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xml Module

The xml package contains interfaces for parsing and manipulating XML documents. Operation complexities and examples are documented on the interface pages:

  • ElementTree — xml.etree.ElementTree: parsing, searching, building and serializing element trees.
  • DOM — xml.dom, xml.dom.minidom and xml.dom.pulldom: document objects, DOM traversal and partial DOM trees built from a stream.
  • SAX — xml.sax and its submodules: parsing with event handlers.
  • Expat — xml.parsers.expat, which re-exports pyexpat: the Expat parser interface.

The package itself holds two string checks, added in Python 3.15. n is the characters in the string checked.

Complexity Reference

Validation helpers

Operation Time Space Notes
xml.is_valid_name(name) O(n) O(1) Python 3.15+. Whether name can be an element or attribute name: one regular-expression match against the whole string
xml.is_valid_text(data) O(n) O(1) Python 3.15+. Whether every character is legal in XML 1.0; the search stops at the first illegal one, so a string that fails early returns early

Checking Names and Text

Both checks read the string once and build nothing from it, so they are cheap enough to run on every name or text node before it is written out.

import sys

if sys.version_info >= (3, 15):
    import xml

    assert xml.is_valid_name('item-1')  # O(n)
    assert not xml.is_valid_name('1item')  # a name cannot start with a digit
    assert not xml.is_valid_name('a<b')

    assert xml.is_valid_text('tab\tand newline\n')  # O(n)
    assert not xml.is_valid_text('bell\x07')  # C0 controls other than TAB, CR and LF

Version Notes

  • Python 3.15+: xml.is_valid_name() and xml.is_valid_text()