xmlfuse

Given two XML documents having the same text, fuses the markup together to create the output XML document.

Installation

pip install xmlfuse

Building and testing:

If you prefer to build from sources, follow these steps:

make venv
make

API

import lxml.etree as et
from xmlfuse.fuse import fuse

xml1 = et.fromstring('<span>Hello, <i>world!</i></span>')
xml2 = et.fromstring('<span><b>Hello</b>, world!</span>')

xml = fuze(xml1, xml2)
assert et.tostring(xml) == b'<span><b>Hello</b>, <i>world!</i></span>'

Input documents must have exactly the same text

Error is raised if text differs. Whitespace does matter!

Example:

xml1 = et.fromstring('<span>Hello</span>')
xml2 = et.fromstring('<span>Good bye</span>')

xml = fuze(xml1, xml2)
# expect RuntimeError raised

Conflicting markup

Sometimes it is not possible to merge two markups, because tags intersect. In such a case one has a choice:

a. Raise an exception and let caller handle the problem b. Resolve by segmenting one of the markups

We treat first document as master, and second as slave. Master markup is never segmented. If there is a conflict between master and slave markups (and if auto_segment flag is True), fuse() will segment slave to make markup consistent.

Example:

xml1 = et.fromstring('<span>Hel<i>lo, world!</i></span>')
xml2 = et.fromstring('<span><b>Hello</b>, world!</span>')

xml = fuze(xml1, xml2)
assert et.tostring(xml) == b'<span><b>Hel<i>lo</i></b></i>, <i>world!</i></span>'

Set auto_segment flag to False to prevent segmentation. Error will be raised instead, if conflict detected.

Ambiguities

When master ans slave markups wrap the same text, there is a nesting ambuguity - which tag should be inner?

We resolve this by consistently trying to put slave markup inside the master. This behavior can be changed by setting the flag prefer_slave_inner to false.

Example:

xml1 = et.fromstring('<span><i>Hello</i>, world!</span>')
xml2 = et.fromstring('<span><b>Hello</b>, world!</span>')

xml = fuze(xml1, xml2, prefer_slave_inner=True)
assert et.tostring(xml) == b'<span><b><i>Hello</i></b>, world!</span>'

xml = fuze(xml1, xml2, prefer_slave_inner=False)
assert et.tostring(xml) == b'<span><i><b>Hello</b></i>, world!</span>'

Slave top-level tag is dropped

Note that top-level tag from slave is not merged. It is just dropped. If you want it to be merged into the output, set strip_slave_top_tag=False.

fuse() signature

fuse(xml1, xml2, *, prefer_slave_inner=True, auto_segment=True, strip_slave_top_tag=True)

Where:

• xml1 is the master XML document (LXML Element object, see http://lxml.de)
• xml2 is the slave XML document
• prefer_slave_inner controls ambigiuty resolution
• auto_segment allows slave smarkup segmentation in case of conflicting markup
• strip_slave_top_tag allows fuse to ignore top-level tag from the slave XML

Returns fused XML document