Universal regex-based XML parsing

Release date: April 1, 2024

Many experts claim (see answers to this question on StackOverflow) that one cannot universally and robustly parse XML using regex. But as of today (April 1, 2024), using the power of Python decorators, I am introducing a robust way of transforming regex-based XML parsers into universal, robust XML parsers.

Example

Here is a cute little example of a function that uses re.findall to find matching patterns in an XML string. To make this robust, we attach the regex_for_xml decorator and specify by which property we want to search for elements. Here we use find_by="tag" to search the XML document for elements of a given tag.

import re
from functools import partial
from decorator import regex_for_xml


@partial(regex_for_xml, find_by="tag")
def findall(pattern, xml):
    """My cool regex-based XML parser."""
    matches = re.findall(pattern, xml)
    return matches

The resulting findall function has an informative doc-string and returns all matching elements in a list:

xml_string = """<?xml version="1.0"?>
<data>
    <country name="Liechtenstein">
        <rank updated="yes">2</rank>
        <year>2008</year>
        <gdppc>141100</gdppc>
        <neighbor name="Austria" direction="E"/>
        <neighbor name="Switzerland" direction="W"/>
    </country>
    <country name="Singapore">
        <rank updated="yes">5</rank>
        <year>2011</year>
        <gdppc>59900</gdppc>
        <neighbor name="Malaysia" direction="N"/>
    </country>
    <country name="Panama">
        <rank updated="yes">69</rank>
        <year>2011</year>
        <gdppc>13600</gdppc>
        <neighbor name="Costa Rica" direction="W"/>
        <neighbor name="Colombia" direction="E"/>
    </country>
</data>"""

findall('gdppc', xml_string)
# [<Element 'gdppc' at 0x10a252980>, <Element 'gdppc' at 0x10a2521b0>, <Element 'gdppc' at 0x10a253ba0>]

(Example XML data taken from the Python Docs)

What the heck?

This is an April fools joke. If you like have a look at the links above, I find them quite entertaining. That being said, you should probably use a dedicated XML parser and avoid regex parsing if you can.

frederikwilde/regex-for-xml

Universal regex-based XML parsing

Example

What the heck?