How to solved "A sequence of more than one item is not allowed as the result of call to mf:extract-year" because my Input para in year one time and two times e.g. (SD NY 1967) 268 F Supp 289, aff’d (2d Cir 1968) after run last two entry's s/b not moved.
Input
<root>
<p content-type="emCase"><named-content content-type="emEntry">A.H. Emery Co. v Marcan Prods. Corp. (SD NY 1967) 268 F Supp 289, aff’d (2d Cir 1968) 389 F2d 11:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">A.M. v Albertsons, LLC (2009) 178 CA4th 455:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">ABBA Rubber Co. v Seaquist (1991) 235 CA3d 1:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">AFL-CIO v Unemployment Ins. Appeals Bd. (1994) 23 CA4th 51:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">AFL-CIO v Unemployment Ins. Appeals Bd. (1996) 13 C4th 1017:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (2017) 2 C5th 1074:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (2018) 2 C5th 1074:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (9th Cir 2017) 865 F3d 1261:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Frlekin v Apple, Inc. (9th Cir 2017) 870 F3d 867:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Frlekin v Apple, Inc. (review granted Sept. 20, 2017, S243805) 2017 Cal Lexis 7496:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Bradford Technols., Inc. v NCV Software.com (ND Cal, Aug. 6, 2013, No. C 11–04621 EDL) 2013 US Dist Lexis 111502:</named-content></p>
<p content-type="emCase"><named-content content-type="emEntry">Bradford Technols., Inc. v NCV Software.com (ND Cal, Jan. 4, 2013, No. C 11–04621 EDL) 2013 US Dist Lexis 1592:</named-content></p>
</root>
XSLT
<xsl:function name="mf:extract-year" as="xs:integer?">
<xsl:param name="input" as="xs:string"/>
<xsl:sequence
select="analyze-string($input, '\((.*?)([0-9]{4})\)')/*:match/*:group[@nr = 2]"/>
</xsl:function>
<xsl:function name="mf:extract-sort" as="xs:string?">
<xsl:param name="input" as="xs:string"/>
<xsl:sequence
select="analyze-string($input, '\((.*?)\)')/*:match/*:group[@nr = 1]"/>
</xsl:function>
<xsl:template match="@*|node()">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="root">
<xsl:copy>
<xsl:for-each-group select="p" group-adjacent="substring-before(named-content[@content-type = 'emEntry'], '(')">
<xsl:apply-templates select="current-group()">
<xsl:sort select="let $year := mf:extract-year(.)
return if ($year) then -$year else 1"/>
<xsl:sort select="let $sort := mf:extract-sort(.)
return if ($sort) then $sort else 1" order="descending"/>
</xsl:apply-templates>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>
Expected output
<root>
<p content-type="emCase">
<named-content content-type="emEntry">A.H. Emery Co. v Marcan Prods. Corp. (SD NY 1967) 268 F Supp 289, aff’d (2d Cir 1968) 389 F2d 11:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">A.M. v Albertsons, LLC (2009) 178 CA4th 455:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">ABBA Rubber Co. v Seaquist (1991) 235 CA3d 1:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">AFL-CIO v Unemployment Ins. Appeals Bd. (1996) 13 C4th 1017:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">AFL-CIO v Unemployment Ins. Appeals Bd. (1994) 23 CA4th 51:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (2018) 2 C5th 1074:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (9th Cir 2017) 865 F3d 1261:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Mendoza v Nordstrom, Inc. (2017) 2 C5th 1074:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Frlekin v Apple, Inc. (review granted Sept. 20, 2017, S243805) 2017 Cal Lexis 7496:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Frlekin v Apple, Inc. (9th Cir 2017) 870 F3d 867:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Bradford Technols., Inc. v NCV Software.com (ND Cal, Aug. 6, 2013, No. C 11–04621 EDL) 2013 US Dist Lexis 111502:</named-content>
</p>
<p content-type="emCase">
<named-content content-type="emEntry">Bradford Technols., Inc. v NCV Software.com (ND Cal, Jan. 4, 2013, No. C 11–04621 EDL) 2013 US Dist Lexis 1592:</named-content>
</p>
</root>
To summarize what we established in the comments, the function to extract the year needs to be adapted to return only the first match with *:match[1] and for data in parenthesis where you also have a complete date we need to extract and use a further sort key:
<xsl:param name="months" as="xs:string*"
select="'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'"/>
<xsl:param name="date-pattern" as="xs:string"
select="'\((.*?)((' || string-join($months, '|') || ')\. ([0-9]{1,2}), ([0-9]{4})).*?\)'"/>
<xsl:output indent="yes"/>
<xsl:function name="mf:extract-date" as="xs:date?">
<xsl:param name="input" as="xs:string"/>
<xsl:sequence
select="let $match := analyze-string($input, $date-pattern)/*:match[1]
return
if ($match)
then xs:date(
$match//*:group[@nr = 5]
|| '-' || format-integer(index-of($months, $match//*:group[@nr = 3]), '00')
|| '-' || format-integer($match//*:group[@nr = 4], '00'))
else ()"/>
</xsl:function>
<xsl:template match="root">
<xsl:copy>
<xsl:for-each-group select="p" group-adjacent="substring-before(named-content[@content-type = 'emEntry'], '(')">
<xsl:apply-templates select="current-group()">
<xsl:sort select="let $year := mf:extract-year(.)
return if ($year) then -$year else 1"/>
<xsl:sort select="let $date := mf:extract-date(.)
return if (exists($date)) then $date else 1" order="descending"/>
<xsl:sort select="let $sort := mf:extract-sort(.)
return if ($sort) then $sort else 1" order="descending"/>
</xsl:apply-templates>
</xsl:for-each-group>
</xsl:copy>
</xsl:template>