Meet ReverseMarkdown

ReverseMarkdown is a Html to Markdown (http://daringfireball.net/projects/markdown/syntax) converter library in C#. Conversion is very reliable since HtmlAgilityPack (HAP) library is used for traversing the Html DOM.

Note that the library implementation is based on the Ruby based Html to Markdown converter xijo/reverse_markdown.

Usage

Install the package from NuGet using Install-Package ReverseMarkdown or clone the repository and built it yourself.

var converter = new ReverseMarkdown.Converter();

string html = "This a sample <strong>paragraph</strong> from <a href=\"http://test.com\">my site</a>";

string result = converter.Convert(html);

^{snippet source | anchor}

Will result in:

This a sample **paragraph** from [my site](http://test.com)

^{snippet source | anchor}

The conversion can be customized:

var config = new ReverseMarkdown.Config
{
    // Include the unknown tag completely in the result (default as well)
    UnknownTags = Config.UnknownTagsOption.PassThrough,
    // generate GitHub flavoured markdown, supported for BR, PRE and table tags
    GithubFlavored = true,
    // will ignore all comments
    RemoveComments = true,
    // remove markdown output for links where appropriate
    SmartHrefHandling = true
};

var converter = new ReverseMarkdown.Converter(config);

^{snippet source | anchor}

Configuration options

• DefaultCodeBlockLanguage - Option to set the default code block language for Github style markdown if class based language markers are not available

• GithubFlavored - Github style markdown for br, pre and table. Default is false

• ListBulletChar - Allows to change the bullet character. Default value is -. Some systems expect the bullet character to be * rather than -, this config allows to change it.

• RemoveComments - Remove comment tags with text. Default is false

• SmartHrefHandling - how to handle <a> tag href attribute

  • false - Outputs [{name}]({href}{title}) even if name and href is identical. This is the default option.

  • true - If name and href equals, outputs just the name. Note that if Uri is not well formed as per Uri.IsWellFormedUriString (i.e string is not correctly escaped like http://example.com/path/file name.docx) then markdown syntax will be used anyway.

    If href contains http/https protocol, and name doesn't but otherwise are the same, output href only

    If tel: or mailto: scheme, but afterwards identical with name, output name only.

• UnknownTags - handle unknown tags.

  • UnknownTagsOption.PassThrough - Include the unknown tag completely into the result. That is, the tag along with the text will be left in output. This is the default
  • UnknownTagsOption.Drop - Drop the unknown tag and its content
  • UnknownTagsOption.Bypass - Ignore the unknown tag but try to convert its content
  • UnknownTagsOption.Raise - Raise an error to let you know

• PassThroughTags - Pass a list of tags to pass through as-is without any processing.

• WhitelistUriSchemes - Specify which schemes (without trailing colon) are to be allowed for <a> and <img> tags. Others will be bypassed (output text or nothing). By default allows everything.

  If string.Empty provided and when href or src schema couldn't be determined - whitelists

  Schema is determined by Uri class, with exception when url begins with / (file schema) and // (http schema)

• TableWithoutHeaderRowHandling - handle table without header rows

  • TableWithoutHeaderRowHandlingOption.Default - First row will be used as header row (default)
  • TableWithoutHeaderRowHandlingOption.EmptyRow - An empty row will be added as the header row

Note that UnknownTags config has been changed to an enumeration in v2.0.0 (breaking change)

Features

• Supports all the established html tags like h1, h2, h3, h4, h5, h6, p, em, strong, i, b, blockquote, code, img, a, hr, li, ol, ul, table, tr, th, td, br
• Can deal with nested lists
• Github Flavoured Markdown conversion supported for br, pre and table. Use var config = new ReverseMarkdown.Config(githubFlavoured:true);. By default table will always be converted to Github flavored markdown immaterial of this flag.

Copyright

Copyright © 2020 Babu Annamalai

License

ReverseMarkdown is licensed under MIT. Refer to License file for more information.