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"""Module that pre-processes the notebook for export to HTML.
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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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import os
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import io
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import hashlib
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from IPython.utils import path
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from IPython.utils.traitlets import Unicode
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from IPython.utils.py3compat import str_to_bytes
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from .base import Preprocessor
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class CSSHTMLHeaderPreprocessor(Preprocessor):
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"""
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Preprocessor used to pre-process notebook for HTML output. Adds IPython notebook
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front-end CSS and Pygments CSS to HTML output.
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"""
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highlight_class = Unicode('.highlight', config=True,
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help="CSS highlight class identifier")
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def __init__(self, *pargs, **kwargs):
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Preprocessor.__init__(self, *pargs, **kwargs)
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self._default_css_hash = None
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def preprocess(self, nb, resources):
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"""Fetch and add CSS to the resource dictionary
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Fetch CSS from IPython and Pygments to add at the beginning
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of the html files. Add this css in resources in the
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"inlining.css" key
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Parameters
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----------
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nb : NotebookNode
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Notebook being converted
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resources : dictionary
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Additional resources used in the conversion process. Allows
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preprocessors to pass variables into the Jinja engine.
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"""
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resources['inlining'] = {}
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resources['inlining']['css'] = self._generate_header(resources)
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return nb, resources
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def _generate_header(self, resources):
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"""
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Fills self.header with lines of CSS extracted from IPython
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and Pygments.
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"""
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from pygments.formatters import HtmlFormatter
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header = []
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# Construct path to IPy CSS
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from IPython.html import DEFAULT_STATIC_FILES_PATH
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sheet_filename = os.path.join(DEFAULT_STATIC_FILES_PATH,
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'style', 'style.min.css')
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# Load style CSS file.
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with io.open(sheet_filename, encoding='utf-8') as f:
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header.append(f.read())
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# Add pygments CSS
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formatter = HtmlFormatter()
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pygments_css = formatter.get_style_defs(self.highlight_class)
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header.append(pygments_css)
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# Load the user's custom CSS and IPython's default custom CSS. If they
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# differ, assume the user has made modifications to his/her custom CSS
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# and that we should inline it in the nbconvert output.
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profile_dir = resources['profile_dir']
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custom_css_filename = os.path.join(profile_dir, 'static', 'custom', 'custom.css')
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if os.path.isfile(custom_css_filename):
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if self._default_css_hash is None:
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self._default_css_hash = self._hash(os.path.join(DEFAULT_STATIC_FILES_PATH, 'custom', 'custom.css'))
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if self._hash(custom_css_filename) != self._default_css_hash:
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with io.open(custom_css_filename, encoding='utf-8') as f:
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header.append(f.read())
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return header
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def _hash(self, filename):
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"""Compute the hash of a file."""
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md5 = hashlib.md5()
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with open(filename) as f:
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md5.update(str_to_bytes(f.read()))
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return md5.digest()
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