using lisp in replacement string

using lisp in replacement string

[Guido Van Hoecke]

Hi,

I am trying to apply what I found in the Emacs manual
-> Search (15 Searching and replacement)
-> Replace (15.10 Replacement Commands)
-> Regexp Replace (15.10.2 Regexp Replacement)
"You can use Lisp expressions to calculate parts of the replacement
string.  To do this, write `\,' followed by the expression in the
replacement string.  Each replacement calculates the value of the
expression and converts it to text without quoting (if it's a string,
this means using the string's contents), and uses it in the replacement
string in place of the expression itself."

So I have a temp buffer with following content
|2+6*21|
|3*15|
|7-3|
and I want to replace the formulas between the '|' characters by the
result of passing them to calc-eval:

(replace-regexp "|\\([^|]*\\)|" \\,(calc-eval \\1) nil (point-min)(point-max))
but this causes Debugger entered--Lisp error: (void-variable \\)

So I try it with single slash:
(replace-regexp "|\\([^|]*\\)|" \,(calc-eval \\1) nil (point-min)(point-max))
and then I get : Symbol's value as variable is void: \,

I got the distinct feeling I'm missing something very basic here...

Please advise

TIA,

Guido

Re: using lisp in replacement string

[Dmitry Gutov]

On 12/24/2014 04:25 PM, Guido Van Hoecke wrote:

> (replace-regexp "|\\([^|]*\\)|" \\,(calc-eval \\1) nil (point-min)(point-max))
> but this causes Debugger entered--Lisp error: (void-variable \\)

The second argument doesn't look like a string to me. Are you missing 
the quotes?

Re: using lisp in replacement string

[Guido Van Hoecke]

Hi Dimitry,

On 24 December 2014 at 15:27, Dmitry Gutov <dgutov@yandex.ru> wrote:

> On 12/24/2014 04:25 PM, Guido Van Hoecke wrote:
>
>  (replace-regexp "|\\([^|]*\\)|" \\,(calc-eval \\1) nil
>> (point-min)(point-max))
>> but this causes Debugger entered--Lisp error: (void-variable \\)
>>
>
> The second argument doesn't look like a string to me. Are you missing the
> quotes?
>
​Not really, if you quote it, it replaces the formulas by the calc-eval
expression :(

Guido​

Re: using lisp in replacement string

[Dmitry Gutov]

On 12/24/2014 04:40 PM, Guido Van Hoecke wrote:

> ​Not really, if you quote it, it replaces the formulas by the calc-eval
> expression :(

If you don't quote it, it's not a string.

Anyway, check out these lines from `replace-regexp' docstring:

"This function is for interactive use only;
in Lisp code use `re-search-forward' and `replace-match' instead."
...
"In interactive calls, the replacement text may contain `\,'"

You're not using it interactively.

Re: using lisp in replacement string

[Nicolas Richard]

Hello,

Guido Van Hoecke <guivho@gmail.com> writes:
> "You can use Lisp expressions to calculate parts of the replacement
> string.  To do this, write `\,' followed by the expression in the
> replacement string.
> [...]
> I got the distinct feeling I'm missing something very basic here...

The \, construct is meant for interactive use.
Try it interactively, then do C-x M-: to see what lisp form it produced.

HTH,

-- 
Nicolas Richard

Re: using lisp in replacement string

[Guido Van Hoecke]

Hi,

"This function is for interactive use only;
>> in Lisp code use `re-search-forward' and `replace-match' instead."
>> ...
>> "In interactive calls, the replacement text may contain `\,'"
>>
>
I still do not get it. Say following content i​n the *scratch* buffer:

|2+6*21|
|3*15|
|7-3|

(defun test1 ()
  "just display the lisp form rather than execute it"
  (interactive)
  (goto-char (point-min))
  (while (re-search-forward "^|\\([^|]*\\)|$" nil t)
    (replace-match "(calc-eval \"\\1\")" nil nil nil 1)))

(defun test2 ()
  "try to replace the searched string with the result of the lisp form"
  (interactive)
  (goto-char (point-min))
  (while (re-search-forward "^|\\([^|]*\\)|$" nil t)
        (replace-match (calc-eval "\\1") nil nil nil 1)))

M-x test1 replaces the first three lines as follows:
|(calc-eval "2+6*21")|
|(calc-eval "3*15")|
|(calc-eval "7-3")|

C-x C-e of each of the calc-eval statements yields the expected result.

After undoing these changes and returning to the initial three lines,
M-x test2 complains:
while: Wrong type argument: stringp, (0 "Expected a number")

Any help would be highly appreciated,


Guido

Re: using lisp in replacement string

[Barry Margolin]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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In article <mailman.16678.1419438348.1147.help-gnu-emacs@gnu.org>,
 Guido Van Hoecke <guivho@gmail.com> wrote:

> Hi,
> 
> "This function is for interactive use only;
> >> in Lisp code use `re-search-forward' and `replace-match' instead."
> >> ...
> >> "In interactive calls, the replacement text may contain `\,'"
> >>
> >
> I still do not get it. Say following content i​n the *scratch* buffer:

This isn't done in replace-match. It's specific to replace-regexp, and 
it checks whether it was invoked interactively rather than from Lisp to 
determine whether to look for that string. It's a total hack.

If you're writing your own Lisp functions, you should use match-string 
to get the matched string or capture group, do whatever you want to 
produce the replacement (e.g. call calc-eval), and then call 
replace-match with this result.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

RE: using lisp in replacement string

[ronaldo.mercado]

Hello, the function below performs a global search-replace

(defun hh ()
  (interactive)
  (let (match-beginning match-end match-string replacement)
    (goto-char (point-min))
    (while (re-search-forward "|\\([^|]*\\)|"  nil t)
      (setq match-beginning (match-beginning 0))
      (setq match-end (match-end 0))
      (setq replacement (concat "|" (calc-eval (match-string 1)) "|") )
      (goto-char match-beginning)
      (re-search-forward "|\\([^|]*\\)|" match-end nil)
      (replace-match replacement t t nil 0))))

I did not understand why I needed to perform re-search-forward twice though. without the second search, results were garbled.

________________________________________
From: help-gnu-emacs-bounces+ronaldo.mercado=diamond.ac.uk@gnu.org [help-gnu-emacs-bounces+ronaldo.mercado=diamond.ac.uk@gnu.org] on behalf of Dmitry Gutov [dgutov@yandex.ru]
Sent: 24 December 2014 14:52
To: Guido Van Hoecke
Cc: help-gnu-emacs
Subject: Re: using lisp in replacement string

On 12/24/2014 04:40 PM, Guido Van Hoecke wrote:

> ​Not really, if you quote it, it replaces the formulas by the calc-eval
> expression :(

If you don't quote it, it's not a string.

Anyway, check out these lines from `replace-regexp' docstring:

"This function is for interactive use only;
in Lisp code use `re-search-forward' and `replace-match' instead."
...
"In interactive calls, the replacement text may contain `\,'"

You're not using it interactively.


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Re: using lisp in replacement string

[Andreas Röhler]

On 24.12.2014 15:25, Guido Van Hoecke wrote:
> Hi,
>
> I am trying to apply what I found in the Emacs manual
> -> Search (15 Searching and replacement)
> -> Replace (15.10 Replacement Commands)
> -> Regexp Replace (15.10.2 Regexp Replacement)
> "You can use Lisp expressions to calculate parts of the replacement
> string.  To do this, write `\,' followed by the expression in the
> replacement string.  Each replacement calculates the value of the
> expression and converts it to text without quoting (if it's a string,
> this means using the string's contents), and uses it in the replacement
> string in place of the expression itself."
>
> So I have a temp buffer with following content
> |2+6*21|
> |3*15|
> |7-3|
> and I want to replace the formulas between the '|' characters by the
> result of passing them to calc-eval:
>
> (replace-regexp "|\\([^|]*\\)|" \\,(calc-eval \\1) nil (point-min)(point-max))
> but this causes Debugger entered--Lisp error: (void-variable \\)
>
> So I try it with single slash:
> (replace-regexp "|\\([^|]*\\)|" \,(calc-eval \\1) nil (point-min)(point-max))
> and then I get : Symbol's value as variable is void: \,
>
> I got the distinct feeling I'm missing something very basic here...
>
> Please advise
>
> TIA,
>
> Guido
>
>

As Dimitry said, \, is for use in interactive call only.
Beside you don't need it, as forms might be evaluated the common way.

Try this:

(defun my-calc-eval ()
   (interactive)
   (let (erg)
     (goto-char (point-min))
     (while (re-search-forward "|\\([^|]+\\)|" nil t 1)
       (save-match-data
	(setq erg (calc-eval (match-string-no-properties 1))))
       ;; (message "%s" (match-string-no-properties 1))
       (delete-region (match-beginning 1) (match-end 1))
       (goto-char (match-beginning 1))
       (insert erg)
       (end-of-line) )))

Re: using lisp in replacement string

[Guido Van Hoecke]

Hi Andreas,

On 25 December 2014 at 10:25, Andreas Röhler <andreas.roehler@easy-emacs.de>
wrote:

> On 24.12.2014 15:25, Guido Van Hoecke wrote:
>
>>
>> So I have a temp buffer with following content
>> |2+6*21|
>> |3*15|
>> |7-3|
>> and I want to replace the formulas between the '|' characters by the
>> result of passing them to calc-eval:
>>
>> (replace-regexp "|\\([^|]*\\)|" \\,(calc-eval \\1) nil
>> (point-min)(point-max))
>> but this causes Debugger entered--Lisp error: (void-variable \\)
>>
>> So I try it with single slash:
>> (replace-regexp "|\\([^|]*\\)|" \,(calc-eval \\1) nil
>> (point-min)(point-max))
>> and then I get : Symbol's value as variable is void: \,
>>
>
> As Dimitry said, \, is for use in interactive call only.
> Beside you don't need it, as forms might be evaluated the common way.
>
> Try this:
>
> (defun my-calc-eval ()
>   (interactive)
>   (let (erg)
>     (goto-char (point-min))
>     (while (re-search-forward "|\\([^|]+\\)|" nil t 1)
>       (save-match-data
>         (setq erg (calc-eval (match-string-no-properties 1))))
>       ;; (message "%s" (match-string-no-properties 1))
>       (delete-region (match-beginning 1) (match-end 1))
>       (goto-char (match-beginning 1))
>       (insert erg)
>       (end-of-line) )))
>
> ​Works like a charm, thanks a lot!

Guido​

Re: using lisp in replacement string

[Emanuel Berg]

Guido Van Hoecke <guivho@gmail.com> writes:

> So I have a temp buffer with following content
> |2+6*21|
> |3*15|
> |7-3|
> and I want to replace the formulas between the '|'
> characters by the result of passing them to
> calc-eval

Yes, you can do that! I did that once with a file like
this:

   normal                         bright
   bk  r   g   y  bl   m   c   w  bk    r   g   y  bl   m   c   w
r  0 233  50 170 100 200   0 150  110 255   0 220 133 255   0 190
g  0   0 150 170 100   0 170 150  110  33 190 220 133   0 190 190
b  0   0  50   0 200 200 170 150  110  33   0   0 255 255 190 190

I thought it could be cool to, for example, add 10% to
each - the span is (as you see) 0 to 255, so +10% from
150 would be ... 177?

Anyway, I got rid of that code because it was much
easier and more powerful to just tweak it by hand,
digit by digit. Still, it is the exact situation as
yours - replace a value by another value, that is a
function of the first value - or, replace x by f(x) -
so I can tell you how I did it. (Let this be a lesson
to naive Elispers - including those who verbalize the
lesson - always keep your code, even that which you
don't use...)

Now: check out this, from the help of
`replace-regexp'.

(while (re-search-forward REGEXP nil t)
  (replace-match TO-STRING nil nil))

So instead of the `replace-match' stuff above, you
write a function that examines `match-beginning',
`match-end', and `match-string', and then use that as
input to your Elisp, to produce the on-the-fly
TO-STRING (in the phrasing of the above Elisp).

Good luck!

(And when you get it to work, post it here :))

-- 
underground experts united

Re: using lisp in replacement string

[Guido Van Hoecke]

Hi Emanuel,


On 29 December 2014 at 05:40, Emanuel Berg <embe8573@student.uu.se> wrote:

> Guido Van Hoecke <guivho@gmail.com> writes:
>
> > So I have a temp buffer with following content
> > |2+6*21|
> > |3*15|
> > |7-3|
> > and I want to replace the formulas between the '|'
> > characters by the result of passing them to
> > calc-eval
>
> Yes, you can do that! I did that once with a file like
> this:
> ​...
> (And when you get it to work, post it here :))
>
> ​The final solution looks like this (the actual input is an 8 column org
table and the field for the computation is the fifth field):

(let (quantity)
      (while (re-search-forward
              "^|[^|]*|[^|]*|[^|]*|[^|]*|\\([^|]+\\)|.*$" nil t 1)
        (save-match-data
          (setq quantity (calc-eval (match-string-no-properties 1))))
        (delete-region (match-beginning 1) (match-end 1))
        (goto-char (match-beginning 1))
        (insert quantity)
        (end-of-line)))

I never found a working replace-match approach.

Many thanks to all volunteers that helped to come to this solution.


Guido