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;;; Error handling in the REPL
;; Copyright (C) 2001, 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
;; This library 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.
;;
;; This library 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
;; Lesser General Public License for more details.
;;
;; You should have received a copy of the GNU Lesser General Public
;; License along with this library; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
;; 02110-1301 USA
;;; Code:
(define-module (system repl error-handling)
#:use-module (system base pmatch)
#:use-module (system vm trap-state)
#:use-module (system repl debug)
#:use-module (ice-9 format)
#:export (call-with-error-handling
with-error-handling))
;;;
;;; Error handling via repl debugging
;;;
(define (error-string stack key args)
(call-with-output-string
(lambda (port)
(let ((frame (and (< 0 (vector-length stack)) (vector-ref stack 0))))
(print-exception port frame key args)))))
(define* (call-with-error-handling thunk #:key
(on-error 'debug) (post-error 'catch)
(pass-keys '(quit)) (trap-handler 'debug)
(report-keys '(stack-overflow out-of-memory)))
(let ((in (current-input-port))
(out (current-output-port))
(err (current-error-port)))
(define (with-saved-ports thunk)
(with-input-from-port in
(lambda ()
(with-output-to-port out
(lambda ()
(with-error-to-port err
thunk))))))
(define (debug-trap-handler frame trap-idx trap-name)
(let* ((tag (and (pair? (fluid-ref %stacks))
(cdr (fluid-ref %stacks))))
(stack (narrow-stack->vector
(make-stack frame)
;; Take the stack from the given frame, cutting 0
;; frames.
0
;; Narrow the end of the stack to the most recent
;; start-stack.
tag
;; And one more frame, because %start-stack
;; invoking the start-stack thunk has its own frame
;; too.
0 (and tag 1)))
(error-msg (if trap-idx
(format #f "Trap ~d: ~a" trap-idx trap-name)
trap-name))
(debug (make-debug stack 0 error-msg)))
(with-saved-ports
(lambda ()
(if trap-idx
(begin
(format #t "~a~%" error-msg)
(format #t "Entering a new prompt. ")
(format #t "Type `,bt' for a backtrace or `,q' to continue.\n")))
((@ (system repl repl) start-repl) #:debug debug)))))
(define (null-trap-handler frame trap-idx trap-name)
#t)
(define le-trap-handler
(case trap-handler
((debug) debug-trap-handler)
((pass) null-trap-handler)
((disabled) #f)
(else (error "Unknown trap-handler strategy" trap-handler))))
(define (report-error key args)
(with-saved-ports
(lambda ()
(run-hook before-error-hook)
(print-exception err #f key args)
(run-hook after-error-hook)
(force-output err))))
(catch #t
(lambda ()
(with-default-trap-handler le-trap-handler
(lambda () (%start-stack #t thunk))))
(case post-error
((report)
(lambda (key . args)
(if (memq key pass-keys)
(apply throw key args)
(begin
(report-error key args)
(if #f #f)))))
((catch)
(lambda (key . args)
(when (memq key pass-keys)
(apply throw key args))
(when (memq key report-keys)
(report-error key args))
(if #f #f)))
(else
(if (procedure? post-error)
(lambda (k . args)
(apply (if (memq k pass-keys) throw post-error) k args))
(error "Unknown post-error strategy" post-error))))
(case on-error
((debug)
(lambda (key . args)
(if (not (memq key pass-keys))
(let* ((tag (and (pair? (fluid-ref %stacks))
(cdr (fluid-ref %stacks))))
(stack (narrow-stack->vector
(make-stack #t)
;; Cut three frames from the top of the stack:
;; make-stack, this one, and the throw handler.
3
;; Narrow the end of the stack to the most recent
;; start-stack.
tag
;; And one more frame, because %start-stack invoking
;; the start-stack thunk has its own frame too.
0 (and tag 1)))
(error-msg (error-string stack key args))
(debug (make-debug stack 0 error-msg)))
(with-saved-ports
(lambda ()
(format #t "~a~%" error-msg)
(format #t "Entering a new prompt. ")
(format #t "Type `,bt' for a backtrace or `,q' to continue.\n")
((@ (system repl repl) start-repl) #:debug debug)))))))
((report)
(lambda (key . args)
(unless (memq key pass-keys)
(report-error key args))
(if #f #f)))
((backtrace)
(lambda (key . args)
(if (not (memq key pass-keys))
(let* ((tag (and (pair? (fluid-ref %stacks))
(cdr (fluid-ref %stacks))))
(frames (narrow-stack->vector
(make-stack #t)
;; Narrow as above, for the debugging case.
3 tag 0 (and tag 1))))
(with-saved-ports (lambda () (print-frames frames)))
(report-error key args)
(if #f #f)))))
((pass)
(lambda (key . args)
;; fall through to rethrow
#t))
(else
(if (procedure? on-error)
(lambda (k . args)
(apply (if (memq k pass-keys) throw on-error) k args))
(error "Unknown on-error strategy" on-error)))))))
(define-syntax-rule (with-error-handling form)
(call-with-error-handling (lambda () form)))
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