What is this?
=============

This is an implementation of John Gruber's "markdown"
(http://daringfireball.net/projects/markdown/) in C.
It uses a PEG grammar to define the syntax. This should allow easy
modification and extension.

It is pretty fast. A 179K text file that takes 5.7 seconds for
Markdown.pl (v. 1.0.1) to parse takes only 0.13 seconds for this
markdown.  It does, however, use a fair amount of memory.

Installing
==========

This program is written in portable ANSI C. For convenience, two
required dependencies are included in the source directory:

  * bsittler's my_getopt option parsing library
    (http://www.geocities.com/bsittler/)

  * Ian Piumarta's peg/leg PEG parser generator
    (http://piumarta.com/software/peg/)

These will be built automatically.

To make the 'markdown' executable:

    make

Then, for usage instructions:

    ./markdown -h

To run John Gruber's Markdown 1.0.3 test suite:

    make test

The test suite will fail on one of the list tests.  Here's why.
Markdown.pl encloses "item one" in the following list in `<p>` tags:

    1.  item one
        * subitem
        * subitem
    
    2.  item two

    3.  item three

peg-markdown does not enclose "item one" in <p> tags unless it has a
following blank line. This is consistent with the official markdown
syntax description, and lets the author of the document choose whether
`<p>` tags are desired.

Hacking
=======

It should be pretty easy to modify markdown.leg to produce other formats
than HTML or LaTeX, and to parse syntax extensions.  A quick guide:

  * To add an output format, add the format to 'formats', modify 'print_element',
    and add functions corresponding to 'print_html_string', 'print_html_element',
    and 'print_html_element_list'.  Also add an option in the main loop that selects
    the new format.

  * To add syntax extensions, define them in the PEG grammar (bottom part
    of markdown.leg), using existing definitions as a guide. If you need
    to add new types of elements (e.g. FOOTNOTE), modify the 'keys'
    enum.  By using `&{ }` rules it should be possible to selectively
    disable extensions depending on command-line options.

  * Note:  Avoid using [^abc] character classes in the grammar, because they
    cause problems with non-ascii input.  Instead, use:  ( !'a' !'b' !'c' . )