markdown-metayaml/meta_yaml.py
2014-12-24 23:37:35 -05:00

115 lines
3.2 KiB
Python

"""
# YAML Meta Data Extension for [Python-Markdown](https://github.com/waylan/Python-Markdown)
This extension adds YAML meta data handling to markdown.
As in the original, meta data is parsed but not used in processing.
(YAML meta data is used e.g. by [pandoc](http://johnmacfarlane.net/pandoc/))
Dependencies: [PyYAML](http://pyyaml.org/)
Basic Usage:
>>> import markdown
>>> text = '''---
... Title: Test Doc.
... Author: Waylan Limberg
... Blank_Data:
... ...
...
... The body. This is paragraph one.
... '''
>>> md = markdown.Markdown(['meta_yaml'])
>>> print(md.convert(text))
<p>The body. This is paragraph one.</p>
>>> print(md.Meta) # doctest: +SKIP
{'blank_data': [''], 'author': ['Waylan Limberg'], 'title': ['Test Doc.']}
Make sure text without Meta Data still works (markdown < 1.6b returns a <p>).
>>> text = ' Some Code - not extra lines of meta data.'
>>> md = markdown.Markdown(['meta_yaml'])
>>> print(md.convert(text))
<pre><code>Some Code - not extra lines of meta data.
</code></pre>
>>> md.Meta
{}
Copyright 2014 Bernhard Fisseni
Based on the meta data extension included with Python-Markdown,
Copyright 2007-2008 [Waylan Limberg](http://achinghead.com).
License: BSD (see LICENSE.md for details)
"""
from __future__ import absolute_import
from __future__ import unicode_literals
from markdown import Extension
from markdown.preprocessors import Preprocessor
import re
import yaml
try:
from yaml import CSafeLoader as Loader
except ImportError:
from yaml import Loader
# Override the default string handling function to always return unicode objects
def construct_yaml_str(self, node):
return self.construct_scalar(node)
Loader.add_constructor(u'tag:yaml.org,2002:str', construct_yaml_str)
class MetaYamlExtension (Extension):
"""Extension for parsing YAML-Metadata with Python-Markdown."""
def extendMarkdown(self, md, md_globals):
"""Add MetaYamlPreprocessor to Markdown instance."""
md.preprocessors.add("meta_yaml", MetaYamlPreprocessor(md), ">meta")
class MetaYamlPreprocessor(Preprocessor):
"""
Get Meta-Data.
A YAML block is delimited by
- a line '---' at the start
- and a '...' or '---' line
at the end.
"""
def run(self, lines):
""" Parse Meta-Data and store in Markdown.Meta. """
yaml_block = []
line = lines.pop(0)
if re.match(r'-{3}', line):
while lines:
line = lines.pop(0)
if re.match(r'(\.{3}|-{3})', line):
break
yaml_block.append(line)
else:
lines.insert(0, line)
if yaml_block:
meta = yaml.load("\n".join(yaml_block), Loader)
# case-insensitize meta data keys:
meta = {
k.lower(): meta[k] for k in meta
}
# PyMarkdown's Meta compat: ensure everything's a list
meta = {
k: v if isinstance(v, list) else [v] for k, v in meta.items()
}
self.markdown.Meta = meta
return lines
def makeExtension(configs={}):
"""set up extension."""
return MetaYamlExtension(configs=configs)