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Re: A variant of match-end, but after replacement?
From: |
Pascal J. Bourguignon |
Subject: |
Re: A variant of match-end, but after replacement? |
Date: |
Mon, 20 Jul 2015 02:33:13 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Marcin Borkowski <mbork@mbork.pl> writes:
>> Not very much:
>>
>> (let ((end (match-end 1))
>> (new-string (replace-match new-text t t string 1)))
>> (do-something-from new-string
>> (+ end (- (length new-string) (length string)))))
>
> I give up. It seems that a PhD in math is not enough to deal with
> string-length arithmetic;-). Shame on me! (OTOH, mails from you often
> teach me that when I have the impression that I'm smart, it's usually
> only an impression.)
Sorry, I was about to write out the equation, but if it's necessary,
I'll do.
(length new-string)
--------------------------------------------------------
(length prefix) (length new) (length suffix)
---------------- ---------------------- ----------------
pppppppppppppppp nnnnnnnnnnnnnnnnnnnnnn ssssssssssssssss
^
|
new-end
(length old-string)
--------------------------------------------------
(length prefix) (length old) (length suffix)
---------------- ---------------- ----------------
pppppppppppppppp oooooooooooooooo ssssssssssssssss
^
|
(match-end)
So, we have:
(= (length suffix) (- (length new-string) new-end))
(= (length suffix) (- (length old-string) (match-end)))
Or, in math:
s = ns-ne
s = os-me
Therefore:
0 = (ns-ne) - (os-me)
<=> 0 = ns - ne - os + me
<=> ne = me + (ns - os)
<=> (= new-end (+ (match-end) (- (length new-string) (length old-string))))
Hence:
(let ((end (match-end 1))
(new-string (replace-match new-text t t old-string 1)))
(do-something-from new-string
(+ end (- (length new-string) (length old-string)))))
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk
- Re: A variant of match-end, but after replacement?, (continued)
- Re: A variant of match-end, but after replacement?, Nicolas Richard, 2015/07/20
- Message not available
- Re: A variant of match-end, but after replacement?, Pascal J. Bourguignon, 2015/07/19
- Re: A variant of match-end, but after replacement?, Marcin Borkowski, 2015/07/19
- Re: A variant of match-end, but after replacement?, Dmitry Gutov, 2015/07/19
- Re: A variant of match-end, but after replacement?, Marcin Borkowski, 2015/07/19
- Message not available
- Re: A variant of match-end, but after replacement?, Pascal J. Bourguignon, 2015/07/19
- Re: A variant of match-end, but after replacement?, Marcin Borkowski, 2015/07/19
- Message not available
- Re: A variant of match-end, but after replacement?, Barry Margolin, 2015/07/19
- Re: A variant of match-end, but after replacement?, Pascal J. Bourguignon, 2015/07/19
- Re: A variant of match-end, but after replacement?, Marcin Borkowski, 2015/07/19
- Message not available
- Re: A variant of match-end, but after replacement?,
Pascal J. Bourguignon <=