97 lines
2.2 KiB
Racket
97 lines
2.2 KiB
Racket
#lang scribble/manual
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@(require scribble/eval (for-label racket data/queue))
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@(define qeval (make-base-eval))
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@(qeval '(require data/queue))
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@title{Imperative Queues}
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@defmodule[data/queue]
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@author[@author+email["Carl Eastlund" "cce@racket-lang.org"]]
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This module provides a simple mutable queue representation,
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first-in/first-out only. Operations on queues mutate it in a
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thread-unsafe way.
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@defproc[(make-queue) queue/c]{
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Produces an empty queue.
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}
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@defproc[(enqueue! [q queue/c] [v any/c]) void?]{
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Adds an element to the back of a queue.
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}
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@defproc[(dequeue! [q nonempty-queue/c]) any/c]{
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Removes an element from the front of a nonempty queue, and returns that
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element.
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@defexamples[#:eval qeval
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(define q (make-queue))
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(enqueue! q 1)
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(dequeue! q)
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(enqueue! q 2)
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(enqueue! q 3)
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(dequeue! q)
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(dequeue! q)]
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}
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@defproc[(queue->list [queue queue/c]) (listof any/c)]{
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Returns an immutable list containing the elements of the queue
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in the order the elements were added.
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@defexamples[#:eval qeval
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(define queue (make-queue))
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(enqueue! queue 8)
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(enqueue! queue 9)
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(enqueue! queue 0)
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(queue->list queue)]
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}
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@defproc[(queue-length [queue queue/c]) integer?]{
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Returns the number of elements in the queue.
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@defexamples[#:eval qeval
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(define queue (make-queue))
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(queue-length queue)
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(enqueue! queue 5)
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(enqueue! queue 12)
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(queue-length queue)
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(dequeue! queue)
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(queue-length queue)]
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}
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@defproc[(queue-empty? [q queue/c]) boolean?]{
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Recognizes whether a queue is empty or not.
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@defexamples[#:eval qeval
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(define q (make-queue))
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(queue-empty? q)
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(enqueue! q 1)
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(queue-empty? q)
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(dequeue! q)
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(queue-empty? q)]
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}
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@defproc[(queue? [v any/c]) boolean?]{
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This predicate recognizes queues.
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@defexamples[#:eval qeval
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(queue? (make-queue))
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(queue? 'not-a-queue)]
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}
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@defproc[(in-queue [queue queue?])
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sequence?]{
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Returns a sequence whose elements are the elements of
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@racket[queue].
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}
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@deftogether[(
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@defthing[queue/c flat-contract?]
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@defthing[nonempty-queue/c flat-contract?]
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)]{
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These contracts recognize queues; the latter requires the queue to
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contain at least one value.
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}
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