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PHP Markdown
PHP Markdown Lib 1.4.1 - 4 May 2013
by Michel Fortin
based on Markdown by John Gruber
This is a library package that includes the PHP Markdown parser and its
sibling PHP Markdown Extra with additional features.
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).
"Markdown" is actually two things: a plain text markup syntax, and a
software tool, originally written in Perl, that converts the plain text
markup to HTML. PHP Markdown is a port to PHP of the original Markdown
program by John Gruber.
* [Full documentation of the Markdown syntax](<>)
- Daring Fireball (John Gruber)
* [Markdown Extra syntax additions](<>)
- Michel Fortin
This library package requires PHP 5.3 or later.
Note: The older plugin/library hybrid package for PHP Markdown and
PHP Markdown Extra is still maintained and will work with PHP 4.0.5 and later.
Before PHP 5.3.7, pcre.backtrack_limit defaults to 100 000, which is too small
in many situations. You might need to set it to higher values. Later PHP
releases defaults to 1 000 000, which is usually fine.
This library package is meant to be used with class autoloading. For autoloading
to work, your project needs have setup a PSR-0-compatible autoloader. See the
included Readme.php file for a minimal autoloader setup. (If you cannot use
autoloading, see below.)
With class autoloading in place, putting the 'Michelf' folder in your
include path should be enough for this to work:
use \Michelf\Markdown;
$my_html = Markdown::defaultTransform($my_text);
Markdown Extra syntax is also available the same way:
use \Michelf\MarkdownExtra;
$my_html = MarkdownExtra::defaultTransform($my_text);
If you wish to use PHP Markdown with another text filter function
built to parse HTML, you should filter the text *after* the `transform`
function call. This is an example with [PHP SmartyPants][psp]:
use \Michelf\Markdown, \Michelf\SmartyPants;
$my_html = Markdown::defaultTransform($my_text);
$my_html = SmartyPants::defaultTransform($my_html);
All these examples are using the static `defaultTransform` static function
found inside the parser class. If you want to customize the parser
configuration, you can also instantiate it directly and change some
configuration variables:
use \Michelf\MarkdownExtra;
$parser = new MarkdownExtra;
$parser->fn_id_prefix = "post22-";
$my_html = $parser->transform($my_text);
To learn more, see the full list of [configuration variables].
[configuration variables]:
### Usage without an autoloader
If you cannot use class autoloading, you can still use `include` or `require`
to access the parser. To load the `\Michelf\Markdown` parser, do it this way:
require_once 'Michelf/';
Or, if you need the `\Michelf\MarkdownExtra` parser:
require_once 'Michelf/';
While the plain `.php` files depend on autoloading to work correctly, using the
`.inc.php` files instead will eagerly load the dependencies that would be
loaded on demand if you were using autoloading.
Public API and Versioning Policy
Version numbers are of the form *major*.*minor*.*patch*.
The public API of PHP Markdown consist of the two parser classes `Markdown`
and `MarkdownExtra`, their constructors, the `transform` and `defaultTransform`
functions and their configuration variables. The public API is stable for
a given major version number. It might get additions when the minor version
number increments.
**Protected members are not considered public API.** This is unconventional
and deserves an explanation. Incrementing the major version number every time
the underlying implementation of something changes is going to give
nonessential version numbers for the vast majority of people who just use the
parser. Protected members are meant to create parser subclasses that behave in
different ways. Very few people create parser subclasses. I don't want to
discourage it by making everything private, but at the same time I can't
guarantee any stable hook between versions if you use protected members.
**Syntax changes** will increment the minor number for new features, and the
patch number for small corrections. A *new feature* is something that needs a
change in the syntax documentation. Note that since PHP Markdown Lib includes
two parsers, a syntax change for either of them will increment the minor
number. Also note that there is nothing perfectly backward-compatible with the
Markdown syntax: all inputs are always valid, so new features always replace
something that was previously legal, although generally nonsensical to do.
To file bug reports please send email to:
Please include with your report: (1) the example input; (2) the output you
expected; (3) the output PHP Markdown actually produced.
If you have a problem where Markdown gives you an empty result, first check
that the backtrack limit is not too low by running `php --info | grep pcre`.
See Installation and Requirement above for details.
Development and Testing
Pull requests for fixing bugs are welcome. Proposed new features are
going meticulously reviewed -- taking into account backward compatibility,
potential side effects, and future extensibility -- before deciding on
acceptance or rejection.
If you make a pull request that includes changes to the parser please add
tests for what is being changed to [MDTest][] and make a pull request there
If you wish to make a donation that will help me devote more time to
PHP Markdown, please visit [] or send Bitcoin to
[1HiuX34czvVPPdhXbUAsAu7pZcesniDCGH]: bitcoin:1HiuX34czvVPPdhXbUAsAu7pZcesniDCGH
Version History
* Added the ability to insert custom HTML attributes everywhere an extra
attribute block is allowed (links, images, headers). Credits to
Peter Droogmans for providing the implementation.
* Added a `url_filter_func` configuration variable which takes a function
that can rewrite any link or image URL to something different.
PHP Markdown Lib 1.4.1 (4 May 2014)
* The HTML block parser will now treat `<figure>` as a block-level element
(as it should) and no longer wrap it in `<p>` or parse it's content with
the as Markdown syntax (although with Extra you can use `markdown="1"`
if you wish to use the Markdown syntax inside it).
* The content of `<style>` elements will now be left alone, its content
won't be interpreted as Markdown.
* Corrected an bug where some inline links with spaces in them would not
work even when surounded with angle brackets:
[link](<s p a c e s>)
* Fixed an issue where email addresses with quotes in them would not always
have the quotes escaped in the link attribute, causing broken links (and
invalid HTML).
* Fixed the case were a link definition following a footnote definition would
be swallowed by the footnote unless it was separated by a blank line.
PHP Markdown Lib 1.4.0 (29 Nov 2013)
* Added support for the `tel:` URL scheme in automatic links.
It gets converted to this (note the `tel:` prefix becomes invisible):
<a href="tel:+1-111-111-1111">+1-111-111-1111</a>
* Added backtick fenced code blocks to MarkdownExtra, originally from
Github-Flavored Markdown.
* Added an interface called MarkdownInterface implemented by both
the Markdown and MarkdownExtra parsers. You can use the interface if
you want to create a mockup parser object for unit testing.
* For those of you who cannot use class autoloading, you can now
include `Michelf/` or `Michelf/` (note
the `.inc.php` extension) to automatically include other files required
by the parser.
PHP Markdown Lib 1.3 (11 Apr 2013)
This is the first release of PHP Markdown Lib. This package requires PHP
version 5.3 or later and is designed to work with PSR-0 autoloading and,
optionally with Composer. Here is a list of the changes since
PHP Markdown Extra 1.2.6:
* Plugin interface for WordPress and other systems is no longer present in
the Lib package. The classic package is still available if you need it:
* Added `public` and `protected` protection attributes, plus a section about
what is "public API" and what isn't in the Readme file.
* Changed HTML output for footnotes: now instead of adding `rel` and `rev`
attributes, footnotes links have the class name `footnote-ref` and
backlinks `footnote-backref`.
* Fixed some regular expressions to make PCRE not shout warnings about POSIX
collation classes (dependent on your version of PCRE).
* Added optional class and id attributes to images and links using the same
syntax as for headers:
[link](url){#id .class}
![img](url){#id .class}
It work too for reference-style links and images. In this case you need
to put those attributes at the reference definition:
[link][linkref] or [linkref]
[linkref]: url "optional title" {#id .class}
* Fixed a PHP notice message triggered when some table column separator
markers are missing on the separator line below column headers.
* Fixed a small mistake that could cause the parser to retain an invalid
state related to parsing links across multiple runs. This was never
observed (that I know of), but it's still worth fixing.
Copyright and License
PHP Markdown Lib
Copyright (c) 2004-2014 Michel Fortin
All rights reserved.
Based on Markdown
Copyright (c) 2003-2005 John Gruber
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the
* Neither the name "Markdown" nor the names of its contributors may
be used to endorse or promote products derived from this software
without specific prior written permission.
This software is provided by the copyright holders and contributors "as
is" and any express or implied warranties, including, but not limited
to, the implied warranties of merchantability and fitness for a
particular purpose are disclaimed. In no event shall the copyright owner
or contributors be liable for any direct, indirect, incidental, special,
exemplary, or consequential damages (including, but not limited to,
procurement of substitute goods or services; loss of use, data, or
profits; or business interruption) however caused and on any theory of
liability, whether in contract, strict liability, or tort (including
negligence or otherwise) arising in any way out of the use of this
software, even if advised of the possibility of such damage.