Spaces:
Sleeping
Sleeping
File size: 12,200 Bytes
f65fe85 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 |
;;; exceptions.scm --- The R6RS exceptions library
;; 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
;; 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
(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))
(rnrs records inspection (6))
(only (guile)
format
newline
display
filter
acons
assv-ref
throw
set-exception-printer!
with-throw-handler
*unspecified*
@@))
;; 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-obj))
(define raise-object-wrapper-continuation
(@@ (rnrs records procedural) raise-object-wrapper-continuation))
(define (with-exception-handler handler thunk)
(with-throw-handler #t
thunk
(lambda (key . args)
(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)
(call/cc (lambda (continuation)
(with-exception-handler
(lambda (variable)
(continuation (cond cond-clause ...)))
(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))))
;;; 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))))
|