shithub: femtolisp

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made cons hashing tail recursive on cdrs
plus one more test

--- a/femtolisp/equal.c

+++ b/femtolisp/equal.c

@@ -308,21 +308,24 @@

         return h;

     case TAG_CONS:

-        if (bound <= 0) {

-            *oob = 1;

-            return 1;

-        }

-        h = bounded_hash(car_(a), bound/2, oob);

-        // bounds balancing: try to share the bounds efficiently

-        // between the car and cdr so we can hash better when a list is

-        // car-shallow and cdr-deep (a common case) or vice-versa.

-        if (*oob)

-            bound/=2;

-        else

-            bound--;

-        h = MIX(h, bounded_hash(cdr_(a), bound, &oob2)+2);

-        // recursive OOB propagation. otherwise this case is slow:

-        // (hash '#2=('#0=(#1=(#1#) . #0#) . #2#))

+        do {

+            if (bound <= 0) {

+                *oob = 1;

+                return h;

+            }

+            h = MIX(h, bounded_hash(car_(a), bound/2, &oob2));

+            // bounds balancing: try to share the bounds efficiently

+            // so we can hash better when a list is cdr-deep (a common case)

+            if (oob2)

+                bound/=2;

+            else

+                bound--;

+            // recursive OOB propagation. otherwise this case is slow:

+            // (hash '#2=((#0=(#1=(#1#) . #0#)) . #2#))

+            *oob = *oob || oob2;

+            a = cdr_(a);

+        } while (iscons(a));

+        h = MIX(h, bounded_hash(a, bound-1, &oob2)+2);

         *oob = *oob || oob2;

         return h;

     }

--- a/femtolisp/unittest.lsp

+++ b/femtolisp/unittest.lsp

@@ -131,6 +131,14 @@

 	      (hash '#1=((1 . #1#) (2 . #1#) . #1#)))))

 (assert (equal?

+	 (hash '(#0=(#0#) 0))

+	 (hash '(#1=(((((#1#))))) 0))))

+

+(assert (not (equal?

+	      (hash '(#0=(#0#) 0))

+	      (hash '(#1=(((((#1#))))) 1)))))

+

+(assert (equal?

 	 (hash #0=[1 [2 [#0#]] 3])

 	 (hash #1=[1 [2 [[1 [2 [#1#]] 3]]] 3])))