正则表达式：计算在不同地方发生的次数

问题描述

正则表达式是否能够匹配可能被其他模式分隔的模式？

例如：Traceback (most recent call last): File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/web.py",line 1703,in _execute result = await result File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/gen.py",line 742,in run yielded = self.gen.throw(*exc_info) # type: ignore File "/usr/local/anaconda3/lib/python3.8/site-packages/notebook/services/sessions/handlers.py",line 69,in post model = yield maybe_future( File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/gen.py",line 735,in run value = future.result() File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/gen.py",in run yielded = self.gen.throw(*exc_info) # type: ignore File "/usr/local/anaconda3/lib/python3.8/site-packages/notebook/services/sessions/sessionmanager.py",line 88,in create_session kernel_id = yield self.start_kernel_for_session(session_id,path,name,type,kernel_name) File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/gen.py",line 100,in start_kernel_for_session kernel_id = yield maybe_future( File "/usr/local/anaconda3/lib/python3.8/site-packages/tornado/gen.py",line 209,in wrapper yielded = next(result) File "/usr/local/anaconda3/lib/python3.8/site-packages/notebook/services/kernels/kernelmanager.py",line 168,in start_kernel super(MappingKernelManager,self).start_kernel(**kwargs) File "/usr/local/anaconda3/lib/python3.8/site-packages/jupyter_client/multikernelmanager.py",line 186,in start_kernel km.start_kernel(**kwargs) File "/usr/local/anaconda3/lib/python3.8/site-packages/jupyter_client/manager.py",line 308,in start_kernel self.kernel = self._launch_kernel(kernel_cmd,**kw) File "/usr/local/anaconda3/lib/python3.8/site-packages/jupyter_client/manager.py",line 215,in _launch_kernel return launch_kernel(kernel_cmd,**kw) File "/usr/local/anaconda3/lib/python3.8/site-packages/jupyter_client/launcher.py",line 135,in launch_kernel proc = Popen(cmd,**kwargs) File "/usr/local/anaconda3/lib/python3.8/subprocess.py",line 854,in __init__ self._execute_child(args,executable,preexec_fn,close_fds,File "/usr/local/anaconda3/lib/python3.8/subprocess.py",line 1702,in _execute_child raise child_exception_type(errno_num,err_msg,err_filename) FileNotFoundError: [Errno 2] No such file or directory: '/Users/sumeet/miniconda3/bin/python'将与AAABB匹配。如何使其与ABABA匹配？

这仅是示例，我不是在寻找一种匹配AAABB所有排列的方法，而是要学习一种通用方法。：-）

解决方法

(?=A{3}B{2})[AB]+

（？= A {3} B {2}）-给定字符串的正向超前，以确保我们恰好具有3个A和2个B。如果结果为true，则开始寻找[AB] +。这完全符合AAABB。

https://regex101.com/r/6xcNb7/3

根据要求更新，并且应与其他排列相匹配。

(?=(?:B*A){3}B*$)|(?=(?:A*B){2}A*$)[AB]{5}

这可以完成工作：

^(?=(?:B*A){3}B*$)(?=(?:A*B){2}A*$)[AB]{5}$

Demo & explanation

外植：

^               # beginning of string
  (?=             # positive lookahead,make sure we have after exactly 3 A:
    (?:             # non capture group
      B*              # 0 or more B
      A               # 1 A
    ){3}            # end group,must appear 3 times
    B*              # 0 or more B
    $               # end of string
  )               # end of string
  (?=(?:A*B){2}A*$)     # same explanation as above for exactly 2 B
  [AB]{5}       # we must have 5 A or B
$               # end of string

regex regex-lookarounds