How can I use XSLT 1.0 to add structure to a non-heirarchal XML file?

问题

I have some non-heirarchal xml that has pseudo-structure. Every object declares a parent (except the "root" object) and zero or more children, but does so using ids and reference attributes rather than a nested structure. I would like to convert this to a nested structure.

<document>
    <object id="6" children="12,15"/>
    <object id="12" parent="6" children="13,18"/>
    <object id="13" parent="12" children="14,16,17"/>
    <object id="14" parent="13"/>
    <object id="15" parent="6" children="21,22"/>
    <object id="16" parent="13"/>
    <object id="17" parent="13"/>
    <object id="18" parent="12" children="23,25"/>
    <object id="19" parent="23"/>
    <object id="21" parent="15"/>
    <object id="22" parent="15"/>
    <object id="23" parent="18" children="19,24"/>
    <object id="24" parent="23"/>
    <object id="25" parent="18"/>
</document>

For the record, the actual document also contains object definitions, which the objects also reference in an attribute, similar to a class but I need to retrieve the element name from the definition by, again, reference id. At some point in the process I convert the names of each "object" to "template" or "subsection". If it simplifies things I can perform this operation after applying the structure. I also have a tokenize "function" for the children attribute, as I am using XSLT 1.0, which doesn't have it built-in.

So for the example above I would like this output:

<document>
    <object id="6">
        <object id="12">
            <object id="13">
                <object id="14"/>
                <object id="16"/>
                <object id="17"/>
            </object>
            <object id="18">
                <object id="23">
                    <object id="19"/>
                    <object id="24"/>
                </object>
                <object id="25"/>
            </object>
        </object>
        <object id="15">
            <object id="21"/>
            <object id="22"/>
        </object>
    </object>
</document>

Please keep in mind that these object elements contain other information, attributes, data, etc. These have been removed to simplify the example, but may add a layer of complexity to the problem.

If possible I would like to do this in an elegant and extensible way. I am not forced to but would prefer to use XSL 1.0 (so that it can be integrated with the existing server software).

Thank you kindly to anyone who can help me or point me in the right direction!

回答1:

Without doing the full XSLT, you could structure your transform like below: Basically, the template for Books would call an apply-templates for chapters, and the template for chapters would apply-templates for topics, etc. The key here, is putting the id from the parent into a variable, so that you can use it in subsequent apply-template calls to find the children.

<document>
   <xsl:apply-templates select="/document/book" />
</document>

<xsl:template match="/document/book">
   <xsl:variable name="bookid">
      <xsl:value-of select="@id"/>
   </xsl:variable>
   <xsl:element name="book">
      <xsl:attribute name="id">
         <xsl:value-of select="@id"/>
      </xsl:attribute>
      <xsl:apply-templates select="/document/chapter[@parent=$bookid]" />
   </xsl:element>
</xsl:template>

<xsl:template match="/document/chapter">
   Template for chapter would be replicated from the book template above
   .
   .
   .
</xsl:template>

回答2:

This short and simple, complete transformation:

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

 <xsl:key name="kChildren" match="object" use="@parent"/>

 <xsl:template match="/*">
   <document>
     <xsl:apply-templates select="*[not(@parent)]"/>
   </document>
 </xsl:template>

 <xsl:template match="object">
  <object id="{@id}">
    <xsl:apply-templates select="key('kChildren', @id)"/>
  </object>
 </xsl:template>
</xsl:stylesheet>

when applied on the provided XML document:

<document>
    <object id="6" children="12,15"/>
    <object id="12" parent="6" children="13,18"/>
    <object id="13" parent="12" children="14,16,17"/>
    <object id="14" parent="13"/>
    <object id="15" parent="6" children="21,22"/>
    <object id="16" parent="13"/>
    <object id="17" parent="13"/>
    <object id="18" parent="12" children="23,25"/>
    <object id="19" parent="23"/>
    <object id="21" parent="15"/>
    <object id="22" parent="15"/>
    <object id="23" parent="18" children="19,24"/>
    <object id="24" parent="23"/>
    <object id="25" parent="18"/>
</document>

produces the wanted, correct result:

<document>
    <object id="6">
        <object id="12">
            <object id="13">
                <object id="14"/>
                <object id="16"/>
                <object id="17"/>
            </object>
            <object id="18">
                <object id="23">
                    <object id="19"/>
                    <object id="24"/>
                </object>
                <object id="25"/>
            </object>
        </object>
        <object id="15">
            <object id="21"/>
            <object id="22"/>
        </object>
    </object>
</document>

Explanation: Proper use of keys.

来源：https://stackoverflow.com/questions/9981835/how-can-i-use-xslt-1-0-to-add-structure-to-a-non-heirarchal-xml-file