bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

[Mekeor Melire]

* lisp/simple.el (cycle-spacing): beside accepting an integer as first
argument N, also allow N to be 'negative-zero. This allows to delete
all spaces including newlines with (cycle-spacing 'negative-zero).
---
 lisp/simple.el | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/lisp/simple.el b/lisp/simple.el
index a5565ab..00df813 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -867,18 +867,20 @@ The first time `cycle-spacing' runs, it saves in this variable:
 its N argument, the original point position, and the original spacing
 around point.")
 
-(defun cycle-spacing (&optional n preserve-nl-back mode)
+(defun cycle-spacing (&optional n-or-negative-zero preserve-nl-back mode)
   "Manipulate whitespace around point in a smart way.
 In interactive use, this function behaves differently in successive
 consecutive calls.
 
 The first call in a sequence acts like `just-one-space'.
 It deletes all spaces and tabs around point, leaving one space
-\(or N spaces).  N is the prefix argument.  If N is negative,
-it deletes newlines as well, leaving -N spaces.
-\(If PRESERVE-NL-BACK is non-nil, it does not delete newlines before point.)
+\(or N spaces).  N is the prefix argument.  If N is a negative integer,
+it deletes newlines as well, leaving -N spaces. If N is 'negative-zero, it
+deletes all spaces and newlines. \(If PRESERVE-NL-BACK is non-nil, it does
+not delete newlines before point.)
 
-The second call in a sequence deletes all spaces.
+The second call in a sequence deletes all spaces. It is skipped if N is 0
+or the symbol 'negative-zero.
 
 The third call in a sequence restores the original whitespace (and point).
 
@@ -890,9 +892,14 @@ the function goes straight to the second step.
 Repeatedly calling the function with different values of N starts a
 new sequence each time."
   (interactive "*p")
-  (let ((orig-pos	 (point))
-	(skip-characters (if (and n (< n 0)) " \t\n\r" " \t"))
-	(num		 (abs (or n 1))))
+  (letrec
+    ((orig-pos	 (point))
+     (n-is-negative-zero (eq n-or-negative-zero 'negative-zero))
+     (n (if (or (null n-or-negative-zero) n-is-negative-zero)
+            0 n-or-negative-zero))
+     (skip-characters (if (or n-is-negative-zero (< n 0)) " \t\n\r" " \t"))
+     (num	      (abs (or n 1))))
+
     (skip-chars-backward (if preserve-nl-back " \t" skip-characters))
     (constrain-to-field nil orig-pos)
     (cond
-- 
2.8.4 (Apple Git-73)

bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

[npostavs]

Mekeor Melire <mekeor.melire@gmail.com> writes:

> * lisp/simple.el (cycle-spacing): beside accepting an integer as first
> argument N, also allow N to be 'negative-zero. This allows to delete
> all spaces including newlines with (cycle-spacing 'negative-zero).

This behaviour can't be used interactively right?  If you want a
function to delete all space including newlines, I think it's better to
add one instead of adding yet another mode to cycle-spacing which won't
even be used by interactive callers.

That is, instead of (cycle-spacing 'negative-zero) something like
(delete-whitespace).

> +  (letrec

You only need let* here, I think.

bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

[Mekeor Melire]

npostavs@users.sourceforge.net writes:

> Mekeor Melire <mekeor.melire@gmail.com> writes:

>> * lisp/simple.el (cycle-spacing): beside accepting an integer as first
>> argument N, also allow N to be 'negative-zero. This allows to delete
>> all spaces including newlines with (cycle-spacing 'negative-zero).

> This behaviour can't be used interactively right?  If you want a
> function to delete all space including newlines, I think it's better to
> add one instead of adding yet another mode to cycle-spacing which won't
> even be used by interactive callers.

> That is, instead of (cycle-spacing 'negative-zero) something like
> (delete-whitespace).

Well, the point is that delete-whitespace would mostly have the same
logic as cycle-spacing. So, should we define a more general function
then, which both delete-whitespace and cycle-spacing would be based
upon?

So, currently `cycle-spacing' is used like this:

    (cycle-spacing &optional N PRESERVE-NL-BACK MODE)

And the problem is that the sign(ature) of N is used to determine
whether to delete newlines as well. So, if N is zero, we have a problem.
So, I think we shouldn't use the signature of N but instead that should
be another argument. But maybe let's use that new argument for a new
function so that cycle-spacing stays backwardscompatible?

So, I propose something like this:

    (defun (cycle-spacing &optional n preserve-nl-back mode)
      (cycle-spacing-general n preserve-nl-back (< n 0) mode))

    (defun (cycle-spacing-general &optional n preserve-nl-back delete-newlines mode)
      ;; use (abs n) in place of n here
      ;; ...
      )

    ;; this is optional:
    (defun (delete-whitespace &optional n preserve-n-back mode)
      (cycle-spacing-general n preserve-nl-back t mode))


>> +  (letrec
>
> You only need let* here, I think.

Uhm, I'm not sure. I'll check it out.


Thanks for your feedback!

bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

[npostavs]

Mekeor Melire <mekeor.melire@gmail.com> writes:

> Well, the point is that delete-whitespace would mostly have the same
> logic as cycle-spacing. So, should we define a more general function
> then, which both delete-whitespace and cycle-spacing would be based
> upon?  So, currently `cycle-spacing' is used like this:
>
>     (cycle-spacing &optional N PRESERVE-NL-BACK MODE)
>
> And the problem is that the sign(ature) of N is used to determine
> whether to delete newlines as well. So, if N is zero, we have a
> problem.

I'm still a bit confused why you specfically want to use cycle-spacing
to delete newlines and spaces.  What logic of cycle-spacing would be
applicable when N is zero?  Can you give an example usage?

bug#27507: [PATCH] Make `cycle-spacing' allow 'negative-zero in place of an integer

[Noam Postavsky]

tags 27507 + moreinfo
quit

npostavs@users.sourceforge.net writes:

> Mekeor Melire <mekeor.melire@gmail.com> writes:
>
>> Well, the point is that delete-whitespace would mostly have the same
>> logic as cycle-spacing. So, should we define a more general function
>> then, which both delete-whitespace and cycle-spacing would be based
>> upon?  So, currently `cycle-spacing' is used like this:
>>
>>     (cycle-spacing &optional N PRESERVE-NL-BACK MODE)
>>
>> And the problem is that the sign(ature) of N is used to determine
>> whether to delete newlines as well. So, if N is zero, we have a
>> problem.
>
> I'm still a bit confused why you specfically want to use cycle-spacing
> to delete newlines and spaces.  What logic of cycle-spacing would be
> applicable when N is zero?  Can you give an example usage?

Ping?