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PHP Markdown
Version 1.0.1oo - Fri 19 May 2006
by Michel Fortin
based on work by John Gruber
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 two things: a plain text markup syntax, and a software
tool, 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.
PHP Markdown can work as a plug-in for WordPress and bBlog, as a
modifier for the Smarty templating engine, or as a remplacement for
textile formatting in any software that support textile.
Full documentation of Markdown's syntax is available on John's
Markdown page: <>
Installation and Requirement
PHP Markdown requires PHP version 4.0.5 or later.
### WordPress ###
PHP Markdown works with [WordPress][wp], version 1.2 or later.
PHP Markdown is already bundled with WordPress. Still, you can find
here the latest version that may be newer than the latest WordPress
1. To use PHP Markdown with WordPress, place the "makrdown.php" file
in the "plugins" folder. This folder is located inside
"wp-content" at the root of your site:
(site home)/wp-content/plugins/
2. Activate the plugin with the administrative interface of
WordPress. In the "Plugins" section you will now find Markdown.
To activate the plugin, click on the "Activate" button on the
same line than Markdown. Your entries will now be formatted by
PHP Markdown.
You can configure PHP Markdown to not apply to the comments on your
WordPress weblog. See the "Configuration" section below.
Note: It is not possible at this time to apply a different set of
filters to different entries. All your entries will be formated by
PHP Markdown. This is currently a limitation of WordPress. If your old
entries are written in HTML (as opposed to another formatting syntax),
your site should not suffer much from installing PHP Markdown.
### bBlog ###
PHP Markdown also works with the latest version of [bBlog][bb].
1. To use PHP Markdown with bBlog, rename "markdown.php" to
"modifier.markdown.php" and place the file in the "bBlog_plugins"
folder. This folder is located inside the "bblog" directory of
your site, like this:
(site home)/bblog/bBlog_plugins/modifier.markdown.php
2. Select "Markdown" as the "Entry Modifier" when you post a new
entry. This setting will only apply to the entry you are editing.
### Replacing Textile ###
Many web programs written in PHP use [Textile][tx] to format your text.
To use PHP Markdown with these programs without having to change the
code, you can use PHP Markdown in "Textile Compatibility Mode."
1. Rename the "markdown.php" file to "classTextile.php".
2. Locate the "classTextile.php" file hidden somewhere inside the
installation of your program (see table below). Replace it with
the PHP Markdown file you just renamed.
As an helper, here you can learn where is the "classTextile.php" file
in some web programs:
Program Location
TextPattern (site home)/textpattern/lib/classTextile.php
Pivot (site home)/pivot/includes/textile/classtextile.php
Contrary to Textile, Markdown does not convert quotes to curly ones
and does not convert multiple hyphens (`--` and `---`) into en- and
em-dashes. If you use PHP Markdown in Textile Compatibility Mode, you
can solve this problem by installing the "smartypants.php" file from
[PHP SmartyPants][psp] beside the "classTextile.php" file. The Textile
Compatibility Mode function will use SmartyPants automatically without
further modification.
### In Your Own Programs ###
You can use PHP Markdown easily in your current PHP program. Simply
include the file and then call the Markdown function on the text you
want to convert:
include_once "markdown.php";
$my_html = Markdown($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 Markdown
function call. This is an example with [PHP SmartyPants][psp]:
$my_html = SmartyPants(Markdown($my_text));
### With Smarty ###
If your program use the [Smarty][sm] template engine, PHP Markdown
can now be used as a modifier for your templates. Rename "markdown.php"
to "modifier.markdown.php" and put it in your smarty plugins folder.
If you are using MovableType 3.1 or later, the Smarty plugin folder is
located at `(MT CGI root)/php/extlib/smarty/plugins`. This will allow
Markdown to work on dynamic pages.
By default, PHP Markdown produces XHTML output for tags with empty
elements. E.g.:
<br />
Markdown can be configured to produce HTML-style tags; e.g.:
To do this, you must edit the "$md_empty_element_suffix" variable
below the "Global default settings" header at the start of the
"markdown.php" file.
### WordPress-Specific Settings ###
By default, the Markdown plugin applies to both posts and comments on
your WordPress weblog. To deactivate one or the other, edit the
`$md_wp_posts` or `$md_wp_comments` variable under the "WordPress
settings" header at the start of the "markdown.php" file.
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.
Version History
1.0.1oo (19 May 2006)
* Converted PHP Markdown to a object-oriented design.
1.0.1c (9 Dec 2005)
* Fixed a problem occurring with PHP 5.1.1 due to a small
change to strings variable replacement behaviour in
this version.
1.0.1b (6 Jun 2005)
* Fixed a bug where an inline image followed by a reference link would
give a completely wrong result.
* Fix for escaped backticks still triggering code spans:
There are two raw backticks here: \` and here: \`, not a code span
* Fix for an ordered list following an unordered list, and the
reverse. There is now a loop in _DoList that does the two
* Fix for nested sub-lists in list-paragraph mode. Previously we got
a spurious extra level of `<p>` tags for something like this:
* this
* sub
* Fixed some incorrect behaviour with emphasis. This will now work
as it should:
*test **thing***
**test *thing***
***thing* test**
***thing** test*
Name: __________
Address: _______
* Correct a small bug in `_TokenizeHTML` where a Doctype declaration
was not seen as HTML.
* Major rewrite of the WordPress integration code that should
correct many problems by preventing default WordPress filters from
tampering with Markdown-formatted text. More details here:
* Added a configuration variable for WordPress that can disable the
Markdown filter on comments.
1.0.1a (15 Apr 2005)
* Fixed an issue where PHP warnings were trigged when converting
text with list items running on PHP 4.0.6. This was comming from
the `rtrim` function which did not support the second argument
prior version 4.1. Replaced by a regular expression.
* Markdown now filter correctly post excerpts and comment
excerpts in WordPress.
* Automatic links and some code sample were "corrected" by
the balenceTag filter in WordPress meant to ensure HTML
is well formed. This new version of PHP Markdown postpone this
filter so that it runs after Markdown.
* Blockquote syntax and some code sample were stripped by
a new WordPress 1.5 filter meant to remove unwanted HTML
in comments. This new version of PHP Markdown postpone this
filter so that it runs after Markdown.
1.0.2b1 (5 Mar 2005)
* Fix for backticks within HTML tag:
<span attr='`ticks`'>like this</span>
* Fix for escaped backticks still triggering code spans:
There are two raw backticks here: \` and here: \`, not a code span
* Improved integration with WordPress. With WordPress 1.5, the
balenceTags filter now runs after Markdown, so it won't
interfere anymore. You can still disable balanceTags from the admin
interface (in Options > Writing) if you want to.
* PHP Markdown now correctly filter text for excerpts in WordPress.
There is still one glitch: autolinks and tags in code samples are
stripped by WordPress when trimming it. A fix for this is possible
with WordPress 1.5, but would require duplicating WordPress entry
trimming code within Markdown, which I can't do because of a license
issue. (Nor do I think it is a good solution to fix this.)
* Improved Textile compatibility mode. Markdown will now honor the
no-image and the lite parameters. In lite mode, no header, blockquote,
list, or code block will be made, and inline HTML is limited
to the following tags:
This is acheived by backslash-escaping block markers before sending
text through the Markdown filter.
The improved Textile comatibility means that the Markdown syntax will now
be processed for comments in TextPattern (only for span elements due to
TextPattern using the lite mode for comments). Sadly, due to TextPattern
tag stripping, sample code in code span and auto-links will be stripped
before the Markdown filter can see them. So I guess I should say it
half-work for comments TextPattern.
1.0.1 (16 Dec 2004):
* Changed the syntax rules for code blocks and spans. Previously,
backslash escapes for special Markdown characters were processed
everywhere other than within inline HTML tags. Now, the contents of
code blocks and spans are no longer processed for backslash escapes.
This means that code blocks and spans are now treated literally,
with no special rules to worry about regarding backslashes.
**IMPORTANT**: This breaks the syntax from all previous versions of
Markdown. Code blocks and spans involving backslash characters will
now generate different output than before.
Implementation-wise, this change was made by moving the call to
`_EscapeSpecialChars()` from the top-level `Markdown()` function to
within `_RunSpanGamut()`.
* Significants performance improvement in `_DoHeader`, `_Detab`
and `_TokenizeHTML`.
* Added `>`, `+`, and `-` to the list of backslash-escapable
characters. These should have been done when these characters
were added as unordered list item markers.
* Inline links using `<` and `>` URL delimiters weren't working:
like [this](<>)
Fixed by moving `_DoAutoLinks()` after `_DoAnchors()` in
* Fixed bug where auto-links were being processed within code spans:
like this: `<>`
Fixed by moving `_DoAutoLinks()` from `_RunBlockGamut()` to
* Sort-of fixed a bug where lines in the middle of hard-wrapped
paragraphs, which lines look like the start of a list item,
would accidentally trigger the creation of a list. E.g. a
paragraph that looked like this:
I recommend upgrading to version
8. Oops, now this line is treated
as a sub-list.
This is fixed for top-level lists, but it can still happen for
sub-lists. E.g., the following list item will not be parsed
* I recommend upgrading to version
8. Oops, now this line is treated
as a sub-list.
Given Markdown's list-creation rules, I'm not sure this can
be fixed.
* Fix for horizontal rules preceded by 2 or 3 spaces or followed by
trailing spaces and tabs.
* Standalone HTML comments are now handled; previously, they'd get
wrapped in a spurious `<p>` tag.
* `_HashHTMLBlocks()` now tolerates trailing spaces and tabs following
HTML comments and `<hr/>` tags.
* Changed special case pattern for hashing `<hr>` tags in
`_HashHTMLBlocks()` so that they must occur within three spaces
of left margin. (With 4 spaces or a tab, they should be
code blocks, but weren't before this fix.)
* Auto-linked email address can now optionally contain
a 'mailto:' protocol. I.e. these are equivalent:
* Fixed annoying bug where nested lists would wind up with
spurious (and invalid) `<p>` tags.
* Changed `_StripLinkDefinitions()` so that link definitions must
occur within three spaces of the left margin. Thus if you indent
a link definition by four spaces or a tab, it will now be a code
* You can now write empty links:
[like this]()
and they'll be turned into anchor tags with empty href attributes.
This should have worked before, but didn't.
* `***this***` and `___this___` are now turned into
Instead of
which isn't valid.
* Fixed problem for links defined with urls that include parens, e.g.:
"Chomsky" was being erroneously treated as the URL's title.
* Double quotes in the title of an inline link used to give strange
results (incorrectly made entities). Fixed.
* Tabs are now correctly changed into spaces. Previously, only
the first tab was converted. In code blocks, the second one was too,
but was not always correctly aligned.
* Fixed a bug where a tab character inserted after a quote on the same
line could add a slash before the quotes.
This is "before" [tab] and "after" a tab.
Previously gave this result:
<p>This is \"before\" [tab] and "after" a tab.</p>
* Removed a call to `htmlentities`. This fixes a bug where multibyte
characters present in the title of a link reference could lead to
invalid utf-8 characters.
* Changed a regular expression in `_TokenizeHTML` that could lead to
a segmentation fault with PHP 4.3.8 on Linux.
* Fixed some notices that could show up if PHP error reporting
E_NOTICE flag was set.
Copyright and License
Copyright (c) 2004-2006 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 distribution.
* 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.
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