bug#30202: 27.0.50; Code refactoring on assq-delete-all assoc-delete-all

[Tino Calancha]

On Mon, 22 Jan 2018, Eli Zaretskii wrote:

> > From: Tino Calancha <tino.calancha@gmail.com>
> > Date: Mon, 22 Jan 2018 14:24:38 +0900
> > Cc: monnier@iro.umontreal.ca
> >
> > yesterday was added (how about to announce it in NEWS file?)
>
> Please just add a NEWS entry if you find a missing one.  Bonus points
> for documenting new functions in the respective manual(s).
Thanks for the suggestion.
Updated the patch with the NEWS entry and manual doc.

--8<-----------------------------cut here---------------start------------->8---
commit a80eda38ac4abefbbfd05719cb8ecd4ad9a85d68
Author: tino calancha <tino.calancha@gmail.com>
Date:   Tue Jan 23 08:52:48 2018 +0900

    Code refactoring

    * lisp/subr.el (assoc-delete-all): Add optional arg TEST.
    (assq-delete-all): Use assoc-delete-all.
    * doc/lispref/lists.texi (Association Lists): Document
    assoc-delete-all in the manual.
    ; * etc/NEWS: Add entry for assoc-delete-all

diff --git a/doc/lispref/lists.texi b/doc/lispref/lists.texi
index 3e2dd13c70..37b8172502 100644
--- a/doc/lispref/lists.texi
+++ b/doc/lispref/lists.texi
@@ -1733,6 +1733,13 @@ Association Lists
 @end example
 @end defun

+@defun assoc-delete-all key alist &optional test
+This function is like @code{assq-delete-all} except that accepts
+an optional argument @var{test} to compare the keys in @var{alist}.
+@var{test} defaults to @code{equal}.  As @code{assq-delete-all},
+this function often modifies the original list structure of @var{alist}.
+@end defun
+
 @defun rassq-delete-all value alist
 This function deletes from @var{alist} all the elements whose @sc{cdr}
 is @code{eq} to @var{value}.  It returns the shortened alist, and
diff --git a/etc/NEWS b/etc/NEWS
index d30f0b087c..c491777781 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -204,6 +204,9 @@ as new-style, bind the new variable 
'force-new-style-backquotes' to t.

 * Lisp Changes in Emacs 27.1

++++
+** New function assoc-delete-all.
+
 ** 'print-quoted' now defaults to t, so if you want to see
 (quote x) instead of 'x you will have to bind it to nil where applicable.

diff --git a/lisp/subr.el b/lisp/subr.el
index 092850a44d..e7a0ffc5be 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -705,17 +705,19 @@ member-ignore-case
     (setq list (cdr list)))
   list)

-(defun assoc-delete-all (key alist)
-  "Delete from ALIST all elements whose car is `equal' to KEY.
+(defun assoc-delete-all (key alist &optional test)
+  "Delete from ALIST all elements whose car is KEY.
+Compare keys with TEST.  Defaults to `equal'.
 Return the modified alist.
 Elements of ALIST that are not conses are ignored."
+  (unless test (setq test #'equal))
   (while (and (consp (car alist))
-             (equal (car (car alist)) key))
+             (funcall test (caar alist) key))
     (setq alist (cdr alist)))
   (let ((tail alist) tail-cdr)
     (while (setq tail-cdr (cdr tail))
       (if (and (consp (car tail-cdr))
-              (equal (car (car tail-cdr)) key))
+              (funcall test (caar tail-cdr) key))
          (setcdr tail (cdr tail-cdr))
        (setq tail tail-cdr))))
   alist)
@@ -724,16 +726,7 @@ assq-delete-all
   "Delete from ALIST all elements whose car is `eq' to KEY.
 Return the modified alist.
 Elements of ALIST that are not conses are ignored."
-  (while (and (consp (car alist))
-             (eq (car (car alist)) key))
-    (setq alist (cdr alist)))
-  (let ((tail alist) tail-cdr)
-    (while (setq tail-cdr (cdr tail))
-      (if (and (consp (car tail-cdr))
-              (eq (car (car tail-cdr)) key))
-         (setcdr tail (cdr tail-cdr))
-       (setq tail tail-cdr))))
-  alist)
+  (assoc-delete-all key alist #'eq))

 (defun rassq-delete-all (value alist)
   "Delete from ALIST all elements whose cdr is `eq' to VALUE.
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