Better use Python slicing

IPython/html/services/notebooks/nbmanager.py

@@ -1,266 +1,265
 """A base class notebook manager.
 
 Authors:
 
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import uuid
 
 from tornado import web
 from urllib import quote, unquote
 
 from IPython.config.configurable import LoggingConfigurable
 from IPython.nbformat import current
 from IPython.utils.traitlets import List, Dict, Unicode, TraitError
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 class NotebookManager(LoggingConfigurable):
 
     # Todo:
     # The notebook_dir attribute is used to mean a couple of different things:
     # 1. Where the notebooks are stored if FileNotebookManager is used.
     # 2. The cwd of the kernel for a project.
     # Right now we use this attribute in a number of different places and
     # we are going to have to disentangle all of this.
     notebook_dir = Unicode(os.getcwdu(), config=True, help="""
             The directory to use for notebooks.
             """)
             
     def named_notebook_path(self, notebook_path):
         
-        l = len(notebook_path)
         names = notebook_path.split('/')
         if len(names) > 1:     
-            name = names[len(names)-1]
-            if name[(len(name)-6):(len(name))] == ".ipynb":
+            name = names[-1]
+            if name.endswith(".ipynb"):
                 name = name
-                path = notebook_path[0:l-len(name)-1]+'/'
+                path = notebook_path[0:-len(name)-1]+'/'
             else:
                 name = None
                 path = notebook_path+'/'
         else:
             name = names[0]
-            if name[(len(name)-6):(len(name))] == ".ipynb":
+            if name.endswith(".ipynb"):
                 name = name
                 path = None
             else:
                 name = None
                 path = notebook_path+'/'
         return name, path
     
     def url_encode(self, path):
         parts = path.split('/')
         path=""
         for part in parts:
            part = quote(part)
            path = os.path.join(path,part)
         return path
 
     def url_decode(self, path):
         parts = path.split('/')
         path=""
         for part in parts:
            part = unquote(part)
            path = os.path.join(path,part)
         return path
 
     def _notebook_dir_changed(self, new):
         """do a bit of validation of the notebook dir"""
         if not os.path.isabs(new):
             # If we receive a non-absolute path, make it absolute.
             abs_new = os.path.abspath(new)
             #self.notebook_dir = os.path.dirname(abs_new)
             return
         if os.path.exists(new) and not os.path.isdir(new):
             raise TraitError("notebook dir %r is not a directory" % new)
         if not os.path.exists(new):
             self.log.info("Creating notebook dir %s", new)
             try:
                 os.mkdir(new)
             except:
                 raise TraitError("Couldn't create notebook dir %r" % new)
                 
     allowed_formats = List([u'json',u'py'])
 
     def add_new_folder(self, path=None):
         new_path = os.path.join(self.notebook_dir, path)
         if not os.path.exists(new_path):
             os.makedirs(new_path) 
         else:
             raise web.HTTPError(409, u'Directory already exists or creation permission not allowed.')
 
     def load_notebook_names(self, path):
         """Load the notebook names into memory.
 
         This should be called once immediately after the notebook manager
         is created to load the existing notebooks into the mapping in
         memory.
         """
         self.list_notebooks(path)
 
     def list_notebooks(self):
         """List all notebooks.
 
         This returns a list of dicts, each of the form::
 
             dict(notebook_id=notebook,name=name)
 
         This list of dicts should be sorted by name::
 
             data = sorted(data, key=lambda item: item['name'])
         """
         raise NotImplementedError('must be implemented in a subclass')
 
 
     def notebook_exists(self, notebook_path):
         """Does a notebook exist?"""
 
 
     def notebook_model(self, notebook_name, notebook_path=None, content=True):
         """ Creates the standard notebook model """
         last_modified, contents = self.read_notebook_object(notebook_name, notebook_path)
         model = {"name": notebook_name, 
                     "path": notebook_path,
                     "last_modified (UTC)": last_modified.ctime()}
         if content == True:
             model['content'] = contents
         return model
 
     def get_notebook(self, notebook_name, notebook_path=None, format=u'json'):
         """Get the representation of a notebook in format by notebook_name."""
         format = unicode(format)
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
         kwargs = {}
         last_mod, nb = self.read_notebook_object(notebook_name, notebook_path)
         if format == 'json':
             # don't split lines for sending over the wire, because it
             # should match the Python in-memory format.
             kwargs['split_lines'] = False
         representation = current.writes(nb, format, **kwargs)
         name = nb.metadata.get('name', 'notebook')
         return last_mod, representation, name
 
     def read_notebook_object(self, notebook_name, notebook_path=None):
         """Get the object representation of a notebook by notebook_id."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def save_new_notebook(self, data, notebook_path = None, name=None, format=u'json'):
         """Save a new notebook and return its name.
 
         If a name is passed in, it overrides any values in the notebook data
         and the value in the data is updated to use that value.
         """
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
 
         try:
             nb = current.reads(data.decode('utf-8'), format)
         except:
             raise web.HTTPError(400, u'Invalid JSON data')
 
         if name is None:
            try:
                name = nb.metadata.name
            except AttributeError:
                raise web.HTTPError(400, u'Missing notebook name')
         nb.metadata.name = name
 
         notebook_name = self.write_notebook_object(nb, notebook_path=notebook_path)
         return notebook_name
 
     def save_notebook(self, data, notebook_path=None, name=None, new_name=None, format=u'json'):
         """Save an existing notebook by notebook_name."""
         if format not in self.allowed_formats:
             raise web.HTTPError(415, u'Invalid notebook format: %s' % format)
 
         try:
             nb = current.reads(data.decode('utf-8'), format)
         except:
             raise web.HTTPError(400, u'Invalid JSON data')
 
         if name is not None:
             nb.metadata.name = name
         self.write_notebook_object(nb, name, notebook_path, new_name)
 
     def write_notebook_object(self, nb, notebook_name=None, notebook_path=None, new_name=None):
         """Write a notebook object and return its notebook_name.
 
         If notebook_name is None, this method should create a new notebook_name.
         If notebook_name is not None, this method should check to make sure it
         exists and is valid.
         """
         raise NotImplementedError('must be implemented in a subclass')
 
     def delete_notebook(self, notebook_name, notebook_path):
         """Delete notebook by notebook_id."""
         raise NotImplementedError('must be implemented in a subclass')
 
     def increment_filename(self, name):
         """Increment a filename to make it unique.
 
         This exists for notebook stores that must have unique names. When a notebook
         is created or copied this method constructs a unique filename, typically
         by appending an integer to the name.
         """
         return name
 
     def new_notebook(self, notebook_path=None):
         """Create a new notebook and return its notebook_id."""
         name = self.increment_filename('Untitled', notebook_path)
         metadata = current.new_metadata(name=name)
         nb = current.new_notebook(metadata=metadata)
         notebook_name = self.write_notebook_object(nb, notebook_path=notebook_path)
         return notebook_name
 
     def copy_notebook(self, name, path=None):
         """Copy an existing notebook and return its notebook_id."""
         last_mod, nb = self.read_notebook_object(name, path)
         name = nb.metadata.name + '-Copy'
         name = self.increment_filename(name, path)
         nb.metadata.name = name
         notebook_name = self.write_notebook_object(nb, notebook_path = path)
         return notebook_name  
     
     # Checkpoint-related
     
     def create_checkpoint(self, notebook_name, notebook_path=None):
         """Create a checkpoint of the current state of a notebook
         
         Returns a checkpoint_id for the new checkpoint.
         """
         raise NotImplementedError("must be implemented in a subclass")
     
     def list_checkpoints(self, notebook_name, notebook_path=None):
         """Return a list of checkpoints for a given notebook"""
         return []
     
     def restore_checkpoint(self, notebook_name, checkpoint_id, notebook_path=None):
         """Restore a notebook from one of its checkpoints"""
         raise NotImplementedError("must be implemented in a subclass")
 
     def delete_checkpoint(self, notebook_name, checkpoint_id, notebook_path=None):
         """delete a checkpoint for a notebook"""
         raise NotImplementedError("must be implemented in a subclass")
     
     def log_info(self):
         self.log.info(self.info_string())
     
     def info_string(self):
         return "Serving notebooks"