import abc
from networkx import nx
import inspect
import logging
[docs]class PluginBase(object):
__metaclass__ = abc.ABCMeta
def __init__(self):
self.logger = logging.getLogger('root')
[docs] @abc.abstractmethod
def get_supported_conversions(self):
"""Return the conversions provided by the plugin implementing this
method.
"""
return
def get_supported_conversions_graph(self):
# Return a graph representing the format conversions
# provided by the plugin.
if not hasattr(self, 'conversions_graph'):
self.conversions_graph = self._generate_graph()
return self.conversions_graph
[docs] @abc.abstractmethod
def convert(self, input_file, output_file, input_format, output_format):
"""Convert a input_file from a specified format to another"""
return
[docs] @abc.abstractmethod
def check_dependencies(self):
"""Check that all neccessary dependencies for a particular plugin
are available in the system, raise an exception otherwise.
"""
return
def _get_plugin_priority(self):
"""To be overridden by plugins.
"""
return 0
def _generate_graph(self):
"""Generate a directed graph where each node is a document format.
The representation of a node pointing to another (e.g. from '.doc' to
'.odt') is called edge and it will contain the name of the plugin being
able to perform the conversion.
The graph is the representation of all the format conversions provided
by this plugin.
"""
G = nx.MultiDiGraph()
conversions = self.get_supported_conversions()
self._add_priority_to_conversions(
self._get_plugin_priority(), conversions)
G.add_edges_from(conversions, plugin=self._get_module_name())
return G
def _get_nodes_from_edges(self, edges):
"""Convert a list of tuple containing format conversions to
a list of the formats in the original list.
"""
nodes = list(set(format for conversion in edges for format in
conversion))
return nodes
def _add_priority_to_conversions(self, priority, conversions):
for i, conversion in enumerate(conversions):
if len(conversion) == 2:
conversions[i] = conversion + \
tuple([dict({"priority": priority})])
return conversions
def _get_module_name(self):
"""Get the name of the module containing the class inheriting from this
class, i.e., the name of the plugin.
"""
current_class = inspect.getfile(self.__class__)
current_module = inspect.getmodulename(current_class)
return current_module