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

[Tino Calancha <tino.calancha@gmail.com>]

On Tue, 23 Jan 2018, Eli Zaretskii wrote:

> An even more minor nit: try to avoid starting a sentence with @var.
> In an Info manual, @var produces UPPER CASE, which looks OK at the
> beginning of a sentence; but in the printed manual, @var produces a
> lower-case word in slant typeface, which makes the sentence begin with
> a lower-case letter.
Excellent! Thank you!
Indeed I found very ugly when I wrote such sentence starting with @{var}; 
I couldn't find an alternative way to say what I wanted to say.  You
summarized the point nicely.

Updated the patch (below).
I will push it by Sunday (4 days from now) if there is no more
activity in thi thread.

--8<-----------------------------cut here---------------start------------->8---
commit 55b82da7a7d0c1e016ef73ef46a7579fd9369cbf
Author: tino calancha <tino.calancha@gmail.com>
Date:   Wed Jan 24 12:03:14 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..761750eb20 100644
--- a/doc/lispref/lists.texi
+++ b/doc/lispref/lists.texi
@@ -1733,6 +1733,14 @@ Association Lists
  @end example
  @end defun

+@defun assoc-delete-all key alist &optional test
+This function is like @code{assq-delete-all} except that it accepts
+an optional argument @var{test}, a predicate function to compare the
+keys in @var{alist}. If omitted or @code{nil}, @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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