text: # Copyright (c) 2006-2021  Andrey Golovizin
  #
  # Permission is hereby granted, free of charge, to any person obtaining
  # a copy of this software and associated documentation files (the
  # "Software"), to deal in the Software without restriction, including
  # without limitation the rights to use, copy, modify, merge, publish,
  # distribute, sublicense, and/or sell copies of the Software, and to
  # permit persons to whom the Software is furnished to do so, subject to
  # the following conditions:
  #
  # The above copyright notice and this permission notice shall be
  # included in all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  # IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  # CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  # TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  from __future__ import unicode_literals
  
  from xml.etree import ElementTree as ET
  
  from pybtex.database import Entry, Person
  from pybtex.database.input import BaseParser
  
  bibtexns = '{http://bibtexml.sf.net/}'
  
  
  def remove_ns(s):
      if s.startswith(bibtexns):
          return s[len(bibtexns):]
  
  
  class Parser(BaseParser):
      default_suffix = '.xml'
  
      def parse_bytes(self, value):
          tree = ET.fromstring(value)
          return self.parse_tree(tree)
  
      def parse_string(self, value):
          return self.parse_bytes(value.encode(self.encoding))
  
      def parse_stream(self, stream):
          tree = ET.parse(stream)
          return self.parse_tree(tree)
  
      def parse_tree(self, tree):
          entries = tree.findall(bibtexns + 'entry')
          self.data.add_entries(self.process_entry(entry) for entry in entries)
          return self.data
  
      def process_entry(self, entry):
          def process_person(person_entry, role):
              persons = person_entry.findall(bibtexns + 'person')
              if persons:
                  for person in persons:
                      process_person(person, role)
              else:
                  text = person_entry.text.strip()
                  if text:
                      e.add_person(Person(text), role)
                  else:
                      names = {}
                      for name in person_entry:
                          names[remove_ns(name.tag)] = name.text
                      e.add_person(Person(**names), role)
  
          id_ = entry.get('id')
          item = list(entry)[0]
          type = remove_ns(item.tag)
          e = Entry(type)
          for field in item:
              field_name = remove_ns(field.tag)
              if field_name in Person.valid_roles:
                  process_person(field, field_name)
              else:
                  field_text = field.text if field.text is not None else ''
                  e.fields[field_name] = field_text
          return id_, e
  