XTRAN Example — Analyze XML Tags & Attributes

Scenario — you want to analyze the use of tags and tag attributes in XML.

XTRAN to the rescue!

XTRAN treats XML as a computer language, in which each tag, line and segment of text, or end tag is a "statement", and each tag attribute is a "statement attribute".

The following example uses an XTRAN rules file comprising 131 non-comment lines of XTRAN's rules language ("meta-code") to analyze all tags and attributes in XML.

The XML mining rules for this example can easily be enhanced to produce DSV output that can be interactively queried using existing XTRAN rules.

The following is an English paraphrase of the XTRAN rules used for this example:

    For each XML tag occurrence
        Tally tag occurrence
        For each of tag's attributes if any
            Tally attribute occurrence for tag
    Sort tags
    For each XML tag seen, alphabetically
        Report tag tally
        Sort attributes for tag
        For each attribute seen for this tag, alphabetically
            Report attribute tally

How can such powerful and generalized XML analysis be automated in only 131 code lines of XTRAN rules? Because there is so much capability already available as part of XTRAN's rules language. These rules take advantage of the following functionality:

Text file input and output
Text manipulation
Text formatting
Delimited list manipulation
Environment variable manipulation
"Per statement" recursive iterator
Access to XTRAN's Internal Representation (XIR)
Navigation in XIR
Meta-variable pointers

Process Flowchart

Here is a flowchart for this process, in which the elements are color coded:

BLUE for XTRAN versions (runnable programs)
ORANGE for XTRAN rules (text files)
RED for code
PURPLE for text data files

XML input:

<tag1><tag2/><tag3 att1="att1v" att2="att2v">
This is the first line of text, followed by a comment.<!-- comment 1 -->
This is the second line of text, with no comment.
</tag3>
<!-- comment 2 -->
This is the third line of text, preceded by a comment.
<tag3>Some text in a "tag3".</tag3>
<tag4 attb="attbv1" atta/>
This is more nonmarkup text.<tag4 attb="attbv2"/>
</tag1>

Output:

Running the rules shown above on the XML input shown above generated the following XTRAN analysis output. Note how each "empty" tag is indicated with a trailing /.

                          XML Tag and Attribute Usage

tag1                1
tag2/               1
tag3                2
    att1        1
    att2        1
tag4/               2
    atta        1
    attb        2