Tim van der Leeuw wrote:
Hi,
I'm trying to create a regular expression for matching some particular
XML strings. I want to extract the contents of a particular XML tag,
only if it follows one tag, but not follows another tag. Complicating
this, is that there can be any number of other tags in between. [...]
Sounds like this would be easier to implement using Python's SAX API.
Here's a short example that does something similar to what you want to
achieve:
import xml.sax
test_str = """
<xml>
<ignore/>
<foo x="1" y="2"/>
<noignore/>
<foo x="3" y="4"/>
</xml>
"""
class MyHandler(xml.sax.handler.ContentHandler):
def __init__(self):
xml.sax.handler.ContentHandler.__init__(self)
self.ignore_next = False
def startElement(self, name, attrs):
if name == "ignore":
self.ignore_next = True
return
elif name == "foo":
if not self.ignore_next:
# handle the element you're interested in here
print "MY ELEMENT", name, "with", dict(attrs)
self.ignore_next = False
xml.sax.parseString(test_str, MyHandler())
In this case, this looks much clearer and easier to understand to me
than regular expressions.
-- Gerhard
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