RosettaCodeData/Task/Queue-Definition/Elena/queue-definition.elena

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import extensions;
class queue<T>
{
T[] theArray;
int theTop;
int theTale;
constructor()
{
theArray := new T[](8);
theTop := 0;
theTale := 0;
}
bool empty()
= theTop == theTale;
push(T object)
{
if (theTale > theArray.Length)
{
theArray := theArray.reallocate(theTale)
};
theArray[theTale] := object;
theTale += 1
}
T pop()
{
if (theTale == theTop)
{ InvalidOperationException.new("Queue is empty").raise() };
T item := theArray[theTop];
theTop += 1;
^ item
}
}
public program()
{
queue<int> q := new queue<int>();
q.push(1);
q.push(2);
q.push(3);
console.printLine(q.pop());
console.printLine(q.pop());
console.printLine(q.pop());
console.printLine("a queue is ", q.empty().iif("empty","not empty"));
console.print("Trying to pop:");
try
{
q.pop()
}
catch(Exception e)
{
console.printLine(e.Message)
}
}