Catch specific error instead of all errors.

IPython/nbconvert/exporters/exporter.py

@@ -1,482 +1,482 b''
 """This module defines Exporter, a highly configurable converter
 that uses Jinja2 to export notebook files into different formats.
 """
 
 #-----------------------------------------------------------------------------
 # 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 __future__ import print_function, absolute_import
 
 # Stdlib imports
 import io
 import os
 import inspect
 import copy
 import collections
 import datetime
 
 # other libs/dependencies
-from jinja2 import Environment, FileSystemLoader, ChoiceLoader
+from jinja2 import Environment, FileSystemLoader, ChoiceLoader, TemplateNotFound
 
 # IPython imports
 from IPython.config.configurable import Configurable
 from IPython.config import Config
 from IPython.nbformat import current as nbformat
 from IPython.utils.traitlets import MetaHasTraits, DottedObjectName, Unicode, List, Dict
 from IPython.utils.importstring import import_item
 from IPython.utils.text import indent
 from IPython.utils import py3compat
 
 from IPython.nbconvert import transformers as nbtransformers
 from IPython.nbconvert import filters
 
 #-----------------------------------------------------------------------------
 # Globals and constants
 #-----------------------------------------------------------------------------
 
 #Jinja2 extensions to load.
 JINJA_EXTENSIONS = ['jinja2.ext.loopcontrols']
 
 default_filters = {
         'indent': indent,
         'markdown2html': filters.markdown2html,
         'ansi2html': filters.ansi2html,
         'filter_data_type': filters.DataTypeFilter,
         'get_lines': filters.get_lines,
         'highlight2html': filters.highlight2html,
         'highlight2latex': filters.highlight2latex,
         'ipython2python': filters.ipython2python,
         'markdown2latex': filters.markdown2latex,
         'markdown2rst': filters.markdown2rst,
         'comment_lines': filters.comment_lines,
         'strip_ansi': filters.strip_ansi,
         'strip_dollars': filters.strip_dollars,
         'strip_files_prefix': filters.strip_files_prefix,
         'html2text' : filters.html2text,
         'add_anchor': filters.add_anchor,
         'ansi2latex': filters.ansi2latex,
         'strip_math_space': filters.strip_math_space,
         'wrap_text': filters.wrap_text,
         'escape_latex': filters.escape_latex
 }
 
 #-----------------------------------------------------------------------------
 # Class
 #-----------------------------------------------------------------------------
 
 class ResourcesDict(collections.defaultdict):
     def __missing__(self, key):
         return ''
 
 
 class Exporter(Configurable):
     """
     Exports notebooks into other file formats.  Uses Jinja 2 templating engine
     to output new formats.  Inherit from this class if you are creating a new
     template type along with new filters/transformers.  If the filters/
     transformers provided by default suffice, there is no need to inherit from
     this class.  Instead, override the template_file and file_extension
     traits via a config file.
 
     {filters}
     """
     
     # finish the docstring
     __doc__ = __doc__.format(filters = '- '+'\n    - '.join(default_filters.keys()))
 
 
     template_file = Unicode(u'default',
             config=True,
             help="Name of the template file to use")
     def _template_file_changed(self, name, old, new):
         if new=='default':
             self.template_file = self.default_template
         else:
             self.template_file = new
     default_template = Unicode(u'')
 
     file_extension = Unicode(
         'txt', config=True, 
         help="Extension of the file that should be written to disk"
         )
 
     template_path = List(['.'], config=True)
 
     default_template_path = Unicode(
         os.path.join("..", "templates"), 
         help="Path where the template files are located.")
 
     template_skeleton_path = Unicode(
         os.path.join("..", "templates", "skeleton"), 
         help="Path where the template skeleton files are located.") 
 
     #Jinja block definitions
     jinja_comment_block_start = Unicode("", config=True)
     jinja_comment_block_end = Unicode("", config=True)
     jinja_variable_block_start = Unicode("", config=True)
     jinja_variable_block_end = Unicode("", config=True)
     jinja_logic_block_start = Unicode("", config=True)
     jinja_logic_block_end = Unicode("", config=True)
     
     #Extension that the template files use.    
     template_extension = Unicode(".tpl", config=True)
 
     #Configurability, allows the user to easily add filters and transformers.
     transformers = List(config=True,
         help="""List of transformers, by name or namespace, to enable.""")
 
     filters = Dict(config=True,
         help="""Dictionary of filters, by name and namespace, to add to the Jinja
         environment.""")
 
     default_transformers = List([nbtransformers.coalesce_streams,
                                  nbtransformers.SVG2PDFTransformer,
                                  nbtransformers.ExtractOutputTransformer,
                                  nbtransformers.CSSHTMLHeaderTransformer,
                                  nbtransformers.RevealHelpTransformer,
                                  nbtransformers.LatexTransformer,
                                  nbtransformers.SphinxTransformer],
         config=True,
         help="""List of transformers available by default, by name, namespace, 
         instance, or type.""")
 
 
     def __init__(self, config=None, extra_loaders=None, **kw):
         """
         Public constructor
     
         Parameters
         ----------
         config : config
             User configuration instance.
         extra_loaders : list[of Jinja Loaders]
             ordered list of Jinja loder to find templates. Will be tried in order
             before the default FileSysteme ones.
         template : str (optional, kw arg)
             Template to use when exporting.
         """
         
         #Call the base class constructor
         c = self.default_config
         if config:
             c.merge(config)
 
         super(Exporter, self).__init__(config=c, **kw)
 
         #Init
         self._init_template(**kw)
         self._init_environment(extra_loaders=extra_loaders)
         self._init_transformers()
         self._init_filters()
 
 
     @property
     def default_config(self):
         return Config()
 
     
     def from_notebook_node(self, nb, resources=None, **kw):
         """
         Convert a notebook from a notebook node instance.
     
         Parameters
         ----------
         nb : Notebook node
         resources : dict (**kw) 
             of additional resources that can be accessed read/write by 
             transformers and filters.
         """
         nb_copy = copy.deepcopy(nb)
         resources = self._init_resources(resources)
 
         # Preprocess
         nb_copy, resources = self._transform(nb_copy, resources)
 
         # Try different template names during conversion.  First try to load the
         # template by name with extension added, then try loading the template
         # as if the name is explicitly specified, then try the name as a 
         # 'flavor', and lastly just try to load the template by module name.
         module_name = self.__module__.split('.')[-1]
         try_names = [self.template_file + self.template_extension,
                      self.template_file,
                      module_name + '_' + self.template_file + self.template_extension,
                      module_name + self.template_extension]
         for try_name in try_names:
             try:
                 self.template = self.environment.get_template(try_name)
                 break
-            except:
+            except TemplateNotFound:
                 pass
 
         if hasattr(self, 'template'):
             output = self.template.render(nb=nb_copy, resources=resources)
         else:
             raise IOError('template file "%s" could not be found' % self.template_file)
         return output, resources
 
 
     def from_filename(self, filename, resources=None, **kw):
         """
         Convert a notebook from a notebook file.
     
         Parameters
         ----------
         filename : str
             Full filename of the notebook file to open and convert.
         """
 
         #Pull the metadata from the filesystem.
         if resources is None:
             resources = ResourcesDict()
         if not 'metadata' in resources or resources['metadata'] == '':
             resources['metadata'] = ResourcesDict()
         basename = os.path.basename(filename)
         notebook_name = basename[:basename.rfind('.')]
         resources['metadata']['name'] = notebook_name
 
         modified_date = datetime.datetime.fromtimestamp(os.path.getmtime(filename))
         resources['metadata']['modified_date'] = modified_date.strftime("%B %-d, %Y")
         
         with io.open(filename) as f:
             return self.from_notebook_node(nbformat.read(f, 'json'), resources=resources,**kw)
 
 
     def from_file(self, file_stream, resources=None, **kw):
         """
         Convert a notebook from a notebook file.
     
         Parameters
         ----------
         file_stream : file-like object
             Notebook file-like object to convert.
         """
         return self.from_notebook_node(nbformat.read(file_stream, 'json'), resources=resources, **kw)
 
 
     def register_transformer(self, transformer, enabled=False):
         """
         Register a transformer.
         Transformers are classes that act upon the notebook before it is
         passed into the Jinja templating engine.  Transformers are also
         capable of passing additional information to the Jinja
         templating engine.
     
         Parameters
         ----------
         transformer : transformer
         """
         if transformer is None:
             raise TypeError('transformer')
         isclass = isinstance(transformer, type)
         constructed = not isclass
 
         #Handle transformer's registration based on it's type
         if constructed and isinstance(transformer, py3compat.string_types):
             #Transformer is a string, import the namespace and recursively call
             #this register_transformer method
             transformer_cls = import_item(transformer)
             return self.register_transformer(transformer_cls, enabled)
         
         if constructed and hasattr(transformer, '__call__'):
             #Transformer is a function, no need to construct it.
             #Register and return the transformer.
             if enabled:
                 transformer.enabled = True
             self._transformers.append(transformer)
             return transformer
 
         elif isclass and isinstance(transformer, MetaHasTraits):
             #Transformer is configurable.  Make sure to pass in new default for 
             #the enabled flag if one was specified.
             self.register_transformer(transformer(parent=self), enabled)
 
         elif isclass:
             #Transformer is not configurable, construct it
             self.register_transformer(transformer(), enabled)
 
         else:
             #Transformer is an instance of something without a __call__ 
             #attribute.  
             raise TypeError('transformer')
 
 
     def register_filter(self, name, jinja_filter):
         """
         Register a filter.
         A filter is a function that accepts and acts on one string.  
         The filters are accesible within the Jinja templating engine.
     
         Parameters
         ----------
         name : str
             name to give the filter in the Jinja engine
         filter : filter
         """
         if jinja_filter is None:
             raise TypeError('filter')
         isclass = isinstance(jinja_filter, type)
         constructed = not isclass
 
         #Handle filter's registration based on it's type
         if constructed and isinstance(jinja_filter, py3compat.string_types):
             #filter is a string, import the namespace and recursively call
             #this register_filter method
             filter_cls = import_item(jinja_filter)
             return self.register_filter(name, filter_cls)
         
         if constructed and hasattr(jinja_filter, '__call__'):
             #filter is a function, no need to construct it.
             self.environment.filters[name] = jinja_filter
             return jinja_filter
 
         elif isclass and isinstance(jinja_filter, MetaHasTraits):
             #filter is configurable.  Make sure to pass in new default for 
             #the enabled flag if one was specified.
             filter_instance = jinja_filter(parent=self)
             self.register_filter(name, filter_instance )
 
         elif isclass:
             #filter is not configurable, construct it
             filter_instance = jinja_filter()
             self.register_filter(name, filter_instance)
 
         else:
             #filter is an instance of something without a __call__ 
             #attribute.  
             raise TypeError('filter')
 
         
     def _init_template(self, **kw):
         """
         Make sure a template name is specified.  If one isn't specified, try to
         build one from the information we know.
         """
         self._template_file_changed('template_file', self.template_file, self.template_file)
         if 'template' in kw:
             self.template_file = kw['template']
         
 
     def _init_environment(self, extra_loaders=None):
         """
         Create the Jinja templating environment.
         """
         here = os.path.dirname(os.path.realpath(__file__))
         loaders = []
         if extra_loaders:
             loaders.extend(extra_loaders)
 
         paths = self.template_path
         paths.extend([os.path.join(here, self.default_template_path),
                       os.path.join(here, self.template_skeleton_path)])
         loaders.append(FileSystemLoader(paths))
 
         self.environment = Environment(
             loader= ChoiceLoader(loaders),
             extensions=JINJA_EXTENSIONS
             )
         
         #Set special Jinja2 syntax that will not conflict with latex.
         if self.jinja_logic_block_start:
             self.environment.block_start_string = self.jinja_logic_block_start
         if self.jinja_logic_block_end:
             self.environment.block_end_string = self.jinja_logic_block_end
         if self.jinja_variable_block_start:
             self.environment.variable_start_string = self.jinja_variable_block_start
         if self.jinja_variable_block_end:
             self.environment.variable_end_string = self.jinja_variable_block_end
         if self.jinja_comment_block_start:
             self.environment.comment_start_string = self.jinja_comment_block_start
         if self.jinja_comment_block_end:
             self.environment.comment_end_string = self.jinja_comment_block_end
 
     
     def _init_transformers(self):
         """
         Register all of the transformers needed for this exporter, disabled
         unless specified explicitly.
         """
         self._transformers = []
 
         #Load default transformers (not necessarly enabled by default).
         if self.default_transformers:
             for transformer in self.default_transformers:
                 self.register_transformer(transformer)
 
         #Load user transformers.  Enable by default.
         if self.transformers:
             for transformer in self.transformers:
                 self.register_transformer(transformer, enabled=True)
  
 
     def _init_filters(self):
         """
         Register all of the filters required for the exporter.
         """
         
         #Add default filters to the Jinja2 environment
         for key, value in default_filters.items():
             self.register_filter(key, value)
 
         #Load user filters.  Overwrite existing filters if need be.
         if self.filters:
             for key, user_filter in self.filters.items():
                 self.register_filter(key, user_filter)
 
 
     def _init_resources(self, resources):
 
         #Make sure the resources dict is of ResourcesDict type.
         if resources is None:
             resources = ResourcesDict()
         if not isinstance(resources, ResourcesDict):
             new_resources = ResourcesDict()
             new_resources.update(resources)
             resources = new_resources 
 
         #Make sure the metadata extension exists in resources
         if 'metadata' in resources:
             if not isinstance(resources['metadata'], ResourcesDict):
                 resources['metadata'] = ResourcesDict(resources['metadata'])
         else:
             resources['metadata'] = ResourcesDict()
             if not resources['metadata']['name']: 
                 resources['metadata']['name'] = 'Notebook'
 
         #Set the output extension
         resources['output_extension'] = self.file_extension
         return resources
         
 
     def _transform(self, nb, resources):
         """
         Preprocess the notebook before passing it into the Jinja engine.
         To preprocess the notebook is to apply all of the 
     
         Parameters
         ----------
         nb : notebook node
             notebook that is being exported.
         resources : a dict of additional resources that
             can be accessed read/write by transformers
             and filters.
         """
         
         # Do a copy.deepcopy first, 
         # we are never safe enough with what the transformers could do.
         nbc =  copy.deepcopy(nb)
         resc = copy.deepcopy(resources)
 
         #Run each transformer on the notebook.  Carry the output along
         #to each transformer
         for transformer in self._transformers:
             nbc, resc = transformer(nbc, resc)
         return nbc, resc