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Convert guile exceptions to R6RS conditions in R6RS exception handlers.

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* module/rnrs/exceptions.scm (&guile): New condition type.

  (guile-condition-converters): New variable.

  (convert-guile-condition, default-guile-condition-converter,
  set-guile-condition-converter!, guile-common-conditions,
  guile-lexical-violation-converter, guile-syntax-violation-converter,
  guile-assertion-violation-converter, guile-system-error-converter,
  guile-undefined-violation-converter, guile-error-converter,
  guile-implementation-restriction-converter): New procedures.

  (with-exception-handler): Catch all exceptions, not just R6RS
  exceptions.  Convert native Guile exceptions to R6RS conditions,
  preserving the original Guile exception information in the &guile
  condition object.

  (raise): If the condition includes a &guile condition, use 'throw' to
  throw the original native guile exception instead of raising an R6RS
  exception.

* test-suite/tests/r6rs-exceptions.test ("guile condition conversions"):
  Add tests.
This commit is contained in:
Mark H Weaver 2013-08-09 18:27:20 -04:00
parent 750ac8c592
commit 02500d4477
2 changed files with 205 additions and 17 deletions
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160
module/rnrs/exceptions.scm
View file

@ -1,6 +1,6 @@
;;; exceptions.scm --- The R6RS exceptions library
;; Copyright (C) 2010, 2011 Free Software Foundation, Inc.
;; Copyright (C) 2010, 2011, 2013 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
@ -29,14 +29,61 @@
newline
display
filter
acons
assv-ref
throw
set-exception-printer!
with-throw-handler
*unspecified*
@@))
(define raise (@@ (rnrs records procedural) r6rs-raise))
(define raise-continuable
;; When a native guile exception is caught by an R6RS exception
;; handler, we convert it to an R6RS compound condition that includes
;; not only the standard condition objects expected by R6RS code, but
;; also a special &guile condition that preserves the original KEY and
;; ARGS passed to the native Guile catch handler.
(define-condition-type &guile &condition
make-guile-condition guile-condition?
(key guile-condition-key)
(args guile-condition-args))
(define (default-guile-condition-converter key args)
(condition (make-serious-condition)
(guile-common-conditions key args)))
(define (guile-common-conditions key args)
(apply (case-lambda
((subr msg margs . _)
(condition (make-who-condition subr)
(make-message-condition msg)
(make-irritants-condition margs)))
(_ (make-irritants-condition args)))
args))
(define (convert-guile-condition key args)
(let ((converter (assv-ref guile-condition-converters key)))
(condition (or (and converter (converter key args))
(default-guile-condition-converter key args))
;; Preserve the original KEY and ARGS in the R6RS
;; condition object.
(make-guile-condition key args))))
;; If an R6RS exception handler chooses not to handle a given
;; condition, it will re-raise the condition to pass it on to the next
;; handler. If the condition was converted from a native Guile
;; exception, we must re-raise using the native Guile facilities and
;; the original exception KEY and ARGS. We arrange for this in
;; 'raise' so that native Guile exception handlers will continue to
;; work when mixed with R6RS code.
(define (raise obj)
(if (guile-condition? obj)
(apply throw (guile-condition-key obj) (guile-condition-args obj))
((@@ (rnrs records procedural) r6rs-raise) obj)))
(define raise-continuable
(@@ (rnrs records procedural) r6rs-raise-continuable))
(define raise-object-wrapper?
(@@ (rnrs records procedural) raise-object-wrapper?))
(define raise-object-wrapper-obj
@ -45,19 +92,22 @@
(@@ (rnrs records procedural) raise-object-wrapper-continuation))
(define (with-exception-handler handler thunk)
(with-throw-handler 'r6rs:exception
(with-throw-handler #t
thunk
(lambda (key . args)
(if (and (not (null? args))
(raise-object-wrapper? (car args)))
(let* ((cargs (car args))
(obj (raise-object-wrapper-obj cargs))
(continuation (raise-object-wrapper-continuation cargs))
(handler-return (handler obj)))
(if continuation
(continuation handler-return)
(raise (make-non-continuable-violation))))
*unspecified*))))
(cond ((not (eq? key 'r6rs:exception))
(let ((obj (convert-guile-condition key args)))
(handler obj)
(raise (make-non-continuable-violation))))
((and (not (null? args))
(raise-object-wrapper? (car args)))
(let* ((cargs (car args))
(obj (raise-object-wrapper-obj cargs))
(continuation (raise-object-wrapper-continuation cargs))
(handler-return (handler obj)))
(if continuation
(continuation handler-return)
(raise (make-non-continuable-violation)))))))))
(define-syntax guard0
(syntax-rules ()
@ -143,4 +193,84 @@
(set-exception-printer! 'r6rs:exception exception-printer)
)
;; Guile condition converters
;;
;; Each converter is a procedure (converter KEY ARGS) that returns
;; either an R6RS condition or #f. If #f is returned,
;; 'default-guile-condition-converter' will be used.
(define (guile-syntax-violation-converter key args)
(apply (case-lambda
((who what where form subform . extra)
(condition (make-syntax-violation form subform)
(make-who-condition who)
(make-message-condition what)))
(_ #f))
args))
(define (guile-lexical-violation-converter key args)
(condition (make-lexical-violation) (guile-common-conditions key args)))
(define (guile-assertion-violation-converter key args)
(condition (make-assertion-violation) (guile-common-conditions key args)))
(define (guile-undefined-violation-converter key args)
(condition (make-undefined-violation) (guile-common-conditions key args)))
(define (guile-implementation-restriction-converter key args)
(condition (make-implementation-restriction-violation)
(guile-common-conditions key args)))
(define (guile-error-converter key args)
(condition (make-error) (guile-common-conditions key args)))
(define (guile-system-error-converter key args)
(apply (case-lambda
((subr msg msg-args errno . rest)
;; XXX TODO we should return a more specific error
;; (usually an I/O error) as expected by R6RS programs.
;; Unfortunately this often requires the 'filename' (or
;; other?) which is not currently provided by the native
;; Guile exceptions.
(condition (make-error) (guile-common-conditions key args)))
(_ (guile-error-converter key args)))
args))
;; TODO: Arrange to have the needed information included in native
;; Guile I/O exceptions, and arrange here to convert them to the
;; proper conditions. Remove the earlier exception conversion
;; mechanism: search for 'with-throw-handler' in the 'rnrs'
;; tree, e.g. 'with-i/o-filename-conditions' and
;; 'with-i/o-port-error' in (rnrs io ports).
;; XXX TODO: How should we handle the 'misc-error', 'vm-error', and
;; 'signal' native Guile exceptions?
;; XXX TODO: Should we handle the 'quit' exception specially?
;; An alist mapping native Guile exception keys to converters.
(define guile-condition-converters
`((read-error . ,guile-lexical-violation-converter)
(syntax-error . ,guile-syntax-violation-converter)
(unbound-variable . ,guile-undefined-violation-converter)
(wrong-number-of-args . ,guile-assertion-violation-converter)
(wrong-type-arg . ,guile-assertion-violation-converter)
(keyword-argument-error . ,guile-assertion-violation-converter)
(out-of-range . ,guile-assertion-violation-converter)
(regular-expression-syntax . ,guile-assertion-violation-converter)
(program-error . ,guile-assertion-violation-converter)
(goops-error . ,guile-assertion-violation-converter)
(null-pointer-error . ,guile-assertion-violation-converter)
(system-error . ,guile-system-error-converter)
(host-not-found . ,guile-error-converter)
(getaddrinfo-error . ,guile-error-converter)
(no-data . ,guile-error-converter)
(no-recovery . ,guile-error-converter)
(try-again . ,guile-error-converter)
(stack-overflow . ,guile-implementation-restriction-converter)
(numerical-overflow . ,guile-implementation-restriction-converter)
(memory-allocation-error . ,guile-implementation-restriction-converter)))
(define (set-guile-condition-converter! key proc)
(set! guile-condition-converters
(acons key proc guile-condition-converters))))

62
test-suite/tests/r6rs-exceptions.test
View file

@ -1,6 +1,6 @@
;;; r6rs-exceptions.test --- Test suite for R6RS (rnrs exceptions)
;;; r6rs-exceptions.test --- Test suite for R6RS (rnrs exceptions) -*- scheme -*-
;; Copyright (C) 2010 Free Software Foundation, Inc.
;; Copyright (C) 2010, 2013 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
@ -20,6 +20,7 @@
(define-module (test-suite test-rnrs-exceptions)
:use-module ((rnrs conditions) :version (6))
:use-module ((rnrs exceptions) :version (6))
:use-module (system foreign)
:use-module (test-suite lib))
(with-test-prefix "with-exception-handler"
@ -96,3 +97,60 @@
(pass-if "guard with cond => syntax"
(guard (condition (condition => error?)) (raise (make-error)))))
(with-test-prefix "guile condition conversions"
(define-syntax-rule (pass-if-condition name expected-condition? body ...)
(pass-if name
(guard (obj ((expected-condition? obj) #t)
(else #f))
body ... #f)))
(pass-if "rethrown native guile exceptions"
(catch #t
(lambda ()
(guard (obj ((syntax-violation? obj) #f))
(vector-ref '#(0 1) 2)
#f))
(lambda (key . args)
(eq? key 'out-of-range))))
(pass-if-condition "syntax-error"
syntax-violation?
(eval '(let) (current-module)))
(pass-if-condition "unbound-variable"
undefined-violation?
variable-that-does-not-exist)
(pass-if-condition "out-of-range"
assertion-violation?
(vector-ref '#(0 1) 2))
(pass-if-condition "wrong-number-of-args"
assertion-violation?
((lambda () #f) 'unwanted-argument))
(pass-if-condition "wrong-type-arg"
assertion-violation?
(vector-ref '#(0 1) 'invalid-index))
(pass-if-condition "keyword-argument-error"
assertion-violation?
((lambda* (#:key a) #f) #:unwanted-keyword 'val))
(pass-if-condition "regular-expression-syntax"
assertion-violation?
(make-regexp "[missing-close-square-bracket"))
(pass-if-condition "null-pointer-error"
assertion-violation?
(dereference-pointer (make-pointer 0)))
(pass-if-condition "read-error"
lexical-violation?
(read (open-input-string "(missing-close-paren"))))
;;; Local Variables:
;;; eval: (put 'pass-if-condition 'scheme-indent-function 1)
;;; End: