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| -rw-r--r-- | Makefile.am | 1 | ||||
| -rw-r--r-- | chickadee/queue.scm | 65 |
2 files changed, 66 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am index f185849..6b52cb7 100644 --- a/Makefile.am +++ b/Makefile.am @@ -43,6 +43,7 @@ SOURCES = \ chickadee/utils.scm \ chickadee/heap.scm \ chickadee/array-list.scm \ + chickadee/queue.scm \ chickadee/audio.scm \ chickadee/input/controller.scm \ chickadee/input/keyboard.scm \ diff --git a/chickadee/queue.scm b/chickadee/queue.scm new file mode 100644 index 0000000..158ac74 --- /dev/null +++ b/chickadee/queue.scm @@ -0,0 +1,65 @@ +;;; Chickadee Game Toolkit +;;; Copyright © 2017 David Thompson <davet@gnu.org> +;;; +;;; Chickadee is free software: you can redistribute it and/or modify +;;; it under the terms of the GNU General Public License as published +;;; by the Free Software Foundation, either version 3 of the License, +;;; or (at your option) any later version. +;;; +;;; Chickadee is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +;;; General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with this program. If not, see +;;; <http://www.gnu.org/licenses/>. + +(define-module (chickadee queue) + #:use-module (ice-9 format) + #:use-module (srfi srfi-9) + #:use-module (srfi srfi-9 gnu) + #:use-module (chickadee array-list) + #:export (make-queue + queue? + queue-empty? + enqueue! + dequeue!)) + +(define-record-type <queue> + (%make-queue input output) + queue? + (input queue-input) + (output queue-output)) + +(define (display-queue q port) + (format port "#<queue length: ~d>" + (+ (array-list-size (queue-input q)) + (array-list-size (queue-output q))))) + +(set-record-type-printer! <queue> display-queue) + +(define (make-queue) + "Return a new, empty queue." + (%make-queue (make-array-list) (make-array-list))) + +(define (queue-empty? q) + "Return #t if Q is empty." + (and (array-list-empty? (queue-input q)) + (array-list-empty? (queue-output q)))) + +(define (enqueue! q item) + "Add ITEM to Q." + (array-list-push! (queue-input q) item)) + +(define (dequeue! q) + "Remove the first element of Q." + (and (not (queue-empty? q)) + (let ((input (queue-input q)) + (output (queue-output q))) + (when (array-list-empty? output) + (let loop () + (unless (array-list-empty? input) + (array-list-push! output (array-list-pop! input)) + (loop)))) + (array-list-pop! output)))) |