Fixed restarting cell to (-) type. Added a final point to the while cycle.

IPython/nbconvert/preprocessors/revealhelp.py

@@ -1,70 +1,72 b''
 """Module that pre-processes the notebook for export via Reveal.
 """
 #-----------------------------------------------------------------------------
 # Copyright (c) 2013, the IPython Development Team.
 #
 # Distributed under the terms of the Modified BSD License.
 #
 # The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from .base import Preprocessor
 from IPython.utils.traitlets import Unicode
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 class RevealHelpPreprocessor(Preprocessor):
 
     url_prefix = Unicode('reveal.js', config=True,
                          help="""The URL prefix for reveal.js.
                          This can be a a relative URL for a local copy of reveal.js,
                          or point to a CDN.
                          
                          For speaker notes to work, a local reveal.js prefix must be used.
                          """
     )
 
     def preprocess(self, nb, resources):
         """
         Called once to 'preprocess' contents of the notebook.
 
         Parameters
         ----------
         nb : NotebookNode
             Notebook being converted
         resources : dictionary
             Additional resources used in the conversion process.  Allows
             preprocessors to pass variables into the Jinja engine.
         """
 
         for worksheet in nb.worksheets:
             for index, cell in enumerate(worksheet.cells):
 
                 #Make sure the cell has slideshow metadata.
                 cell.metadata.slide_type = cell.get('metadata', {}).get('slideshow', {}).get('slide_type', '-')
 
-                #Get the slide type.  If type is start of subslide or slide,
+                #Get the slide type. If type is start of subslide or slide,
                 #end the last subslide/slide.
                 if cell.metadata.slide_type in ['slide']:
                     worksheet.cells[index - 1].metadata.slide_helper = 'slide_end'
                 if cell.metadata.slide_type in ['subslide']:
                     worksheet.cells[index - 1].metadata.slide_helper = 'subslide_end'
+                #Prevent the rendering of "do nothing" cells before fragments
                 if cell.metadata.slide_type in ['fragment']:
-                    try:
-                        i = 1
-                        while 1:
-                            worksheet.cells[index + i].metadata.frag_helper = 'fragment_end'
-                            i += 1
-                    except IndexError as e:
-                        pass #Last cell doesn't have a next one
+                    i = 1
+                    while i < len(worksheet.cells) - index:
+                        worksheet.cells[index + i].metadata.frag_helper = 'fragment_end'
+                        i += 1
+                #Restart the slide_helper when the cell status is changed
+                #to "do nothing".
+                if cell.metadata.slide_type in ['-']:
+                    worksheet.cells[index - 1].metadata.slide_helper = '-'
 
         if not isinstance(resources['reveal'], dict):
             resources['reveal'] = {}
         resources['reveal']['url_prefix'] = self.url_prefix
         return nb, resources