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Re: I need an idea for practise!

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On 7/17/2014 1:20 PM, Chris Angelico wrote:

> By the way, one specific point about RR's advice: A colorizer should
> *not* be written using regexps. It'd make for an absolute nightmare of
> impossible-to-debug regexp strings, plus there are fundamental
> limitations on what you can accomplish with them. You need to use a
> lexer - a lexical analyzer. Basically, to correctly colorize code, you
> need to have something equivalent to the first part of the language
> interpreter, but with a lot more tolerance for errors. That's a pretty
> big thing to write as regexps.

It depends on how deeply one wants to colorize. idlelib.ColorDelegator 
colors comments, strings, keywords, builtin names, and names following 
'def' and 'class' with the following regexes.

def any(name, alternates):
     "Return a named group pattern matching list of alternates."
     return "(?P<%s>" % name + "|".join(alternates) + ")"

def make_pat():
     kw = r"\b" + any("KEYWORD", keyword.kwlist) + r"\b"
     builtinlist = [str(name) for name in dir(builtins)
                                         if not name.startswith('_') and \
                                         name not in keyword.kwlist]
     # self.file = open("file") :
     # 1st 'file' colorized normal, 2nd as builtin, 3rd as string
     builtin = r"([^.'\"\\#]\b|^)" + any("BUILTIN", builtinlist) + r"\b"
     comment = any("COMMENT", [r"#[^\n]*"])
     stringprefix = r"(\br|u|ur|R|U|UR|Ur|uR|b|B|br|Br|bR|BR|rb|rB|Rb|RB)?"
     sqstring = stringprefix + r"'[^'\\\n]*(\\.[^'\\\n]*)*'?"
     dqstring = stringprefix + r'"[^"\\\n]*(\\.[^"\\\n]*)*"?'
     sq3string = stringprefix + r"'''[^'\\]*((\\.|'(?!''))[^'\\]*)*(''')?"
     dq3string = stringprefix + r'"""[^"\\]*((\\.|"(?!""))[^"\\]*)*(""")?'
     string = any("STRING", [sq3string, dq3string, sqstring, dqstring])
     return kw + "|" + builtin + "|" + comment + "|" + string +\
            "|" + any("SYNC", [r"\n"])

prog = re.compile(make_pat(), re.S)
idrog = re.compile(r"\s+(\w+)", re.S)
asprog = re.compile(r".*?\b(as)\b")

I am not sure if the separate definition for as is still needed, or is a 
holdover from when 'as' was not a keyword except in certain contexts.

-- 
Terry Jan Reedy

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Thread

I need an idea for practise! Nicholas Cannon <nicholascannon1@gmail.com> - 2014-07-17 02:59 -0700
  Re: I need an idea for practise! alister <alister.nospam.ware@ntlworld.com> - 2014-07-17 10:13 +0000
  Re: I need an idea for practise! Abhiram R <abhi.darkness@gmail.com> - 2014-07-17 19:03 +0530
  Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 00:20 +1000
  Re: I need an idea for practise! Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-17 09:34 -0700
    Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 03:20 +1000
      Re: I need an idea for practise! Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-17 12:30 -0700
        Re: I need an idea for practise! Paul McNett <paul@mcnettware.com> - 2014-07-17 13:21 -0700
        Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 12:03 +1000
          Re: I need an idea for practise! Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-17 20:07 -0700
            Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 13:23 +1000
              Re: I need an idea for practise! Rick Johnson <rantingrickjohnson@gmail.com> - 2014-07-17 21:06 -0700
                Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 16:00 +1000
    Re: I need an idea for practise! Terry Reedy <tjreedy@udel.edu> - 2014-07-17 17:46 -0400
    Re: I need an idea for practise! Chris Angelico <rosuav@gmail.com> - 2014-07-18 12:04 +1000
  Re: I need an idea for practise! Orochi <kartikjagdale11@gmail.com> - 2014-07-17 11:05 -0700
    Re: I need an idea for practise! AudreyJean <iamAudreyJean@gmail.com> - 2014-07-18 08:42 -0700
  Re: I need an idea for practise! Nicholas Cannon <nicholascannon1@gmail.com> - 2014-07-17 19:03 -0700

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