docutils:获取嵌套节点的行号

Question

当用docutils解析重构的文本片段并遍历文档节点树时，大多数节点不会在源文本中提供行号。示例：

import io
from pathlib import Path
import docutils.frontend
import docutils.nodes
import docutils.parsers.rst


text = '''
Fizz
====

Lorem ipsum

Buzz
****

Lorem ``ipsum``

.. code-block:: python

   x = 0

.. note::

   Dolor sit amet

   .. code-block:: python

      y = 1
'''


class MyVisitor(docutils.nodes.GenericNodeVisitor):
    def default_visit(self, node):
        print('node: {:>15}, line: {}'.format(type(node).__name__, node.line))


if __name__ == '__main__':
    default_settings = docutils.frontend.OptionParser(components=(docutils.parsers.rst.Parser,)).get_default_values()
    document = docutils.utils.new_document('mydocs', default_settings)
    parser = docutils.parsers.rst.Parser()
    parser.parse(io.StringIO(text).read(), document)
    visitor = MyVisitor(document)
    document.walk(visitor)

运行此代码将产生：

node:        document, line: None
node:         section, line: 3
node:           title, line: 3
node:            Text, line: None
node:       paragraph, line: 5
node:            Text, line: None
node:         section, line: 8
node:           title, line: 8
node:            Text, line: None
node:       paragraph, line: 10
node:            Text, line: None
node:         literal, line: None
node:            Text, line: None
node:   literal_block, line: 15
node:          inline, line: None
node:            Text, line: None
node:            Text, line: None
node:          inline, line: None
node:            Text, line: None
node:            Text, line: None
node:          inline, line: None
node:            Text, line: None
node:            note, line: None
node:       paragraph, line: 18
node:            Text, line: None
node:   literal_block, line: None
node:          inline, line: None
node:            Text, line: None
node:            Text, line: None
node:          inline, line: None
node:            Text, line: None
node:            Text, line: None
node:          inline, line: None
node:            Text, line: None

看起来没有一个嵌套节点记录了行号。是否可以在自定义节点visitor impl中访问此信息？我不希望所有节点（如单独的单词节点）都提供行号，但示例代码段中的note和嵌套的code-block都不提供行号。你知道吗