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Re: bulk replacement on region, buffer, file?


From: Pascal J. Bourguignon
Subject: Re: bulk replacement on region, buffer, file?
Date: Thu, 10 Dec 2015 04:13:07 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)

Tom Roche <Tom_Roche@pobox.com> writes:

> I would appreciate pointers to code that enables "bulk replacement" of
> numerous string tuples ({to-replace, replace-with}) in a single
> call. What I mean, why I ask:
>
> I frequently scrape blocks of text from PDFs into Emacs text
> buffers. After I do so, I usually want to replace lots of strings in
> the buffer. E.g. (using '|' to delimit the strings),
>
> |CO 2| -> |CO2|
> |- | -> ||
> |“| -> |"|
> |”| -> |"|
> |[weird unicodes used for bulleting]| -> |*|
>
> which I do manually by calling `M-x replace-string` or similar
> interactive or regexp function. I'd prefer instead to call something
> that
>
> 1. could be called on a region (if selected) or buffer (if not)

You can use functions that are not designed to work on a region,
restricting them to a narrowed region with narrow-to-region. (This is
why it is important to always use point-min and point-max, and not eg. 0
and buffer-size, because point-min and point-max take into account the
narrowing).

   (save-excursion
     (narrow-to-region start end)
     ...)



> 2. could read from a user-editable property file of replacement tuples
> (like those above), similar to `abbrev_defs` but without some
> constraints of the latter that annoy in this usecase. E.g. (unless I'm
> missing something), I cannot use `abbrev` to replace the
> space-delimited 'CO 2' with 'CO2'.

You can read lisp sexps from files with:

  (with-file "~/.your-replacements.sexp"
     (goto-char (point-min)) ; in case the file is already open.
     (read (current-buffer)))

> 3. would, for every {to-replace, replace-with} tuple in the file,
>
> * if `to-replace` found, replace every instance with `replace-with`
> * if `to-replace` not found, goto next tuple
>
> Is there elisp to do this? 

Yes.

I use:

    (progn (goto-char (point-min))
           (replace-multiple-strings
            '(("CO 2" . "CO2")
              ("- " . "")
              ("“" . "\"")
              ("”" . "\"")
              ("[weird unicodes used for bulleting]" . "*"))))
  

So wrapping all together:

    (save-excursion
     (narrow-to-region start end)
     (goto-char (point-min))
     (replace-multiple-strings
      (with-file "~/.your-replacements.sexp"
        (goto-char (point-min)) ; in case the file is already open.
        (read (current-buffer)))))


with-file and replace-multiple-strings are found in pjb-emacs.el
https://github.com/informatimago/emacs/blob/master/pjb-emacs.el


-- 
__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


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