Saxon

Reported by user:

regex problem in Saxon-HE 9.8.0.7N (and possibly other versions).

When using the native .NET regex engine (using the ";n" flag), capturing groups seem to be ignored.

Here is a style sheet that isolates the issue:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
    <xsl:variable name="input" select="'abc'"/>
    <xsl:variable name="pattern" select="'a(.)c'"/>
    <xsl:variable name="replacement" select="'x$1z'"/>
    <xsl:template match="/">
        <data>
            <test><xsl:value-of select="replace($input, $pattern, $replacement)"/> (default)</test>
            <test><xsl:value-of select="replace($input, $pattern, $replacement, ';j')"/> (Java)</test>
            <test><xsl:value-of select="replace($input, $pattern, $replacement, ';n')"/> (.NET)</test>
        </data>
    </xsl:template>
</xsl:stylesheet>

When executed (on Windows 7, using ASP.NET or the Transform.exe tool) I get:

<data>
   <test>xbz (default)</test>
   <test>xbz (Java)</test>
   <test>xz (.NET)</test>
</data>

The capturing group syntax should be valid on .NET as well:

https://docs.microsoft.com/en-us/dotnet/standard/base-types/grouping-constructs-in-regular-expressions#matched_subexpression

There is, however, an option called ExplicitCapture that disables capturing with plain parentheses:

https://docs.microsoft.com/en-us/dotnet/standard/base-types/regular-expression-options

I couldn't help noticing that this option is activated with a .NET specific flag "n".