Source code:
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The 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.
Note
If you need to parse untrusted or unauthenticated data, see
.
Changed in version 3.7.1: The SAX parser no longer processes general external entities by default to increase security by default. To enable processing of external entities, pass a custom parser instance in:
fromxml.dom.pulldomimportparsefromxml.saximportmake_parserfromxml.sax.handlerimportfeature_external_gesparser=make_parser()parser.setFeature(feature_external_ges,True)parse(filename,parser=parser)Example:
fromxml.domimportpulldomdoc=pulldom.parse('sales_items.xml')forevent,nodeindoc:ifevent==pulldom.START_ELEMENTandnode.tagName=='item':ifint(node.getAttribute('price'))>50:doc.expandNode(node)print(node.toxml())event is one of the following constants, and node is the node which the event is about. The nodes implement the
interfaces; they are created by the DOM implementation given to
, which is
by default.
xml.dom.pulldom.START_DOCUMENT
xml.dom.pulldom.END_DOCUMENT
The start and the end of the document. node is the
.
xml.dom.pulldom.START_ELEMENT
xml.dom.pulldom.END_ELEMENT
The start tag and the end tag of an element. node is the
.
xml.dom.pulldom.CHARACTERS
Character data. node is the
node.
xml.dom.pulldom.IGNORABLE_WHITESPACE
White space in element content, as declared in the DTD. node is the
node.
A comment. node is the
node.
xml.dom.pulldom.PROCESSING_INSTRUCTION
A processing instruction. node is the
node.
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
method and switch to DOM-related processing.
classxml.dom.pulldom.PullDOM(documentFactory=None)
Subclass of
xml.sax.handler.ContentHandler
which turns SAX events into the events of the pull parser. The nodes are created, but they are not added to the tree, unless
is called. documentFactory, if given, is a DOM implementation used to create the document; by default the implementation of
is used.
classxml.dom.pulldom.SAX2DOM(documentFactory=None)
Subclass of
which also adds every created node to the tree, so that the complete document is built.
xml.dom.pulldom.parse(stream_or_string, parser=None, bufsize=None)
Return a
from the given input. stream_or_string may be either a file name, or a file-like object. parser, if given, must be an
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
function instead:
xml.dom.pulldom.parseString(string, parser=None)
Return a
that represents the string. string must be a
instance; to parse bytes, pass a binary file object to
.
xml.dom.pulldom.default_bufsize
Default value for the bufsize parameter to
.
The value of this variable can be changed before calling
and the new value will take effect.
DOMEventStream Objects
classxml.dom.pulldom.DOMEventStream(stream, parser, bufsize)
Produce the events for the data read from the file object stream by the
parser. The data is read by bufsize bytes, or characters for a text stream, at a time.
Changed in version 3.11: Support for
method has been removed.
getEvent()
Return the next (event,node) tuple, or None at the end of the document. See above for the events and the corresponding nodes. The current node does not contain information about its children, unless
is called.
expandNode(node)
Expands all children of node into node. Example:
fromxml.domimportpulldomxml='<html><title>Foo</title> <p>Some text <div>and more</div></p> </html>'doc=pulldom.parseString(xml)forevent,nodeindoc:ifevent==pulldom.START_ELEMENTandnode.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())reset()
Discard the events which are not read yet and prepare the object for parsing a new document.
clear()
Release the parser and the document. The stream is not closed, and the object can no longer be used.