Generate XPath using XPath

Question

I have two separate types of XML documents (one is a.xml & the other is b.xml). Document a.xml, is my main source document, on which I have to run queries. Document b.xml contains all possible information to fetch records from a.xml.

Document: «a.xml»

<rs>
    <r id="r1">
        <f0>typeA</f0>
        <f1>contains value1, value2 and value3</f1>
    </r>
    <r id="r2">
        <f0>typeB</f0>
        <f1>contains value4 and value7</f1>
    </r>
    <r id="r3">
        <f0>typeA</f0>
        <f1>contains value2 and value5</f1>
    </r>
    <r id="r4">
        <f0>typeC</f0>
        <f1>contains value1 and value6</f1>
    </r>
    <r id="r5">
        <f0>typeA</f0>
        <f1>contains value5</f1>
    </r>
    <r id="r6">
        <f0>typeC</f0>
        <f1>contains value1, value2 and value3</f1>
    </r>
</rs>

---

Document: «b.xml»

<?xml version="1.0"?>
<qs>
    <q id="q1">
        <i0>typeA</i0>
        <i1>value1|value2|value3</i1>
        <i2>value18|value35</i2>
        <i3>value1|value7</i3>
    </q>
    <q id="q2">
        <i0>typeB</i0>
        <i1>value2|value7</i1>
        <i2>value9|value20</i2>
        <i3>value4</i3>
    </q>
</qs>

---

Now I like to generate dynamic XPath selector strings based on the values of b.xml to be stored in Document c.xml. And it would look like:

Document c.xml

<xps>
    <xp id="q1">
        <t1>/rs/r[contains(f0,'typeA') 
                and contains(f1,'value1') 
                and contains(f1,'value2') 
                and contains(f1,'value3')]</t1>
        <t2>/rs/r[contains(f0,'typeA') 
                and contains(f1,'value18') 
                and contains(f1,'value35')]</t2>
        <t3>/rs/r[contains(f0,'typeA') 
                and contains(f1,'value1') 
                and contains(f1,'value7')]</t3>
    </xp>
    <xp id="q2">
        <t1>/rs/r[contains(f0,'typeB') 
                and contains(f1,'value2') 
                and contains(f1,'value7')]</t1>
        <t2>/rs/r[contains(f0,'typeA') 
                and contains(f1,'value9') 
                and contains(f1,'value20')]</t2>
        <t3>/rs/r[contains(f0,'typeA') 
                and contains(f1,'value4')]</t3>
    </xp>
</xps>

---

If somebody here having any idea, how to do that job in XSLT version 1.0. Thanks in advance.

Answer 1

You cannot use a variable as an xpath selector in xslt version 1, however there are likely other ways you might accomplish this task. If you provide an idea of the problem rather than your intended solution people might be able to help :)

Answer 2

Here is a solution in XSLT 1.0:

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

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

    <xsl:template match="/">
        <xps>
            <xsl:apply-templates/>
        </xps>
    </xsl:template>

    <xsl:template match="q">
        <xp id="{@id}">
            <xsl:apply-templates/>
        </xp>
    </xsl:template>

    <xsl:template match="*[starts-with(name(), 'i')][not(self::i0)]">
        <xsl:element name="t{substring-after(name(), 'i')}">
            <xsl:text>/rs/r[contains(f0, '</xsl:text>
            <xsl:value-of select="preceding-sibling::i0"/>
            <xsl:text>')</xsl:text>
            <xsl:call-template name="more-conditions">
                <xsl:with-param name="list" select="."/>
            </xsl:call-template>
            <xsl:text>]</xsl:text>
        </xsl:element>
    </xsl:template>

    <xsl:template name="more-conditions">
        <xsl:param name="list"/>
        <xsl:param name="delimiter" select="'|'"/>

        <xsl:choose>
            <xsl:when test="contains($list, $delimiter)">
                <xsl:call-template name="more-conditions">
                    <xsl:with-param name="list" select="substring-before($list, $delimiter)"/>
                </xsl:call-template>
                <xsl:call-template name="more-conditions">
                    <xsl:with-param name="list" select="substring-after($list, $delimiter)"/>
                </xsl:call-template>
            </xsl:when>
            <xsl:otherwise>
                <xsl:text> and contains(f1, '</xsl:text>
                <xsl:value-of select="$list"/>
                <xsl:text>')</xsl:text>
            </xsl:otherwise>
        </xsl:choose>
    </xsl:template>

</xsl:stylesheet>

Applied to your input document, it produces the following output:

<xps>
    <xp id="q1">
        <t1>/rs/r[contains(f0, 'typeA') and contains(f1, 'value1') and contains(f1, 'value2') and contains(f1, 'value3')]</t1>
        <t2>/rs/r[contains(f0, 'typeA') and contains(f1, 'value18') and contains(f1, 'value35')]</t2>
        <t3>/rs/r[contains(f0, 'typeA') and contains(f1, 'value1') and contains(f1, 'value7')]</t3>
    </xp>
    <xp id="q2">
        <t1>/rs/r[contains(f0, 'typeB') and contains(f1, 'value2') and contains(f1, 'value7')]</t1>
        <t2>/rs/r[contains(f0, 'typeB') and contains(f1, 'value9') and contains(f1, 'value20')]</t2>
        <t3>/rs/r[contains(f0, 'typeB') and contains(f1, 'value4')]</t3>
    </xp>
</xps>

I added some of the whitespace. You can modify the transform based on your needs, but this should get you started.