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Common Lisp implementation running on the JVM
;;; restart.lisp
;;;
;;; Copyright (C) 2003-2005 Peter Graves
;;; $Id$
;;;
;;; This program 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 2
;;; 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 General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with this program; if not, write to the Free Software
;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
;;;
;;; As a special exception, the copyright holders of this library give you
;;; permission to link this library with independent modules to produce an
;;; executable, regardless of the license terms of these independent
;;; modules, and to copy and distribute the resulting executable under
;;; terms of your choice, provided that you also meet, for each linked
;;; independent module, the terms and conditions of the license of that
;;; module. An independent module is a module which is not derived from
;;; or based on this library. If you modify this library, you may extend
;;; this exception to your version of the library, but you are not
;;; obligated to do so. If you do not wish to do so, delete this
;;; exception statement from your version.
;;; Adapted from CMUCL/SBCL.
(in-package #:system)
(defun read-evaluated-form ()
(fresh-line *query-io*)
(%format *query-io* "Enter a form to be evaluated:~%")
(list (eval (read *query-io*))))
(defvar *restart-clusters* ())
(defvar *condition-restarts* ())
(defstruct restart
name
function
report-function
interactive-function
(test-function #'(lambda (c) (declare (ignore c)) t)))
(defmacro restart-bind (bindings &body forms)
`(let ((*restart-clusters*
(cons (list
,@(mapcar #'(lambda (binding)
`(make-restart
:name ',(car binding)
:function ,(cadr binding)
,@(cddr binding)))
bindings))
*restart-clusters*)))
,@forms))
(defun compute-restarts (&optional condition)
(let ((associated ())
(other ()))
(dolist (alist *condition-restarts*)
(if (eq (car alist) condition)
(setq associated (cdr alist))
(setq other (append (cdr alist) other))))
(let ((res ()))
(dolist (restart-cluster *restart-clusters*)
(dolist (restart restart-cluster)
(when (and (or (not condition)
(member restart associated)
(not (member restart other)))
(funcall (restart-test-function restart) condition))
(push restart res))))
(nreverse res))))
(defun restart-report (restart stream)
(funcall (or (restart-report-function restart)
(let ((name (restart-name restart)))
(lambda (stream)
(if name (%format stream "~S" name)
(%format stream "~S" restart)))))
stream))
(defun print-restart (restart stream)
(if *print-escape*
(print-unreadable-object (restart stream :type t :identity t)
(prin1 (restart-name restart) stream))
(restart-report restart stream)))
(defun find-restart (name &optional condition)
(let ((restarts (compute-restarts condition)))
(dolist (restart restarts)
(when (or (eq restart name) (eq (restart-name restart) name))
(return-from find-restart restart)))))
(defun find-restart-or-control-error (identifier &optional condition)
(or (find-restart identifier condition)
(error 'control-error
:format-control "Restart ~S is not active."
:format-arguments (list identifier))))
(defun invoke-restart (restart &rest values)
(let ((real-restart (find-restart-or-control-error restart)))
(apply (restart-function real-restart) values)))
(defun interactive-restart-arguments (real-restart)
(let ((interactive-function (restart-interactive-function real-restart)))
(if interactive-function
(funcall interactive-function)
'())))
(defun invoke-restart-interactively (restart)
(let* ((real-restart (find-restart-or-control-error restart))
(args (interactive-restart-arguments real-restart)))
(apply (restart-function real-restart) args)))
(defun parse-keyword-pairs (list keys)
(do ((l list (cddr l))
(k '() (list* (cadr l) (car l) k)))
((or (null l) (not (member (car l) keys)))
(values (nreverse k) l))))
(defmacro with-keyword-pairs ((names expression &optional keywords-var) &body forms)
(let ((temp (member '&rest names)))
(unless (= (length temp) 2)
(error "&REST keyword is ~:[missing~;misplaced~]." temp))
(let ((key-vars (ldiff names temp))
(key-var (or keywords-var (gensym)))
(rest-var (cadr temp)))
(let ((keywords (mapcar #'(lambda (x) (intern (string x) (find-package "KEYWORD")))
key-vars)))
`(multiple-value-bind (,key-var ,rest-var)
(parse-keyword-pairs ,expression ',keywords)
(let ,(mapcar #'(lambda (var keyword) `(,var (getf ,key-var ,keyword)))
key-vars keywords)
,@forms))))))
(defun transform-keywords (&key report interactive test)
(let ((result ()))
(when report
(setf result (list* (if (stringp report)
`#'(lambda (stream)
(write-string ,report stream))
`#',report)
:report-function
result)))
(when interactive
(setf result (list* `#',interactive
:interactive-function
result)))
(when test
(setf result (list* `#',test :test-function result)))
(nreverse result)))
;; "If the restartable-form is a list whose car is any of the symbols SIGNAL,
;; ERROR, CERROR, or WARN (or is a macro form which macroexpands into such a
;; list), then WITH-CONDITION-RESTARTS is used implicitly to associate the
;; indicated restarts with the condition to be signaled."
(defun munge-restart-case-expression (expression env)
(let ((exp (macroexpand expression env)))
(if (consp exp)
(let* ((name (car exp))
(args (if (eq name 'cerror) (cddr exp) (cdr exp))))
(if (member name '(SIGNAL ERROR CERROR WARN))
(let ((n-cond (gensym)))
`(let ((,n-cond (coerce-to-condition ,(first args)
(list ,@(rest args))
',(case name
(WARN 'simple-warning)
(SIGNAL 'simple-condition)
(t 'simple-error))
',name)))
(with-condition-restarts
,n-cond
(car *restart-clusters*)
,(if (eq name 'cerror)
`(cerror ,(second exp) ,n-cond)
`(,name ,n-cond)))))
expression))
expression)))
(defmacro restart-case (expression &body clauses &environment env)
(let ((block-tag (gensym))
(temp-var (gensym))
(data
(mapcar #'(lambda (clause)
(with-keyword-pairs ((report interactive test
&rest forms)
(cddr clause))
(list (car clause)
(gensym)
(transform-keywords :report report
:interactive interactive
:test test)
(cadr clause)
forms)))
clauses)))
`(block ,block-tag
(let ((,temp-var nil))
(tagbody
(restart-bind
,(mapcar #'(lambda (datum)
(let ((name (nth 0 datum))
(tag (nth 1 datum))
(keys (nth 2 datum)))
`(,name #'(lambda (&rest temp)
(setq ,temp-var temp)
(go ,tag))
,@keys)))
data)
(return-from ,block-tag
,(munge-restart-case-expression expression env)))
,@(mapcan #'(lambda (datum)
(let ((tag (nth 1 datum))
(bvl (nth 3 datum))
(body (nth 4 datum)))
(list tag
`(return-from ,block-tag
(apply #'(lambda ,bvl ,@body)
,temp-var)))))
data))))))
(defmacro with-simple-restart ((restart-name format-string
&rest format-arguments)
&body forms)
`(restart-case (progn ,@forms)
(,restart-name ()
:report (lambda (stream)
(simple-format stream ,format-string ,@format-arguments))
(values nil t))))
(defmacro with-condition-restarts (condition-form restarts-form &body body)
(let ((n-cond (gensym)))
`(let ((*condition-restarts*
(cons (let ((,n-cond ,condition-form))
(cons ,n-cond
(append ,restarts-form
(cdr (assoc ,n-cond *condition-restarts*)))))
*condition-restarts*)))
,@body)))
(defun abort (&optional condition)
(invoke-restart (find-restart-or-control-error 'abort condition))
(error 'control-error
:format-control "ABORT restart failed to transfer control dynamically."))
(defun muffle-warning (&optional condition)
(invoke-restart (find-restart-or-control-error 'muffle-warning condition)))
(defun continue (&optional condition)
(let ((restart (find-restart 'continue condition)))
(when restart
(invoke-restart restart))))
(defun store-value (value &optional condition)
(let ((restart (find-restart 'store-value condition)))
(when restart
(invoke-restart restart value))))
(defun use-value (value &optional condition)
(let ((restart (find-restart 'use-value condition)))
(when restart
(invoke-restart restart value))))
(defun warn (datum &rest arguments)
(let ((condition (coerce-to-condition datum arguments 'simple-warning 'warn)))
(require-type condition 'warning)
(restart-case (signal condition)
(muffle-warning ()
:report "Skip warning."
(return-from warn nil)))
(let ((badness (etypecase condition
(style-warning 'style-warning)
(warning 'warning))))
(fresh-line *error-output*)
(simple-format *error-output* "~S: ~A~%" badness condition)))
nil)
(defun style-warn (format-control &rest format-arguments)
(warn 'style-warning
:format-control format-control
:format-arguments format-arguments))
(defun cerror (continue-string datum &rest arguments)
(with-simple-restart (continue "~A" (apply #'simple-format nil continue-string arguments))
(let ((condition (coerce-to-condition datum arguments 'simple-error 'error)))
(with-condition-restarts condition (list (find-restart 'continue))
(signal condition)
(invoke-debugger condition))))
nil)
(defun query-function ()
(format *query-io* "~&Enter a form to be evaluated: ")
(force-output *query-io*)
(multiple-value-list (eval (read *query-io*))))
(defun undefined-function-called (name arguments)
(finish-output)
(loop
(restart-case
(error 'undefined-function :name name)
(continue ()
:report "Try again.")
(use-value (value)
:report "Specify a function to call instead."
:interactive query-function
(return-from undefined-function-called
(apply value arguments)))
(return-value (&rest values)
:report (lambda (stream)
(format stream "Return one or more values from the call to ~S." name))
:interactive query-function
(return-from undefined-function-called
(values-list values))))
(when (fboundp name)
(return (apply name arguments)))))