Han-Wen Nienhuys <[EMAIL PROTECTED]> writes:
>> I think the right fix is to change the weak hashtable marking
>> algorithm to properly cope with circular references like this. I will
>> try this and then come back to you.
>
> Interesting. How would you go about doing that?
The marking would would rougly look like this (some special cases are
not considered, like improper alists):
mark OBJ:
if mark of OBJ is set:
return
set mark of OBJ
if OBJ is a weak vector
put it on POSTPONED_OBJECTS
else
mark references of OBJ
gc:
POSTPONED_OBJECTS = '()
mark all root references
while POSTPONED_OBJECTS not empty
OBJS = POSTPONED_OBJECTS
POSTPONED_OBJECTS = '()
mark_weak_vector all OBJS
sweep
mark_weak_vector OBJ:
for all elements ELT of OBJ:
for all pairs P on list ELT:
if P is marked, break
ITEM = car of P
if ITEM is a pair:
if (OBJ has weak keys and car of ITEM is unmarked)
or (OBJ has weak values and cdr of ITEM is unmarked)
remove P from ELT
else:
mark ITEM (recursively)
set mark of P
The non-trivial stuff is to integrate this properly with the abstract
hashtables (but I have basically done this already as well).
--
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