Data commit

Task/Queue-Usage/Prolog/queue-usage.pro

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