bug#63509: [PATCH] Make copy-tree work with records

[Joseph Turner via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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Eli Zaretskii <eliz@gnu.org> writes:

>  - NEWS entry

I updated the 29 entry. Should I move it to 30?

>  - update for the ELisp manual

Changes made in patch:

- updated the entry in lists.texi
- added a new entry in records.texi
- added entry in the vector group in shortdoc.el

>  - preferably added tests to regression-test this feature

Done.

> I also think we should rename the second argument, as VECP no longer
> fits.

How about VECTOR-LIKE-P? See patch.

Joseph


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From 14383e9fe8a107f597d06ad486a441b761cc6ade Mon Sep 17 00:00:00 2001
From: Joseph Turner <joseph@breatheoutbreathe.in>
Date: Sun, 14 May 2023 21:02:15 -0700
Subject: [PATCH] Make copy-tree work with records

---
 doc/lispref/lists.texi      |  9 +++++----
 doc/lispref/records.texi    | 12 ++++++++++++
 etc/NEWS.29                 |  5 +++++
 lisp/emacs-lisp/shortdoc.el |  2 ++
 lisp/subr.el                | 14 +++++++-------
 test/lisp/subr-tests.el     | 31 +++++++++++++++++++++++++++++++
 6 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/doc/lispref/lists.texi b/doc/lispref/lists.texi
index 22a5f7f1239..16ed0358974 100644
--- a/doc/lispref/lists.texi
+++ b/doc/lispref/lists.texi
@@ -696,16 +696,17 @@ not a list, the sequence's elements do not become elements of the
 resulting list.  Instead, the sequence becomes the final @sc{cdr}, like
 any other non-list final argument.
 
-@defun copy-tree tree &optional vecp
+@defun copy-tree tree &optional vector-like-p
 This function returns a copy of the tree @var{tree}.  If @var{tree} is a
 cons cell, this makes a new cons cell with the same @sc{car} and
 @sc{cdr}, then recursively copies the @sc{car} and @sc{cdr} in the
 same way.
 
 Normally, when @var{tree} is anything other than a cons cell,
-@code{copy-tree} simply returns @var{tree}.  However, if @var{vecp} is
-non-@code{nil}, it copies vectors too (and operates recursively on
-their elements).  This function cannot cope with circular lists.
+@code{copy-tree} simply returns @var{tree}.  However, if
+@var{vector-like-p} is non-@code{nil}, it copies vectors and records
+too (and operates recursively on their elements).  This function
+cannot cope with circular lists.
 @end defun
 
 @defun flatten-tree tree
diff --git a/doc/lispref/records.texi b/doc/lispref/records.texi
index 26c6f30a6b5..0f44198a6b0 100644
--- a/doc/lispref/records.texi
+++ b/doc/lispref/records.texi
@@ -81,6 +81,18 @@ This function returns a new record with type @var{type} and
 @end example
 @end defun
 
+@defun copy-tree tree &optional vector-like-p
+This function copies a record when @var{vector-like-p} is
+non-@code{nil}.
+
+@example
+@group
+(copy-tree (record 'foo "a"))
+     @result{} #s(foo "a")
+@end group
+@end example
+@end defun
+
 @node Backward Compatibility
 @section Backward Compatibility
 
diff --git a/etc/NEWS.29 b/etc/NEWS.29
index fa428d9c790..ae9a89203bf 100644
--- a/etc/NEWS.29
+++ b/etc/NEWS.29
@@ -4897,6 +4897,11 @@ Instead, Emacs uses the already-existing 'make-directory' handlers.
 This can let a caller know whether it created DIR.  Formerly,
 'make-directory's return value was unspecified.
 
++++
+** 'copy-tree' now correctly copies records when its optional second
+argument is non-nil.  The second argument has been renamed from VECP
+to VECTOR-LIKE-P since it now works with both vectors and records.
+
 \f
 * Changes in Emacs 29.1 on Non-Free Operating Systems
 
diff --git a/lisp/emacs-lisp/shortdoc.el b/lisp/emacs-lisp/shortdoc.el
index 9a6f5dd12ce..6580e0e4e0c 100644
--- a/lisp/emacs-lisp/shortdoc.el
+++ b/lisp/emacs-lisp/shortdoc.el
@@ -833,6 +833,8 @@ A FUNC form can have any number of `:no-eval' (or `:no-value'),
   (seq-subseq
    :eval (seq-subseq [1 2 3 4 5] 1 3)
    :eval (seq-subseq [1 2 3 4 5] 1))
+  (copy-tree
+   :eval (copy-tree [1 2 3 4]))
   "Mapping Over Vectors"
   (mapcar
    :eval (mapcar #'identity [1 2 3]))
diff --git a/lisp/subr.el b/lisp/subr.el
index 03d3324f3d8..83735933963 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -824,26 +824,26 @@ of course, also replace TO with a slightly larger value
                 next (+ from (* n inc)))))
       (nreverse seq))))
 
-(defun copy-tree (tree &optional vecp)
+(defun copy-tree (tree &optional vector-like-p)
   "Make a copy of TREE.
 If TREE is a cons cell, this recursively copies both its car and its cdr.
 Contrast to `copy-sequence', which copies only along the cdrs.  With second
-argument VECP, this copies vectors as well as conses."
+argument VECTOR-LIKE-P, this copies vectors and records as well as conses."
   (declare (side-effect-free error-free))
   (if (consp tree)
       (let (result)
 	(while (consp tree)
 	  (let ((newcar (car tree)))
-	    (if (or (consp (car tree)) (and vecp (vectorp (car tree))))
-		(setq newcar (copy-tree (car tree) vecp)))
+	    (if (or (consp (car tree)) (and vector-like-p (or (vectorp (car tree)) (recordp (car tree)))))
+		(setq newcar (copy-tree (car tree) vector-like-p)))
 	    (push newcar result))
 	  (setq tree (cdr tree)))
 	(nconc (nreverse result)
-               (if (and vecp (vectorp tree)) (copy-tree tree vecp) tree)))
-    (if (and vecp (vectorp tree))
+               (if (and vector-like-p (or (vectorp tree) (recordp tree))) (copy-tree tree vector-like-p) tree)))
+    (if (and vector-like-p (or (vectorp tree) (recordp tree)))
 	(let ((i (length (setq tree (copy-sequence tree)))))
 	  (while (>= (setq i (1- i)) 0)
-	    (aset tree i (copy-tree (aref tree i) vecp)))
+	    (aset tree i (copy-tree (aref tree i) vector-like-p)))
 	  tree)
       tree)))
 
diff --git a/test/lisp/subr-tests.el b/test/lisp/subr-tests.el
index 8f46c2af136..4ebb68556be 100644
--- a/test/lisp/subr-tests.el
+++ b/test/lisp/subr-tests.el
@@ -1206,5 +1206,36 @@ final or penultimate step during initialization."))
     (should (equal a-dedup '("a" "b" "a" "b" "c")))
     (should (eq a a-dedup))))
 
+(ert-deftest subr--copy-tree ()
+  (should (eq (copy-tree nil) nil))
+  (let* ((a (list (list "a") "b" (list "c") "g"))
+         (copy1 (copy-tree a))
+         (copy2 (copy-tree a t)))
+    (should (equal a copy1))
+    (should (equal a copy2))
+    (should-not (eq a copy1))
+    (should-not (eq a copy2)))
+  (let* ((a (list (list "a") "b" (list "c" (record 'foo "d")) (list ["e" "f"]) "g"))
+         (copy1 (copy-tree a))
+         (copy2 (copy-tree a t)))
+    (should (equal a copy1))
+    (should (equal a copy2))
+    (should-not (eq a copy1))
+    (should-not (eq a copy2)))
+  (let* ((a (record 'foo "a" (record 'bar "b")))
+         (copy1 (copy-tree a))
+         (copy2 (copy-tree a t)))
+    (should (equal a copy1))
+    (should (equal a copy2))
+    (should (eq a copy1))
+    (should-not (eq a copy2)))
+  (let* ((a ["a" "b" ["c" ["d"]]])
+         (copy1 (copy-tree a))
+         (copy2 (copy-tree a t)))
+    (should (equal a copy1))
+    (should (equal a copy2))
+    (should (eq a copy1))
+    (should-not (eq a copy2))))
+
 (provide 'subr-tests)
 ;;; subr-tests.el ends here
-- 
2.40.1