Re: Getting partial matches from a string without forking an outside pro

On Sat, Jan 08, 2005 at 09:56:11PM +0100, Ruud H.G. van Tol wrote:

> Toen wij Ruud H.G. van Tol kietelden, kwam er dit uit:
> > Toen wij Robert Allerstorfer kietelden, kwam er dit uit:
> >
> > > deleting 2
> > > characters from the end is nearly impossible without forking an
> > > outside process".
> > That remark is about strings like "xxxxxx6xxx6xxx6xxxx".
> >
> > Check out the various uses of rep.inc on how to create regexes that
> > can do exactly what Jari names 'nearly impossible'.
> >
> >   var = 'xxxxxx6xxx6xxx6xxxx'
> >
> >   :0
> >   *  1^1 var ?? .
> >   * -2^0
> >   {
> >     rep_Repeat = "$="
> >     rep_String = '.'
> >
> >     INCLUDERC = 'inc/rep.inc'   # rep_Return becomes 17 dots
> >
> >     :0
> >     *$ var ?? ^^\/$rep_Return
> >     { var_Left = "$MATCH" }
>     :0
>     * var ?? ()\/..^^
>     { var_Right = "$MATCH" }
>
> >   }

Not bad.  I think it still doesn't need to be so complicated.
Here is my solution.

Set "$LOP" to however many chars you want to delete.  The string
being lopped is called $FOO here.


First, set your string to $FOO.  Mine will be 25 x's for testing.

 FOO = "xxxxx"  # five chars
 FOO = "$FOO$FOO$FOO$FOO$FOO"  # twenty-five chars (pretend we don't know len)

Now set $LOP.

 LOP = 3  # num of chars to lop off


Here comes the recipe:

#################################################
 :0
 *       1^1 FOO ?? .
 * $ -$LOP^0
 {
    LEN = $= 
    INCLUDERC = lop.rc
 }

#################################################

And here's the lop.rc:

#################################################
 :0
 * $ $LEN^0
 *     -1^0  FOO ?? ^^\/.
 {
    LEN =  $=
    BAR = "$BAR$MATCH"

    SWITCHRC = $_
 }

 FOO = "$BAR$MATCH"

#################################################

-- 
dman

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