gumbo

Gumbo - A pure-C HTML5 parser.

Gumbo is an implementation of the HTML5 parsing algorithm <http://www.whatwg.org/specs/web-apps/current-work/multipage/#auto-toc-12>_ implemented as a pure C99 library with no outside dependencies. It's designed to serve as a building block for other tools and libraries such as linters, validators, templating languages, and refactoring and analysis tools. This package contains the library itself, Python ctypes bindings for the library, and adapters for html5lib and BeautifulSoup (3.2) that give it the same API as those libaries.

Goals & features:

• Robust and resilient to bad input.

• Simple API that can be easily wrapped by other languages.

• Support for source locations and pointers back to the original text.

• Relatively lightweight, with no outside dependencies.

• Passes all html5lib-0.95 tests <https://github.com/html5lib/html5lib-tests>_.

• Tested on over 2.5 billion pages from Google's index.

Non-goals:

• Execution speed. Gumbo gains some of this by virtue of being written in C, but it is not an important consideration for the intended use-case, and was not a major design factor.

• Support for encodings other than UTF-8. For the most part, client code can convert the input stream to UTF-8 text using another library before processing.

• Security. Gumbo was initially designed for a product that worked with trusted input files only. We're working to harden this and make sure that it behaves as expected even on malicious input, but for now, Gumbo should only be run on trusted input or within a sandbox.

• C89 support. Most major compilers support C99 by now; the major exception (Microsoft Visual Studio) should be able to compile this in C++ mode with relatively few changes. (Bug reports welcome.)

Wishlist (aka "We couldn't get these into the original release, but are hoping to add them soon"):

• Support for recent HTML5 spec changes to support the template tag.

• Support for fragment parsing.

• Full-featured error reporting.

• Bindings in other languages.

Installation

pip install gumbo should do it. If you have a local copy, python setup.py install from the root directory.

The html5lib <https://pypi.python.org/pypi/html5lib/0.999>_ and BeautifulSoup <https://pypi.python.org/pypi/BeautifulSoup/3.2.1>_ adapters require that their respective libraries be installed separately to work.

Basic Usage

For the ctypes bindings:

.. code-block:: python

import gumbo

with gumbo.parse(text) as output:
    root = output.contents.root.contents
    # root is a Node object representing the root of the parse tree
    # tree-walk over it as necessary.

For the BeautifulSoup bindings:

.. code-block:: python

import gumbo

soup = gumbo.soup_parse(text)
# soup is a BeautifulSoup object representing the parse tree.

For the html5lib bindings:

.. code-block:: python

from gumbo import html5lib

doc = html5lib.parse(text[, treebuilder='lxml'])

Recommended best-practice for Python usage is to use one of the adapters to an existing API (personally, I prefer BeautifulSoup) and write your program in terms of those. The raw CTypes bindings should be considered building blocks for higher-level libraries and rarely referenced directly.

See the source code, Pydoc, and implementation of soup_adapter and html5lib_adapter for more information.

A note on API/ABI compatibility

We'll make a best effort to preserve API compatibility between releases. The initial release is a 0.9 (beta) release to solicit comments from early adopters, but if no major problems are found with the API, a 1.0 release will follow shortly, and the API of that should be considered stable. If changes are necessary, we follow [semantic versioning][].

We make no such guarantees about the ABI, and it's very likely that subsequent versions may require a recompile of client code. For this reason, we recommend NOT using Gumbo data structures throughout a program, and instead limiting them to a translation layer that picks out whatever data is needed from the parse tree and then converts that to persistent data structures more appropriate for the application. The API is structured to encourage this use, with a single delete function for the whole parse tree, and is not designed with mutation in mind.

Most of this is transparent to Python usage, as the Python adapters are all built with this in mind. However, since ctypes requires ABI compatibility, it does mean you'll have to re-deploy the gumboc library and C extension when upgrading to a new version.