Introduction to how Python uses regular expressions to filter or replace HTML tags

This article mainly introduces how Python uses regular expressions to filter or replace HTML tags. It briefly introduces Python's regular expression-related syntax and analyzes Python's regular expression-based HTML tag filtering and replacement related operating techniques in combination with specific examples. , Friends who need it can refer to

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Key content of python regular expression:

python regular expression Formula escape character:

. Matches any character except line breaks
\w Matches letters or numbers or underscores or Chinese characters
\s Matches any whitespace character
\d Match numbers
\b Match the beginning or end of a word
^ Match the beginning of a string
$ Match the end of a string
\W Match anything that is not a letter, number, underscore, or Chinese character The character
\S matches any character that is not a whitespace character
\D matches any character that is not a digit
\B matches a position that is not the beginning or end of a word
[^x] matches anything other than x Any character
[^aeiou] matches any character except the letters aeiou

Commonly used Python regular expression qualifier code/grammar description:

*Repeat zero times or more
+Repeat one or more times
?Repeat zero or once
{n}Repeat n times
{n,} Repeat n times or more
{n,m}Repeat n to m times
About python regular expression named group:
Named group:(?P....)
This article also mentions delimitation (it starts with a question mark, if it is forward there is a '&' sign, if it is not there is a '!' sign):
Forward delimitation (?<=...)
Backward delimitation (?=…)
Forward non-delimitation (?Backward non-delimitation (?!.....)

Python removes (filters) HTML tags through regular expressions sample code

#-*- coding:utf-8 -*-
import re
##过滤HTML中的标签
# 将HTML中标签等信息去掉
# @param htmlstr HTML字符串.
def filter_tags(htmlstr):
  # 先过滤CDATA
  re_cdata = re.compile("//<!
CDATA\[[>]∗//
\]>", re.I) #匹配CDATA
  re_script = re.compile(&#39;<\s*script[^>]*>[^<]*<\s*/\s*script\s*>&#39;, re.I) # Script
  re_style = re.compile(&#39;<\s*style[^>]*>[^<]*<\s*/\s*style\s*>&#39;, re.I) # style
  re_br = re.compile(&#39;<br\s*?/?>&#39;) # 处理换行
  re_h = re.compile(&#39;</?\w+[^>]*>&#39;) # HTML标签
  re_comment = re.compile(&#39;<!--[^>]*-->&#39;) # HTML注释
  s = re_cdata.sub(&#39;&#39;, htmlstr) # 去掉CDATA
  s = re_script.sub(&#39;&#39;, s) # 去掉SCRIPT
  s = re_style.sub(&#39;&#39;, s) # 去掉style
  s = re_br.sub(&#39;\n&#39;, s) # 将br转换为换行
  s = re_h.sub(&#39;&#39;, s) # 去掉HTML 标签
  s = re_comment.sub(&#39;&#39;, s) # 去掉HTML注释
  # 去掉多余的空行
  blank_line = re.compile(&#39;\n+&#39;)
  s = blank_line.sub(&#39;\n&#39;, s)
  s = replaceCharEntity(s) # 替换实体
  return s
##替换常用HTML字符实体.
# 使用正常的字符替换HTML中特殊的字符实体.
# 你可以添加新的实体字符到CHAR_ENTITIES中,处理更多HTML字符实体.
# @param htmlstr HTML字符串.
def replaceCharEntity(htmlstr):
  CHAR_ENTITIES = {&#39;nbsp&#39;: &#39; &#39;, &#39;160&#39;: &#39; &#39;,
           &#39;lt&#39;: &#39;<&#39;, &#39;60&#39;: &#39;<&#39;,
           &#39;gt&#39;: &#39;>&#39;, &#39;62&#39;: &#39;>&#39;,
           &#39;amp&#39;: &#39;&&#39;, &#39;38&#39;: &#39;&&#39;,
           &#39;quot&#39;: &#39;"&#39;&#39;"&#39;, &#39;34&#39;: &#39;"&#39;, }
  re_charEntity = re.compile(r&#39;?(?P<name>\w+);&#39;)
  sz = re_charEntity.search(htmlstr)
  while sz:
    entity = sz.group() # entity全称，如>
    key = sz.group(&#39;name&#39;) # 去除&;后entity,如>为gt
    try:
      htmlstr = re_charEntity.sub(CHAR_ENTITIES[key], htmlstr, 1)
      sz = re_charEntity.search(htmlstr)
    except KeyError:
      # 以空串代替
      htmlstr = re_charEntity.sub(&#39;&#39;, htmlstr, 1)
      sz = re_charEntity.search(htmlstr)
  return htmlstr
def repalce(s, re_exp, repl_string):
  return re_exp.sub(repl_string, s)
if __name__ == &#39;__main__&#39;:
  s = file(&#39;test.html&#39;).read()
  news = filter_tags(s)
  print news

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