python-abp

This repository contains a library for working with Adblock Plus filter lists and the script that is used for building Adblock Plus filter lists from the form in which they are authored into the format suitable for consumption by the adblocking software.

Installation

Prerequisites:

Linux, Mac OS X or Windows (any modern Unix should work too),
Python (2.7 or 3.5+),
pip.

To install:

$ pip install -U python-abp

Rendering of filter lists

The filter lists are originally authored in relatively smaller parts focused on a particular type of filters, related to a specific topic or relevant for particular geographical area. We call these parts filter list fragments (or just fragments) to distinguish them from full filter lists that are consumed by the adblocking software such as Adblock Plus.

Rendering is a process that combines filter list fragments into a filter list. It starts with one fragment that can include other ones and so forth. The produced filter list is marked with a version, a timestamp and a checksum.

Python-abp contains a script that can do this called flrender:

$ flrender fragment.txt filterlist.txt

This will take the top level fragment in fragment.txt, render it and save into filterlist.txt.

Fragments might reference other fragments that should be included into them. The references come in two forms: http(s) includes and local includes:

%include http://www.server.org/dir/list.txt%
%include easylist:easylist/easylist_general_block.txt%

The first instruction contains a URL that will be fetched and inserted at the point of reference. The second one contains a path inside easylist repository. flrender needs to be able to find a copy of the repository on the local filesystem. We use -i option to point it to to the right directory:

$ flrender -i easylist=/home/abc/easylist input.txt output.txt

Now the second reference above will be resolved to /home/abc/easylist/easylist/easylist_general_block.txt and the fragment will be loaded from this file.

Directories that contain filter list fragments that are used during rendering are called sources. They are normally working copies of the repositories that contain filter list fragments. Each source is identified by a name: that's the part that comes before ":" in the include instruction and it should be the same as what comes before "=" in the -i option.

Commonly used sources have generally accepted names. For example the main EasyList repository is referred to as easylist. If you don't know all the source names that are needed to render some list, just run flrender and it will report what it's missing:

$ flrender easylist.txt output/easylist.txt
Unknown source: 'easylist' when including 'easylist:easylist/easylist_gener
al_block.txt' from 'easylist.txt'

You can clone the necessary repositories to a local directory and add -i options accordingly.

Library API

Python-abp can also be used as a library for parsing filter lists. For example to read a filter list (we use Python 3 syntax here but the API is the same):

from abp.filters import parse_filterlist

with open('filterlist.txt') as filterlist:
    for line in parse_filterlist(filterlist):
        print(line)

If filterlist.txt contains a filter list:

[Adblock Plus 2.0]
! Title: Example list

abc.com,cdf.com##div#ad1
abc.com/ad$image
@@/abc\.com/
...

the output will look something like:

Header(version='Adblock Plus 2.0')
Metadata(key='Title', value='Example list')
EmptyLine()
Filter(text='abc.com,cdf.com##div#ad1', selector={'type': 'css', 'value': 'div#ad1'}, action='hide', options=[('domain', [('abc .com', True), ('cdf.com', True)])])
Filter(text='abc.com/ad$image', selector={'type': 'url-pattern', 'value': 'abc.com/ad'}, action='block', options=[('image', True)])
Filter(text='@@/abc\\.com/', selector={'type': 'url-regexp', 'value': 'abc\\.com'}, action='allow', options=[])
...

abp.filters module also exports a lower-level function for parsing individual lines of a filter list: parse_line. It returns a parsed line object just like the items in the iterator returned by parse_filterlist.

For further information on the library API use help() on abp.filters and its contents in interactive Python session, read the docstrings or look at the tests for some usage examples.

Testing

Unit tests for python-abp are located in the /tests directory. Pytest is used for quickly running the tests during development. Tox is used for testing in different environments (Python 2.7, Python 3.5+ and PyPy) and code quality reporting.

In order to execute the tests, first create and activate development virtualenv:

$ python setup.py devenv
$ . devenv/bin/activate

With the development virtualenv activated use pytest for a quick test run:

(devenv) $ pytest tests

and tox for a comprehensive report:

(devenv) $ tox

Development

When adding new functionality, add tests for it (preferably first). Code coverage (as measured by tox -e qa) should not decrease and the tests should pass in all Tox environments.

All public functions, classes and methods should have docstrings compliant with NumPy/SciPy documentation guide. One exception is the constructors of classes that the user is not expected to instantiate (such as exceptions).

termith / python-abp