Grouping the immediate nodes in XSLT - xslt

Question

I am using the XSLT 1.0 version and I have the below XML to transform,
<Root>
<Child No="1" Month="0" Date="13/08/2014" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="2" Month="1" Date="13/09/2014" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="3" Month="2" Date="13/10/2014" Payment="200">
<Totals amount="200"/>
</Child>
<Child No="4" Month="3" Date="13/11/2014" Payment="300">
<Totals amount="300"/>
</Child>
<Child No="5" Month="4" Date="13/12/2014" Payment="300">
<Totals amount="300"/>
</Child>
<Child No="6" Month="5" Date="13/01/2015" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="7" Month="6" Date="13/01/2015" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="8" Month="7" Date="13/01/2015" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="9" Month="8" Date="13/01/2015" Payment="100">
<Totals amount="100"/>
</Child>
<Child No="10" Month="9" Date="13/01/2015" Payment="100">
<Totals amount="100"/>
</Child>
</Root>
I wanted to transform The XML as
<PPS>
<PP>
<Ps>
<StartMonth>0</StartMonth>
<EndMonth>1</EndMonth>
<P>
<Amount>100</Amount>
<startP>1</startP>
</P>
<P>
<Amount>100</Amount>
<startP>2</startP>
</P>
</Ps>
</PP>
<PP>
<Ps>
<StartMonth>2</StartMonth>
<EndMonth>2</EndMonth>
<P>
<Amount>200</Amount>
<startP>3</startP>
</P>
</Ps>
</PP>
<PP>
<Ps>
<StartMonth>3</StartMonth>
<EndMonth>4</EndMonth>
<P>
<Amount>300</Amount>
<startP>4</startP>
</P>
<P>
<Amount>300</Amount>
<startP>5</startP>
</P>
</Ps>
</PP>
<PP>
<Ps>
<StartMonth>5</StartMonth>
<EndMonth>9</EndMonth>
<P>
<Amount>100</Amount>
<startP>6</startP>
</P>
<P>
<Amount>100</Amount>
<startP>7</startP>
</P>
<P>
<Amount>100</Amount>
<startP>8</startP>
</P>
<P>
<Amount>100</Amount>
<startP>9</startP>
</P>
<P>
<Amount>100</Amount>
<startP>10</startP>
</P>
</Ps>
</PP>
</PPS>
every time I wanted to create a "P" differing from the last Payment.
Here is the pseudo code, create a new PP, when child[n]/Payment <> child[n-1]/Payment.
P.S., I do not want to consider the Totals node even it has some values.
Many Thanks in advance.

Answer 1

You can use the following XSLT. It wouldn't have been so long if it was in XSLT2.0:
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" indent="yes" omit-xml-declaration="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/Root">
<PPS>
<xsl:for-each select="Child">
<xsl:variable name="Payment" select="#Payment"/>
<xsl:variable name="start-end">
<StartMonth>
<xsl:value-of select="#Month"/>
</StartMonth>
<xsl:choose>
<xsl:when test="following-sibling::*[1][self::Child and #Payment = $Payment]">
<EndMonth>
<xsl:apply-templates select="following-sibling::*[1]" mode="month">
<xsl:with-param name="Payment" select="$Payment"/>
</xsl:apply-templates>
</EndMonth>
</xsl:when>
<xsl:otherwise>
<EndMonth>
<xsl:value-of select="#Month"/>
</EndMonth>
</xsl:otherwise>
</xsl:choose>
</xsl:variable>
<xsl:if test="not(preceding-sibling::*[1][self::Child and #Payment = $Payment])">
<PP>
<Ps>
<xsl:copy-of select="$start-end"/>
<xsl:apply-templates select="current()"/>
<xsl:apply-templates select="following-sibling::*[1][self::Child and #Payment = $Payment]">
<xsl:with-param name="Payment" select="$Payment"/>
</xsl:apply-templates>
</Ps>
</PP>
</xsl:if>
</xsl:for-each>
</PPS>
</xsl:template>
<xsl:template match="Child">
<xsl:param name="Payment"/>
<P>
<Amount>
<xsl:value-of select="#Payment"/>
</Amount>
<startP>
<xsl:value-of select="#No"/>
</startP>
</P>
<xsl:apply-templates select="following-sibling::*[1][self::Child and #Payment = $Payment]">
<xsl:with-param name="Payment" select="$Payment"/>
</xsl:apply-templates>
</xsl:template>
<xsl:template match="Child" mode="month">
<xsl:param name="Payment"/>
<xsl:choose>
<xsl:when test="following-sibling::*[1][self::Child and #Payment = $Payment]">
<xsl:apply-templates select="following-sibling::*[1]" mode="month">
<xsl:with-param name="Payment" select="$Payment"/>
</xsl:apply-templates>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="#Month"/>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>