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;; This file is part of eris-cl.
;; Copyright (C) 2022 Piotr Szarmański
;; eris-cl is free software: you can redistribute it and/or modify it under the
;; terms of the GNU Lesser General Public License as published by the Free
;; Software Foundation, either version 3 of the License, or (at your option) any
;; later version.
;; eris-cl 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
;; eris-cl. If not, see <https://www.gnu.org/licenses/>.
(in-package :eris)
(defclass file-backend (encoding-backend decoding-backend)
((directory :initarg :directory :type (or string pathname)
:documentation
"Directory containing ERIS data.")))
(define-condition file-backend-error (error)
())
(define-condition directory-error (file-backend-error)
((message :type string :initarg :message))
(:report (lambda (condition stream)
(format stream "~a" (slot-value condition 'message)))))
(defmethod shared-initialize :after ((file-backend file-backend) slot-names
&rest initargs
&key (directory nil directory-p)
&allow-other-keys)
(declare (ignore initargs slot-names))
(when (or (null directory-p) (null (pathname-directory directory)))
(error 'directory-error :message "Incorrectly specified directory."))
(with-slots (directory output-function fetch-function) file-backend
(when (or (pathname-name directory)))
(setf fetch-function
(lambda (reference)
(let* ((base32 (bytes-to-base32-unpadded reference))
(file (merge-pathnames directory base32)))
(if (probe-file file)
(alexandria:read-file-into-byte-vector file)
(error 'missing-block :reference reference))))
output-function
(lambda (block reference)
(let* ((base32 (bytes-to-base32-unpadded reference))
(file (merge-pathnames directory base32)))
(unless (probe-file file)
(alexandria:write-byte-vector-into-file block file)))
block))))
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