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Last active Dec 3, 2018

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Piedown

Piedown is a small python script that converts Markdown text to HTML using only regular expressions. It was much inspired by jbroadway's Slimdown.

Usage

To convert a page.md file written in Markdown to a page.html file, use:

  cat page.md | piedown.py > page.html

If you only want to preview what the generated HTML will be like, use:

  cat page.md | piedown.py
#!/usr/bin/python3
"""
Piedown is a small python script that converts Markdown text
to HTML using only regular expressions.
Usage:
cat page.md | piedown.py > page.html
Where:
- 'page.md' is the Markdown source file; and
- 'page.html' is the generated file containing the produced HTML.
LEGAL:
This work is inspired by the work of Johnny Broadway <johnny@johnnybroadway.com>
on Slimdown <https://gist.github.com/jbroadway/2836900> which is licensed under
the MIT license <http://opensource.org/licenses/MIT>.
This work is licensed under the MIT LICENSE <http://opensource.org/licenses/MIT>
with copyright attribution to: Lucas Possatti (2015).
"""
import re
import sys
import collections
########################
### Helper Functions ###
########################
def paragraph(match_obj):
line = match_obj.group(1)
trimmed = line.strip()
if re.search(r'^<\/?(ul|ol|li|h|p|bl)', trimmed):
return "\n" + line + "\n"
return "\n<p>{}</p>\n".format(trimmed);
def ul_list(match_obj):
item = match_obj.group(1);
return "\n<ul>\n\t<li>{}</li>\n</ul>".format(item.strip());
def ol_list(match_obj):
item = match_obj.group(1);
return "\n<ol>\n\t<li>{}</li>\n</ol>".format(item.strip());
def blockquote(match_obj):
item = match_obj.group(2);
return "\n<blockquote>{}</blockquote>".format(item.strip());
def header(match_obj):
level = len(match_obj.group(1))
title = match_obj.group(2).strip()
return '<h{0}>{1}</h{0}>'.format(level, title)
########################
### Rules Definition ###
########################
rules = collections.OrderedDict()
rules[r'(#+)(.*)'] = header # headers
rules[r'\[([^\[]+)\]\(([^\)]+)\)'] = r'<a href="\2">\1</a>' # links
rules[r'(\*\*|__)(.*?)\1'] = r'<strong>\2</strong>' # bold
rules[r'(\*|_)(.*?)\1'] = r'<em>\2</em>' # emphasis
rules[r'\~\~(.*?)\~\~'] = r'<del>\1</del>' # del
rules[r'\:\"(.*?)\"\:'] = r'<q>\1</q>' # quote
rules[r'`(.*?)`'] = r'<code>\1</code>' # inline code
rules[r'\n\*(.*)'] = ul_list # ul lists
rules[r'\n[0-9]+\.(.*)'] = ol_list # ol lists
rules[r'\n(&gt;|\>)(.*)'] = blockquote # blockquotes
rules[r'\n-{5,}'] = r"\n<hr />" # horizontal rule
rules[r'\n([^\n]+)\n'] = paragraph # add paragraphs
rules[r'<\/ul>\s?<ul>'] = r'' # fix extra ul
rules[r'<\/ol>\s?<ol>'] = r'' # fix extra ol
rules[r'<\/blockquote><blockquote>'] = r"\n" # fix extra blockquote
#######################
### Render Function ###
#######################
def render(text):
text = '\n' + text + '\n'
for regex, replacement in rules.items():
text = re.sub(regex, replacement, text)
return text.strip()
############
### Main ###
############
if __name__ == '__main__':
input_text = sys.stdin.read()
rendered_text = render(input_text)
print(rendered_text)
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