+SCM
+Prob::equal_p (SCM sa, SCM sb)
+{
+ /* This comparison function is only designed to make the copy
+ constructor preserve equality.
+
+ Perhaps it would be better to use a more strict definition of
+ equality; e.g., that two probs are equal iff they can be
+ distinguished by calls to ly:prob-property.
+ */
+ Prob *probs[2] = {Prob::unsmob (sa), Prob::unsmob (sb)};
+ SCM props[2][2];
+ int i;
+
+ for (i = 0; i < 2; i++)
+ {
+ props[i][0] = probs[i]->immutable_property_alist_;
+ props[i][1] = probs[i]->mutable_property_alist_;
+ }
+
+ if (strcmp (probs[0]->class_name (), probs[1]->class_name ()))
+ return SCM_BOOL_F;
+
+ /* Compare mutable and immutable lists, element by element. */
+ for (i = 0; i < 2; i++)
+ {
+ SCM aprop = props[0][i];
+ SCM bprop = props[1][i];
+
+ for (;
+ scm_is_pair (aprop) && scm_is_pair (bprop);
+ aprop = scm_cdr (aprop), bprop = scm_cdr (bprop))
+ {
+ SCM aval = scm_cdar (aprop);
+ SCM bval = scm_cdar (bprop);
+ if (scm_caar (aprop) != scm_caar (bprop)
+ || (!(Input::is_smob (aval) && Input::is_smob (bval))
+ &&
+ !to_boolean (scm_equal_p (aval, bval))))
+ return SCM_BOOL_F;
+ }
+
+ /* is one list shorter? */
+ if (aprop != SCM_EOL || bprop != SCM_EOL)
+ return SCM_BOOL_F;
+ }
+
+ return SCM_BOOL_T;
+}