Convert apropos-internal from C to Lisp (Bug#44529)

This runs insignificantly faster in C, and is already fast enough on
reasonably modern hardware.  We might as well lift it to Lisp.
This benchmark can be used to verify:

  (benchmark-run 10 (apropos-command "test"))
  => (0.12032415399999999 2 0.014772391999999995) ; C
  => (0.13513192100000002 2 0.017216643000000004) ; Lisp

* lisp/subr.el (apropos-internal): New defun, converted from C.
* src/keymap.c (Fapropos_internal): Remove defun.
(apropos_accum): Remove function.
(apropos_predicate, apropos_accumulate): Remove variables.
(syms_of_keymap): Remove defsubr for Fapropos_internal, and
definitions of the above variables.
* test/src/keymap-tests.el (keymap-apropos-internal)
(keymap-apropos-internal/predicate): Move tests from here...
* test/lisp/subr-tests.el (apropos-apropos-internal)
(apropos-apropos-internal/predicate): ...to here.

lisp/subr.el

@@ -5845,6 +5845,22 @@ This is the simplest safe way to acquire and release a mutex."
 	   (progn ,@body)
 	 (mutex-unlock ,sym)))))
 
+
+;;; Apropos.
+
+(defun apropos-internal (regexp &optional predicate)
+  "Show all symbols whose names contain match for REGEXP.
+If optional 2nd arg PREDICATE is non-nil, (funcall PREDICATE SYMBOL) is done
+for each symbol and a symbol is mentioned only if that returns non-nil.
+Return list of symbols found."
+  (let (found)
+    (mapatoms (lambda (symbol)
+                (when (and (string-match regexp (symbol-name symbol))
+                           (or (not predicate)
+                               (funcall predicate symbol)))
+                  (push symbol found))))
+    (sort found #'string-lessp)))
+
 
 ;;; Misc.
 

src/keymap.c

@@ -3243,49 +3243,11 @@ describe_vector (Lisp_Object vector, Lisp_Object prefix, Lisp_Object args,
     }
 }
 
-/* Apropos - finding all symbols whose names match a regexp.		*/
-static Lisp_Object apropos_predicate;
-static Lisp_Object apropos_accumulate;
-
-static void
-apropos_accum (Lisp_Object symbol, Lisp_Object string)
-{
-  register Lisp_Object tem;
-
-  tem = Fstring_match (string, Fsymbol_name (symbol), Qnil);
-  if (!NILP (tem) && !NILP (apropos_predicate))
-    tem = call1 (apropos_predicate, symbol);
-  if (!NILP (tem))
-    apropos_accumulate = Fcons (symbol, apropos_accumulate);
-}
-
-DEFUN ("apropos-internal", Fapropos_internal, Sapropos_internal, 1, 2, 0,
-       doc: /* Show all symbols whose names contain match for REGEXP.
-If optional 2nd arg PREDICATE is non-nil, (funcall PREDICATE SYMBOL) is done
-for each symbol and a symbol is mentioned only if that returns non-nil.
-Return list of symbols found.  */)
-  (Lisp_Object regexp, Lisp_Object predicate)
-{
-  Lisp_Object tem;
-  CHECK_STRING (regexp);
-  apropos_predicate = predicate;
-  apropos_accumulate = Qnil;
-  map_obarray (Vobarray, apropos_accum, regexp);
-  tem = Fsort (apropos_accumulate, Qstring_lessp);
-  apropos_accumulate = Qnil;
-  apropos_predicate = Qnil;
-  return tem;
-}
-
 void
 syms_of_keymap (void)
 {
   DEFSYM (Qkeymap, "keymap");
   DEFSYM (Qdescribe_map_tree, "describe-map-tree");
-  staticpro (&apropos_predicate);
-  staticpro (&apropos_accumulate);
-  apropos_predicate = Qnil;
-  apropos_accumulate = Qnil;
 
   DEFSYM (Qkeymap_canonicalize, "keymap-canonicalize");
 
@@ -3429,7 +3391,6 @@ be preferred.  */);
   defsubr (&Stext_char_description);
   defsubr (&Swhere_is_internal);
   defsubr (&Sdescribe_buffer_bindings);
-  defsubr (&Sapropos_internal);
 }
 
 void

test/lisp/subr-tests.el

@@ -597,6 +597,18 @@ See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=19350."
     (undo-boundary)
     (undo)
     (should (equal (buffer-string) ""))))
+
+;;; Apropos.
+
+(ert-deftest apropos-apropos-internal ()
+  (should (equal (apropos-internal "^next-line$") '(next-line)))
+  (should (>= (length (apropos-internal "^help")) 100))
+  (should-not (apropos-internal "^test-a-missing-symbol-foo-bar-zot$")))
+
+(ert-deftest apropos-apropos-internal/predicate ()
+  (should (equal (apropos-internal "^next-line$" #'commandp) '(next-line)))
+  (should (>= (length (apropos-internal "^help" #'commandp)) 15))
+  (should-not (apropos-internal "^next-line$" #'keymapp)))
 
 (provide 'subr-tests)
 ;;; subr-tests.el ends here

test/src/keymap-tests.el

@@ -248,19 +248,6 @@ g .. h		foo
 0 .. 3		foo
 ")))))
 
-
-;;;; apropos-internal
-
-(ert-deftest keymap-apropos-internal ()
-  (should (equal (apropos-internal "^next-line$") '(next-line)))
-  (should (>= (length (apropos-internal "^help")) 100))
-  (should-not (apropos-internal "^test-a-missing-symbol-foo-bar-zut$")))
-
-(ert-deftest keymap-apropos-internal/predicate ()
-  (should (equal (apropos-internal "^next-line$" #'commandp) '(next-line)))
-  (should (>= (length (apropos-internal "^help" #'commandp)) 15))
-  (should-not (apropos-internal "^next-line$" #'keymapp)))
-
 (provide 'keymap-tests)
 
 ;;; keymap-tests.el ends here