Functional Queues

Denys Duchier

module

x-oz://system/adt/Queue.ozf

This module provides a functional implemention of queues

Exports

The modules exports the following constructors:

{Queue.new ?Q}

returns a new functional queue instance Q, currently empty

{Queue.newFromList +L ?Q}

returns a new functional queue instance Q, initialized with the elements of list L

Instance API

Each functional queue instance Q has the following features:

{Q.get ?V}

returns the next value V available from Q, or raises exception empty if none

{Q.put +V}

enters a new value V into the queue

{Q.getPut ?Old +New}

atomically, gets the next value Old available from Q and enters the value New. If Q was empty, New is Old and Q is still empty

{Q.top ?V}

returns the next value V available from Q without actually removing it from Q

{Q.toList ?L}

returns the list L of all values in Q

{Q.toListKill ?L}

returns the list L of all values in Q and makes Q unusable until a subsequent {Q.reset}. This is more efficient that {Q.toList ?L} because no copy is required

{Q.isEmpty ?B}

returns true iff Q is empty

{Q.reset}

discards Q's content and resets it to an empty queue

{Q.clone ?Q2}

returns a new functional queue instance Q2 which is a clone of Q