2006-07-27 20:04:56 +01:00
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% A library to implement queues of DB Terms
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2006-07-16 02:41:07 +01:00
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:- module(dbqueue, [
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db_enqueue/2,
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db_dequeue/2,
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db_clean_queue/1
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]).
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:- unhide('$init_db_queue').
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:- unhide('$db_enqueue').
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:- unhide('$db_dequeue').
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db_enqueue(Name,El) :- var(Name),
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throw(error(instantiation_error(Name),db_enqueue(Name,El))).
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db_enqueue(Name,El) :- \+ atom(Name), !,
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throw(error(type_error_atom(Name),db_enqueue(Name,El))).
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db_enqueue(Name,El) :-
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recorded('$db_queue',[Name|Ref],_), !,
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prolog:'$db_enqueue'(Ref, El).
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db_enqueue(Name,El) :-
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prolog:'$init_db_queue'(Ref),
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recorda('$db_queue',[Name|Ref],_),
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prolog:'$db_enqueue'(Ref,El).
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db_dequeue(Name,El) :- var(Name),
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throw(error(instantiation_error(Name),db_dequeue(Name,El))).
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db_dequeue(Name,El) :- \+ atom(Name), !,
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throw(error(type_error_atom(Name),db_dequeue(Name,El))).
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db_dequeue(Name,El) :-
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recorded('$db_queue',[Name|Ref],R),
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( prolog:'$db_dequeue'(Ref, El) ->
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true
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;
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erase(R),
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fail
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).
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db_clean_queue(Name) :-
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recorded('$db_queue',[Name|Ref],R), !,
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erase(R),
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db_dequeue_all(Ref).
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db_clean_queue(_).
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db_dequeue_all(Ref) :-
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( prolog:'$db_dequeue'(Ref, _) -> db_dequeue_all(Ref) ; true ).
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