Pub.dev package GitHub repository

Markdown

A simple-setup Markdown syntax parser for Dart.
Create your own custom Markdown syntax.

Features

  • Simple Markdown syntax setup
  • Generic Markdown-base for any use-case
  • Apply the Markdown to any text
  • Attach placeholders to modify the input

Getting started

Install it using pub:

dart pub add marked

And import the package:

import 'package:marked/marked.dart';

Usage

Create a Markdown instance with all the placeholders you want to use.

Then, use the apply method to parse the Markdown syntax.

import 'package:marked/marked.dart';

final markdown = Markdown.map({
  '**': (text, match) => '<b>$text</b>',
  '*': (text, match) => '<i>$text</i>',
  '__': (text, match) => '<u>$text</u>',
});

void main() {
  print(
    markdown.apply('''
      Hello **World**!
      __Looks *pretty* easy__
    ''')
  );

  // Output:
  //   Hello <b>World</b>!
  //   <u>Looks <i>pretty</i> easy</u>
}

Placeholders

Placeholders are modular elements that can be used to create a Markdown syntax. They are used to replace a specific part of the text that matches a pattern.

MarkdownPlaceholder(RegExp(r'\*\*(.*?)\*\*'), (text, match) => '<b>$text</b>');

To make it easier to create placeholders, there are some predefined methods:

MarkdownPlaceholder.enclosed('**', (text, match) => '<b>$text</b>');
// Hello **World**! -> Hello <b>World</b>!

MarkdownPlaceholder.tag('strong', (text, match) => '<b>$text</b>');
// Hello <strong>World</strong>! -> Hello <b>World</b>!

MarkdownPlaceholder.regexp(r'\*\*(.*?)\*\*', (text, match) => '<b>$text</b>');
// Hello **World**! -> Hello <b>World</b>!

Placeholder Mapping

To Simplify the markdown definition, you may transform a set of entries into placeholders, given the related string key. Using the Markdown.map() method.

Usage example, with the following placeholder equivalent:

'*': (text, match) => '<b>$text</b>'
  MarkdownPlaceholder.enclosed('*', (text, match) => '<b>$text</b>'),

'<custom>': (text, match) => '[$text]'
  MarkdownPlaceholder.tag('custom', (text, match) => '[$text]'),

'/\*([^*]+)\*/': (text, match) => '<b>$text</b>'
  MarkdownPlaceholder.regexp('/\*([^*]+)\*/', (text, match) => '<b>$text</b>'),

A prefix can be used to ensure the right placeholder is used.

'enclosed: *': (text, match) => '<b>$text</b>'
'tag: <custom>': (text, match) => '[$text]'
'regexp: \*([^*]+)\*': (text, match) => '<b>$text</b>'

Types of placeholders:

Type Description Prefix Symbol
Normal Applies the default placeholder, which is enclosed. normal: None
Enclosed Starts and ends with the same token, like * for *text*. enclosed: None
Basic Single token placeholder, for a basic replacement. basic: None
Sticky Same as enclosed, but tokens must be next to a character. sticky: [...]
Split Splits the start token at | to set the end token, like /* | */ matching with /*text*/. split: ... | ...
RegExp Matches a regular expression, the text is the first capture group. regexp: /.../
Tag Starts with a tag of type <tag> and ending with </tag>, HTML-like.
Tags may have properties, key[="value"], defined as <tag prop1|...>, and can be fetched using match.tagProperties.		 tag: <...>

Note: When using a unique character token, the created placeholders will be symmetrical with no nesting, this is so it's more intuitive.

Escaping

To escape a placeholder, you can use the \ character. You may also escape the escape character, instances of \\ will be replaced with \, since they are escaped.

An input can be manually escaped and unescaped using the methods markdown.escape(input) and markdown.unescape(input).

Example

import 'package:marked/marked.dart';

final htmlMarkdown = Markdown({
  MarkdownPlaceholder.enclosed('**', (text, match) => '<b>$text</b>'),
  MarkdownPlaceholder.enclosed('*', (text, match) => '<i>$text</i>'),
  MarkdownPlaceholder.enclosed('~~', (text, match) => '<strike>$text</strike>'),
  MarkdownPlaceholder.enclosed('`', (text, match) => '<code>$text</code>'),
});

void main() {
  print(htmlMarkdown.apply('HTML Markdown: **bold** *italic* ~~strike~~ `code`'));
  
  // [Output]
  //   HTML Markdown: <b>bold</b> <i>italic</i> <strike>strike</strike> <code>code</code>
}

More Examples:

Libraries

marked