Modify SUBST to:

* use satisfies-test-p to check if tree items satisfy the test
* return the same (sub)tree if no substitution has been done. Implementation
  dependent test is changed accordingly.

diff --git a/src/list.lisp b/src/list.lisp
index f7e15ec..d0ec517 100644 (file)
--- a/src/list.lisp
+++ b/src/list.lisp
@@ -114,14 +114,17 @@
     (s tree)))
 
 (defun subst (new old tree &key key (test #'eql testp) (test-not #'eql test-not-p))
-  (when (and testp test-not-p)
-    (error "Both test and test-not are set"))
   (labels ((s (x)
-             (let ((key-val (if key (funcall key x) x)))
-               (cond
-                 ((funcall (if test-not-p test-not test) key-val old) new)
-                 ((atom x) x)
-                 (t (cons (s (car x)) (s (cdr x))))))))
+             (cond ((satisfies-test-p old x :key key :test test :testp testp
+                                      :test-not test-not :test-not-p test-not-p)
+                    new)
+                   ((atom x) x)
+                   (t (let ((a (s (car x)))
+                            (b (s (cdr x))))
+                        (if (and (eq a (car x))
+                                 (eq b (cdr x)))
+                            x
+                            (cons a b)))))))
     (s tree)))
 
 (defun copy-list (x)

diff --git a/tests/list.lisp b/tests/list.lisp
index 77b93c6..7ce643e 100644 (file)
--- a/tests/list.lisp
+++ b/tests/list.lisp
@@ -97,7 +97,7 @@
 (let ((tree1 '(1 (1 2) (1 2 3) (1 2 3 4))))
   (test (equal (subst "two" 2 tree1) '(1 (1 "two") (1 "two" 3) (1 "two" 3 4))))
   (test (equal (subst "five" 5 tree1) '(1 (1 2) (1 2 3) (1 2 3 4))))
-  (test (not (eq tree1 (subst "five" 5 tree1)))) ; Implementation dependent
+  (test (eq tree1 (subst "five" 5 tree1))) ; Implementation dependent
   (test (equal tree1 '(1 (1 2) (1 2 3) (1 2 3 4)))))
 (test (equal (subst 'tempest 'hurricane
                     '(shakespeare wrote (the hurricane)))