DataType:queue

A queue is a first-in, first-out data structure. Items Pushed are inserted at the rear, or 'tail' of the queue. Items removed, or Popped are taken from the 'front' of the queue.

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This Data Type is referenced in MQ2Collections, and accessed by Top-Level Object(s): queue

Members

Type	Member	Description
bool	IsEmpty	True if Count = 0, False otherwise.
	Push[string]	True if the item was pushed successfully.
int	Count	Number of items inserted onto the queue.
string	Peek	False is returned if IsEmpty is true.
	Pop

Examples

Sub QueueTest
    /declare q queue

    /echo 'Starting Queue Test'
    /echo 'Queue is Empty: ${q.IsEmpty}'
    
    | Push entries on the queue and pop them off.
    | Note: entries are inserted (Pushed) in and removed
    | (Popped) in the same order. That is, Pushing A, B, C, D, E
    | and then Popping them will return A, B, C, D, E.
    /echo 'Pushing items onto the Queue.'

    /if (!${q.Push[A]}) {
    	/echo 'Queue Push of A failed.'
	/endmacro
    }
    /if (!${q.Push[B]}) {
    	/echo 'Queue Push of B failed.'
	/endmacro
    }
    /if (!${q.Push[C]}) {
    	/echo 'Queue Push of C failed.'
	/endmacro
    }
    /if (!${q.Push[D]}) {
    	/echo 'Queue Push of D failed.'
	/endmacro
    }
    /if (!${q.Push[E]}) {
    	/echo 'Queue Push of E failed.'
	/endmacro
    }

    /declare count int
    /varset count ${q.Count}
    /if (${count} != 5) {
    	/echo 'Queue count is: ${count} and should be 5.'
	/endmacro
    }

    /echo 'Queue is Empty: ${q.IsEmpty}'
    
    | Peek at the front item:
    /echo 'Front item is: ${q.Peek}'
    
    | Pop items off the queue.

    /echo 'Popping item off queue: ${q.Pop}'
    /echo 'Popping item off queue: ${q.Pop}'
    /echo 'Popping item off queue: ${q.Pop}'
    /echo 'Popping item off queue: ${q.Pop}'
    /echo 'Popping item off queue: ${q.Pop}'

    /echo 'Queue is Empty: ${q.IsEmpty}'
    /echo 'Ending Queue Test'
    
    /return

Notes

• Pop decreases Count by 1 unless IsEmpty is true.
• Push increases Count by 1. IsEmpty will never be true after calling Push.
• Peek retrieves the oldest element Pushed onto the queue. Count is not modified by calling Peek.

See also

• queue

• Data Types