Simplify cl-get using `plist-member'

* lisp/emacs-lisp/cl-extra.el (cl-get, cl-getf, cl--set-getf): Use
`plist-member' instead of explicit loop.
* test/lisp/emacs-lisp/cl-extra-tests.el: New tests.

lisp/emacs-lisp/cl-extra.el

@@ -593,13 +593,7 @@ too large if positive or too small if negative)."
 \n(fn SYMBOL PROPNAME &optional DEFAULT)"
   (declare (compiler-macro cl--compiler-macro-get)
            (gv-setter (lambda (store) (ignore def) `(put ,sym ,tag ,store))))
-  (or (get sym tag)
-      (and def
-           ;; Make sure `def' is really absent as opposed to set to nil.
-	   (let ((plist (symbol-plist sym)))
-	     (while (and plist (not (eq (car plist) tag)))
-	       (setq plist (cdr (cdr plist))))
-	     (if plist (car (cdr plist)) def)))))
+  (cl-getf (symbol-plist sym) tag def))
 (autoload 'cl--compiler-macro-get "cl-macs")
 
 ;;;###autoload
@@ -618,26 +612,20 @@ PROPLIST is a list of the sort returned by `symbol-plist'.
 				  ,(funcall setter
 					    `(cl--set-getf ,getter ,k ,val))
 				  ,val)))))))))
-  (setplist '--cl-getf-symbol-- plist)
-  (or (get '--cl-getf-symbol-- tag)
-      ;; Originally we called cl-get here,
-      ;; but that fails, because cl-get has a compiler macro
-      ;; definition that uses getf!
-      (when def
-        ;; Make sure `def' is really absent as opposed to set to nil.
-	(while (and plist (not (eq (car plist) tag)))
-	  (setq plist (cdr (cdr plist))))
-	(if plist (car (cdr plist)) def))))
+  (let ((val-tail (cdr-safe (plist-member plist tag))))
+    (if val-tail (car val-tail) def)))
 
 ;;;###autoload
 (defun cl--set-getf (plist tag val)
-  (let ((p plist))
-    (while (and p (not (eq (car p) tag))) (setq p (cdr (cdr p))))
-    (if p (progn (setcar (cdr p) val) plist) (cl-list* tag val plist))))
+  (let ((val-tail (cdr-safe (plist-member plist tag))))
+    (if val-tail (progn (setcar val-tail val) plist)
+      (cl-list* tag val plist))))
 
 ;;;###autoload
 (defun cl--do-remf (plist tag)
   (let ((p (cdr plist)))
+    ;; Can't use `plist-member' here because it goes to the cons-cell
+    ;; of TAG and we need the one before.
     (while (and (cdr p) (not (eq (car (cdr p)) tag))) (setq p (cdr (cdr p))))
     (and (cdr p) (progn (setcdr p (cdr (cdr (cdr p)))) t))))
 

test/lisp/emacs-lisp/cl-extra-tests.el

@@ -0,0 +1,38 @@
+;;; cl-extra-tests.el --- tests for emacs-lisp/cl-extra.el  -*- lexical-binding:t -*-
+
+;; Copyright (C) 2013-2017 Free Software Foundation, Inc.
+
+;; This file is part of GNU Emacs.
+
+;; This program is free software: you can redistribute it and/or
+;; modify it under the terms of the GNU General Public License as
+;; published by the Free Software Foundation, either version 3 of the
+;; License, or (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful, but
+;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see `http://www.gnu.org/licenses/'.
+
+;;; Code:
+
+(require 'cl-lib)
+(require 'ert)
+
+(ert-deftest cl-get ()
+  (put 'cl-get-test 'x 1)
+  (put 'cl-get-test 'y nil)
+  (should (eq (cl-get 'cl-get-test 'x) 1))
+  (should (eq (cl-get 'cl-get-test 'y :none) nil))
+  (should (eq (cl-get 'cl-get-test 'z :none) :none)))
+
+(ert-deftest cl-getf ()
+  (let ((plist '(x 1 y nil)))
+    (should (eq (cl-getf plist 'x) 1))
+    (should (eq (cl-getf plist 'y :none) nil))
+    (should (eq (cl-getf plist 'z :none) :none))))
+
+;;; cl-extra-tests.el ends here