398 lines
14 KiB
Python
398 lines
14 KiB
Python
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"""
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Python Markdown
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A Python implementation of John Gruber's Markdown.
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Documentation: https://python-markdown.github.io/
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GitHub: https://github.com/Python-Markdown/markdown/
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PyPI: https://pypi.org/project/Markdown/
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Started by Manfred Stienstra (http://www.dwerg.net/).
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Maintained for a few years by Yuri Takhteyev (http://www.freewisdom.org).
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Currently maintained by Waylan Limberg (https://github.com/waylan),
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Dmitry Shachnev (https://github.com/mitya57) and Isaac Muse (https://github.com/facelessuser).
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Copyright 2007-2018 The Python Markdown Project (v. 1.7 and later)
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Copyright 2004, 2005, 2006 Yuri Takhteyev (v. 0.2-1.6b)
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Copyright 2004 Manfred Stienstra (the original version)
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License: BSD (see LICENSE.md for details).
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"""
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import codecs
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import sys
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import logging
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import importlib
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from . import util
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from .preprocessors import build_preprocessors
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from .blockprocessors import build_block_parser
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from .treeprocessors import build_treeprocessors
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from .inlinepatterns import build_inlinepatterns
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from .postprocessors import build_postprocessors
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from .extensions import Extension
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from .serializers import to_html_string, to_xhtml_string
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from .util import BLOCK_LEVEL_ELEMENTS
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__all__ = ['Markdown', 'markdown', 'markdownFromFile']
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logger = logging.getLogger('MARKDOWN')
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class Markdown:
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"""Convert Markdown to HTML."""
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doc_tag = "div" # Element used to wrap document - later removed
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output_formats = {
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'html': to_html_string,
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'xhtml': to_xhtml_string,
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}
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def __init__(self, **kwargs):
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"""
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Creates a new Markdown instance.
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Keyword arguments:
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* `extensions`: A list of extensions.
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If an item is an instance of a subclass of `markdown.extension.Extension`, the instance will be used
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as-is. If an item is of type string, first an entry point will be loaded. If that fails, the string is
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assumed to use Python dot notation (`path.to.module:ClassName`) to load a `markdown.Extension` subclass. If
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no class is specified, then a `makeExtension` function is called within the specified module.
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* `extension_configs`: Configuration settings for extensions.
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* `output_format`: Format of output. Supported formats are:
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* `xhtml`: Outputs XHTML style tags. Default.
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* `html`: Outputs HTML style tags.
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* `tab_length`: Length of tabs in the source. Default: 4
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"""
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self.tab_length = kwargs.get('tab_length', 4)
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self.ESCAPED_CHARS = ['\\', '`', '*', '_', '{', '}', '[', ']',
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'(', ')', '>', '#', '+', '-', '.', '!']
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self.block_level_elements = BLOCK_LEVEL_ELEMENTS.copy()
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self.registeredExtensions = []
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self.docType = ""
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self.stripTopLevelTags = True
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self.build_parser()
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self.references = {}
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self.htmlStash = util.HtmlStash()
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self.registerExtensions(extensions=kwargs.get('extensions', []),
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configs=kwargs.get('extension_configs', {}))
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self.set_output_format(kwargs.get('output_format', 'xhtml'))
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self.reset()
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def build_parser(self):
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""" Build the parser from the various parts. """
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self.preprocessors = build_preprocessors(self)
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self.parser = build_block_parser(self)
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self.inlinePatterns = build_inlinepatterns(self)
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self.treeprocessors = build_treeprocessors(self)
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self.postprocessors = build_postprocessors(self)
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return self
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def registerExtensions(self, extensions, configs):
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"""
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Register extensions with this instance of Markdown.
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Keyword arguments:
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* `extensions`: A list of extensions, which can either
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be strings or objects.
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* `configs`: A dictionary mapping extension names to `configs` options.
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"""
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for ext in extensions:
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if isinstance(ext, str):
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ext = self.build_extension(ext, configs.get(ext, {}))
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if isinstance(ext, Extension):
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ext.extendMarkdown(self)
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logger.debug(
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'Successfully loaded extension "%s.%s".'
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% (ext.__class__.__module__, ext.__class__.__name__)
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)
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elif ext is not None:
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raise TypeError(
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'Extension "{}.{}" must be of type: "{}.{}"'.format(
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ext.__class__.__module__, ext.__class__.__name__,
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Extension.__module__, Extension.__name__
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)
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)
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return self
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def build_extension(self, ext_name, configs):
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"""
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Build extension from a string name, then return an instance.
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First attempt to load an entry point. The string name must be registered as an entry point in the
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`markdown.extensions` group which points to a subclass of the `markdown.extensions.Extension` class.
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If multiple distributions have registered the same name, the first one found is returned.
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If no entry point is found, assume dot notation (`path.to.module:ClassName`). Load the specified class and
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return an instance. If no class is specified, import the module and call a `makeExtension` function and return
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the `Extension` instance returned by that function.
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"""
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configs = dict(configs)
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entry_points = [ep for ep in util.get_installed_extensions() if ep.name == ext_name]
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if entry_points:
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ext = entry_points[0].load()
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return ext(**configs)
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# Get class name (if provided): `path.to.module:ClassName`
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ext_name, class_name = ext_name.split(':', 1) if ':' in ext_name else (ext_name, '')
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try:
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module = importlib.import_module(ext_name)
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logger.debug(
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'Successfully imported extension module "%s".' % ext_name
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)
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except ImportError as e:
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message = 'Failed loading extension "%s".' % ext_name
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e.args = (message,) + e.args[1:]
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raise
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if class_name:
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# Load given class name from module.
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return getattr(module, class_name)(**configs)
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else:
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# Expect `makeExtension()` function to return a class.
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try:
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return module.makeExtension(**configs)
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except AttributeError as e:
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message = e.args[0]
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message = "Failed to initiate extension " \
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"'%s': %s" % (ext_name, message)
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e.args = (message,) + e.args[1:]
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raise
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def registerExtension(self, extension):
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""" This gets called by the extension """
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self.registeredExtensions.append(extension)
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return self
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def reset(self):
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"""
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Resets all state variables so that we can start with a new text.
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"""
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self.htmlStash.reset()
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self.references.clear()
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for extension in self.registeredExtensions:
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if hasattr(extension, 'reset'):
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extension.reset()
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return self
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def set_output_format(self, format):
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""" Set the output format for the class instance. """
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self.output_format = format.lower().rstrip('145') # ignore number
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try:
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self.serializer = self.output_formats[self.output_format]
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except KeyError as e:
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valid_formats = list(self.output_formats.keys())
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valid_formats.sort()
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message = 'Invalid Output Format: "%s". Use one of %s.' \
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% (self.output_format,
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'"' + '", "'.join(valid_formats) + '"')
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e.args = (message,) + e.args[1:]
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raise
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return self
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def is_block_level(self, tag):
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"""Check if the tag is a block level HTML tag."""
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if isinstance(tag, str):
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return tag.lower().rstrip('/') in self.block_level_elements
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# Some ElementTree tags are not strings, so return False.
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return False
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def convert(self, source):
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"""
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Convert markdown to serialized XHTML or HTML.
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Keyword arguments:
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* `source`: Source text as a Unicode string.
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Markdown processing takes place in five steps:
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1. A bunch of `preprocessors` munge the input text.
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2. `BlockParser()` parses the high-level structural elements of the
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pre-processed text into an `ElementTree`.
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3. A bunch of `treeprocessors` are run against the `ElementTree`. One
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such `treeprocessor` runs `InlinePatterns` against the `ElementTree`,
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detecting inline markup.
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4. Some post-processors are run against the text after the `ElementTree`
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has been serialized into text.
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5. The output is written to a string.
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"""
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# Fix up the source text
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if not source.strip():
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return '' # a blank Unicode string
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try:
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source = str(source)
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except UnicodeDecodeError as e: # pragma: no cover
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# Customize error message while maintaining original traceback
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e.reason += '. -- Note: Markdown only accepts Unicode input!'
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raise
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# Split into lines and run the line preprocessors.
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self.lines = source.split("\n")
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for prep in self.preprocessors:
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self.lines = prep.run(self.lines)
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# Parse the high-level elements.
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root = self.parser.parseDocument(self.lines).getroot()
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# Run the tree-processors
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for treeprocessor in self.treeprocessors:
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newRoot = treeprocessor.run(root)
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if newRoot is not None:
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root = newRoot
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# Serialize _properly_. Strip top-level tags.
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output = self.serializer(root)
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if self.stripTopLevelTags:
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try:
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start = output.index(
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'<%s>' % self.doc_tag) + len(self.doc_tag) + 2
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end = output.rindex('</%s>' % self.doc_tag)
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output = output[start:end].strip()
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except ValueError as e: # pragma: no cover
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if output.strip().endswith('<%s />' % self.doc_tag):
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# We have an empty document
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output = ''
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else:
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# We have a serious problem
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raise ValueError('Markdown failed to strip top-level '
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'tags. Document=%r' % output.strip()) from e
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# Run the text post-processors
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for pp in self.postprocessors:
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output = pp.run(output)
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return output.strip()
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def convertFile(self, input=None, output=None, encoding=None):
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"""Converts a markdown file and returns the HTML as a Unicode string.
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Decodes the file using the provided encoding (defaults to `utf-8`),
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passes the file content to markdown, and outputs the html to either
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the provided stream or the file with provided name, using the same
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encoding as the source file. The `xmlcharrefreplace` error handler is
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used when encoding the output.
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**Note:** This is the only place that decoding and encoding of Unicode
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takes place in Python-Markdown. (All other code is Unicode-in /
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Unicode-out.)
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Keyword arguments:
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* `input`: File object or path. Reads from `stdin` if `None`.
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* `output`: File object or path. Writes to `stdout` if `None`.
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* `encoding`: Encoding of input and output files. Defaults to `utf-8`.
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"""
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encoding = encoding or "utf-8"
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# Read the source
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if input:
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if isinstance(input, str):
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input_file = codecs.open(input, mode="r", encoding=encoding)
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else:
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input_file = codecs.getreader(encoding)(input)
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text = input_file.read()
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input_file.close()
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else:
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text = sys.stdin.read()
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if not isinstance(text, str): # pragma: no cover
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text = text.decode(encoding)
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text = text.lstrip('\ufeff') # remove the byte-order mark
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# Convert
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html = self.convert(text)
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# Write to file or stdout
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if output:
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if isinstance(output, str):
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output_file = codecs.open(output, "w",
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encoding=encoding,
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errors="xmlcharrefreplace")
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output_file.write(html)
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output_file.close()
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else:
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writer = codecs.getwriter(encoding)
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output_file = writer(output, errors="xmlcharrefreplace")
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output_file.write(html)
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# Don't close here. User may want to write more.
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else:
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# Encode manually and write bytes to stdout.
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html = html.encode(encoding, "xmlcharrefreplace")
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try:
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# Write bytes directly to buffer (Python 3).
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sys.stdout.buffer.write(html)
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except AttributeError: # pragma: no cover
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# Probably Python 2, which works with bytes by default.
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sys.stdout.write(html)
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return self
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"""
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EXPORTED FUNCTIONS
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=============================================================================
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Those are the two functions we really mean to export: `markdown()` and
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`markdownFromFile()`.
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"""
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def markdown(text, **kwargs):
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"""Convert a markdown string to HTML and return HTML as a Unicode string.
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This is a shortcut function for `Markdown` class to cover the most
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basic use case. It initializes an instance of `Markdown`, loads the
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necessary extensions and runs the parser on the given text.
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Keyword arguments:
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* `text`: Markdown formatted text as Unicode or ASCII string.
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* Any arguments accepted by the Markdown class.
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Returns: An HTML document as a string.
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"""
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md = Markdown(**kwargs)
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return md.convert(text)
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def markdownFromFile(**kwargs):
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"""Read markdown code from a file and write it to a file or a stream.
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This is a shortcut function which initializes an instance of `Markdown`,
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and calls the `convertFile` method rather than `convert`.
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Keyword arguments:
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* `input`: a file name or readable object.
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* `output`: a file name or writable object.
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* `encoding`: Encoding of input and output.
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* Any arguments accepted by the `Markdown` class.
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"""
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md = Markdown(**kwargs)
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md.convertFile(kwargs.get('input', None),
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kwargs.get('output', None),
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kwargs.get('encoding', None))
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