Hi there.
I have the following problem and I don't know the best
way to solve it. I have a gigantic, ground Prolog term.
In this term there are some subterms of the form
f(..., ..., ..., N)
where N is a (small) integer. The computation consists
of three phases:
1) a traversal of the original gigantic term;
2) a second traversal which copies the original term
into a new term that is equal to the original apart
from the fact that some of the integers (N) have been
replaced by some other integers;
3) a traversal of the new, modified term.
What happens is that:
a) the copy of point (2) is too expensive;
b) the original term is no longer needed after point (2);
c) there is no backtracking involved.
The obvious solution would be to avoid the copy in point (2)
and replace it with a destructive update of the few integers
that need to be changed. I have read the documentation of
setarg/3 and nb_setarg/3, and none seems to do what I want:
setarg/3 does trailing, which I don't want;
nb_setarg(+Arg, +Term, +Value) has the problem that
"[if] Term is not atomic [which is my case], it is
duplicated using duplicate_term/2", and this duplication
is precisely what I want to avoid.
Am I missing something?
Note that I am very willing to destructively modify the
term using C/C++ code (actually, this would be even better
for me). And portability is not an issue.
Thanks a lot for any hint,
Roberto
--
Prof. Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/mailto:
bagnara@...
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