module/rnrs/io/ports.scm

   1 ;;;; ports.scm --- R6RS port API                    -*- coding: utf-8 -*-
   2
   3 ;;;;    Copyright (C) 2009, 2010, 2011 Free Software Foundation, Inc.
   4 ;;;;
   5 ;;;; This library is free software; you can redistribute it and/or
   6 ;;;; modify it under the terms of the GNU Lesser General Public
   7 ;;;; License as published by the Free Software Foundation; either
   8 ;;;; version 3 of the License, or (at your option) any later version.
   9 ;;;;
  10 ;;;; This library is distributed in the hope that it will be useful,
  11 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 ;;;; Lesser General Public License for more details.
  14 ;;;;
  15 ;;;; You should have received a copy of the GNU Lesser General Public
  16 ;;;; License along with this library; if not, write to the Free Software
  17 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18
  19 ;;; Author: Ludovic Courtès <ludo@gnu.org>
  20
  21 ;;; Commentary:
  22 ;;;
  23 ;;; The I/O port API of the R6RS is provided by this module.  In many areas
  24 ;;; it complements or refines Guile's own historical port API.  For instance,
  25 ;;; it allows for binary I/O with bytevectors.
  26 ;;;
  27 ;;; Code:
  28
  29 (library (rnrs io ports (6))
  30   (export eof-object eof-object?
  31
  32           ;; auxiliary types
  33           file-options buffer-mode buffer-mode?
  34           eol-style native-eol-style error-handling-mode
  35           make-transcoder transcoder-codec transcoder-eol-style
  36           transcoder-error-handling-mode native-transcoder
  37           latin-1-codec utf-8-codec utf-16-codec
  38
  39           ;; input & output ports
  40           port? input-port? output-port?
  41           port-eof?
  42           port-transcoder binary-port? textual-port? transcoded-port
  43           port-position set-port-position!
  44           port-has-port-position? port-has-set-port-position!?
  45           call-with-port close-port
  46
  47           ;; input ports
  48           open-bytevector-input-port
  49           open-string-input-port
  50           open-file-input-port
  51           make-custom-binary-input-port
  52
  53           ;; binary input
  54           get-u8 lookahead-u8
  55           get-bytevector-n get-bytevector-n!
  56           get-bytevector-some get-bytevector-all
  57
  58           ;; output ports
  59           open-bytevector-output-port
  60           open-string-output-port
  61           open-file-output-port
  62           make-custom-binary-output-port
  63           call-with-bytevector-output-port
  64           call-with-string-output-port
  65           make-custom-textual-output-port
  66           flush-output-port
  67
  68           ;; binary output
  69           put-u8 put-bytevector
  70
  71           ;; textual input
  72           get-char get-datum get-line get-string-all get-string-n get-string-n!
  73           lookahead-char
  74
  75           ;; textual output
  76           put-char put-datum put-string
  77
  78           ;; standard ports
  79           standard-input-port standard-output-port standard-error-port
  80           current-input-port current-output-port current-error-port
  81
  82           ;; condition types
  83           &i/o i/o-error? make-i/o-error
  84           &i/o-read i/o-read-error? make-i/o-read-error
  85           &i/o-write i/o-write-error? make-i/o-write-error
  86           &i/o-invalid-position i/o-invalid-position-error?
  87           make-i/o-invalid-position-error
  88           &i/o-filename i/o-filename-error? make-i/o-filename-error
  89           i/o-error-filename
  90           &i/o-file-protection i/o-file-protection-error?
  91           make-i/o-file-protection-error
  92           &i/o-file-is-read-only i/o-file-is-read-only-error?
  93           make-i/o-file-is-read-only-error
  94           &i/o-file-already-exists i/o-file-already-exists-error?
  95           make-i/o-file-already-exists-error
  96           &i/o-file-does-not-exist i/o-file-does-not-exist-error?
  97           make-i/o-file-does-not-exist-error
  98           &i/o-port i/o-port-error? make-i/o-port-error
  99           i/o-error-port
 100           &i/o-decoding-error i/o-decoding-error?
 101           make-i/o-decoding-error
 102           &i/o-encoding-error i/o-encoding-error?
 103           make-i/o-encoding-error i/o-encoding-error-char)
 104   (import (ice-9 binary-ports)
 105           (only (rnrs base) assertion-violation)
 106           (rnrs enums)
 107           (rnrs records syntactic)
 108           (rnrs exceptions)
 109           (rnrs conditions)
 110           (rnrs files) ;for the condition types
 111           (srfi srfi-8)
 112           (ice-9 rdelim)
 113           (except (guile) raise display)
 114           (prefix (only (guile) display)
 115                   guile:))
 116
 117
 118 \f
 119 ;;;
 120 ;;; Auxiliary types
 121 ;;;
 122
 123 (define-enumeration file-option
 124   (no-create no-fail no-truncate)
 125   file-options)
 126
 127 (define-enumeration buffer-mode
 128   (none line block)
 129   buffer-modes)
 130
 131 (define (buffer-mode? symbol)
 132   (enum-set-member? symbol (enum-set-universe (buffer-modes))))
 133
 134 (define-enumeration eol-style
 135   (lf cr crlf nel crnel ls none)
 136   eol-styles)
 137
 138 (define (native-eol-style)
 139   (eol-style none))
 140
 141 (define-enumeration error-handling-mode
 142   (ignore raise replace)
 143   error-handling-modes)
 144
 145 (define-record-type (transcoder %make-transcoder transcoder?)
 146   (fields codec eol-style error-handling-mode))
 147
 148 (define* (make-transcoder codec
 149                           #:optional
 150                           (eol-style (native-eol-style))
 151                           (handling-mode (error-handling-mode replace)))
 152   (%make-transcoder codec eol-style handling-mode))
 153
 154 (define (native-transcoder)
 155   (make-transcoder (or (fluid-ref %default-port-encoding)
 156                        (latin-1-codec))))
 157
 158 (define (latin-1-codec)
 159   "ISO-8859-1")
 160
 161 (define (utf-8-codec)
 162   "UTF-8")
 163
 164 (define (utf-16-codec)
 165   "UTF-16")
 166
 167 \f
 168 ;;;
 169 ;;; Internal helpers
 170 ;;;
 171
 172 (define (with-i/o-filename-conditions filename thunk)
 173   (with-throw-handler 'system-error
 174       thunk
 175     (lambda args
 176       (let ((errno (system-error-errno args)))
 177         (let ((construct-condition
 178                (cond ((= errno EACCES)
 179                       make-i/o-file-protection-error)
 180                      ((= errno EEXIST)
 181                       make-i/o-file-already-exists-error)
 182                      ((= errno ENOENT)
 183                       make-i/o-file-does-not-exist-error)
 184                      ((= errno EROFS)
 185                       make-i/o-file-is-read-only-error)
 186                      (else
 187                       make-i/o-filename-error))))
 188           (raise (construct-condition filename)))))))
 189
 190 (define (with-i/o-port-error port make-primary-condition thunk)
 191   (with-throw-handler 'system-error
 192       thunk
 193     (lambda args
 194       (let ((errno (system-error-errno args)))
 195         (if (memv errno (list EIO EFBIG ENOSPC EPIPE))
 196             (raise (condition (make-primary-condition)
 197                               (make-i/o-port-error port)))
 198             (apply throw args))))))
 199
 200 (define-syntax with-textual-output-conditions
 201   (syntax-rules ()
 202     ((_ port body0 body ...)
 203      (with-i/o-port-error port make-i/o-write-error
 204        (lambda () (with-i/o-encoding-error body0 body ...))))))
 205
 206 (define-syntax with-textual-input-conditions
 207   (syntax-rules ()
 208     ((_ port body0 body ...)
 209      (with-i/o-port-error port make-i/o-read-error
 210        (lambda () (with-i/o-decoding-error body0 body ...))))))
 211
 212 \f
 213 ;;;
 214 ;;; Input and output ports.
 215 ;;;
 216
 217 (define (port-transcoder port)
 218   "Return the transcoder object associated with @var{port}, or @code{#f}
 219 if the port has no transcoder."
 220   (cond ((port-encoding port)
 221          => (lambda (encoding)
 222               (make-transcoder
 223                encoding
 224                (native-eol-style)
 225                (case (port-conversion-strategy port)
 226                  ((error) 'raise)
 227                  ((substitute) 'replace)
 228                  (else
 229                   (assertion-violation 'port-transcoder
 230                                        "unsupported error handling mode"))))))
 231         (else
 232          #f)))
 233
 234 (define (binary-port? port)
 235   "Returns @code{#t} if @var{port} does not have an associated encoding,
 236 @code{#f} otherwise."
 237   (not (port-encoding port)))
 238
 239 (define (textual-port? port)
 240   "Always returns @code{#t}, as all ports can be used for textual I/O in
 241 Guile."
 242   #t)
 243
 244 (define (port-eof? port)
 245   (eof-object? (if (binary-port? port)
 246                    (lookahead-u8 port)
 247                    (lookahead-char port))))
 248
 249 (define (transcoded-port port transcoder)
 250   "Return a new textual port based on @var{port}, using
 251 @var{transcoder} to encode and decode data written to or
 252 read from its underlying binary port @var{port}."
 253   ;; Hackily get at %make-transcoded-port.
 254   (let ((result ((@@ (ice-9 binary-ports) %make-transcoded-port) port)))
 255     (set-port-encoding! result (transcoder-codec transcoder))
 256     (case (transcoder-error-handling-mode transcoder)
 257       ((raise)
 258        (set-port-conversion-strategy! result 'error))
 259       ((replace)
 260        (set-port-conversion-strategy! result 'substitute))
 261       (else
 262        (error "unsupported error handling mode"
 263               (transcoder-error-handling-mode transcoder))))
 264     result))
 265
 266 (define (port-position port)
 267   "Return the offset (an integer) indicating where the next octet will be
 268 read from/written to in @var{port}."
 269
 270   ;; FIXME: We should raise an `&assertion' error when not supported.
 271   (seek port 0 SEEK_CUR))
 272
 273 (define (set-port-position! port offset)
 274   "Set the position where the next octet will be read from/written to
 275 @var{port}."
 276
 277   ;; FIXME: We should raise an `&assertion' error when not supported.
 278   (seek port offset SEEK_SET))
 279
 280 (define (port-has-port-position? port)
 281   "Return @code{#t} is @var{port} supports @code{port-position}."
 282   (and (false-if-exception (port-position port)) #t))
 283
 284 (define (port-has-set-port-position!? port)
 285   "Return @code{#t} is @var{port} supports @code{set-port-position!}."
 286   (and (false-if-exception (set-port-position! port (port-position port)))
 287        #t))
 288
 289 (define (call-with-port port proc)
 290   "Call @var{proc}, passing it @var{port} and closing @var{port} upon exit of
 291 @var{proc}.  Return the return values of @var{proc}."
 292   (call-with-values
 293       (lambda () (proc port))
 294     (lambda vals
 295       (close-port port)
 296       (apply values vals))))
 297
 298 (define* (call-with-bytevector-output-port proc #:optional (transcoder #f))
 299   (receive (port extract) (open-bytevector-output-port transcoder)
 300     (call-with-port port proc)
 301     (extract)))
 302
 303 (define (open-string-input-port str)
 304   "Open an input port that will read from @var{str}."
 305   (with-fluids ((%default-port-encoding "UTF-8"))
 306     (open-input-string str)))
 307
 308 (define* (open-file-input-port filename
 309                                #:optional
 310                                (file-options (file-options))
 311                                (buffer-mode (buffer-mode block))
 312                                maybe-transcoder)
 313   (let ((port (with-i/o-filename-conditions filename
 314                 (lambda ()
 315                   (with-fluids ((%default-port-encoding #f))
 316                     (open filename O_RDONLY))))))
 317     (cond (maybe-transcoder
 318            (set-port-encoding! port (transcoder-codec maybe-transcoder))))
 319     port))
 320
 321 (define (open-string-output-port)
 322   "Return two values: an output port that will collect characters written to it
 323 as a string, and a thunk to retrieve the characters associated with that port."
 324   (let ((port (with-fluids ((%default-port-encoding "UTF-8"))
 325                 (open-output-string))))
 326     (values port
 327             (lambda () (get-output-string port)))))
 328
 329 (define* (open-file-output-port filename
 330                                 #:optional
 331                                 (file-options (file-options))
 332                                 (buffer-mode (buffer-mode block))
 333                                 maybe-transcoder)
 334   (let* ((flags (logior O_WRONLY
 335                         (if (enum-set-member? 'no-create file-options)
 336                             0
 337                             O_CREAT)
 338                         (if (enum-set-member? 'no-truncate file-options)
 339                             0
 340                             O_TRUNC)
 341                         (if (enum-set-member? 'no-fail file-options)
 342                             0
 343                             O_EXCL)))
 344          (port (with-i/o-filename-conditions filename
 345                  (lambda ()
 346                    (with-fluids ((%default-port-encoding #f))
 347                      (open filename flags))))))
 348     (cond (maybe-transcoder
 349            (set-port-encoding! port (transcoder-codec maybe-transcoder))))
 350     port))
 351
 352 (define (call-with-string-output-port proc)
 353   "Call @var{proc}, passing it a string output port. When @var{proc} returns,
 354 return the characters accumulated in that port."
 355   (let ((port (open-output-string)))
 356     (proc port)
 357     (get-output-string port)))
 358
 359 (define (make-custom-textual-output-port id
 360                                          write!
 361                                          get-position
 362                                          set-position!
 363                                          close)
 364   (make-soft-port (vector (lambda (c) (write! (string c) 0 1))
 365                           (lambda (s) (write! s 0 (string-length s)))
 366                           #f ;flush
 367                           #f ;read character
 368                           close)
 369                   "w"))
 370
 371 (define (flush-output-port port)
 372   (force-output port))
 373
 374 \f
 375 ;;;
 376 ;;; Textual output.
 377 ;;;
 378
 379 (define-condition-type &i/o-encoding &i/o-port
 380   make-i/o-encoding-error i/o-encoding-error?
 381   (char i/o-encoding-error-char))
 382
 383 (define-syntax with-i/o-encoding-error
 384   (syntax-rules ()
 385     "Convert Guile throws to `encoding-error' to `&i/o-encoding-error'."
 386     ((_ body ...)
 387      ;; XXX: This is heavyweight for small functions like `put-char'.
 388      (with-throw-handler 'encoding-error
 389        (lambda ()
 390          (begin body ...))
 391        (lambda (key subr message errno port chr)
 392          (raise (make-i/o-encoding-error port chr)))))))
 393
 394 (define (put-char port char)
 395   (with-textual-output-conditions port (write-char char port)))
 396
 397 (define (put-datum port datum)
 398   (with-textual-output-conditions port (write datum port)))
 399
 400 (define* (put-string port s #:optional start count)
 401   (with-textual-output-conditions port
 402    (cond ((not (string? s))
 403           (assertion-violation 'put-string "expected string" s))
 404          ((and start count)
 405           (display (substring/shared s start (+ start count)) port))
 406          (start
 407           (display (substring/shared s start (string-length s)) port))
 408          (else
 409           (display s port)))))
 410
 411 ;; Defined here to be able to make use of `with-i/o-encoding-error', but
 412 ;; not exported from here, but from `(rnrs io simple)'.
 413 (define* (display object #:optional (port (current-output-port)))
 414   (with-textual-output-conditions port (guile:display object port)))
 415
 416 \f
 417 ;;;
 418 ;;; Textual input.
 419 ;;;
 420
 421 (define-condition-type &i/o-decoding &i/o-port
 422   make-i/o-decoding-error i/o-decoding-error?)
 423
 424 (define-syntax with-i/o-decoding-error
 425   (syntax-rules ()
 426     "Convert Guile throws to `decoding-error' to `&i/o-decoding-error'."
 427     ((_ body ...)
 428      ;; XXX: This is heavyweight for small functions like `get-char' and
 429      ;; `lookahead-char'.
 430      (with-throw-handler 'decoding-error
 431        (lambda ()
 432          (begin body ...))
 433        (lambda (key subr message errno port)
 434          (raise (make-i/o-decoding-error port)))))))
 435
 436 (define (get-char port)
 437   (with-textual-input-conditions port (read-char port)))
 438
 439 (define (get-datum port)
 440   (with-textual-input-conditions port (read port)))
 441
 442 (define (get-line port)
 443   (with-textual-input-conditions port (read-line port 'trim)))
 444
 445 (define (get-string-all port)
 446   (with-textual-input-conditions port (read-delimited "" port 'concat)))
 447
 448 (define (get-string-n port count)
 449   "Read up to @var{count} characters from @var{port}.
 450 If no characters could be read before encountering the end of file,
 451 return the end-of-file object, otherwise return a string containing
 452 the characters read."
 453   (let* ((s (make-string count))
 454          (rv (get-string-n! port s 0 count)))
 455     (cond ((eof-object? rv) rv)
 456           ((= rv count)     s)
 457           (else             (substring/shared s 0 rv)))))
 458
 459 (define (lookahead-char port)
 460   (with-textual-input-conditions port (peek-char port)))
 461
 462 \f
 463 ;;;
 464 ;;; Standard ports.
 465 ;;;
 466
 467 (define (standard-input-port)
 468   (with-fluids ((%default-port-encoding #f))
 469     (dup->inport 0)))
 470
 471 (define (standard-output-port)
 472   (with-fluids ((%default-port-encoding #f))
 473     (dup->outport 1)))
 474
 475 (define (standard-error-port)
 476   (with-fluids ((%default-port-encoding #f))
 477     (dup->outport 2)))
 478
 479 )
 480
 481 ;;; ports.scm ends here