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yap-6.3/packages/meld/meldi.yap

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:- module(meld_interpreter,
[
live/0,
delete/1,
push/1,
first/2,
min/3,
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max/3,
minval/3,
maxval/3
]).
:- use_module(meldp,
[
run/1
]).
:- use_module(library(nb),
[
nb_queue/1,
nb_queue_enqueue/2,
nb_queue_dequeue/2
]).
:- initialization
init_meld_queue.
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:- dynamic speculative_delete/3.
live :-
repeat,
( pop(Goal) ->
format('-~w~n',[Goal]),
run(Goal),
fail
;
!,
done
).
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done :-
speculative_delete(_, _, _), !,
push_residuals,
live.
done :-
current_predicate(meld_program:P),
P \= run/1,
% P \= neighbor/2,
% P \= root/1,
listing(meld_program:P),
fail.
done.
delete(Fact) :-
nb_getval(meld_queue, Queue),
retract(meld_program:Fact),
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nb_queue_enqueue(Queue, deleted(Fact)),
live.
pop(Goal) :-
nb_getval(meld_queue, Queue),
nb_queue_dequeue(Queue, Goal).
push(Goal) :-
clause(meld_program:Goal,_,Ref),
!,
increase_reference_count(Ref),
fail.
push(Goal) :-
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format('+~w~n',[Goal]),
nb_getval(meld_queue, Queue), !,
assert(meld_program:Goal),
nb_queue_enqueue(Queue, Goal).
% create a queue
init_meld_queue :-
nb_queue(Queue),
nb_setval(meld_queue, Queue).
first(Skel,Goal) :-
meld_program:Skel, !,
cache(Goal).
first(_,Goal) :-
cache(Goal),
push(Goal).
max(Skel,Arg,Goal) :-
meld_program:Skel,
arg(Arg, Skel, A0),
arg(Arg, Goal, AN),
AN =< A0, !,
delete(Skel),
cache(Goal).
max(Skel,_,Goal) :-
clean(Skel),
cache(Goal),
push(Goal).
min(Skel,Arg,Goal) :-
meld_program:Skel,
arg(Arg, Skel, A0),
arg(Arg, Goal, AN),
AN >= A0, !,
delete(Skel),
cache(Goal).
min(Skel,_,Goal) :-
clean(Skel),
cache(Goal),
push(Goal).
clean(Skel) :-
% format('D~w~n',[Skel]),
retractall(meld_program:Skel).
cache(Goal) :-
clause(meld_cache:Goal,_,Ref),
!,
increase_reference_count(Ref).
cache(Goal) :-
assert(meld_cache:Goal).
deleted(Goal) :-
clause(meld_program:Goal,_,Ref),
decrease_reference_count(Ref),
!,
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force_delete(Goal, Ref),
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complete_delete(Goal).
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deleted(Goal) :-
retract(speculative_delete(Goal, Ref, Count)), !,
NCount is Count-1,
(
NCount > 0
->
assert(speculative_delete(Goal, Ref, Count))
;
true
).
deleted(Goal) :-
% format('-~w~n',[Goal]),
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complete_delete(Goal).
complete_delete(Goal) :-
nb_getval(meld_queue, Queue), !,
retract(meld_program:Goal),
nb_queue_enqueue(Queue, deleted(Goal)).
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force_delete(Goal, Ref) :-
current_reference_count(Ref, Count),
assert(speculative_delete(Goal, Ref, Count)).
push_residuals :-
retract(speculative_delete(Goal, _, _)),
push(Goal),
fail.
push_residuals.
%
% first, cleanup cache
%
delete_from_first(_,Goal) :-
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clause(meld_program:Goal,_,Ref), !,
(
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decrease_reference_count(Ref)
->
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true
;
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force_delete(Goal, Ref)
),
erase(Ref),
retract(meld_cache:Goal),
retract(meld_program:Goal),
push(deleted(Goal)),
once(meld_cache:VGoal),
push(VGoal).
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delete_from_first(Goal) :-
retract(speculative_delete(Goal, Ref, Count)), !,
NCount is Count-1,
(
NCount > 0
->
assert(speculative_delete(Goal, Ref, Count))
;
true
).
delete_from_first(Goal) :-
retract(meld_cache:Goal),
push(deleted(Goal)).
delete_from_max(VGoal,Arg,Goal) :-
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clause(meld_program:Goal,_,Ref), !,
(
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decrease_reference_count(Ref)
->
true
;
force_delete(Goal, Ref)
),
erase(Ref),
retract(meld_cache:Goal),
push(deleted(Goal)),
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new_max(VGoal, Arg).
delete_from_max(Goal) :-
retract(speculative_delete(Goal, Ref, Count)), !,
NCount is Count-1,
(
NCount > 0
->
assert(speculative_delete(Goal, Ref, Count))
;
true
).
delete_from_max(Goal) :-
retract(meld_cache:Goal),
push(deleted(Goal)).
new_max(VGoal,Arg) :-
arg(Arg, VGoal, A),
maxval(A, meld_cache:VGoal, VGoal),
push(VGoal).
delete_from_min(VGoal,Arg,Goal) :-
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clause(meld_program:Goal,_,Ref), !,
(
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decrease_reference_count(Ref)
->
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true
;
force_delete(Goal, Ref)
),
erase(Ref),
retract(meld_cache:Goal),
push(deleted(Goal)),
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new_min(VGoal, Arg).
delete_from_min(Goal) :- !,
retract(speculative_delete(Goal, Ref, Count)),
NCount is Count-1,
(
NCount > 0
->
assert(speculative_delete(Goal, Ref, Count))
;
true
).
delete_from_min(Goal) :-
retract(meld_cache:Goal),
push(deleted(Goal)).
new_min(VGoal,Arg) :-
arg(Arg, VGoal, A),
minval(A, meld_cache:VGoal, VGoal),
push(VGoal).
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:- meta_predicate minval(+,:,-), maxval(+,:,-).
maxval(V,G,GMax) :-
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Memory = f(-inf,[]),
(
call(G),
arg(1, Memory, V0),
V > V0,
nb_setarg(1, Memory, V),
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nb_setarg(2, Memory, V.GMax),
fail
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;
arg(2, Memory, V.GMax)
).
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minval(V,G,GMin) :-
Memory = f(+inf,[]),
(
call(G),
arg(1, Memory, V0),
V < V0,
nb_setarg(1, Memory, V),
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nb_setarg(2, Memory, V.GMin),
fail
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;
arg(2, Memory, V.GMin)
).