RegEx Replace Text -- strip leading and trailing spaces

[Alex Tweedly]

Trevor DeVore wrote:

> This will strip leading and trailing whitespace from a multiline 
> string.  But given that you say that word 1 to -1 is that much faster 
> I am going to switch to that.  Those of us still trying to break away 
> from our previous languages like to complicate things on occasion ;)
>
> Is there a way to do ltrim (trim whitespace on left of string) in 
> plain transcript?  Right now I just use:
>
> function str_lTrim pString
>     get replaceText(pString, "^[ \t\r\n]+", "")
>     return it
> end str_lTrim
>
>
function str_lTrim pString
   if word 1 of pString  is empty then return empty    -- deal with case 
of all whitespace
  return  char (offset(word 1 of pString, pString)) to -1 of pString
end pString

The timings are fairly data dependent, but this is about 20% faster for 
most cases, and not slower for any I found.

If you know you aren't dealing with all-whitespace strings, you can 
remove that test line, and get another 10% improvement.

You can take any of those and improve by another 5% by passing the 
parameter by reference; avoids a data copy, and since you don't modify 
it, there's no downside.

BUT - in all those cases, the overhead of the function call is far more 
significant than the actual operation, so you can get another 50% saving 
by doing the replaceText (or chunk test) in-line rather than as a 
function.  You may prefer to use the function anyway for the sake of 
code that is easier to read - but if you have one or two crucial spots, 
it may be worth in-lining the operation..

-- 
Alex Tweedly       http://www.tweedly.net



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