;;; exceptions.scm --- The R6RS exceptions library
-;; Copyright (C) 2010 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
(library (rnrs exceptions (6))
(export guard with-exception-handler raise raise-continuable)
(import (rnrs base (6))
+ (rnrs control (6))
(rnrs conditions (6))
(rnrs records procedural (6))
- (only (guile) with-throw-handler @@))
+ (rnrs records inspection (6))
+ (only (guile)
+ format
+ 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
(@@ (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 ()
- ((_ (variable cond-clause ...) body)
+ ((_ (variable cond-clause ...) . body)
(call/cc (lambda (continuation)
(with-exception-handler
(lambda (variable)
(continuation (cond cond-clause ...)))
- (lambda () body)))))))
+ (lambda () . body)))))))
(define-syntax guard
(syntax-rules (else)
- ((_ (variable cond-clause ... . ((else else-clause ...))) body)
- (guard0 (variable cond-clause ... (else else-clause ...)) body))
- ((_ (variable cond-clause ...) body)
- (guard0 (variable cond-clause ... (else (raise variable))) body))))
-)
+ ((_ (variable cond-clause ... . ((else else-clause ...))) . body)
+ (guard0 (variable cond-clause ... (else else-clause ...)) . body))
+ ((_ (variable cond-clause ...) . body)
+ (guard0 (variable cond-clause ... (else (raise variable))) . body))))
+
+ ;;; Exception printing
+
+ (define (exception-printer port key args punt)
+ (cond ((and (= 1 (length args))
+ (raise-object-wrapper? (car args)))
+ (let ((obj (raise-object-wrapper-obj (car args))))
+ (cond ((condition? obj)
+ (display "ERROR: R6RS exception:\n" port)
+ (format-condition port obj))
+ (else
+ (format port "ERROR: R6RS exception: `~s'" obj)))))
+ (else
+ (punt))))
+
+ (define (format-condition port condition)
+ (let ((components (simple-conditions condition)))
+ (if (null? components)
+ (format port "Empty condition object")
+ (let loop ((i 1) (components components))
+ (cond ((pair? components)
+ (format port " ~a. " i)
+ (format-simple-condition port (car components))
+ (when (pair? (cdr components))
+ (newline port))
+ (loop (+ i 1) (cdr components))))))))
+
+ (define (format-simple-condition port condition)
+ (define (print-rtd-fields rtd field-names)
+ (let ((n-fields (vector-length field-names)))
+ (do ((i 0 (+ i 1)))
+ ((>= i n-fields))
+ (format port " ~a: ~s"
+ (vector-ref field-names i)
+ ((record-accessor rtd i) condition))
+ (unless (= i (- n-fields 1))
+ (newline port)))))
+ (let ((condition-name (record-type-name (record-rtd condition))))
+ (let loop ((rtd (record-rtd condition))
+ (rtd.fields-list '())
+ (n-fields 0))
+ (cond (rtd
+ (let ((field-names (record-type-field-names rtd)))
+ (loop (record-type-parent rtd)
+ (cons (cons rtd field-names) rtd.fields-list)
+ (+ n-fields (vector-length field-names)))))
+ (else
+ (let ((rtd.fields-list
+ (filter (lambda (rtd.fields)
+ (not (zero? (vector-length (cdr rtd.fields)))))
+ (reverse rtd.fields-list))))
+ (case n-fields
+ ((0) (format port "~a" condition-name))
+ ((1) (format port "~a: ~s"
+ condition-name
+ ((record-accessor (caar rtd.fields-list) 0)
+ condition)))
+ (else
+ (format port "~a:\n" condition-name)
+ (let loop ((lst rtd.fields-list))
+ (when (pair? lst)
+ (let ((rtd.fields (car lst)))
+ (print-rtd-fields (car rtd.fields) (cdr rtd.fields))
+ (when (pair? (cdr lst))
+ (newline port))
+ (loop (cdr lst)))))))))))))
+
+ (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))))
HCoop / bpt / guile.git / blobdiff