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an implementation of queues in the DB.

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git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1674 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
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vsc 2006-07-16 01:41:07 +00:00
parent 3af669d7d2
commit 24b78dbf8b
1 changed files with 46 additions and 0 deletions
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46
library/dbqueues.yap Normal file
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:- module(dbqueue, [
db_enqueue/2,
db_dequeue/2,
db_clean_queue/1
]).
:- unhide('$init_db_queue').
:- unhide('$db_enqueue').
:- unhide('$db_dequeue').
db_enqueue(Name,El) :- var(Name),
throw(error(instantiation_error(Name),db_enqueue(Name,El))).
db_enqueue(Name,El) :- \+ atom(Name), !,
throw(error(type_error_atom(Name),db_enqueue(Name,El))).
db_enqueue(Name,El) :-
recorded('$db_queue',[Name|Ref],_), !,
prolog:'$db_enqueue'(Ref, El).
db_enqueue(Name,El) :-
prolog:'$init_db_queue'(Ref),
recorda('$db_queue',[Name|Ref],_),
prolog:'$db_enqueue'(Ref,El).
db_dequeue(Name,El) :- var(Name),
throw(error(instantiation_error(Name),db_dequeue(Name,El))).
db_dequeue(Name,El) :- \+ atom(Name), !,
throw(error(type_error_atom(Name),db_dequeue(Name,El))).
db_dequeue(Name,El) :-
recorded('$db_queue',[Name|Ref],R),
( prolog:'$db_dequeue'(Ref, El) ->
true
;
erase(R),
fail
).
db_clean_queue(Name) :-
recorded('$db_queue',[Name|Ref],R), !,
erase(R),
db_dequeue_all(Ref).
db_clean_queue(_).
db_dequeue_all(Ref) :-
( prolog:'$db_dequeue'(Ref, _) -> db_dequeue_all(Ref) ; true ).