From: ahoward <ahoward@...>
Date: 2002-11-15T02:20:33+09:00
Subject: Re: regex help

On Thu, 14 Nov 2002, why the lucky stiff wrote:

[snip]
stiff>   quote1_re = /((?:''|[^'])+)/
[snip]

TESTING REGEX ((?:''|[^'])+)

        '        did not match        -
        ''       matched           ('')
        '''      matched           ('')
        ''''     matched         ('''')
        'a       matched            (a)
        a'       matched            (a)
        ''a      matched          (''a)
        a''      matched          (a'')
        '''a     matched           ('')
        a'''     matched          (a'')
        ''''a    matched        (''''a)
        a''''    matched        (a'''')

TESTING REGEX (?:^|[^'])('(?:[^']|'')*')(?:[^']|$)

        '        did not match        -
        ''       matched           ('')
        '''      did not match        -
        ''''     matched         ('''')
        'a       did not match        -
        a'       did not match        -
        ''a      matched           ('')
        a''      matched           ('')
        '''a     did not match        -
        a'''     did not match        -
        ''''a    matched         ('''')
        a''''    matched         ('''')


THE PROGRAM

  #!/usr/bin/env ruby

  regexs = [
	    %r{((?:''|[^'])+)},
	    %r{(?:^|[^'])('(?:[^']|'')*')(?:[^']|$)}
	   ]
  strings = %w(
	       ' '' ''' '''' 'a a'
	       ''a a'' '''a a''' ''''a a''''
	      )
  regexs.each do |r|
    puts "\nTESTING REGEX #{r.source}\n\n"
    strings.each do |s|
      m = r.match s
      format = "\t%-8.8s %-13.13s %8.8s\n"
      if m
	printf format, s, 'matched', "(#{m[1]})"
      else
	printf format, s, 'did not match', '-'
      end
    end
  end




(?:^|[^'])('(?:[^']|'')*')(?:[^']|$)

  * beginning with the start of string or not a '
  * followed by a '
  * followed by zero or more of not ' or ''
  * followed by a '
  * ending with the end of string or not a '
  * the quoted string is captured, nothing else is


-ara


-- 

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 | Ara Howard
 | NOAA Forecast Systems Laboratory
 | Information and Technology Services
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