| 1 | ;;; -*- Mode: Lisp -*-
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| 2 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 3 | ;;;
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| 4 | ;;; Copyright (C) 1999, 2002, 2009, 2015 Marek Rychlik <rychlik@u.arizona.edu>
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| 5 | ;;;
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| 6 | ;;; This program is free software; you can redistribute it and/or modify
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| 7 | ;;; it under the terms of the GNU General Public License as published by
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| 8 | ;;; the Free Software Foundation; either version 2 of the License, or
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| 9 | ;;; (at your option) any later version.
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| 10 | ;;;
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| 11 | ;;; This program is distributed in the hope that it will be useful,
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| 12 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | ;;; GNU General Public License for more details.
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| 15 | ;;;
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| 16 | ;;; You should have received a copy of the GNU General Public License
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| 17 | ;;; along with this program; if not, write to the Free Software
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| 18 | ;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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| 19 | ;;;
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| 20 | ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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| 21 |
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| 22 | (defpackage "PRIORITY-QUEUE"
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| 23 | (:use :cl :heap)
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| 24 | (:export "PRIORITY-QUEUE"
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| 25 | "ENQUEUE"
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| 26 | "DEQUEUE"
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| 27 | "QUEUE-EMPTY-P"
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| 28 | "QUEUE-SIZE"
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| 29 | )
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| 30 | (:documentation "Implements a priority queue."))
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| 31 |
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| 32 | (in-package :priority-queue)
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| 33 |
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| 34 | (defclass priority-queue ()
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| 35 | ((heap :initarg :heap :reader priority-queue-heap)
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| 36 | (test :initarg :test :reader priority-queue-test))
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| 37 | (:documentation "Representa a priority queue based on heaps.
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| 38 | Slots HEAP and TEST are read-only after they are initialized."))
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| 39 |
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| 40 | (defmethod initialize-instance :after ((self priority-queue)
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| 41 | &key
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| 42 | (element-type 'fixnum)
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| 43 | (test #'<=)
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| 44 | (element-key #'identity))
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| 45 | (with-slots (heap (test-x test))
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| 46 | self
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| 47 | (setf heap (make-heap :element-type element-type)
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| 48 | test-x #'(lambda (x y) (funcall test (funcall element-key y) (funcall element-key x))))))
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| 49 |
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| 50 | (defgeneric enqueue (self item)
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| 51 | (:method ((self priority-queue) (item t))
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| 52 | (with-slots (heap test)
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| 53 | self
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| 54 | (heap-insert heap item test))
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| 55 | self))
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| 56 |
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| 57 | (defgeneric dequeue (self)
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| 58 | (:method ((self priority-queue))
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| 59 | (with-slots (heap test)
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| 60 | self
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| 61 | (heap-remove heap test))))
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| 62 |
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| 63 | (defgeneric queue-empty-p (self)
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| 64 | (:method ((self priority-queue))
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| 65 | (with-slots (heap)
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| 66 | self
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| 67 | (heap-empty-p heap))))
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| 68 |
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| 69 | (defgeneric queue-size (self)
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| 70 | (:method ((self priority-queue))
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| 71 | (with-slots (heap)
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| 72 | self
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| 73 | (heap-size heap))))
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