XSLT - replace specific content of the text() node with a new node - regex

Question

I have a xml like this,
<doc>
<p>Biological<sub>89</sub> bases<sub>4456</sub> for<sub>8910</sub> sexual<sub>4456</sub>
differences<sub>8910</sub> in<sub>4456</sub> the brain exist in a wide range of
vertebrate species, including chickens<sub>8910</sub> Recently<sub>8910</sub> the
dogma<sub>8910</sub> of<sub>4456</sub> hormonal dependence for the sexual
differentiation of the brain has been challenged.</p>
</doc>
As you can see there are <sub> nodes and text() node contains inside the <p> node. and every <sub> node end, there is a text node, starting with a space. (eg: <sub>89</sub> bases : here before 'bases' text appear there is a space exists.) I need to replace those specific spaces with nodes.
SO the expected output should look like this,
<doc>
<p>Biological<sub>89</sub><s/>bases<sub>4456</sub><s/>for<sub>8910</sub><s/>sexual<sub>4456</sub>
<s/>differences<sub>8910</sub><s/>in<sub>4456</sub><s/>the brain exist in a wide range of
vertebrate species, including chickens<sub>8910</sub><s/>Recently<sub>8910</sub><s/>the
dogma<sub>8910</sub><s/>of<sub>4456</sub><s/>hormonal dependence for the sexual
differentiation of the brain has been challenged.</p>
</doc>
to do this I can use regular expression like this,
<xsl:template match="p/text()">
<xsl:analyze-string select="." regex="( )">
<xsl:matching-substring>
<xsl:choose>
<xsl:when test="regex-group(1)">
<s/>
</xsl:when>
</xsl:choose>
</xsl:matching-substring>
<xsl:non-matching-substring>
<xsl:value-of select="."/>
</xsl:non-matching-substring>
</xsl:analyze-string>
</xsl:template>
But this adds <s/> nodes to every spaces in the text() node. But I only need thi add nodes to that specific spaces.
Can anyone suggest me a method how can I do this..

Answer 1

If you only want to match text nodes that start with a space and are preceded by a sub element, you can put the condition in your template match
<xsl:template match="p/text()[substring(., 1, 1) = ' '][preceding-sibling::node()[1][self::sub]]">
And if you just want to remove the space at the start of the string, a simple replace will do.
<xsl:value-of select="replace(., '^\s+', '')" />
Try this XSLT
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:output method="xml" indent="no" />
<xsl:template match="p/text()[substring(., 1, 1) = ' '][preceding-sibling::node()[1][self::sub]]">
<s />
<xsl:value-of select="replace(., '^\s+', '')" />
</xsl:template>
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>

Answer 2

Just change the regex like so ^( ): it will match only the spaces at the beginning of the text part.
With this XSL snipped:
<xsl:analyze-string select="." regex="^( )">
Here is the result I obtain:
<p>Biological<sub>89</sub><s></s>bases<sub>4456</sub><s></s>for<sub>8910</sub><s></s>sexual<sub>4456</sub>
differences<sub>8910</sub><s></s>in<sub>4456</sub><s></s>the brain exist in a wide range of
vertebrate species, including chickens<sub>8910</sub><s></s>Recently<sub>8910</sub><s></s>the
dogma<sub>8910</sub><s></s>of<sub>4456</sub><s></s>hormonal dependence for the sexual
differentiation of the brain has been challenged.
</p>