Actively searching with Regular Expressions

[jlm699]

I have an application that is build on wxPython and have run into a small but annoying problem. I use a Search Control in my toolbar just as in the ToolBar example. Now when the user enters say PrmID[ ... this gets passed to a regular expression search function, however this obviously raises the exception saying that there is an unexpected end to the regular expression. What I would like to do is replace '[' with '\[', however using the string.replace function yields 'PrmID\\[' (escaping the escape character, but not the character I would like to have escaped). My code of what I've tried is as follows:

   def OnTextEntered(self, evt):
        text = self.GetValue()
        if re.search('\[', text) and not re.search('\]', text):
            text.replace('[', '\[')
        if self.DoSearch(text, evt):
            if text not in self.searches:
                self.searches.append(text)
                if len(self.searches) > self.maxSearches:
                    del self.searches[0]
                self.SetMenu(self.MakeMenu())
 

And the doSearch function...

    def DoSearch(self,  text, event=None):
        if not len(self.data_bak):
            return False
 
        # 10014 is the Event type for wx.EVT_MENU
        # 10164 is the Event type for wx.EVT_TEXT (adaptive search)
        # 10165 is the Event type for wx.EVT_TEXT_ENTER
        valid_events = [10014, 10165]
 
        regex = re.compile(text.upper())
        tool = self.tb.FindById(Global.OnTB_ActSearch_Id)
        if tool.IsToggled():
            self.lc.DeleteAllItems()
            for entry in range(len(self.data_bak)):
                if text:
                    if regex.search(self.data_bak[entry][0].upper()):
                        self.lc.Append(self.data_bak[entry])
                else:
                    self.lc.Append(self.data_bak[entry])
            return False
        elif not tool.IsToggled() and event.GetEventType() in valid_events:
            idx = self.lc.FindItem(self.currentItem + 1, text, True)
            if idx != -1:
                self.lc.Focus(idx)
                self.lc.Select(idx)
            return True
 

BTW, basically this application has a listing of Parameter names and values in a ListControl (self.lc), which when initially opened is backed-up by a two-dimensional array (self.data_bak).
This 'active search' will modify what the user sees in the listctrl (making sure to update the back-up as well), just as they type it (I wanted to reproduce the Search function from the upper right corner of iTunes). The toggle check is there because the user has a toggle button on the toolbar to turn this active search on or off.
So if anybody has any ideas as to how to replace '[' in a string with literally '\[' I would appreciate it. I've played around with raw strings and even tried using a crazy combination of raw strings and the repr function to no avail.

An example of parameter names is P_SWID_PrmID[0].

To reiterate, I simply need to take the user input and escape any bracket characters so that the regex.search function does not mistake it for the start/end of a regular expression character class.

[bartonc]

I'm not too familiar with regular expressions yet, but how 'buot making a character class of one character? re doesn't mind the the syntax of this pattern:

import re
>>> s = 'PrmID['
>>> re.sub('[[]', '[', s)
'PrmID['
>>> 

So, it seems that you could use:

s.replace('[', '[[]')

[bvdet]

I'm not too familiar with regular expressions yet, but how 'buot making a character class of one character? re doesn't mind the the syntax of this pattern:

import re
>>> s = 'PrmID['
>>> re.sub('[[]', '[', s)
'PrmID['
>>> 

So, it seems that you could use:

s.replace('[', '[[]')

Good point Barton. I checked it out also:

>>> s = 'P_SWID_PrmID[0]'
>>> searchStr = 'Prmid['
>>> import re
>>> patt = re.compile(searchStr.replace('[', '[[]'), re.IGNORECASE)
>>> m = patt.search(s)
>>> m
<_sre.SRE_Match object at 0x00D5A9C0>
>>> patt = re.compile(searchStr, re.IGNORECASE)
Traceback (most recent call last):
  File "<interactive input>", line 1, in ?
  File "C:\Python23\lib\sre.py", line 179, in compile
    return _compile(pattern, flags)
  File "C:\Python23\lib\sre.py", line 230, in _compile
    raise error, v # invalid expression
error: unexpected end of regular expression
>>> patt.findall(s)
['PrmID[']
>>> 

[jlm699]

Wow, thanks guys! That's elegant yet so simple! I was lazy and just replaced every occurance of '[' or ']' with '.' (I figured, if the user knows that much of the name they'll know the number contained within the brackets so actually finding a match to the bracket wasn't too terribly important)

But thanks for the great suggestions!