allow highlighting language to be set from notebook metadata

IPython/nbconvert/exporters/exporter.py

@@ -115,6 +115,9 b' class Exporter(LoggingConfigurable):'
         """
         nb_copy = copy.deepcopy(nb)
         resources = self._init_resources(resources)
+        
+        if 'language' in nb['metadata']:
+            resources['language'] = nb['metadata']['language'].lower()
 
         # Preprocess
         nb_copy, resources = self._preprocess(nb_copy, resources)

IPython/nbconvert/templates/html/basic.tpl

@@ -41,7 +41,7 b' In [{{ cell.prompt_number }}]:'
 
 {% block input %}
 <div class="input_area box-flex1">
-{{ cell.input | highlight2html(metadata=cell.metadata) }}
+{{ cell.input | highlight2html(language=resources.get('language'), metadata=cell.metadata) }}
 </div>
 {%- endblock input %}
 

IPython/nbconvert/templates/latex/style_python.tplx

@@ -16,6 +16,6 b''
 
 ((* block input scoped *))
     \begin{Verbatim}[commandchars=\\\{\}]
-((( cell.input | highlight2latex(strip_verbatim=True) | add_prompts )))
+((( cell.input | highlight2latex(language=resources.get('language'), strip_verbatim=True) | add_prompts )))
     \end{Verbatim}
 ((* endblock input *))