Subject: Re: [Fwd: [linux-audio-dev] Command parser?]
From: Erik Steffl (esteffl_AT_pbi.net)
Date: Thu Aug 24 2000 - 00:54:32 EEST
I have found out that simply using few variables for clarity is
usually good enough to document the regular expression (poor man's
reverb:-), something like this:
$dateRE = '[0-9]{8}';
$timeRE = '[0-9]{6}';
$str1 = 'string.20000823.193000';
$str2 = 'string.200x0823.193000';
if($str1 =~ /$date[.]$time/) { print "1st matched\n"; }
if($str2 =~ /$date[.]$time/) { print "2nd matched\n"; }
erik
Paul Winkler wrote:
>
> > Maurizio Umberto Puxeddu wrote:
> > > You should have a look to the Python standard library, in particular
> > > mudules like re (regular espressions) and cmd (a framework for command
> > > interpreter), but there are modules for audio data handling too!
>
> I'm also a great fan of python for this sort of thing. But while
> regular expressions are extremely powerful, they're also really
> gunky-looking. It's annoying to have to come back to your code a
> week later and try to remember what you meant by
> m{ \(
> (
> (?> [^()]+ )
> |
> \( [^()]* \)
> )+
> \)
> }x
>
> (snipped from the perlre man page).
>
> But there's a Better Way(tm).
> With Python you can use the reverb module.
> It allows you to create regular expressions in a syntax that is
> actually readable by humans instead of "resembling quoted line
> noise".
> Reverb (Regular Expressions - Verbose) can be downloaded from
> http://pobox.com/~JasonHarper/
>
> Here's some example code. This searches a string and spits out
> everything that looks like a US-style phone number. It's pretty
> complex but it does quite a good job - it can deal with almost any
> typical way people type US phone numbers, and it actually breaks the
> numbers down into their component parts.
>
> #!/usr/bin/env python
>
> from reverb import * # Make nice regular expressions instead of
> gobbledygook.
>
> # Let's come up with some really ugly variations...
> test_string = """
> (914) 657-0000
> 212- 300-8299 ,
>
> 555 1212
> 666- 3434
> 1 888 777 - 2121 , 1 -( 246) 732 2222
> 1 222 333 4444 ,1 (444) 888
> 2000
> """
>
> # Regular expression to extract plain old phone numbers.
> # This is quite complicated, but it needs to deal with all of the
> above.
>
> # Some explanations:
>
> # group() means you can later refer to this part of the regexp by
> name.
>
> # The numeric arguments to repeated() give the minimum and maximum
> # number of repeats, so repeated(digit(3,3)) matches exactly 3
> digits.
>
> # The last argument to RE() is two flags that affect its behavior.
> # IGNORECASE does the obvious, DOTALL means whitespace can include
> # newlines.
>
> phonegrabber= RE(wordbreak +
> group(optional(wordbreak + group(digit,
> name="prefix") +
> optional(whitespace) +
> optional("-")
> ) + optional(whitespace) +
> optional(optional("(") +
> group(optional(whitespace) +
> repeated(digit, 3, 3) +
> optional(whitespace)
> , name="area") +
> optional( text(")") | "-") +
> optional(whitespace)
> ) +
> group(optional(whitespace) +
> repeated(digit, 3, 3) +
> optional(whitespace)
> , name="exchange") +
> required("-" | whitespace) +
> group(repeated(digit, 4, 4)
> , name='last_4')
> , name='phone_number') +
> optional(whitespace)
> , IGNORECASE | DOTALL
> )
>
> ############ Now do the actual work. ###################
>
> def test():
> global test_string
>
> phones = phonegrabber.findall(test_string)
> # That returns a list of tuples containing all the matched
> groups.
> # The string format % operator will insert values from a tuple
> into
> # a string.
> for p in phones:
> print """Number: %s
> Prefix: %s Area: %s Exchange: %s Number: %s
> """ % p
>
> # Now remove all numbers from the string.
> test_string = phonegrabber.sub('', test_string)
> # No more numbers ... let's make sure by examining the string.
> print "Leftovers:\n", test_string
>
> test()
>
> # End of script.
>
> --
> ................. paul winkler ..................
> slinkP arts: music, sound, illustration, design, etc.
> web page: http://www.slinkp.com
> A member of ARMS: http://www.reacharms.com
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