49 lines
1005 B
Prolog
49 lines
1005 B
Prolog
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% definitions of queue
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empty(U-V) :-
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unify_with_occurs_check(U, V).
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push(Queue, Value, NewQueue) :-
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append_dl(Queue, [Value|X]-X, NewQueue).
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pop([X|V]-U, X, V-U) :-
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\+empty([X|V]-U).
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append_dl(X-Y, Y-Z, X-Z).
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% use of queue
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queue :-
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% create an empty queue
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empty(Q),
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format('Create queue ~w~n~n', [Q]),
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% add numbers 1 and 2
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write('Add numbers 1 and 2 : '),
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push(Q, 1, Q1),
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push(Q1, 2, Q2),
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% display queue
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format('~w~n~n', [Q2]),
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% pop element
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pop(Q2, V, Q3),
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% display results
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format('Pop : Value ~w Queue : ~w~n~n', [V, Q3]),
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% test the queue
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write('Test of the queue : '),
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( empty(Q3) -> writeln('Queue empy'); writeln('Queue not empty')), nl,
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% pop the elements
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write('Pop the queue : '),
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pop(Q3, V1, Q4),
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format('Value ~w Queue : ~w~n~n', [V1, Q4]),
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write('Pop the queue : '),
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pop(Q4, _V, _Q5).
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