Source code: Lib/xml/dom/pulldom.py
xml.dom.pulldom module provides a “pull parser” which can also be asked to produce DOM-accessible fragments of the document where necessary. The basic concept involves pulling “events” from a stream of incoming XML and processing them. In contrast to SAX which also employs an event-driven processing model together with callbacks, the user of a pull parser is responsible for explicitly pulling events from the stream, looping over those events until either processing is finished or an error condition occurs.
from xml.dom import pulldom doc = pulldom.parse('sales_items.xml') for event, node in doc: if event == pulldom.START_ELEMENT and node.tagName == 'item': if int(node.getAttribute('price')) > 50: doc.expandNode(node) print(node.toxml())
event is a constant and can be one of:
node is an object of type
Since the document is treated as a “flat” stream of events, the document “tree” is implicitly traversed and the desired elements are found regardless of their depth in the tree. In other words, one does not need to consider hierarchical issues such as recursive searching of the document nodes, although if the context of elements were important, one would either need to maintain some context-related state (i.e. remembering where one is in the document at any given point) or to make use of the
DOMEventStream.expandNode() method and switch to DOM-related processing.
xml.dom.pulldom.parse(stream_or_string, parser=None, bufsize=None)
DOMEventStream from the given input. stream_or_string may be either a file name, or a file-like object. parser, if given, must be an
XMLReader object. This function will change the document handler of the parser and activate namespace support; other parser configuration (like setting an entity resolver) must have been done in advance.
If you have XML in a string, you can use the
parseString() function instead:
DOMEventStream that represents the (Unicode) string.
Default value for the bufsize parameter to
The value of this variable can be changed before calling
parse() and the new value will take effect.
class xml.dom.pulldom.DOMEventStream(stream, parser, bufsize)
Return a tuple containing event and the current node as
xml.dom.minidom.Document if event equals
xml.dom.minidom.Element if event equals
xml.dom.minidom.Text if event equals
CHARACTERS. The current node does not contain informations about its children, unless
expandNode() is called.
Expands all children of node into node. Example:
from xml.dom import pulldom xml = '<html><title>Foo</title> <p>Some text <div>and more</div></p> </html>' doc = pulldom.parseString(xml) for event, node in doc: if event == pulldom.START_ELEMENT and node.tagName == 'p': # Following statement only prints '<p/>' print(node.toxml()) doc.expandNode(node) # Following statement prints node with all its children '<p>Some text <div>and more</div></p>' print(node.toxml())
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