def extract_prefix()

in src/graph_notebook/network/sparql/SPARQLNetwork.py [0:0]

• 27 lines of code
• 10 McCabe index (conditional complexity)

    def extract_prefix(self, uri: str) -> str:
        """
        extracts the prefix and stores the namespace of a given uri to shorten the text
        used for displaying to the user

        :param uri: the full uri value. such as http://kelvinlawrence.net/air-routes/resource/24
        :return: the prefix of the uri, such as 'resource'
        """
        if not (uri.startswith('http://') or uri.startswith('https://')):
            return None

        hash_index = uri.find('#')
        last_slash_index = uri.rfind('/', 0, hash_index)
        if hash_index != -1:  # for example: http://www.w3.org/1999/02/22-rdf-syntax-ns#type
            namespace = uri[:hash_index + 1]
            prefix = uri[last_slash_index + 1:hash_index]
        else:
            second_last_slash_index = uri.rindex('/', 0, last_slash_index)
            namespace = uri[:last_slash_index + 1]
            prefix = uri[second_last_slash_index + 1:last_slash_index]

        if namespace in self.namespace_to_prefix:
            return self.namespace_to_prefix[namespace]
        else:
            if prefix in self.prefix_to_namespace:
                # this prefix is already reserved, we need to generate a new one.
                # look at the previous section and attempt to append it to the prefix
                num = 2
                while True:
                    generated_prefix = f'{prefix}-{num}'
                    if generated_prefix not in self.prefix_to_namespace:
                        prefix = generated_prefix
                        break
                    else:
                        num += 1

            self.namespace_to_prefix[namespace] = prefix
            self.prefix_to_namespace[prefix] = namespace
            return prefix