- a Sphinx extension to translate source code to reST

This modules enables Sphinx to read in source files by converting the source code to reST before passing the file on to Sphinx. The overall design:

  1. Monkeypatch Sphinx to include source files in the build, keeping the source file’s extension intact. (Sphinx strips the extension of reST files).
  2. When Sphinx reads a source file, check to see if the file’s extension is intact. If so, it’s a source file; translate it to reST then pass it on to Sphinx.


These are listed in the order prescribed by PEP 8.

Standard library

import os.path
from os import path

For glob_to_lexer matching.

import fnmatch

For saving Enki info.

import codecs

Third-party imports

from sphinx.util import get_matching_files
import sphinx.environment
from sphinx.util.osutil import SEP
import pygments.util

Local application imports

from .CodeToRest import code_to_rest_string, get_lexer
from .CommentDelimiterInfo import SUPPORTED_GLOBS
from . import __version__

source-read event

The source-read event occurs when a source file is read. If it’s code, this routine changes it into reST.

def _source_read(

The name of the document that was read. It contains a path relative to the project directory and (typically) no extension.


A list whose single element is the contents of the source file.


If the docname’s extension doesn’t change when asking for its full path, then it’s source code. Normally, the docname of foo.rst is foo; only for source code is the docname of foo.c also foo.c. Look up the name and extension using doc2path.

    docname_ext = app.env.doc2path(docname, None)
    if os.path.normpath(docname_ext) == os.path.normpath(docname):

See if it’s an extension we should process.

            base_docname = os.path.basename(docname)

See if source_file matches any of the globs.

            lexer = None
            lfg = app.config.CodeChat_lexer_for_glob
            for glob, lexer_alias in lfg.items():
                if fnmatch.fnmatch(base_docname, glob):

On a match, pass the specified lexer alias.

                    lexer = get_lexer(alias=lexer_alias)

Do this after checking the CodeChat_lexer_for_glob list, since this will raise an exception on failure.

            lexer = lexer or get_lexer(filename=base_docname, code=source[0])

  'Converted using the {} lexer.'.format(
            source[0] = code_to_rest_string(source[0], lexer=lexer)
        except (KeyError, pygments.util.ClassNotFound):

We don’t support this language.



Sphinx doesn’t naturally look for source files. Simply adding all supported source file extensions to‘s source_suffix doesn’t work, since foo.c and foo.h will now both been seen as the docname foo, making then indistinguishable.

get_matching_docs patch

So, do a bit of monkeypatching: for source files, make their docname the same as the file name; for reST file, allow Sphinx to strip off the extension as before. The first patch accomplishes this. It comes from sphinx.util, line 92 and following in Sphinx 1.3.1.

def _get_matching_docs(dirname, suffixes, exclude_matchers=()):
    """Get all file names (without suffixes) matching a suffix in a directory,

    Exclude files and dirs matching a pattern in *exclude_patterns*.
    suffixpatterns = ['*' + s for s in suffixes]

The following line was added.

    source_suffixpatterns = ( SUPPORTED_GLOBS |
                             set(_config.CodeChat_lexer_for_glob.keys()) )
    for filename in get_matching_files(dirname, exclude_matchers):
        for suffixpattern in suffixpatterns:
            if fnmatch.fnmatch(filename, suffixpattern):
                yield filename[:-len(suffixpattern)+1]

The following code was added.

        for source_suffixpattern in source_suffixpatterns:
            if fnmatch.fnmatch(filename, source_suffixpattern):
                yield filename

Note that this is referenced in sphinx.environment by from sphinx.util import get_matching_docs. So, where to patch is in sphinx.environment instead of sphinx.util.

sphinx.environment.get_matching_docs = _get_matching_docs

doc2path patch

Next, the way docnames get transformed back to a full path needs to be fixed for source files. Specifically, a docname might be the source file, without adding an extension. This code comes from sphinx.environment of Sphinx 1.3.1. See also the official doc2path Sphinx docs.

def _doc2path(self, docname, base=True, suffix=None):
    """Return the filename for the document name.

    If *base* is True, return absolute path under self.srcdir.
    If *base* is None, return relative path to self.srcdir.
    If *base* is a path string, return absolute path under that.
    If *suffix* is not None, add it instead of config.source_suffix.
    docname = docname.replace(SEP, path.sep)
    if suffix is None:
        for candidate_suffix in self.config.source_suffix:
            if path.isfile(path.join(self.srcdir, docname) +
                suffix = candidate_suffix

Three lines of code added here – check for the no-extenion case.

            if path.isfile(path.join(self.srcdir, docname)):
                suffix = ''

document does not exist

                suffix = self.config.source_suffix[0]
    if base is True:
        return path.join(self.srcdir, docname) + suffix
    elif base is None:
        return docname + suffix
        return path.join(base, docname) + suffix

sphinx.environment.BuildEnvironment.doc2path = _doc2path

Enki support

Enki, which hosts CodeChat, needs to know the HTML file extension. So, save it to a file for Enki to read. Note that this can’t be done in Extension setup, since the values in aren’t loaded yet. See also global_config. Instead, wait for the builder-inited event, when the config settings are available.

def _builder_inited(

See app.


        with'sphinx-enki-info.txt', 'wb', 'utf-8') as f:
    except TypeError:

If html_file_suffix is None (TypeError), Enki will assume .html.


Extension setup

This routine defines the entry point called by Sphinx to initialize this extension.

def setup(

See app.


Ensure we’re using at least Sphinx v1.3 using require_sphinx.


Use the source-read event hook to transform source code to reST before Sphinx processes it.

    app.connect('source-read', _source_read)

Add the CodeChat.css style sheet using add_stylesheet.


Add the CodeChat_lexer_for_glob config value. See add_config_value.

    app.add_config_value('CodeChat_lexer_for_glob', {}, 'html')

Use the builder-inited event to write out settings specified in

    app.connect('builder-inited', _builder_inited)

An ugly hack: we need to get to the Config object after‘s values have been loaded. They aren’t loaded yet, so we store the config object to access it later when it is loaded.

    global _config
    _config = app.config
    return {'version' : __version__,
            'parallel_read_safe' : True }