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;;;; util.lisp -- some utilities
;; Copyright (C) 2022 Colin Okay
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU Affero General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;; This program 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 Affero General Public License for more details.
;; You should have received a copy of the GNU Affero General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
(in-package :oneliners.api)
(defun plist-find (indicator plist &key (test 'eq) (key 'identity))
(loop for (ind val . more) on plist by #'cddr
when (funcall test indicator (funcall key ind))
return val))
(defmacro with-plist ((&rest keys) plist &rest body)
(let ((the-plist (gensym)))
`(let ((,the-plist ,plist))
(let
,(loop for key in keys
collect `(,key (plist-find (symbol-name ',key)
,the-plist
:test #'string-equal
:key #'symbol-name)))
,@body))))
(defclass queue-buffer ()
((front :initform (list))
(back :initform (list))
(size :initform 0)
(capacity :initarg :capacity)))
(defun make-qb (capacity)
(make-instance 'queue-buffer :capacity capacity))
(defun qb-empty-p (q)
(zerop (slot-value q 'size)))
(defun qb-full-p (q)
(= (slot-value q 'size) (slot-value q 'capacity)))
(defun enqueue-qb (q x)
(when (qb-full-p q) (dequeue-qb q))
(with-slots (size back) q
(push x back)
(incf size)))
(defun dequeue-qb (q &optional default)
(with-slots (front back size) q
(cond
((plusp size)
(when (null front)
(setf front (nreverse back)
back nil))
(decf size)
(pop front))
(t default))))
(defun qb-look (q &key limit reversep)
"Get a list of the queue, but don't remove items from it. REVERSEP,
when T, Puts the newest items first."
;TODO: an inefficient but straightforward implementation, possibly improve.
(with-slots (front back) q
(let ((seq
(if reversep
(nconc (copy-seq back) (reverse front))
(nconc (copy-seq front) (reverse back)))))
(if limit
(a:subseq* seq 0 limit)
seq))))
(defun drop-last (xs &optional (howmany 1))
(reverse (nthcdr 1 (reverse xs))))
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