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"""Module that pre-processes the notebook for export via Reveal."""
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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 .base import Preprocessor
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from IPython.utils.traitlets import Unicode
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class RevealHelpPreprocessor(Preprocessor):
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url_prefix = Unicode('reveal.js', config=True,
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help="""The URL prefix for reveal.js.
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This can be a a relative URL for a local copy of reveal.js,
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or point to a CDN.
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For speaker notes to work, a local reveal.js prefix must be used.
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"""
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)
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def preprocess(self, nb, resources):
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"""
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Called once to 'preprocess' contents of the notebook.
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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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for index, cell in enumerate(nb.cells):
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#Make sure the cell has slideshow metadata.
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cell.metadata.slide_type = cell.get('metadata', {}).get('slideshow', {}).get('slide_type', '-')
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for index, cell in enumerate(nb.cells):
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# Get the slide type. If type is start, subslide, or slide,
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# end the last subslide/slide.
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if cell.metadata.slide_type in ['slide']:
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nb.cells[index - 1].metadata.slide_helper = 'slide_end'
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if cell.metadata.slide_type in ['subslide']:
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nb.cells[index - 1].metadata.slide_helper = 'subslide_end'
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# Prevent the rendering of "do nothing" cells before fragments
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# Group fragments passing frag_number to the data-fragment-index
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if cell.metadata.slide_type in ['fragment']:
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nb.cells[index].metadata.frag_number = index
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i = 1
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while i < len(nb.cells) - index:
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# We need to break the loop when a new slide or subslide is
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# found to avoid the propagation of the data-fragment-index
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# across multiple slides/subslides
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if nb.cells[index + i].metadata.slideshow.slide_type in ['slide', 'subslide']:
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break
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else:
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nb.cells[index + i].metadata.frag_helper = 'fragment_end'
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nb.cells[index + i].metadata.frag_number = index
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i += 1
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# Restart the slide_helper when the cell status is changed
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# to other types.
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if cell.metadata.slide_type in ['-', 'skip', 'notes', 'fragment']:
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nb.cells[index - 1].metadata.slide_helper = '-'
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if not isinstance(resources['reveal'], dict):
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resources['reveal'] = {}
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resources['reveal']['url_prefix'] = self.url_prefix
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return nb, resources
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