def choose_include_text(s, params, source_path):
  """Given the contents of a file and !inc[these params], return matching lines

  If there was a problem matching parameters, return empty list.

  :param s: file's text
  :param params: string like "start-at=foo&end-at=bar"
  :param source_path: path to source .md. Useful in error messages
  """
  lines = s.splitlines()
  start_after = None
  start_at = None
  end_before = None
  end_at = None

  for term in params.split("&"):
    if '=' in term:
      param, value = [p.strip() for p in term.split('=', 1)]
    else:
      param, value = term.strip(), ''
    if not param: continue
    if param == "start-after":
      start_after = value
    elif param == "start-at":
      start_at = value
    elif param == "end-before":
      end_before = value
    elif param == "end-at":
      end_at = value
    else:
      raise TaskError('Invalid include directive "{0}"'
                      ' in {1}'.format(params, source_path))

  chosen_lines = []
  # two loops, one waits to "start recording", one "records"
  for line_ix in range(0, len(lines)):
    line = lines[line_ix]
    if (not start_at) and (not start_after):
      # if we didn't set a start-* param, don't wait to start
      break
    if start_at is not None and start_at in line:
      break
    if start_after is not None and start_after in line:
      line_ix += 1
      break
  else:
    # never started recording:
    return ''
  for line_ix in range(line_ix, len(lines)):
    line = lines[line_ix]
    if end_before is not None and end_before in line:
      break
    chosen_lines.append(line)
    if end_at is not None and end_at in line:
      break
  else:
    if (end_before or end_at):
      # we had an end- filter, but never encountered it.
      return ''
  return '\n'.join(chosen_lines)
dataset/ETHPy150Open pantsbuild/pants/src/python/pants/backend/docgen/tasks/markdown_to_html_utils.py/choose_include_text/original