Earmark—A Pure Elixir Markdown Processor

Dependency

{ :earmark, "> x.y.z" }

Usage

API

  html_doc = Earmark.to_html(markdown)

  html_doc = Earmark.to_html(markdown, options)

(See the documentation for to_html for options)

Command line

$ mix escript.build
$ ./earmark file.md

Some options defined in the Earmark.Options struct can be specified as command line switches.

Use

$ ./earmark --help

to find out more, but here is a short example

$ ./earmark --smartypants false --code-class-prefix "a- b-" file.md

will call

Earmark.to_html( ..., %Earmark.Options{smartypants: false, code_class_prefix: "a- b-"})

Supports

Standard Gruber markdown.

Extensions

Tables

Github Flavored Markdown tables are supported

    State | Abbrev | Capital
    ----: | :----: | -------
    Texas | TX     | Austin
    Maine | ME     | Augusta

Tables may have leading and trailing vertical bars on each line

    | State | Abbrev | Capital |
    | ----: | :----: | ------- |
    | Texas | TX     | Austin  |
    | Maine | ME     | Augusta |

Tables need not have headers, in which case all column alignments default to left.

    | Texas | TX     | Austin  |
    | Maine | ME     | Augusta |

Currently we assume there are always spaces around interior vertical bars. It isn't clear what the expectation is.

Adding HTML attributes with the IAL extension

HTML attributes can be added to any block-level element. We use the Kramdown syntax: add the line {:attrs} following the block.

attrs can be one or more of:

.className
#id
name=value, name="value", or name='value'

Malformed attributes are ignored and a warning is issued to stderr.

If you need to render IAL-like test verbatim escape it:

{:alpha, 42}

This of course is not necessary in code blocks or text lines containing an IAL-like string, as in

the returned tuple should be {:error, "I wish you hadn't done that"}

For example:

    # Warning
    {: .red}

    Do not turn off the engine
    if you are at altitude.
    {: .boxed #warning spellcheck="true"}

Limitations

Nested block-level HTML is correctly handled only if each HTML tag appears on its own line. So
```
  <div>
  <div>
  hello
  </div>
  </div>
```
will work. However. the following won't
```
  <div><div>
  hello
  </div></div>
```
John Gruber's tests contain an ambiguity when it comes to lines that might be the start of a list inside paragraphs.
One test says that
```
  This is the text
  * of a paragraph
  that I wrote
```
is a single paragraph. The "*" is not significant. However, another test has
```
  *   A list item
      * an another
```
and expects this to be a nested list. But, in reality, the second could just be the continuation of a paragraph.
I've chosen always to use the second interpretation—a line that looks like a list item will always be a list item.
Rendering of block and inline elements.
Block or void HTML elements that are at the absolute beginning of a line end the preceeding paragraph.
Thusly
```
  mypara
  <hr>
```
Becomes
```
  <p>mypara</p>
  <hr>
```
While
```
  mypara
   <hr>
```
will be transformed into
```
  <p>mypara
   <hr></p>
```

Integration

Syntax Highlightning

All backquoted or fenced code blocks with a language string are rendered with the given language as a class attribute of the code tag.

For example:

  ```elixir
     @tag :hello
  ```

will be rendered as

   <pre><code class="elixir">...

If you want to integrate with a syntax highlighter with different conventions you can add more classes by specifying prefixes that will be put before the language string.

Prism.js for example needs a class language-elixir. In order to achieve that goal you can add language- as a code_class_prefix to Earmark.Options.

In the following example we want more than one additional class, so we add more prefixes.

  Earmark.to_html(..., %Earmark.Options{code_class_prefix: "lang- language-"})

which is rendering

   <pre><code class="elixir lang-elixiri language-elixir">...

As for all other options code_class_prefix can be passed into the earmark executable as follows:

  earmark --code-class-prefix "language- lang-" ...

Security

Please be aware that Markdown is not a secure format. It produces HTML from Markdown and HTML. It is your job to sanitize and or filter the output of Markdown.html if you cannot trust the input and are to serve the produced HTML on the Web.

Author

Licensed under the same terms as Elixir, which is Apache 2.0.

Details

Given a markdown document (as either a list of lines or a string containing newlines), return an HTML representation.

The options are a %Earmark.Options{} structure:

renderer: ModuleName
The module used to render the final document. Defaults to Earmark.HtmlRenderer
gfm: boolean
True by default. Turns on Github Flavored Markdown extensions
breaks: boolean
Only applicable if gfm is enabled. Makes all line breaks significant (so every line in the input is a new line in the output.
smartypants: boolean
Turns on smartypants processing, so quotes become curly, two or three hyphens become en and em dashes, and so on. True by default.

So, to format the document in original and disable smartypants, you'd call

alias Earmark.Options
result = Earmark.to_html(original, %Options{smartypants: false})

LICENSE

Same as Elixir, which is Apache License v2.0. Please refer to LICENSE for details.