Python Standard Library

The xmllib Module

The xmlib module provides a simple XML parser, using regular expressions to pull the XML data apart, as shown in Example 5-1. The parser does basic checks on the document, such as a check to see that there is only one top-level element and a check to see that all tags are balanced.

You feed XML data to this parser piece by piece (as data arrives over a network, for example). The parser calls methods in itself for start tags, data sections, end tags, and entities, among other things.

If you’re only interested in a few tags, you can define special start_tag and end_tag methods, where tag is the tag name. The start functions are called with the attributes given as a dictionary.

Example 5-1. Using the xmllib Module to Extract Information from an Element

File: xmllib-example-1.py

import xmllib

class Parser(xmllib.XMLParser):
    # get quotation number

    def _ _init_ _(self, file=None):
        xmllib.XMLParser._ _init_ _(self)
        if file:
            self.load(file)

    def load(self, file):
        while 1:
            s = file.read(512)
            if not s:
                break
            self.feed(s)
        self.close()

    def start_quotation(self, attrs):
        print "id =>", attrs.get("id")
        raise EOFError

try:
    c = Parser()
    c.load(open("samples/sample.xml"))
except EOFError:
    pass

id => 031

Example 5-2 contains a simple (and incomplete) rendering engine. The parser maintains an element stack (_ _tags), which it passes to the renderer, together with text fragments. The renderer looks up the current tag hierarchy in a style dictionary, and if it isn’t already there, ...