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Re: regexp help

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Jake Jarvis wrote:

> On 07.09.2012 06:37, wrote Andrew Poulos:
>> I have a string
>> var str = 'This is some text.';
>> 
>> Within that string I need to find whether a whole word exists. The test
>> is to be case insensitive. The word to test for is held in the var 'k'.
>> 
>> When I try this:
>> 
>> var k = 'SOME';
>> var myRe = new RegExp("b" + k + "b", "i");
>> var found = myRe.test(str);
>> 
>> I expected 'found' to return true. What am I doing wrong?
> 
> You are not escaping the two 'b' characters.
> 
> There are 2 levels here: the level of the regular expression in which
> you want '\b', and the level of the pattern string in which you need
> '\\b', because strings have their own escape rules which apply first and
> under those '\b' means "backspace character", whereas '\\b' means
> "backslash b".

In addition, \b is not sufficient in most cases as it matches a boundary 
between a "word character" and "not-a-word-character".  Word characters are 
those matched by `\w', which in turn is defined as the equivalent of [0-9A-
Za-z_].  Non-ASCII letters are not included.  Even basically English text 
can contain non-ASCII characters (borrowed from or written in other 
languages):

<http://stackoverflow.com/questions/1015844/how-to-remove-all-characters-
from-a-string/8568325#8568325> f.

Which gives me the idea that a Unicode mode for jsx.regexp.RegExp() to 
replace \b, \w and \W – in addition to or using the already implemented 
Unicode character properties (\p{Lu} et al.) – would come in handy.  
Comments anyone?


PointedEars
-- 
Sometimes, what you learn is wrong. If those wrong ideas are close to the 
root of the knowledge tree you build on a particular subject, pruning the 
bad branches can sometimes cause the whole tree to collapse.
  -- Mike Duffy in cljs, <news:Xns9FB6521286DB8invalidcom@94.75.214.39>

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regexp help Andrew Poulos <ap_prog@hotmail.com> - 2012-09-07 14:37 +1000
  Re: regexp help Jake Jarvis <pig_in_shoes@yahoo.com> - 2012-09-07 10:55 +0200
    Re: regexp help Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-07 15:36 +0200
      Re: regexp help Andrew Poulos <ap_prog@hotmail.com> - 2012-09-08 10:27 +1000
        Re: regexp help Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-08 09:34 +0200
      Re: regexp help "Scott Sauyet" <3103invalid@webnews.fastusenet.org> - 2012-09-11 16:51 +0000
        Re: regexp help Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-11 22:31 +0200
          Re: regexp help "Scott Sauyet" <3103invalid@webnews.fastusenet.org> - 2012-09-19 11:56 +0000
            Re: regexp help Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-19 18:51 +0200
              Re: regexp help Scott Sauyet <scott.sauyet@gmail.com> - 2012-09-19 12:52 -0700
                Re: regexp help Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-09-20 02:13 +0200
                Re: regexp help Scott Sauyet <scott.sauyet@gmail.com> - 2012-09-20 06:51 -0700
                Re: regexp help Dr J R Stockton <reply1237@merlyn.demon.co.uk.invalid> - 2012-09-20 20:23 +0100
      Re: regexp help "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2012-09-11 14:55 -0700

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