1991, 2006 The Apache Software Foundation or its licensors, as
> applicable.
> unexpected exception: java.util.regex.PatternSyntaxException: No such group
> yet exists
at this point in the pattern near index: 0
> \1
> ^
> unexpected exception: java.util.regex.PatternSyntaxException: No such group
> yet exists
at this point in the pattern near index: 0
> \1
> ^
> java.util.regex.PatternSyntaxException: No such group yet exists at this
> point in the
pattern near index: 0
> \1
> ^
> at java.util.regex.Pattern.processTerminal(Pattern.java:950)
> at java.util.regex.Pattern.processSubExpression(Pattern.java:593)
> at java.util.regex.Pattern.processExpression(Pattern.java:376)
> at java.util.regex.Pattern.compileImpl(Pattern.java:279)
> at java.util.regex.Pattern.compile(Pattern.java:261)
> at java.util.regex.Pattern.compile(Pattern.java:1155)
> at java.lang.String.replaceAll(String.java:1782)
> at test.main(test.java:13)
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