305ba3eca9
In PyYAML tag types are mapped to python types (http://pyyaml.org/wiki/PyYAMLDocumentation#YAMLtagsandPythontypes) In contrast, in Markdown Meta-Data extension, values are strings (https://pythonhosted.org/Markdown/extensions/meta_data.html). The BaseLoader class only construct basic Python objects: lists, dictionaries and Unicode strings so will likely perform more as expected.
110 lines
3.0 KiB
Python
110 lines
3.0 KiB
Python
"""
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# YAML Meta Data Extension for [Python-Markdown](https://github.com/waylan/Python-Markdown)
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This extension adds YAML meta data handling to markdown.
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As in the original, meta data is parsed but not used in processing.
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(YAML meta data is used e.g. by [pandoc](http://johnmacfarlane.net/pandoc/))
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Dependencies: [PyYAML](http://pyyaml.org/)
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Basic Usage:
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>>> import markdown
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>>> text = '''---
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... Title: Test Doc.
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... Author: Waylan Limberg
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... Blank_Data:
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... ...
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...
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... The body. This is paragraph one.
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... '''
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>>> md = markdown.Markdown(['meta_yaml'])
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>>> print(md.convert(text))
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<p>The body. This is paragraph one.</p>
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>>> print(md.Meta) # doctest: +SKIP
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{'blank_data': [''], 'author': ['Waylan Limberg'], 'title': ['Test Doc.']}
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Make sure text without Meta Data still works (markdown < 1.6b returns a <p>).
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>>> text = ' Some Code - not extra lines of meta data.'
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>>> md = markdown.Markdown(['meta_yaml'])
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>>> print(md.convert(text))
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<pre><code>Some Code - not extra lines of meta data.
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</code></pre>
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>>> md.Meta
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{}
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Copyright 2014 Bernhard Fisseni
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Based on the meta data extension included with Python-Markdown,
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Copyright 2007-2008 [Waylan Limberg](http://achinghead.com).
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License: BSD (see LICENSE.md for details)
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"""
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from __future__ import absolute_import
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from __future__ import unicode_literals
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from markdown import Extension
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from markdown.preprocessors import Preprocessor
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import yaml
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try:
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from yaml import CBaseLoader as Loader
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except ImportError:
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from yaml import BaseLoader
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# Override the default string handling function to always return unicode objects
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def construct_yaml_str(self, node):
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return self.construct_scalar(node)
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Loader.add_constructor(u'tag:yaml.org,2002:str', construct_yaml_str)
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class MetaYamlExtension (Extension):
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"""Extension for parsing YAML-Metadata with Python-Markdown."""
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def extendMarkdown(self, md, md_globals):
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"""Add MetaYamlPreprocessor to Markdown instance."""
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md.preprocessors.add("meta_yaml", MetaYamlPreprocessor(md), ">meta")
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class MetaYamlPreprocessor(Preprocessor):
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"""
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Get Meta-Data.
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A YAML block is delimited by
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- a line '---' at the start
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- and a '...' or '---' line
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at the end.
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"""
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def run(self, lines):
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""" Parse Meta-Data and store in Markdown.Meta. """
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yaml_block = []
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line = lines.pop(0)
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if line == "---":
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while lines:
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line = lines.pop(0)
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if line in ("---", "..."):
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break
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yaml_block.append(line)
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else:
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lines.insert(0, line)
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if yaml_block:
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meta = yaml.load("\n".join(yaml_block), Loader)
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# Compat with PyMarkdown's meta: Keys are lowercase, values are lists
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meta = {k.lower(): v if isinstance(v, list) else [v] for k, v in meta.items()}
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self.markdown.Meta = meta
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return lines
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def makeExtension(configs={}):
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"""set up extension."""
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return MetaYamlExtension(configs=configs)
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