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"""Markdown filters
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This file contains a collection of utility filters for dealing with
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markdown within Jinja templates.
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"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import print_function
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# Stdlib imports
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import os
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import subprocess
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from io import TextIOWrapper, BytesIO
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import re
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import mistune
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from pygments import highlight
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from pygments.lexers import get_lexer_by_name
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from pygments.formatters import HtmlFormatter
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from pygments.util import ClassNotFound
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# IPython imports
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from IPython.nbconvert.utils.pandoc import pandoc
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from IPython.nbconvert.utils.exceptions import ConversionException
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from IPython.utils.decorators import undoc
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from IPython.utils.process import get_output_error_code
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from IPython.utils.py3compat import cast_bytes
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from IPython.utils.version import check_version
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marked = os.path.join(os.path.dirname(__file__), "marked.js")
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_node = None
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__all__ = [
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'markdown2html',
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'markdown2html_pandoc',
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'markdown2html_marked',
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'markdown2html_mistune',
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'markdown2latex',
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'markdown2rst',
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]
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class NodeJSMissing(ConversionException):
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"""Exception raised when node.js is missing."""
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pass
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def markdown2latex(source, extra_args=None):
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"""Convert a markdown string to LaTeX via pandoc.
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This function will raise an error if pandoc is not installed.
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Any error messages generated by pandoc are printed to stderr.
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Parameters
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----------
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source : string
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Input string, assumed to be valid markdown.
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Returns
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-------
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out : string
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Output as returned by pandoc.
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"""
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return pandoc(source, 'markdown', 'latex', extra_args=extra_args)
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@undoc
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class MathBlockGrammar(mistune.BlockGrammar):
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block_math = re.compile("^\$\$(.*?)\$\$", re.DOTALL)
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latex_environment = re.compile(r"^\\begin\{([a-z]*\*?)\}(.*?)\\end\{\1\}",
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re.DOTALL)
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@undoc
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class MathBlockLexer(mistune.BlockLexer):
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default_features = ['block_math', 'latex_environment'] + mistune.BlockLexer.default_features
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def __init__(self, rules=None, **kwargs):
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if rules is None:
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rules = MathBlockGrammar()
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super(MathBlockLexer, self).__init__(rules, **kwargs)
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def parse_block_math(self, m):
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"""Parse a $$math$$ block"""
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self.tokens.append({
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'type': 'block_math',
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'text': m.group(1)
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})
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def parse_latex_environment(self, m):
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self.tokens.append({
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'type': 'latex_environment',
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'name': m.group(1),
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'text': m.group(2)
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})
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@undoc
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class MathInlineGrammar(mistune.InlineGrammar):
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math = re.compile("^\$(.+?)\$")
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text = re.compile(r'^[\s\S]+?(?=[\\<!\[_*`~$]|https?://| {2,}\n|$)')
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@undoc
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class MathInlineLexer(mistune.InlineLexer):
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default_features = ['math'] + mistune.InlineLexer.default_features
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def __init__(self, renderer, rules=None, **kwargs):
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if rules is None:
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rules = MathInlineGrammar()
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super(MathInlineLexer, self).__init__(renderer, rules, **kwargs)
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def output_math(self, m):
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return self.renderer.inline_math(m.group(1))
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@undoc
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class MarkdownWithMath(mistune.Markdown):
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def __init__(self, renderer, **kwargs):
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if 'inline' not in kwargs:
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kwargs['inline'] = MathInlineLexer
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if 'block' not in kwargs:
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kwargs['block'] = MathBlockLexer
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super(MarkdownWithMath, self).__init__(renderer, **kwargs)
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def parse_block_math(self):
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return self.renderer.block_math(self.token['text'])
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def parse_latex_environment(self):
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return self.renderer.latex_environment(self.token['name'], self.token['text'])
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@undoc
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class IPythonRenderer(mistune.Renderer):
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def block_code(self, code, lang):
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if lang:
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try:
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lexer = get_lexer_by_name(lang, stripall=True)
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except ClassNotFound:
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code = lang + '\n' + code
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lang = None
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if not lang:
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return '\n<pre><code>%s</code></pre>\n' % \
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mistune.escape(code)
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formatter = HtmlFormatter()
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return highlight(code, lexer, formatter)
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# Pass math through unaltered - mathjax does the rendering in the browser
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def block_math(self, text):
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return '$$%s$$' % text
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def latex_environment(self, name, text):
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return r'\begin{%s}%s\end{%s}' % (name, text, name)
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def inline_math(self, text):
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return '$%s$' % text
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def markdown2html_mistune(source):
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"""Convert a markdown string to HTML using mistune"""
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return MarkdownWithMath(renderer=IPythonRenderer()).render(source)
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def markdown2html_pandoc(source, extra_args=None):
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"""Convert a markdown string to HTML via pandoc"""
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extra_args = extra_args or ['--mathjax']
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return pandoc(source, 'markdown', 'html', extra_args=extra_args)
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def _find_nodejs():
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global _node
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if _node is None:
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# prefer md2html via marked if node.js >= 0.9.12 is available
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# node is called nodejs on debian, so try that first
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_node = 'nodejs'
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if not _verify_node(_node):
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_node = 'node'
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return _node
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def markdown2html_marked(source, encoding='utf-8'):
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"""Convert a markdown string to HTML via marked"""
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command = [_find_nodejs(), marked]
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try:
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p = subprocess.Popen(command,
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stdin=subprocess.PIPE, stdout=subprocess.PIPE
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)
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except OSError as e:
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raise NodeJSMissing(
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"The command '%s' returned an error: %s.\n" % (" ".join(command), e) +
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"Please check that Node.js is installed."
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)
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out, _ = p.communicate(cast_bytes(source, encoding))
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out = TextIOWrapper(BytesIO(out), encoding, 'replace').read()
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return out.rstrip('\n')
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# The mistune renderer is the default, because it's simple to depend on it
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markdown2html = markdown2html_mistune
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def markdown2rst(source, extra_args=None):
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"""Convert a markdown string to ReST via pandoc.
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This function will raise an error if pandoc is not installed.
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Any error messages generated by pandoc are printed to stderr.
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Parameters
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----------
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source : string
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Input string, assumed to be valid markdown.
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Returns
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-------
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out : string
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Output as returned by pandoc.
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"""
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return pandoc(source, 'markdown', 'rst', extra_args=extra_args)
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def _verify_node(cmd):
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"""Verify that the node command exists and is at least the minimum supported
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version of node.
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Parameters
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----------
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cmd : string
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Node command to verify (i.e 'node')."""
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try:
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out, err, return_code = get_output_error_code([cmd, '--version'])
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except OSError:
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# Command not found
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return False
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if return_code:
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# Command error
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return False
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return check_version(out.lstrip('v'), '0.9.12')
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