How to implement a dynamic array in xslt

You can declare a dynamic array like this:

<xsl:variable name="myarray">
    <item ord="-1" index="-1"/>
</xsl:variable>

Code with some tests (i assume you've already learned how to program loops in XSLT so i don't get into more detail here):

Code

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

    <xsl:output method="xml" indent="yes"/> 

    <xsl:variable name="myarray">
        <item ord="-1" index="-1"/>
    </xsl:variable>
        
    <xsl:template match="/">
        <xsl:param name="index"/>
        <xsl:param name="value"/>
        <xsl:if test="./*[@index = $index] and $value">
            <xsl:variable name="myOrd" select="./*[@index = $index]/@ord"/>
            <xsl:copy-of select="./*[@ord &lt; $myOrd]"/>
            <item ord="{./*[@index = $index]/@ord}" index="{$index}"><xsl:value-of select="$value"/></item>
            <xsl:copy-of select="./*[@ord &gt; $myOrd]"/>
        </xsl:if>
        <xsl:if test="./*[@index = $index] and not($value)">
            <xsl:variable name="myOrd" select="./*[@index = $index]/@ord"/>
            <xsl:copy-of select="./*[@ord &lt; $myOrd]"/>
            <xsl:copy-of select="./*[@ord &gt; $myOrd]"/>
        </xsl:if>
        <xsl:if test="not(./*[@index = $index])">
            <xsl:variable name="maxOrd" select="number(./*[last()]/@ord + 1)"/>
            <xsl:copy-of select="./*[@ord &lt; $maxOrd]"/>
            <item ord="{$maxOrd}" index="{$index}"><xsl:value-of select="$value"/></item>
        </xsl:if>
    </xsl:template>

    <xsl:template name="test"> 

        <!-- start of the loop -->

        <!-- iteration step 1 -->
        <xsl:variable name="myarray"> 
            <xsl:apply-templates select="$myarray">
                <xsl:with-param name="index" select="3"/>
                <xsl:with-param name="value" select="'value at 3'"/>
            </xsl:apply-templates>
        </xsl:variable>
        <xsl:apply-templates select="$myarray" mode="dump"/>
        <dump step="1">
            <xsl:copy-of select="$myarray/*[@ord &gt;= 0]"/>
        </dump>

        <!-- iteration step 2 -->
        <xsl:variable name="myarray"> 
            <xsl:apply-templates select="$myarray">
                <xsl:with-param name="index" select="15"/>
                <xsl:with-param name="value" select="'value at 15'"/>
            </xsl:apply-templates>
        </xsl:variable>
        <xsl:apply-templates select="$myarray" mode="dump"/>
        <dump step="2">
            <xsl:copy-of select="$myarray/*[@ord &gt;= 0]"/>
        </dump>

        <!-- iteration step 3 -->
        <xsl:variable name="myarray"> 
            <xsl:apply-templates select="$myarray">
                <xsl:with-param name="index" select="5"/>
                <xsl:with-param name="value" select="'value at 5'"/>
            </xsl:apply-templates>
        </xsl:variable>
        <xsl:apply-templates select="$myarray" mode="dump"/>
        <dump step="3">
            <xsl:copy-of select="$myarray/*[@ord &gt;= 0]"/>
        </dump>

        <!-- iteration step 4 -->
        <xsl:variable name="myarray"> 
            <xsl:apply-templates select="$myarray">
                <xsl:with-param name="index" select="5"/>
                <xsl:with-param name="value" select="'newValue at 5'"/>
            </xsl:apply-templates>
        </xsl:variable>
        <xsl:apply-templates select="$myarray" mode="dump"/>
        <dump step="4">
            <xsl:copy-of select="$myarray/*[@ord &gt;= 0]"/>
        </dump>
        
        <!-- iteration step 5 -->
        <xsl:variable name="myarray"> 
            <xsl:apply-templates select="$myarray">
                <xsl:with-param name="index" select="15"/>
                <xsl:with-param name="value" select="''"/>
            </xsl:apply-templates>
        </xsl:variable>
        <xsl:apply-templates select="$myarray" mode="dump"/>
        <dump step="5">
            <xsl:copy-of select="$myarray/*[@ord &gt;= 0]"/>
        </dump>

        <!-- end of the loop -->
    </xsl:template> 

    <xsl:template match="/" mode="dump">
        <xsl:message>Array:</xsl:message>
        <xsl:for-each select="*[@index &gt; -1]">
            <xsl:sort select="@index" data-type="number"/>
            <xsl:message>
                <xsl:value-of select="concat('array[',@index,'] = ',.)"/>
            </xsl:message>
        </xsl:for-each>
    </xsl:template> 
    
</xsl:stylesheet>

Comment

• step 1: set value at index 3
• step 2: set value at index 15
• step 3: set value at index 5
• step 4: set value at index 5 (new value)
• step 5: remove value at index 15

Console Output

Array:
array[3] = value at 3
Array:
array[3] = value at 3
array[15] = value at 15
Array:
array[3] = value at 3
array[5] = value at 5
array[15] = value at 15
Array:
array[3] = value at 3
array[5] = newValue at 5
array[15] = value at 15
Array:
array[3] = value at 3
array[5] = newValue at 5

XML Output

  <?xml version="1.0" encoding="UTF-8"?>
  <dump step="1">
     <item ord="0" index="3">value at 3</item>
  </dump>
  <dump step="2">
     <item ord="0" index="3">value at 3</item>
     <item ord="1" index="15">value at 15</item>
  </dump>
  <dump step="3">
     <item ord="0" index="3">value at 3</item>
     <item ord="1" index="15">value at 15</item>
     <item ord="2" index="5">value at 5</item>
  </dump>
  <dump step="4">
     <item ord="0" index="3">value at 3</item>
     <item ord="1" index="15">value at 15</item>
     <item ord="2" index="5">newValue at 5</item>
  </dump>
  <dump step="5">
     <item ord="0" index="3">value at 3</item>
     <item ord="2" index="5">newValue at 5</item>
  </dump>