+def add_table_of_contents(root):
+ sections = []
+
+ for element in root.iterdescendants():
+ if element.tag in ('h2', 'h3'):
+ if element.tag == 'h3' and len(sections) and sections[-1][0] == 'h2':
+ sections[-1][2].append((element.tag, ''.join(element.xpath('descendant-or-self::text()')), []))
+ else:
+ sections.append((element.tag, ''.join(element.xpath('descendant-or-self::text()')), []))
+
+ toc = etree.Element('div')
+ toc.set('id', 'toc')
+ toc_header = etree.SubElement(toc, 'h2')
+ toc_header.text = u'Spis treści'
+ toc_list = etree.SubElement(toc, 'ol')
+
+ for section, text, subsections in sections:
+ section_element = etree.SubElement(toc_list, 'li')
+ section_element.text = text
+ if len(subsections):
+ subsection_list = etree.SubElement(section_element, 'ol')
+ for subsection, text, _ in subsections:
+ subsection_element = etree.SubElement(subsection_list, 'li')
+ subsection_element.text = text
+ root.insert(0, toc)
+