python - 使用正则表达式或 lxml 在 Python 中提取 HTML 注释？

Question

如何使用 Python 从文档中提取所有 HTML 样式注释？

我尝试过使用正则表达式:

text = 'hello, world <!-- comment -->'
re.match('<!--(.*?)-->', text)

但它什么也没产生。我不明白这一点，因为相同的正则表达式在 https://regex101.com/ 的同一个字符串上运行良好。

更新:我的文档实际上是一个XML文件，我正在使用pyquery(基于lxml)解析文档，但我不认为lxml可以extract comments that aren't inside a node 。该文档如下所示:

<?xml version="1.0" encoding="UTF-8"?>
<clinical_study rank="220398">
  <intervention_browse>
    <!-- CAUTION:  The following MeSH terms are assigned with an imperfect algorithm  -->
    <mesh_term>Freund's Adjuvant</mesh_term>
    <mesh_term>Keyhole-limpet hemocyanin</mesh_term>
  </intervention_browse>
  <!-- Results have not yet been posted for this study                                -->
</clinical_study>

更新2:感谢您提出其他答案，但我已经使用lxml 广泛解析了文档，并且不想使用BeautifulSoup 重写所有内容。已相应更新标题。

Answer 1

这似乎为我打印了评论:

from lxml import etree
txt = """<?xml version="1.0" encoding="UTF-8"?>
<clinical_study rank="220398">
  <intervention_browse>
    <!-- CAUTION:  The following MeSH terms are assigned with an imperfect algorithm  -->
    <mesh_term>Freund's Adjuvant</mesh_term>
    <mesh_term>Keyhole-limpet hemocyanin</mesh_term>
  </intervention_browse>
  <!-- Results have not yet been posted for this study                                -->
</clinical_study>"""
root = etree.XML(txt)
print root[0][0]

要获取最后评论:

comments = [itm for itm in root if itm.tag is etree.Comment]:
if comments:
    print comments[-1]