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75 lines
1.3 KiB
Plaintext
75 lines
1.3 KiB
Plaintext
unit queue;
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interface
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type
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fixed_string = String[20];
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link = ^node;
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node = record
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data : fixed_string;
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next : link;
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prev : link
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end;
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queue_obj = record
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alement : link;
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zlement : link;
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end;
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procedure enqueue(q : queue_obj; v: fixed_string);
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function dequeue(q : queue_obj) : fixed_string;
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function is_empty(q : queue_obj) : Boolean;
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function init_queue: queue_obj;
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implementation
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procedure enqueue(q : queue_obj; v: fixed_string);
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var
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t : link;
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begin
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t := GetMem(SizeOf(node));
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t^.data := v;
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t^.prev := q.zlement^.prev;
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t^.prev^.next := t;
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q.zlement^.prev := t;
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t^.next := q.zlement;
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end;
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function dequeue(q : queue_obj): fixed_string;
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var
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t: link;
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begin
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if is_empty(q) = false then
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begin
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t := q.alement^.next;
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dequeue := t^.data;
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q.alement^.next := t^.next;
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FreeMem(t);
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end;
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end;
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function is_empty(q : queue_obj): Boolean;
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begin
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if q.zlement^.prev = q.alement then
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is_empty := true
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else
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is_empty := false;
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if q.alement^.next = q.zlement then
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is_empty := true;
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end;
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function init_queue: queue_obj;
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var
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q : queue_obj;
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begin
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q.alement := GetMem(SizeOf(node));
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q.zlement := GetMem(SizeOf(node));
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q.alement^.next := q.zlement;
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q.alement^.prev := q.alement;
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q.zlement^.next := q.zlement;
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q.zlement^.prev := q.alement;
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init_queue := q;
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end;
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begin
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{ Main Body }
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end. |