process complicated conditional checks with XSLT 1.0 - xslt

Question

I have an XML file like so:
<root>
<node ID="1" />
<node ID="2" />
<node ID="3" />
<node ID="4" />
<node ID="5" />
<node ID="6" />
<node ID="7" get="1" />
<node ID="8" get="1 & 3" />
<node ID="9" get="(2 | 23) & 3" />
<node ID="10" get="((2 | 3) & 1) & 15" />
</root>
Ignore the first 6 nodes for a second. My XSLT is processing nodes 7-10. What I want to do is "process" the "get" as a formula to get true or false based on if a node exists and the formula. & is logical and and | is logical or.
So for example:
node 7 XSLT would return true since node 1 exists
node 8 XLST would return true since both node 1 and node 3 exist
node 9 would return true because node 2 and node 3 exists (even though node 23 does not because of the or
node 10 would return false because node 15 does not exists
Is there anyway to do something like this with pure XSLT 1.0?
If it matters, I can modify the format of the get value if there is some other format that'll make it easier to do what I want.
What I assume needs to happen is I send the value of the get for each node that I want to check (7-10 in this case) to a function that would "process" the formula and return true or false.

Answer 1

If it matters, I can modify the format of the get value if there is
some other format that'll make it easier to do what I want.
Well, if you reformat the get value so that:
a logical AND is written as and;
a logical OR is written as or;
each node is referred to as node[#ID=N], instead of just its ID number,
so that your input XML would actually look like this:
XML
<root>
<node ID="1" />
<node ID="2" />
<node ID="3" />
<node ID="4" />
<node ID="5" />
<node ID="6" />
<node ID="7" get="node[#ID=1]" />
<node ID="8" get="node[#ID=1] and node[#ID=3]" />
<node ID="9" get="(node[#ID=1] or node[#ID=23]) and node[#ID=3]" />
<node ID="10" get="((node[#ID=2] or node[#ID=1]) and node[#ID=1]) and node[#ID=15]" />
</root>
you can then apply the following stylesheet:
XSLT 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:axsl="http://www.w3.org/1999/XSL/TransformAlias">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:namespace-alias stylesheet-prefix="axsl" result-prefix="xsl"/>
<xsl:template match="/root">
<axsl:stylesheet version="1.0">
<axsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<axsl:template match="/root">
<output>
<xsl:for-each select="node[#get]">
<result ID="{#ID}">
<axsl:value-of select="boolean({#get})"/>
</result>
</xsl:for-each>
</output>
</axsl:template>
</axsl:stylesheet>
</xsl:template>
</xsl:stylesheet>
to receive this result:
<?xml version="1.0" encoding="UTF-8"?>
<axsl:stylesheet xmlns:axsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<axsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<axsl:template match="/root">
<output>
<result ID="7">
<axsl:value-of select="boolean(node[#ID=1])"/>
</result>
<result ID="8">
<axsl:value-of select="boolean(node[#ID=1] and node[#ID=3])"/>
</result>
<result ID="9">
<axsl:value-of select="boolean((node[#ID=1] or node[#ID=23]) and node[#ID=3])"/>
</result>
<result ID="10">
<axsl:value-of select="boolean(((node[#ID=2] or node[#ID=1]) and node[#ID=1])and node[#ID=15])"/>
</result>
</output>
</axsl:template>
</axsl:stylesheet>
This result is a valid XSLT stylesheet. Applying it to your input XML will produce the following result:
<?xml version="1.0" encoding="UTF-8"?>
<output>
<result ID="7">true</result>
<result ID="8">true</result>
<result ID="9">true</result>
<result ID="10">false</result>
</output>