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;;; -*- Mode: LISP; Syntax: ANSI-Common-Lisp; Base: 10 -*-
;; See the file LICENCE for licence information
;; The framework where everything hangs together.
(in-package :cl-store)
(defvar *store-used-packages* nil
"If non-nil will serialize each used package otherwise will
only store the package name")
(defvar *nuke-existing-packages* nil
"Whether or not to overwrite existing packages on restoration.")
(defvar *nuke-existing-classes* nil
"Do we overwrite existing class definitions on restoration.")
(defvar *store-class-superclasses* nil
"Whether or not to store the superclasses of a stored class.")
(defvar *store-class-slots* t
"Whether or not to serialize slots which are class allocated.")
(declaim (type backend *default-backend* *current-backend*))
(defvar *default-backend*)
(defvar *current-backend*)
;; conditions
;; From 0.2.3 all conditions which are signalled from
;; store or restore will signal a store-error or a
;; restore-error respectively inside a handler-bind.
(defun cl-store-report (condition stream)
(aif (caused-by condition)
(format stream "~A" it)
(apply #'format stream (format-string condition)
(format-args condition))))
(define-condition cl-store-error (error)
((caused-by :accessor caused-by :initarg :caused-by
:initform nil)
(format-string :accessor format-string :initarg :format-string
:initform "Unknown")
(format-args :accessor format-args :initarg :format-args :initform nil))
(:report cl-store-report)
(:documentation "Root cl-store condition"))
(define-condition store-error (cl-store-error)
(:documentation "Error thrown when storing an object fails."))
(define-condition restore-error (cl-store-error)
(:documentation "Error thrown when restoring an object fails."))
(defun store-error (format-string &rest args)
(error 'store-error :format-string format-string :format-args args))
(defun restore-error (format-string &rest args)
(error 'restore-error :format-string format-string :format-args args))
;; entry points
(defun store-to-file (obj place backend)
(declare (type backend backend)
(optimize speed))
(let ((element-type (stream-type backend)))
(with-open-file (s place :element-type element-type
:direction :output :if-exists :supersede)
(backend-store backend s obj))))
(defgeneric store (obj place &optional designator)
(:documentation "Store OBJ into Stream PLACE using backend BACKEND.")
(:method ((obj t) (place t) &optional (designator *default-backend*))
"Store OBJ into Stream PLACE using backend BACKEND."
(declare (optimize speed))
(let* ((backend (backend-designator->backend designator))
(*current-backend* backend)
(*read-eval* nil))
(handler-bind ((error (lambda (c)
(signal 'store-error :caused-by c))))
(backend-store backend place obj)))))
(defgeneric backend-store (backend place obj)
(:method ((backend backend) (place stream) (obj t))
"The default. Checks the streams element-type, stores the backend code
and calls store-object."
(declare (optimize speed))
(store-backend-code backend place)
(store-object obj place backend)
(:method ((backend backend) (place string) (obj t))
"Store OBJ into file designator PLACE."
(store-to-file obj place backend))
(:method ((backend backend) (place pathname) (obj t))
"Store OBJ into file designator PLACE."
(store-to-file obj place backend))
(:documentation "Method wrapped by store, override this method for
custom behaviour (see circularities.lisp)."))
(defgeneric store-backend-code (backend stream)
(:method ((backend backend) (stream t))
(declare (optimize speed))
(when-let (magic (magic-number backend))
(store-32-bit magic stream)))
"Store magic-number of BACKEND, when present, into STREAM."))
(defun store-object (obj stream &optional (backend *current-backend*))
"Store OBJ into STREAM. Not meant to be overridden,
use backend-store-object instead"
(backend-store-object backend obj stream))
(defgeneric backend-store-object (backend obj stream)
"Wrapped by store-object, override this to do custom storing
(see circularities.lisp for an example).")
(:method ((backend backend) (obj t) (stream t))
"The default, just calls internal-store-object."
(declare (optimize speed))
(internal-store-object backend obj stream)))
(defgeneric internal-store-object (backend obj place)
(:documentation "Method which is specialized by defstore-? macros.")
(:method ((backend backend) (obj t) (place t))
"If call falls back here then OBJ cannot be serialized with BACKEND."
(store-error "Cannot store objects of type ~A with backend ~(~A~)."
(type-of obj) (name backend))))
;; restoration
(defgeneric restore (place &optional backend)
"Restore and object FROM PLACE using BACKEND. Not meant to be
overridden, use backend-restore instead")
(:method (place &optional (designator *default-backend*))
"Entry point for restoring objects (setfable)."
(declare (optimize speed))
(let* ((backend (backend-designator->backend designator))
(*current-backend* backend)
(*read-eval* nil))
(handler-bind ((error (lambda (c)
(signal 'restore-error :caused-by c))))
(backend-restore backend place)))))
(defgeneric backend-restore (backend place)
(:documentation "Wrapped by restore. Override this to do custom restoration")
(:method ((backend backend) (place stream))
"Restore the object found in stream PLACE using backend BACKEND.
Checks the magic-number and invokes backend-restore-object"
(declare (optimize speed))
(check-magic-number backend place)
(backend-restore-object backend place))
(:method ((backend backend) (place string))
"Restore the object found in file designator PLACE using backend BACKEND."
(restore-from-file place backend))
(:method ((backend backend) (place pathname))
"Restore the object found in file designator PLACE using backend BACKEND."
(restore-from-file place backend)))
(defun restore-from-file (place backend)
(declare (optimize speed))
(let ((element-type (stream-type backend)))
(with-open-file (s place :element-type element-type :direction :input)
(backend-restore backend s))))
(defun (setf restore) (new-val place &optional (backend *default-backend*))
(store new-val place backend))
(defgeneric check-magic-number (backend stream)
(:method ((backend backend) (stream t))
(let ((magic-number (magic-number backend)))
(declare (type (or null ub32) magic-number))
(when magic-number
(let ((val (read-32-bit stream nil)))
(declare (type ub32 val))
(cond ((= val magic-number) nil)
((member val (compatible-magic-numbers backend))
((member val (old-magic-numbers backend))
(restore-error "Stream contains an object stored with an ~
incompatible version of backend ~A." (name backend)))
(t (restore-error "Stream does not contain a stored object~
for backend ~A."
(name backend))))))))
"Check to see if STREAM actually contains a stored object for BACKEND."))
(defun lookup-reader (val readers)
(gethash val readers))
(defgeneric get-next-reader (backend place)
"Method which must be specialized for BACKEND to return
the next function to restore an object from PLACE.
If no reader is found return a second value which will be included
in the error.")
(:method ((backend backend) (place t))
(declare (ignore place))
"The default, throw an error."
(restore-error "get-next-reader must be specialized for backend ~(~A~)."
(name backend))))
;; Wrapper for backend-restore-object so we don't have to pass
;; a backend object around all the time
(eval-when (:compile-toplevel :load-toplevel :execute)
(defun restore-object (place &optional (backend *current-backend*))
"Restore the object in PLACE using BACKEND"
(backend-restore-object backend place)))
(defgeneric backend-restore-object (backend place)
"Find the next function to call with BACKEND and invoke it with PLACE.")
(:method ((backend backend) (place t))
"The default"
(internal-restore-object backend (get-next-reader backend place) place)))
(defgeneric internal-restore-object (backend type place))
;; EOF
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