Regular Expression Question

bonekrusher · April 16th, 2007, 05:05 PM

Hi,

I am currently trying to analyze a string for a pattern, but I dont think I have the concept right. I am looking for a pattern like:

[\d{2}]\-[\d{2}]\-[\d{2}]

00-00-00

I am able to return the string which cotains the pattern, however I want to be able to just return the pattern.. e.g

21-00-00

Code:

<xsl:variable name="numbers" as="xs:string*">
                                    <xsl:analyze-string select="." regex="[\d{2}]\-[\d{2}]\-[\d{2}]">
                                        <xsl:matching-substring>
                                            <xsl:sequence select="."/>
                                        </xsl:matching-substring>
                                    </xsl:analyze-string>
                                </xsl:variable>
                                <xsl:variable name="all" select="replace(.,'([^0-9\.][^0-9\.][^-])','')"/>
                                <xsl:value-of select="$all"/>

I can't figure out this line

<xsl:variable name="all" select="replace(.,'([^0-9\.][^0-9\.][^-])','')"/>

mhkay · April 16th, 2007, 09:25 PM

I think your variable $numbers is OK, except that the regex attribute is an AVT and therefore all curly braces need to be doubled - a popular gotcha.

I'm afraid I can't figure out your $all variable either. I've no idea what you're trying to achieve with this.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

bonekrusher · April 17th, 2007, 06:08 AM

Hi Michael,

Thanks for the guidance on AVT - curly brackets...

As for the regex:

I am trying to extract a number that has this pattern:

##-##-##

However the following replace() extracts all the numbers, even if they do not match the pattern:

<xsl:variable name="all" select="replace(.,'[^\d\-]','')"/>

"The policy number 21-00-00 is in section 1"

would return:

21-00-001

Perfered output:

21-00-00

Thanks for the help.

mhkay · April 17th, 2007, 06:33 AM

Well,

'([^0-9\.][^0-9\.][^-])'

means "a character that isn't a digit or dot, followed by a character that isn't a digit or dot, followed by a character that isn't a hyphen".

So if you apply that to

"The policy number 21-00-00 is in section 1"

Then it will first match "The", then " po", then "lic", then "y n", then "umb", then "er " (by chance the number of characters before the 21-00-00 is a multiple of three), then " is", then " in", then " se", then "cti", then "on ". It doesn't match the final "1" so that is left in your string after the replacement (the same would be true if the final "1" were "A").

So you've definitely got the concept wrong!

I'm not sure why you don't like the analyze-string solution, but if you want to do this using replace, and if there's only one occurrence of the dd-dd-dd in your input string, then you can use

replace($in, '^.*(\d\d-\d\d-\d\d).*$', '$1')

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

bonekrusher · April 17th, 2007, 06:58 AM

Hi Michael,

I took your suggestion and used the analyze-string method. Not escaping the curly brackets was the problem.

Thanks again!