How to remove particular element with content, based on its position

Question

Suggest for, how to remove 'mi' containg text 'aaaaa',

• if it is found under first child of msub and last position (text node)
• if it is found under second child of msub and first position (text node)

For quick review I placed comment in input XML as requirement. (XSLT 2)

Input XML:

<root>
<math>
<msub>
    <mrow>
        <mi mathcolor="red">aaaaa</mi>
        <mi>H</mi>
        <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's first child's last content -->
    </mrow>
    <mrow>
        <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's second child's first content -->
        <mn>2</mn>
        <mi mathcolor="red">aaaaa</mi>
    </mrow>
</msub>

<mi>log</mi>

<msub>
    <mrow>
        <mfence>
            <mrow>
                <mi mathcolor="red">aaaaa</mi>
                <mi>H</mi>
                <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's first child's last content -->
            </mrow>
        </mfence>
    </mrow>
    <mrow>
        <mrow>
            <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's second child's first content -->
            <mn>2</mn>
            <mi mathcolor="red">aaaaa</mi>
        </mrow>
    </mrow>
</msub>
</math>
</root>

XSLT:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>
    <xsl:template match="@*|node()">
        <xsl:copy><xsl:apply-templates select="node()|@*"/></xsl:copy>
    </xsl:template>

<xsl:template match="msub/*[count(preceding-sibling::*)=1]">
    <xsl:variable name="var1" select="descendant-or-self::text()[normalize-space(.)!=''][1]"/>
    <xsl:for-each select="mi[contains(., 'aaaa')]">
        <xsl:choose>
            <xsl:when test="contains($var1, 'aaaa')">
                <remove/>
            </xsl:when>
            <xsl:otherwise>
                <xsl:copy><xsl:apply-templates select="node()|@*"/></xsl:copy>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:for-each>
</xsl:template>

<xsl:template match="msub/*[count(preceding-sibling::*)=0]">
    <xsl:variable name="var1" select="descendant-or-self::text()[normalize-space(.)!=''][position()=last()]"/>
    <xsl:for-each select="mi[contains(., 'aaaa')]">
        <xsl:choose>
            <xsl:when test="contains($var1, 'aaaa')">
                <remove/>
            </xsl:when>
            <xsl:otherwise>
                <xsl:copy><xsl:apply-templates select="node()|@*"/></xsl:copy>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:for-each>
</xsl:template>

</xsl:stylesheet>

Required Result:

<root>
<math>
<msub>
    <mrow>
        <mi mathcolor="red">aaaaa</mi>
        <mi>H</mi>
        <remove/>
    </mrow>
    <mrow>
        <remove/>
        <mn>2</mn>
        <mi mathcolor="red">aaaaa</mi>
    </mrow>
</msub>

<mi>log</mi>

<msub>
    <mrow>
        <mfence>
            <mrow>
                <mi mathcolor="red">aaaaa</mi>
                <mi>H</mi>
                <remove/>
            </mrow>
        </mfence>
    </mrow>
    <mrow>
        <mrow>
            <remove/>
            <mn>2</mn>
            <mi mathcolor="red">aaaaa</mi>
        </mrow>
    </mrow>
</msub>
</math>
</root>

Answer 1

You could do something like this...

XML Input

<root>
    <math>
        <msub>
            <mrow>
                <mi mathcolor="red">aaaaa</mi>
                <mi>H</mi>
                <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's first child's last content -->
            </mrow>
            <mrow>
                <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's second child's first content -->
                <mn>2</mn>
                <mi mathcolor="red">aaaaa</mi>
            </mrow>
        </msub>

        <mi>log</mi>

        <msub>
            <mrow>
                <mfence>
                    <mrow>
                        <mi mathcolor="red">aaaaa</mi>
                        <mi>H</mi>
                        <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's first child's last content -->
                    </mrow>
                </mfence>
            </mrow>
            <mrow>
                <mrow>
                    <mi mathcolor="red">aaaaa</mi><!-- MI (with content 'aaaaa') to be removed, bcs MSUB's second child's first content -->
                    <mn>2</mn>
                    <mi mathcolor="red">aaaaa</mi>
                </mrow>
            </mrow>
        </msub>
    </math>
</root>

XSLT 1.0

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output indent="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="@*|node()[not(self::comment())]">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>

    <xsl:template match="
        msub/mrow[position()=last()]//mi[position()=1 and contains(.,'aaaaa')]|
        msub/mrow[position()=1]//mi[position()=last() and contains(.,'aaaaa')]"
        priority="1">
        <remove/>
    </xsl:template>

</xsl:stylesheet>

XML Output

<root>
   <math>
      <msub>
         <mrow>
            <mi mathcolor="red">aaaaa</mi>
            <mi>H</mi>
            <remove/>
         </mrow>
         <mrow>
            <remove/>
            <mn>2</mn>
            <mi mathcolor="red">aaaaa</mi>
         </mrow>
      </msub>
      <mi>log</mi>
      <msub>
         <mrow>
            <mfence>
               <mrow>
                  <mi mathcolor="red">aaaaa</mi>
                  <mi>H</mi>
                  <remove/>
               </mrow>
            </mfence>
         </mrow>
         <mrow>
            <mrow>
               <remove/>
               <mn>2</mn>
               <mi mathcolor="red">aaaaa</mi>
            </mrow>
         </mrow>
      </msub>
   </math>
</root