def postprocess_link(self, entry):
        """
        Attempt to load full-text content from resource.
        """

        if not self.follow_links:
            return

        if type(entry.link) is not list:
            entry.link = [entry.link]

        for link in list(entry.link):
            if not os.path.exists(link):
                continue

            mime_type = magic.from_file(link, mime=True)
            if mime_type == 'application/pdf':
                structuredfeature = extract_pdf(link)
            elif mime_type == 'text/plain':
                structuredfeature = extract_text(link)
            else:
                structuredfeature = None

            if not structuredfeature:
                continue

            fset_name = mime_type.split('/')[-1] + '_text'
            if not fset_name in self.full_text:
                self.full_text[fset_name] = {}

            if hasattr(self, 'index_by'):
                ident = getattr(entry, self.index_by)
                if type(ident) is list:
                    ident = ident[0]
            else:   # If `index_by` is not set, use `uri` by default.
                ident = entry.uri

            self.full_text[fset_name][ident] = structuredfeature
Attempt to load full-text content from resource.