Priority Queue Glossary

#Q-UNDERFLOW ( -- x )

The throw number that priority queues throw on underflow, i.e. if you try to fetch a value from an empty priority queue.

#Q-OVERFLOW ( -- x )

The throw number that priority queues throw on overflow, i.e. if you try to append or store a value to a priority queue that has reached its capacity.

Priority-Queue: ( maxsize <name> -- )

Define a new priority queue named <name> with the capacity maxsize. When later <name> is executed it leaves its address on the data stack.

q! ( key val q -- )

Store an item consisting of the priority key and the value val into the the priority queue q using the priority to determine its position. If the priority queue has reached its capacity, then throw a #Q-OVERFLOW exception.

q. ( q -- )

Display a text representation of the priority queue q. Useful for debugging.

q@ ( q -- key val )

Retrieve the first item - priority key and value val -- from the priority queue q. If the queue is empty, throw a #Q-UNDERFLOW exception.

q-append ( key val q -- )

Append an item consisting of the priority key and the value val to the end of the priority queue q, regardless of the priority value. If the priority queue has reached its capacity, then throw a #Q-OVERFLOW exception.

q-clear ( q -- )

Remove all items from the priority queue q.

q-drop ( q -- )

Remove the first item from the priority queue q. If the queue is empty, throw a #Q-UNDERFLOW exception.

q-empty? ( q -- f )

Return true if the priority queue q is empty, false otherwise.

q-full? ( q -- f )

Return true if the priority queue q is completely filled up, false otherwise.

q-size ( q -- u )

Get the number of items u actually in the priority queue q.