3f36d054f6
On a simple benchmark of:
(let ([N 100000]
[M 20]
[q (make-queue)])
(time (for ([i (in-range M)])
(for ([i (in-range (* i N))]) (enqueue! q i))
(unless (for/and ([i (in-range (* i N))]) (list i (dequeue! q)))
(error "poof")))))
I get these timings:
original version: cpu time: 24438 real time: 24439 gc time: 8164
single-links: cpu time: 17848 real time: 17849 gc time: 4859
this version: cpu time: 6519 real time: 6519 gc time: 3032
In addition, cleaned up the documentation a little, and mention the fact
that it is not thread safe.
64 lines
1.4 KiB
Racket
64 lines
1.4 KiB
Racket
#lang scribble/manual
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@(require scribble/eval "utils.rkt" (for-label racket unstable/queue))
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@(define qeval (eval/require 'unstable/queue))
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@title{Imperative Queues}
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@defmodule[unstable/queue]
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@unstable[@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-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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@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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