Txtmark - Java markdown processor

Copyright (C) 2011-2015 René Jeschke rene_jeschke@yahoo.de
See LICENSE.txt for licensing information.

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Txtmark is yet another markdown processor for the JVM.

• It is easy to use:

  String result = txtmark.Processor.process("This is ***TXTMARK***");
  

• It is fast (see below)
  ... well, it is the fastest markdown processor on the JVM right now. (This might be outdated, but txtmark is still flippin' fast.)

• It does not depend on other libraries, so classpathing txtmark.jar is sufficient to use Txtmark in your project.

For an in-depth explanation of markdown have a look at the original Markdown Syntax.

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Maven repository

Txtmark is available on maven central.

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Txtmark extensions

To enable Txtmark's extended markdown parsing you can use the $PROFILE$ mechanism:

[$PROFILE$]: extended

This seemed to me as the easiest and safest way to enable different behaviours. Just put this line into your Txtmark file like you would use reference links.

Behavior changes when using [$PROFILE$]: extended

• Lists and code blocks end a paragraph

  In normal markdown the following:

  This is a paragraph
  * and this is not a list
  

  Will produce:

  <p>This is a paragraph
  * and this is not a list</p>
  

  When using Txtmark extensions this changes to:

  <p>This is a paragraph</p>
  <ul>
  <li>and this is not a list</li>
  </ul>
  

• Text anchors

  Headlines and list items may recieve an ID which you can refer to using links.

  ## Headline with ID ##     {#headid}
  
  Another headline with ID   {#headid2}
  ------------------------
  
  * List with ID             {#listid}
  
  Links: [Foo] (#headid)
  

  this will produce:

  <h2 id="headid">Headline with ID</h2>
  <h2 id="headid2">Another headline with ID</h2>
  <ul>
  <li id="listid">List with ID</li>
  </ul>
  <p>Links: <a href="#headid">Foo</a></p>
  

  The ID must be the last thing on the first line.

  All spaces before {# get removed, so you can't use an ID and a manual line break in the same line.

• Auto HTML entities

  • (C) becomes © - ©
  • (R) becomes ® - ®
  • (TM) becomes ™ - ™
  • -- becomes – - –
  • --- becomes — - —
  • ... becomes … - …
  • << becomes « - «
  • >> becomes » - »
  • "Hello" becomes “Hello” - “Hello”

• Underscores (Emphasis)

  Underscores in the middle of a word don't result in emphasis.

  Con_cat_this
  

  normally produces this:

  Con<em>cat</em>this
  

• Superscript

  You can use ^ to mark a span as superscript.

  2^2^ = 4
  

  turns into

  2<sup>2</sup> = 4
  

• Abbreviations

  Abbreviations are defined like reference links, but using a * instead of a link and must be single-line only.

  [Git]: * "Fast distributed revision control system"
  

  and used like this

  This is [Git]!
  

  which will produce

  This is <abbr title="Fast distributed revision control system">Git</abbr>!
  

• Fenced code blocks

  ```
  This is code!
  ```
  
  ~~~
  Another code block
  ~~~
  
  ~~~
  You can also mix flavours
  ```
  

  Fenced code block delimiter lines do start with at least three of `` or `~

  It is possible to add meta data to the beginning line. Everything trailing after `` or `~ is then considered meta data. These are all valid meta lines:

  ```python
  ~ ~ ~ ~ ~java
  ``` ``` ``` this is even more meta
  

  The meta information that you provide here can be used with a BlockEmitter to include e.g. syntax highlighted code blocks. Here's an example:

  public class CodeBlockEmitter implements BlockEmitter
  {
      private static void append(StringBuilder out, List<String> lines)
      {
          out.append("<pre class=\"pre_no_hl\">");
          for (final String l : lines)
          {
              Utils.escapedAdd(out, l);
              out.append('\n');
          }
          out.append("</pre>");
      }
  
      @Override
      public void emitBlock(StringBuilder out, List<String> lines, String meta)
      {
          if (Strings.isEmpty(meta))
          {
              append(out, lines);
          }
          else
          {
              try
              {
                  // Utils#highlight(...) is not included with txtmark, it's sole purpose
                  // is to show what the meta can be used for
                  out.append(Utils.highlight(lines, meta));
                  out.append('\n');
              }
              catch (final IOException e)
              {
                  // Ignore or do something, still, pump out the lines
                  append(out, lines);
              }
          }
      }
  }
  

  You can then set the BlockEmitter in the txtmark Configuration using Configuration.Builder#setCodeBlockEmitter(BlockEmitter emitter).

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Markdown conformity

Txtmark passes all tests inside MarkdownTest_1.0_2007-05-09 except of two:

1. Images.text

   Fails because Txtmark doesn't produce empty 'title' image attributes.
   (IMHO: Images ... OK)

2. Literal quotes in titles.text

   What the frell ... this test will continue to FAIL.
   Sorry, but using unescaped " in a title which should be surrounded by " is unacceptable for me ;)

   Change:

   Foo [bar](/url/ "Title with "quotes" inside").
   [bar]: /url/ "Title with "quotes" inside"
   

   to:

   Foo [bar](/url/ "Title with \"quotes\" inside").
   [bar]: /url/ "Title with \"quotes\" inside"
   

   and Txtmark will produce the correct result.
   (IMHO: Literal quotes in titles ... OK)

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Where Txtmark is not like Markdown

• Txtmark does not produce empty title attributes in link and image tags.

• Unescaped " in link titles starting with " are not recognized and result in unexpected behaviour.

• Due to a different list parsing approach some things get interpreted differently:

  * List
  > Quote
  

  will produce when processed with Markdown:

  <p><ul>
  <li>List</p>
  
  <blockquote>
   <p>Quote</li>
  </ul></p>
  </blockquote>
  

  and this when produced with Txtmark:

  <ul>
  <li>List<blockquote><p>Quote</p>
  </blockquote>
  </li>
  </ul>
  

  Another one:

  * List
  ====
  

  will produce when processed with Markdown:

  <h1>* List</h1>
  

  and this when produced with Txtmark:

  <ul>
  <li><h1>List</h1>
  </li>
  </ul>
  

• List of escapeable characters:

  \   [   ]   (   )   {   }   #
  "   '   .   <   >   +   -   _
  !   `   ^
  

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Performance comparison of markdown processors for the JVM

Remarks: These benchmarks are too old to be of any value. I leave them here as a reference, though.

Based on this benchmark suite.

Excerpt from the original post concerning this benchmark suite:

Most of these tests are of course unrealistic: Who would write a text where each word is a link? Yet they serve an important use: It makes it possible for the developer to pinpoint the parts of the parser where there is most room for improvement. Also, it explains why certain texts might render much faster in one Processor than in another.

Benchmark system:

• Ubuntu Linux 10.04 32 Bit
• Intel(R) Core(TM) 2 Duo T7500 @ 2.2GHz
• Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
• Java HotSpot(TM) Server VM (build 19.1-b02, mixed mode)

Test	Actuarius		PegDown		Knockoff		Txtmark
	1st Run (ms)	2nd Run (ms)	1st Run (ms)	2nd Run (ms)	1st Run (ms)	2nd Run (ms)	1st Run (ms)	2nd Run (ms)
Plain Paragraphs	1127	577	1273	1037	740	400	157	64
Every Word Emphasized	1562	1001	1523	1513	13982	13221	54	46
Every Word Strong	1125	997	1115	1114	9543	9647	44	41
Every Word Inline Code	382	277	1058	1052	9116	9074	51	39
Every Word a Fast Link	2257	1600	537	531	3980	3410	109	55
Every Word Consisting of Special XML Chars	4045	4270	2985	3044	312	377	778	775
Every Word wrapped in manual HTML tags	3334	2919	901	896	3863	3736	73	62
Every Line with a manual line break	510	588	1445	1440	1527	1130	56	56
Every word with a full link	452	246	1045	996	1884	1819	86	55
Every word with a full image	268	150	1140	1132	1985	1908	38	36
Every word with a reference link	9847	9082	18956	18719	121136	115416	1525	1380
Every block a quote	445	206	1312	1301	478	457	50	45
Every block a codeblock	70	87	373	376	161	175	60	22
Every block a list	920	912	1720	1725	622	651	55	55
All tests together	3281	2885	5184	5196	10130	10460	206	196

Benchmarked versions:

Actuarius version: 0.2
PegDown version: 0.8.5.4
Knockoff version: 0.7.3-15

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Mentioned/related projects

Markdown is Copyright (C) 2004 by John Gruber
SmartyPants is Copyright (C) 2003 by John Gruber
Actuarius is Copyright (C) 2010 by Christoph Henkelmann
Knockoff is Copyright (C) 2009-2011 by Tristan Juricek
PegDown is Copyright (C) 2010 by Mathias Doenitz
PHP Markdown & Extra is Copyright (C) 2009 Michel Fortin

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Project link: https://github.com/rjeschke/txtmark