Pegdown Migration

PegdownOptionsAdapter class converts pegdown Extensions.* flags to flexmark options and extensions list. Pegdown Extensions.java is included for convenience. These are located in flexmark-profile-pegdown module, was added to Maven but you can grab the source from this repo: PegdownOptionsAdapter.java and if you need it Extensions.java and make your own version, modified to your project's needs.

You can pass your extension flags to static PegdownOptionsAdapter.flexmarkOptions(int) or you can instantiate PegdownOptionsAdapter and use convenience methods to set, add and remove extension flags. PegdownOptionsAdapter.getFlexmarkOptions() will return a fresh copy of DataHolder every time with the options reflecting pegdown extension flags.

import com.vladsch.flexmark.html.HtmlRenderer;
import com.vladsch.flexmark.parser.Parser;
import com.vladsch.flexmark.profile.pegdown.Extensions;
import com.vladsch.flexmark.profile.pegdown.PegdownOptionsAdapter;
import com.vladsch.flexmark.util.data.DataHolder;

public class PegdownOptions {
     final private static DataHolder OPTIONS = PegdownOptionsAdapter.flexmarkOptions(
            Extensions.ALL
    );

    static final Parser PARSER = Parser.builder(OPTIONS).build();
    static final HtmlRenderer RENDERER = HtmlRenderer.builder(OPTIONS).build();

    // use the PARSER to parse and RENDERER to render with pegdown compatibility
}

Strict pegdown HTML parsing Mode

Default flexmark-java pegdown emulation uses less strict HTML block parsing which interrupts an HTML block on a blank line. Pegdown only interrupts an HTML block on a blank line if all tags in the HTML block are closed.

To get closer to original pegdown HTML block parsing behavior use the method which takes a boolean strictHtml argument:

import com.vladsch.flexmark.html.HtmlRenderer;
import com.vladsch.flexmark.parser.Parser;
import com.vladsch.flexmark.profile.pegdown.Extensions;
import com.vladsch.flexmark.profile.pegdown.PegdownOptionsAdapter;
import com.vladsch.flexmark.util.data.DataHolder;

public class PegdownOptions {
     final private static DataHolder OPTIONS = PegdownOptionsAdapter.flexmarkOptions(true,
            Extensions.ALL
    );

    static final Parser PARSER = Parser.builder(OPTIONS).build();
    static final HtmlRenderer RENDERER = HtmlRenderer.builder(OPTIONS).build();

    // use the PARSER to parse and RENDERER to render with pegdown compatibility
}

You can find more Java Samples are available.

Available Extensions via PegdownOptionsAdapter

ℹ️ flexmark-java has many more extensions and configuration options than pegdown in addition to extensions available in pegdown 1.6.0, the following extensions are available:

SMARTS: Beautifies ... . . ., -- and --- to …, …, – and — respectively.
QUOTES: Beautifies single quotes ', ", << and >> to ‘ ’ ‛, “ ” ‟, « and »
SMARTYPANTS: Convenience extension enabling both, SMARTS and QUOTES, at once.
ABBREVIATIONS: Abbreviations in the way of PHP Markdown Extra.
ANCHORLINKS: Generate anchor links for headers by taking the first range of alphanumerics and spaces.
HARDWRAPS: Alternative handling of newlines, see Github-flavoured-Markdown
AUTOLINKS: Plain, undelimited autolinks the way Github-flavoured-Markdown implements them.
TABLES: Tables similar to MultiMarkdown (which is in turn like the PHP Markdown Extra: tables tables, but with colspan support).
DEFINITIONS: Definition lists in the way of PHP Markdown Extra: definition list.
FENCED_CODE_BLOCKS: Fenced Code Blocks in the way of PHP Markdown Extra: fenced code or Github-flavoured-Markdown.
SUPPRESS_HTML_BLOCKS: Suppresses the output of HTML blocks.
SUPPRESS_INLINE_HTML: Suppresses the output of inline HTML elements.
WIKILINKS: Support [[Wiki-style links]] with a customizable URL rendering logic.
STRIKETHROUGH: Support ~~strikethroughs~~ as supported in Pandoc and Github-flavoured-Markdown.
ATXHEADERSPACE: Require a space between the # and the header title text, as per Github-flavoured-Markdown. Frees up # without a space to be just plain text.
FORCELISTITEMPARA: Wrap a list item or definition term in <p> tags if it contains more than a simple paragraph.
RELAXEDHRULES: allow horizontal rules without a blank line following them.
TASKLISTITEMS: parses bullet lists of the form * [ ], * [x] and * [X] to create Github-flavoured-Markdown task list items.
EXTANCHORLINKS: Generate anchor links for headers using complete contents of the header.
- Spaces and non-alphanumerics replaced by -, multiple dashes trimmed to one.
- Anchor link is added as first element inside the header with empty content: <h1><a name="header"></a>header</h1>
EXTANCHORLINKS_WRAP: used in conjunction with above to create an anchor that wraps header content: <h1><a name="header">header</a></h1>
TOC: used to enable table of contents extension [TOC] The TOC tag has the following format: [TOC style]. style consists of space separated list of options:
- levels=levelList where level list is a comma separated list of levels or ranges. Default is to include heading levels 2 and 3. Examples:
  - levels=4 include levels 2, 3 and 4
  - levels=2-4 include levels 2, 3 and 4. same as levels=4
  - levels=2-4,5 include levels 2, 3, 4 and 5
  - levels=1,3 include levels 1 and 3
- text to only include the text of the heading
- formatted to include text and inline formatting
- bullet to use a bullet list for the TOC items
- numbered to use a numbered list for TOC items
- hierarchy: hierarchical list of headings
- flat: flat list of headings
- reversed: flat reversed list of headings
- increasing: flat, alphabetically increasing by heading text
- decreasing: flat, alphabetically decreasing by heading text
MULTI_LINE_IMAGE_URLS: enables parsing of image urls spanning more than one line the format is strict ![alt text](urladdress? must be the last non-blank segment on a line. The terminating ) or "title") must be the first non-indented segment on the line. Everything in between is sucked up as part of the URL except for blank lines.
RELAXED_STRONG_EMPHASIS_RULES: allow Strong/Emphasis marks to start when not preceded by alphanumeric for _ and as long as not surrounded by spaces for * instead of only when preceded by spaces.
SUBSCRIPT: subscript extension ~subscript~
SUPERSCRIPT: superscript extension ^superscript^
INSERTED: inserted or underlined extension ++inserted++

FOOTNOTES: Support MultiMarkdown style footnotes: [^n] for footnote reference and [^n]: Footnote text for footnotes. Where n is one or more digit, letter, -, _ or .. Footnotes will be put at the bottom of the page, sequentially numbered in order of appearance of the footnote reference. Footnotes that are not referenced will NOT be included in the HTML output.

This paragraph has a footnote[^1] and another footnote[^two].

This one has more but out of sequence[^4] and[^eight].

[^two]: Footnote 2 with a bit more text
    and another continuation line

[^1]: Footnote 1

[^3]: Unused footnote, it will not be added to the end of the page.

[^4]: Out of sequence footnote

[^eight]: Have one that is used.

will generate:

<div>
    <hr/>
    <p>This paragraph has a footnote<sup id="fnref-1"><a href="#fn-1" class="footnote-ref">1</a></sup> and another footnote<sup id="fnref-2"><a href="#fn-2" class="footnote-ref">2</a></sup>.</p>
    <p>This one has more but out of sequence<sup id="fnref-3"><a href="#fn-3" class="footnote-ref">3</a></sup> and<sup id="fnref-4"><a href="#fn-4" class="footnote-ref">4</a></sup>. </p>
    <hr/>
    <div class="footnotes">
       <ol style="list-style-type: decimal;">
           <li id="fn-1"><p>Footnote 1<a href="#fnref-1" class="footnote-backref">&#8617;</a></p></li>
           <li id="fn-2"><p>Footnote 2 with a bit more text  and another continuation line<a href="#fnref-2" class="footnote-backref">&#8617;</a></p></li>
           <li id="fn-3"><p>Out of sequence footnote<a href="#fnref-3" class="footnote-backref">&#8617;</a></p></li>
           <li id="fn-4"><p>Have one that is used.<a href="#fnref-4" class="footnote-backref">&#8617;</a></p></li>
       </ol>
    </div>
</div>