Python XML Parsing without root

I wanted to parse a fairly huge xml-like file which doesn't have any root element. The format of the file is:

<tag1>
<tag2>
</tag2>
</tag1>

<tag1>
<tag3/>
</tag1>

What I tried:

1. tried using ElementTree but it returned a "no root" error. (Is there any other python library which can be used for parsing this file?)
2. tried adding an extra tag to wrap the entire file and then parse it using Element-Tree. However, I would like to use some more efficient method, in which I would not need to alter the original xml file.

Solution 1:

ElementTree.fromstringlist accepts an iterable (that yields strings).

Using it with itertools.chain:

import itertools
import xml.etree.ElementTree as ET
# import xml.etree.cElementTree as ET

with open('xml-like-file.xml') as f:
    it = itertools.chain('<root>', f, '</root>')
    root = ET.fromstringlist(it)

# Do something with `root`
root.find('.//tag3')

Solution 2:

How about instead of editing the file do something like this

import xml.etree.ElementTree as ET

with file("xml-file.xml") as f:
    xml_object = ET.fromstringlist(["<root>", f.read(), "</root>"])

Solution 3:

lxml.html can parse fragments:

from lxml import html
s = """<tag1>
 <tag2>
 </tag2>
</tag1>

<tag1>
 <tag3/>
</tag1>"""
doc = html.fromstring(s)
for thing in doc:
    print thing
    for other in thing:
        print other
"""
>>> 
<Element tag1 at 0x3411a80>
<Element tag2 at 0x3428990>
<Element tag1 at 0x3428930>
<Element tag3 at 0x3411a80>
>>>
"""

Courtesy this SO answer

And if there is more than one level of nesting:

def flatten(nested):
    """recusively flatten nested elements

    yields individual elements
    """
    for thing in nested:
        yield thing
        for other in flatten(thing):
            yield other
doc = html.fromstring(s)
for thing in flatten(doc):
    print thing

Similarly, lxml.etree.HTML will parse this. It adds html and body tags:

d = etree.HTML(s)
for thing in d.iter():
    print thing

""" 
<Element html at 0x3233198>
<Element body at 0x322fcb0>
<Element tag1 at 0x3233260>
<Element tag2 at 0x32332b0>
<Element tag1 at 0x322fcb0>
<Element tag3 at 0x3233148>
"""