increment counter in XSLT 1.0

Question

This is the input XML:

<Move-Afile>
  <Afile>
    <Item>
      <PackNumber>1234</PackNumber>
    </Item>
    <Item>
      <PackNumber>567</PackNumber>
    </Item>
    <Item>
      <PackNumber>567</PackNumber>
    </Item>
    <Item>
      <PackNumber>126</PackNumber>
    </Item>
    <Item>
      <PackNumber>876</PackNumber>
    </Item>
  </Afile>
</Move-Afile>

<Item> is an unbounded element which contains <PackNumber> as a child element. For each pack number we need to increment the counter variable, but here one condition is present like if previous <PackNumber> is equal to current <PackNumber> we have to ignore the counter (there is no need to increment) like below output.

Inside the for-each, can we get the counter like below XSLT sample?

This is my XSLT template

<xsl:template match="/">
  <A>
    <target>
      <xsl:for-each select="/inp1:Move-Afile/inp1:Afile/inp1:Item/inp1:PalletNumber">

        <xsl:variable name="count">
          <!-- get the count here-->
        </xsl:variable>

        <counter>$count</counter>
        <PNumber><xsl:value-of select="."/></PNumber>

      </xsl:for-each>
    </target>
  </A>
</xsl:template>

This is the XML output:

<A>
  <target>
    <Item>
      <counter>1</counter><!-- if previous <PackNumber> is not equal to current <PackNumber> increment the count-->
      <PNumber>1234</PNumber>
    </Item>
    <Item>
      <counter>2</counter><!-- if previous <PackNumber> is not equal to current <PackNumber> increment the count-->
      <PNumber>567</PNumber>
    </Item>
    <Item><!-- if previous <PackNumber> is  equal to current <PackNumber> ignore the count-->no need to increment 
      <PNumber>567</PNumber>
    </Item>
    <Item>
      <counter>3</counter><!-- if previous <PackNumber> is not equal to current <PackNumber> increment the count-->
      <PNumber>126</PNumber>
    </Item>
    <Item><!-- if previous <PackNumber> is  equal to current <PackNumber> ignore the count-->no need to increment 
      <PNumber>126</PNumber>
    </Item>
  </target>
</A>

XML output 2:

<?xml version="1.0"?>
<A>
  <target>
    <counter>1</counter>
    <PNumber>1234</PNumber>
    <counter>2</counter>
    <PNumber>567</PNumber>
    <!-- IF PNumber is equal we have to ignore the Total loop -->
    <counter>3</counter>
    <PNumber>126</PNumber>
    <counter>4</counter>
    <PNumber>876</PNumber>
  </target>
</A>

Answer 1

Try this:

    <?xml version="1.0" encoding="utf-8"?>
    <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
        <xsl:output indent="yes"/>

        <xsl:template match="@*|node()">
            <xsl:copy>
                <xsl:apply-templates select="@*|node()"/>
            </xsl:copy>
        </xsl:template>

        <xsl:template match="text()" />

        <xsl:template match="PackNumber">
            <xsl:if test="not(preceding::PackNumber =.)" >
                <!-- if previous <PackNumber> is not equal to current <PackNumber> t-->

                <counter>
                    <xsl:value-of select="count(preceding::PackNumber[not(preceding::PackNumber= .)])+1"/>
                </counter>
            </xsl:if>
            <PNumber>
                <xsl:value-of select="."/>
            </PNumber>

        </xsl:template>

    <xsl:template match="/">
        <A>
            <target>
                <xsl:apply-templates select="//Item"/>
            </target>
        </A>
    </xsl:template>
    </xsl:stylesheet>

Update according the changed question:
get the count here (inside a for each loop as variable)
Try this:

    <?xml version="1.0" encoding="utf-8"?>

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

        <xsl:template match="@*|node()">
            <xsl:copy>
                <xsl:apply-templates select="@*|node()"/>
            </xsl:copy>
        </xsl:template>

        <xsl:template match="text()" />

        <xsl:template match="PackNumber" mode="count">
                <xsl:value-of select="count(preceding::PackNumber
                          [not(preceding::PackNumber= .)and not( . = current()/. ) ])+1"/>
        </xsl:template>

        <xsl:template match="/">
            <A>
                <target>
                    <xsl:for-each select="//Item/PackNumber">
                        <xsl:variable name="count">
                            <xsl:apply-templates select="." mode="count"/>
                        </xsl:variable>
                                <counter>
                                    <xsl:value-of select="$count"/>
                                </counter>
                                <PNumber>
                                    <xsl:value-of select="."/>
                                </PNumber>
                    </xsl:for-each>
                </target>
            </A>
        </xsl:template>
    </xsl:stylesheet>

Update Output:

<?xml version="1.0"?>
<A>
  <target>
    <counter>1</counter>
    <PNumber>1234</PNumber>
    <counter>2</counter>
    <PNumber>567</PNumber>
    <counter>2</counter>
    <PNumber>567</PNumber>
    <counter>3</counter>
    <PNumber>126</PNumber>
    <counter>4</counter>
    <PNumber>876</PNumber>
  </target>
</A>

Answer 2

Here is a short and very efficient solution, using Muenchian grouping:

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

 <xsl:key name="kPackNByVal" match="PackNumber" use="."/>

 <xsl:template match="Afile">
     <A>
       <target>
         <xsl:apply-templates select=
         "*/*[generate-id() = generate-id(key('kPackNByVal',.)[1])]"/>
       </target>
     </A>
 </xsl:template>

 <xsl:template match="PackNumber">
   <counter><xsl:value-of select="position()"/></counter>
   <PNumber><xsl:value-of select="."/></PNumber>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied on the provided XML document:

<Move-Afile>
  <Afile>
    <Item>
      <PackNumber>1234</PackNumber>
    </Item>
    <Item>
      <PackNumber>567</PackNumber>
    </Item>
    <Item>
      <PackNumber>567</PackNumber>
    </Item>
    <Item>
      <PackNumber>126</PackNumber>
    </Item>
    <Item>
      <PackNumber>876</PackNumber>
    </Item>
  </Afile>
</Move-Afile>

the wanted, correct result is produced:

<A>
   <target>
      <counter>1</counter>
      <PNumber>1234</PNumber>
      <counter>2</counter>
      <PNumber>567</PNumber>
      <counter>3</counter>
      <PNumber>126</PNumber>
      <counter>4</counter>
      <PNumber>876</PNumber>
   </target>
</A>