discount 0.1.0STABLE

A Python interface for Discount, the C Markdown parser

This Python package is a ctypes binding of David Loren’s Discount, a C implementation of John Gruber’s Markdown.

Contents

• Introduction

• Using the Markdown class

• Using libmarkdown

• Running the test suite

• Source code and reporting bugs

• License

• Credits

Introduction

Markdown is a text-to-HTML conversion tool for web writers. Markdown allows you to write using an easy-to-read, easy-to-write plain text format, then convert it to structurally valid XHTML (or HTML).

The discount Python module contains two things of interest:

• libmarkdown, a submodule that provides access to the public C functions defined by Discount.

• Markdown, a helper class built on top of libmarkdown, providing a more familiar Pythonic interface

Using the Markdown class

The Markdown class wraps the c functions exposed in the libmarkdown submodule and handles the ctypes leg work for you. If you want to use the Discount functions directly, skip to the next section about libmarkdown.

Let’s take a look at a simple example:

import sys
import discount

mkd = discount.Markdown(sys.stdin)
mkd.write_html_content(sys.stdout)

Markdown takes one required argument, input_file_or_string, which is either a file object or a string-like object.

Note: There are limitations to what kind of file-like objects can be passed to Markdown. File-like objects like StringIO can’t be handled at the C level in the same way as OS file objects like sys.stdin and sys.stdout, or file objects returned by the builtin open() method.

Markdown also has methods for getting the output as a string, instead of writing to a file-like object. Let’s look at a modified version of the first example, this time using strings:

import discout

mkd = discount.Markdown('`test`')
print mkd.get_html_content()

The Markdown class constructor also takes optional boolean keyword arguments that map to Discount flags compilation flags.

toc

Generate table-of-contents headers (each generated <h1>, <h2>, etc will include a id=”name” argument.) Use get_html_toc() or write_html_toc() to generate the table-of-contents itself.

strict

Disable relaxed emphasis and superscripts.

autolink

Greedily expand links; if a url is encountered, convert it to a hyperlink even if it isn’t surrounded with <>s.

safelink

Be paranoid about how [][] is expanded into a link - if the url isn’t a local reference, http://, https://, ftp://, or news://, it will not be converted into a hyperlink.

ignore_header

Do not process the pandoc document header, but treat it like regular text.

ignore_links

Do not allow <a or expand [][] into a link.

ignore_images

Do not allow <img or expand ![][] into a image.

ignore_tables

Don’t process PHP Markdown Extra tables.

ignore_smartypants

Disable SmartyPants processing.

ignore_embedded_html

Disable all embedded HTML by replacing all <’s with &lt;.

ignore_pseudo_protocols

Do not process pseudo-protocols.

Pandoc header elements can be retrieved with the methods get_pandoc_title(), get_pandoc_author() and get_pandoc_date().

The converted HTML document parts can be retrieved as a string with the get_html_css(), get_html_toc() and get_html_content() methods, or written to a file with the write_html_css(fp), write_html_toc(fp) and write_html_content(fp) methods, where fp is the output file descriptor.

Under some conditions, the functions in libmarkdown may return integer error codes. These errors are raised as a MarkdownError exceptions when using the Markdown class.

Using libmarkdown

If you are familiar with using the C library and would rather use Discount library directly, libmarkdown is what you are looking for; it’s simply a thin wrapper around the original C implementation. libmarkdown exposes the public functions and flags documented on the Discount homepage.

In Python you’ll need to do some extra work preparing Python objects you want to pass to libmarkdown’s functions.

Most of these functions accept FILE* and char** types as their arguments, which require some additional ctypes boilerplate.

To get a FILE* from a Python file descriptor for use with libmarkdown, use the following pattern:

i = ctypes.pythonapi.PyFile_AsFile(sys.stdin)
o = ctypes.pythonapi.PyFile_AsFile(sys.stdout)
doc = libmarkdown.mkd_in(i, 0)
libmarkdown.markdown(doc, o, 0))

For libmarkdown functions to which you pass a char**, use the following pattern:

cp = ctypes.c_char_p('')
ln = libmarkdown.mkd_document(doc, ctypes.byref(cp))
html_text = cp.value[:ln]

It is important to initialize c_char_p with an empty string.

Running the test suite

Tests are available with the source distibution of discount in the tests.py file. The C shared object should be compiled first:

python setup.py build_ext

Then you can run the tests:

python tests.py

Source code and reporting bugs

You can obtain the source code and report bugs on GitHub project page.

License

See the LICENSE file in the source distribution for details.

Credits

discount is maintained by Tamas Kemenczy, and is funded by Trapeze. The Discount C library is written and maintained by David Loren and contributors. See the AUTHORS file for details.