410 lines
16 KiB
Markdown
410 lines
16 KiB
Markdown
PHP Markdown
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============
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PHP Markdown Lib 1.8.0 - 14 Jan 2018
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by Michel Fortin
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<https://michelf.ca/>
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based on Markdown by John Gruber
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<https://daringfireball.net/>
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Introduction
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------------
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This is a library package that includes the PHP Markdown parser and its
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sibling PHP Markdown Extra with additional features.
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Markdown is a text-to-HTML conversion tool for web writers. Markdown
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allows you to write using an easy-to-read, easy-to-write plain text
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format, then convert it to structurally valid XHTML (or HTML).
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"Markdown" is actually two things: a plain text markup syntax, and a
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software tool, originally written in Perl, that converts the plain text
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markup to HTML. PHP Markdown is a port to PHP of the original Markdown
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program by John Gruber.
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* [Full documentation of the Markdown syntax](<https://daringfireball.net/projects/markdown/>)
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— Daring Fireball (John Gruber)
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* [Markdown Extra syntax additions](<https://michelf.ca/projects/php-markdown/extra/>)
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— Michel Fortin
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Requirement
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-----------
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This library package requires PHP 5.3 or later.
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Note: The older plugin/library hybrid package for PHP Markdown and
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PHP Markdown Extra is no longer maintained but will work with PHP 4.0.5 and
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later.
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Before PHP 5.3.7, pcre.backtrack_limit defaults to 100 000, which is too small
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in many situations. You might need to set it to higher values. Later PHP
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releases defaults to 1 000 000, which is usually fine.
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Usage
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-----
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To use this library with Composer, first install it with:
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$ composer require michelf/php-markdown
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Then include Composer's generated vendor/autoload.php to [enable autoloading]:
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require 'vendor/autoload.php';
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Without Composer, for autoloading to work, your project needs an autoloader
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compatible with PSR-4 or PSR-0. See the included Readme.php file for a minimal
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autoloader setup. (If you cannot use autoloading, see below.)
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With class autoloading in place:
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use Michelf\Markdown;
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$my_html = Markdown::defaultTransform($my_text);
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Markdown Extra syntax is also available the same way:
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use Michelf\MarkdownExtra;
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$my_html = MarkdownExtra::defaultTransform($my_text);
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If you wish to use PHP Markdown with another text filter function
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built to parse HTML, you should filter the text *after* the `transform`
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function call. This is an example with [PHP SmartyPants]:
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use Michelf\Markdown, Michelf\SmartyPants;
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$my_html = Markdown::defaultTransform($my_text);
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$my_html = SmartyPants::defaultTransform($my_html);
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All these examples are using the static `defaultTransform` static function
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found inside the parser class. If you want to customize the parser
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configuration, you can also instantiate it directly and change some
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configuration variables:
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use Michelf\MarkdownExtra;
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$parser = new MarkdownExtra;
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$parser->fn_id_prefix = "post22-";
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$my_html = $parser->transform($my_text);
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To learn more, see the full list of [configuration variables].
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[enable autoloading]: https://getcomposer.org/doc/01-basic-usage.md#autoloading
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[PHP SmartyPants]: https://michelf.ca/projects/php-smartypants/
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[configuration variables]: https://michelf.ca/projects/php-markdown/configuration/
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### Usage without an autoloader
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If you cannot use class autoloading, you can still use `include` or `require`
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to access the parser. To load the `Michelf\Markdown` parser, do it this way:
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require_once 'Michelf/Markdown.inc.php';
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Or, if you need the `Michelf\MarkdownExtra` parser:
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require_once 'Michelf/MarkdownExtra.inc.php';
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While the plain `.php` files depend on autoloading to work correctly, using the
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`.inc.php` files instead will eagerly load the dependencies that would be
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loaded on demand if you were using autoloading.
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Public API and Versioning Policy
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---------------------------------
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Version numbers are of the form *major*.*minor*.*patch*.
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The public API of PHP Markdown consist of the two parser classes `Markdown`
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and `MarkdownExtra`, their constructors, the `transform` and `defaultTransform`
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functions and their configuration variables. The public API is stable for
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a given major version number. It might get additions when the minor version
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number increments.
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**Protected members are not considered public API.** This is unconventional
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and deserves an explanation. Incrementing the major version number every time
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the underlying implementation of something changes is going to give
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nonessential version numbers for the vast majority of people who just use the
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parser. Protected members are meant to create parser subclasses that behave in
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different ways. Very few people create parser subclasses. I don't want to
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discourage it by making everything private, but at the same time I can't
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guarantee any stable hook between versions if you use protected members.
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**Syntax changes** will increment the minor number for new features, and the
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patch number for small corrections. A *new feature* is something that needs a
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change in the syntax documentation. Note that since PHP Markdown Lib includes
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two parsers, a syntax change for either of them will increment the minor
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number. Also note that there is nothing perfectly backward-compatible with the
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Markdown syntax: all inputs are always valid, so new features always replace
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something that was previously legal, although generally nonsensical to do.
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Bugs
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----
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To file bug reports please send email to:
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<michel.fortin@michelf.ca>
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Please include with your report: (1) the example input; (2) the output you
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expected; (3) the output PHP Markdown actually produced.
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If you have a problem where Markdown gives you an empty result, first check
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that the backtrack limit is not too low by running `php --info | grep pcre`.
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See Installation and Requirement above for details.
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Development and Testing
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-----------------------
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Pull requests for fixing bugs are welcome. Proposed new features are
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going to be meticulously reviewed -- taking into account backward compatibility,
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potential side effects, and future extensibility -- before deciding on
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acceptance or rejection.
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If you make a pull request that includes changes to the parser please add
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tests for what is being changed to [MDTest][] and make a pull request there
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too.
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[MDTest]: https://github.com/michelf/mdtest/
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Donations
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---------
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If you wish to make a donation that will help me devote more time to
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PHP Markdown, please visit [michelf.ca/donate] or send Bitcoin to
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[1HiuX34czvVPPdhXbUAsAu7pZcesniDCGH].
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[michelf.ca/donate]: https://michelf.ca/donate/#!Thanks%20for%20PHP%20Markdown
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[1HiuX34czvVPPdhXbUAsAu7pZcesniDCGH]: bitcoin:1HiuX34czvVPPdhXbUAsAu7pZcesniDCGH
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Version History
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---------------
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PHP Markdown Lib 1.8.0 (14 Jan 2018)
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* Autoloading with Composer now uses PSR-4.
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* HTML output for Markdown Extra footnotes now include `role` attributes
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with values from [WAI-ARIA](https://www.w3.org/TR/dpub-aria/) to
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make them more accessible.
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(Thanks to Tobias Bengfort)
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* In Markdown Extra, added the `hashtag_protection` configuration variable.
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When set to `true` it prevents ATX-style headers with no space after the initial
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hash from being interpreted as headers. This way your precious hashtags
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are preserved.
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(Thanks to Jaussoin Timothée for the implementation.)
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PHP Markdown Lib 1.7.0 (29 Oct 2016)
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* Added a `hard_wrap` configuration variable to make all newline characters
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in the text become `<br>` tags in the HTML output. By default, according
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to the standard Markdown syntax these newlines are ignored unless they a
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preceded by two spaces. Thanks to Jonathan Cohlmeyer for the implementation.
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* Improved the parsing of list items to fix problematic cases that came to
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light with the addition of `hard_wrap`. This should have no effect on the
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output except span-level list items that ended with two spaces (and thus
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ended with a line break).
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* Added a `code_span_content_func` configuration variable which takes a
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function that will convert the content of the code span to HTML. This can
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be useful to implement syntax highlighting. Although contrary to its
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code block equivalent, there is no syntax for specifying a language.
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Credits to styxit for the implementation.
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* Fixed a Markdown Extra issue where two-space-at-end-of-line hard breaks
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wouldn't work inside of HTML block elements such as `<p markdown="1">`
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where the element expects only span-level content.
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* In the parser code, switched to PHPDoc comment format. Thanks to
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Robbie Averill for the help.
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PHP Markdown Lib 1.6.0 (23 Dec 2015)
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Note: this version was incorrectly released as 1.5.1 on Dec 22, a number
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that contradicted the versioning policy.
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* For fenced code blocks in Markdown Extra, can now set a class name for the
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code block's language before the special attribute block. Previously, this
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class name was only allowed in the absence of the special attribute block.
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* Added a `code_block_content_func` configuration variable which takes a
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function that will convert the content of the code block to HTML. This is
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most useful for syntax highlighting. For fenced code blocks in Markdown
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Extra, the function has access to the language class name (the one outside
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of the special attribute block). Credits to Mario Konrad for providing the
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implementation.
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* The curled arrow character for the backlink in footnotes is now followed
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by a Unicode variant selector to prevent it from being displayed in emoji
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form on iOS.
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Note that in older browsers the variant selector is often interpreted as a
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separate character, making it visible after the arrow. So there is now a
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also a `fn_backlink_html` configuration variable that can be used to set
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the link text to something else. Credits to Dana for providing the
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implementation.
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* Fixed an issue in MarkdownExtra where long header lines followed by a
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special attribute block would hit the backtrack limit an cause an empty
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string to be returned.
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PHP Markdown Lib 1.5.0 (1 Mar 2015)
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* Added the ability start ordered lists with a number different from 1 and
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and have that reflected in the HTML output. This can be enabled with
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the `enhanced_ordered_lists` configuration variable for the Markdown
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parser; it is enabled by default for Markdown Extra.
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Credits to Matt Gorle for providing the implementation.
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* Added the ability to insert custom HTML attributes with simple values
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everywhere an extra attribute block is allowed (links, images, headers).
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The value must be unquoted, cannot contains spaces and is limited to
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alphanumeric ASCII characters.
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Credits to Peter Droogmans for providing the implementation.
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* Added a `header_id_func` configuration variable which takes a function
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that can generate an `id` attribute value from the header text.
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Credits to Evert Pot for providing the implementation.
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* Added a `url_filter_func` configuration variable which takes a function
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that can rewrite any link or image URL to something different.
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PHP Markdown Lib 1.4.1 (4 May 2014)
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* The HTML block parser will now treat `<figure>` as a block-level element
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(as it should) and no longer wrap it in `<p>` or parse it's content with
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the as Markdown syntax (although with Extra you can use `markdown="1"`
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if you wish to use the Markdown syntax inside it).
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* The content of `<style>` elements will now be left alone, its content
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won't be interpreted as Markdown.
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* Corrected an bug where some inline links with spaces in them would not
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work even when surounded with angle brackets:
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[link](<s p a c e s>)
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* Fixed an issue where email addresses with quotes in them would not always
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have the quotes escaped in the link attribute, causing broken links (and
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invalid HTML).
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* Fixed the case were a link definition following a footnote definition would
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be swallowed by the footnote unless it was separated by a blank line.
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PHP Markdown Lib 1.4.0 (29 Nov 2013)
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* Added support for the `tel:` URL scheme in automatic links.
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<tel:+1-111-111-1111>
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It gets converted to this (note the `tel:` prefix becomes invisible):
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<a href="tel:+1-111-111-1111">+1-111-111-1111</a>
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* Added backtick fenced code blocks to MarkdownExtra, originally from
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Github-Flavored Markdown.
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* Added an interface called MarkdownInterface implemented by both
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the Markdown and MarkdownExtra parsers. You can use the interface if
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you want to create a mockup parser object for unit testing.
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* For those of you who cannot use class autoloading, you can now
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include `Michelf/Markdown.inc.php` or `Michelf/MarkdownExtra.inc.php` (note
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the `.inc.php` extension) to automatically include other files required
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by the parser.
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PHP Markdown Lib 1.3 (11 Apr 2013)
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This is the first release of PHP Markdown Lib. This package requires PHP
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version 5.3 or later and is designed to work with PSR-0 autoloading and,
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optionally with Composer. Here is a list of the changes since
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PHP Markdown Extra 1.2.6:
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* Plugin interface for WordPress and other systems is no longer present in
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the Lib package. The classic package is still available if you need it:
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<https://michelf.ca/projects/php-markdown/classic/>
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* Added `public` and `protected` protection attributes, plus a section about
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what is "public API" and what isn't in the Readme file.
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* Changed HTML output for footnotes: now instead of adding `rel` and `rev`
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attributes, footnotes links have the class name `footnote-ref` and
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backlinks `footnote-backref`.
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* Fixed some regular expressions to make PCRE not shout warnings about POSIX
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collation classes (dependent on your version of PCRE).
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* Added optional class and id attributes to images and links using the same
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syntax as for headers:
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[link](url){#id .class}
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{#id .class}
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It work too for reference-style links and images. In this case you need
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to put those attributes at the reference definition:
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[link][linkref] or [linkref]
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![img][linkref]
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[linkref]: url "optional title" {#id .class}
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* Fixed a PHP notice message triggered when some table column separator
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markers are missing on the separator line below column headers.
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* Fixed a small mistake that could cause the parser to retain an invalid
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state related to parsing links across multiple runs. This was never
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observed (that I know of), but it's still worth fixing.
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Copyright and License
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---------------------
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PHP Markdown Lib
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Copyright (c) 2004-2016 Michel Fortin
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<https://michelf.ca/>
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All rights reserved.
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Based on Markdown
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Copyright (c) 2003-2005 John Gruber
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<https://daringfireball.net/>
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the
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distribution.
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* Neither the name "Markdown" nor the names of its contributors may
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be used to endorse or promote products derived from this software
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without specific prior written permission.
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This software is provided by the copyright holders and contributors "as
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is" and any express or implied warranties, including, but not limited
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to, the implied warranties of merchantability and fitness for a
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particular purpose are disclaimed. In no event shall the copyright owner
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or contributors be liable for any direct, indirect, incidental, special,
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exemplary, or consequential damages (including, but not limited to,
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procurement of substitute goods or services; loss of use, data, or
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profits; or business interruption) however caused and on any theory of
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liability, whether in contract, strict liability, or tort (including
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negligence or otherwise) arising in any way out of the use of this
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software, even if advised of the possibility of such damage.
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