Converting perl snippet to java

Question

I want to rewrite a perl code in java:

sub validate_and_fix_regex {
    my $regex = $_[0];
    eval { qr/$regex/ };
    if ($@) {
        $regex = rquote($regex);
    }
    return $regex;
}

sub rquote {
    my $string = $_[0] || return;
    $string =~ s/([^A-Za-z_0-9 "'\\])/\\$1/g;
    return $string;
}

the code gets a regex and fix it if it has any escaped character. i cant find any alternative for eval { qr/$regex/ }; and $string =~ s/([^A-Za-z_0-9 "'\\])/\\$1/g; in java.

ikegami · Accepted Answer · 2015-06-29 00:19:03Z

2

For qr, check out Pattern.compile, which throws a PatternSyntaxException if the given string isn't a valid regex.
For s///, check out String.replaceAll.
eval BLOCK is named try in Java.

Putting it all together: you would want to invoke Pattern.compile in the body of a try-catch. If you catch a PatternSyntaxExpression, you would invoke rquote, and use String.replaceAll there.

edited Jun 29, 2015 at 0:19

ikegami

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answered Jun 28, 2015 at 6:31

yshavit

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6 Comments

mrd abd Over a year ago

what is $1? how use it in String.replaceAll

yshavit Over a year ago

Do you know what it is in the original perl you posted? If not, that would be where to start, but that's a different question, and I'd recommend you read up on Perl's regexes (and regexes in general). If you do understand that, I'm not sure what the question is -- the String.replaceAll docs link to plenty of good docs.

mrd abd Over a year ago

The orginal code is here: github.com/sullo/nikto/blob/master/program/plugins/… line 3000.

mrd abd Over a year ago

thanks for help.. $1 is capture group. and String.replaceAll doesn't support capture group. stackoverflow.com/a/1277171/2730925 is used instead of replaceALL.

yshavit Over a year ago

String.replaceAll absolutely supports capture groups. "hello world".replaceAll("l(\\w)", "_$1") results in "he_lo wor_d".

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