Re: [PATCH] Several tweaks for R6RS ports

[Andreas Rottmann]

Andreas Rottmann <address@hidden> writes:

> Hi!
>
> Here's a few patches related to R6RS port support, in short:
>
> - Add missing `get-string-n!' and `get-string-n'
> - Fix a few missing exports
> - A bit of work on transcoder-related stuff
>
Attached is an updated version of the "rnrs-transcoders" patch; relative
to its predecessor, it just adds `textual-port?' to the exports in
`(rnrs)' and has a few tweaks to the ChangeLog entries.

From: Andreas Rottmann <address@hidden>
Subject: Enhance transcoder-related functionality of `(rnrs io ports)'

* module/rnrs/io/ports.scm (transcoder-eol-style)
  (transcoder-error-handling-mode): Export these.
  (textual-port?): Implement this procedure and export it.
* module/rnrs.scm: Export these here as well.

* module/rnrs/io/ports.scm (port-transcoder): Implement this procedure.
  (binary-port?): Treat only ports without an encoding as binary ports, 
  add docstring.

* module/rnrs/io/ports.scm: (standard-input-port, standard-output-port)
  (standard-error-port): Ensure these are created without an encoding.
  (eol-style): Add `none' as enumeration member.
  (native-eol-style): Switch to `none' from `lf'.

* test-suite/tests/r6rs-ports.test (7.2.7 Input ports)
  (8.2.10 Output ports): Test binary-ness of `standard-input-port',
  `standard-output-port' and `standard-error-port'.
  (8.2.6 Input and output ports): Add test for `port-transcoder'.

---
 module/rnrs.scm                  |    6 +++-
 module/rnrs/io/ports.scm         |   42 +++++++++++++++++++++++++++++--------
 test-suite/tests/r6rs-ports.test |   32 ++++++++++++++++++++++++++--
 3 files changed, 66 insertions(+), 14 deletions(-)

diff --git a/module/rnrs.scm b/module/rnrs.scm
index 476a3ab..6fde880 100644
--- a/module/rnrs.scm
+++ b/module/rnrs.scm
@@ -162,12 +162,14 @@
 
          file-options buffer-mode buffer-mode?
          eol-style native-eol-style error-handling-mode
-         make-transcoder transcoder-codec native-transcoder
+         make-transcoder transcoder-codec transcoder-eol-style
+          transcoder-error-handling-mode native-transcoder
          latin-1-codec utf-8-codec utf-16-codec
          
          eof-object? port? input-port? output-port? eof-object port-eof?
          port-transcoder
-         binary-port? transcoded-port port-position set-port-position!
+         binary-port? textual-port? transcoded-port
+         port-position set-port-position!
          port-has-port-position? port-has-set-port-position!?
           close-port call-with-port
          open-bytevector-input-port make-custom-binary-input-port get-u8 
diff --git a/module/rnrs/io/ports.scm b/module/rnrs/io/ports.scm
index b98811a..097c9d3 100644
--- a/module/rnrs/io/ports.scm
+++ b/module/rnrs/io/ports.scm
@@ -32,13 +32,14 @@
           ;; auxiliary types
           file-options buffer-mode buffer-mode?
           eol-style native-eol-style error-handling-mode
-          make-transcoder transcoder-codec native-transcoder
+          make-transcoder transcoder-codec transcoder-eol-style
+          transcoder-error-handling-mode native-transcoder
           latin-1-codec utf-8-codec utf-16-codec
            
           ;; input & output ports
           port? input-port? output-port?
           port-eof?
-          port-transcoder binary-port? transcoded-port
+          port-transcoder binary-port? textual-port? transcoded-port
           port-position set-port-position!
           port-has-port-position? port-has-set-port-position!?
           call-with-port close-port
@@ -128,11 +129,11 @@
   (enum-set-member? symbol (enum-set-universe (buffer-modes))))
 
 (define-enumeration eol-style
-  (lf cr crlf nel crnel ls)
+  (lf cr crlf nel crnel ls none)
   eol-styles)
 
 (define (native-eol-style)
-  (eol-style lf))
+  (eol-style none))
 
 (define-enumeration error-handling-mode
   (ignore raise replace)
@@ -189,10 +190,30 @@
 ;;;
 
 (define (port-transcoder port)
-  (error "port transcoders are not supported" port))
+  "Return the transcoder object associated with @var{port}, or @code{#f}
+if the port has no transcoder."
+  (cond ((port-encoding port)
+         => (lambda (encoding)
+              (make-transcoder
+               encoding
+               (native-eol-style)
+               (case (port-conversion-strategy port)
+                 ((error) 'raise)
+                 ((substitute) 'replace)
+                 (else
+                  (assertion-violation 'port-transcoder
+                                       "unsupported error handling mode"))))))
+        (else
+         #f)))
 
 (define (binary-port? port)
-  ;; So far, we don't support transcoders other than the binary transcoder.
+  "Returns @code{#t} if @var{port} does not have an associated encoding,
address@hidden otherwise."
+  (not (port-encoding port)))
+
+(define (textual-port? port)
+  "Always returns @var{#t}, as all ports can be used for textual I/O in
+Guile."
   #t)
 
 (define (port-eof? port)
@@ -396,13 +417,16 @@ return the characters accumulated in that port."
 ;;;
 
 (define (standard-input-port)
-  (dup->inport 0))
+  (with-fluids ((%default-port-encoding #f))
+    (dup->inport 0)))
 
 (define (standard-output-port)
-  (dup->outport 1))
+  (with-fluids ((%default-port-encoding #f))
+    (dup->outport 1)))
 
 (define (standard-error-port)
-  (dup->outport 2))
+  (with-fluids ((%default-port-encoding #f))
+    (dup->outport 2)))
 
 )
 
diff --git a/test-suite/tests/r6rs-ports.test b/test-suite/tests/r6rs-ports.test
index df056a4..d0f5666 100644
--- a/test-suite/tests/r6rs-ports.test
+++ b/test-suite/tests/r6rs-ports.test
@@ -397,7 +397,11 @@
 
       (close-port port)
       (gc) ; Test for marking a closed port.
-      closed?)))
+      closed?))
+
+  (pass-if "standard-input-port is binary"
+    (with-fluids ((%default-port-encoding "UTF-8"))
+      (binary-port? (standard-input-port)))))
 

 (with-test-prefix "8.2.10 Output ports"
@@ -509,7 +513,15 @@
       (put-bytevector port source)
       (and (= sink-pos (bytevector-length source))
            (not eof?)
-           (bytevector=? sink source)))))
+           (bytevector=? sink source))))
+
+  (pass-if "standard-output-port is binary"
+    (with-fluids ((%default-port-encoding "UTF-8"))
+      (binary-port? (standard-output-port))))
+
+  (pass-if "standard-error-port is binary"
+    (with-fluids ((%default-port-encoding "UTF-8"))
+      (binary-port? (standard-error-port)))))
 

 (with-test-prefix "8.2.6  Input and output ports"
@@ -565,7 +577,21 @@
                         (char=? (i/o-encoding-error-char c) #\λ)
                         (bytevector=? (get) (string->utf8 "The letter ")))))
           (put-string tp "The letter λ cannot be represented in Latin-1.")
-          #f)))))
+          #f))))
+
+  (pass-if "port-transcoder [binary port]"
+    (not (port-transcoder (open-bytevector-input-port #vu8()))))
+
+  (pass-if "port-transcoder [transcoded port]"
+    (let* ((p (transcoded-port (open-bytevector-input-port (string->utf8 
"foo"))
+                               (make-transcoder (utf-8-codec))))
+           (t (port-transcoder p)))
+      (and t
+           (transcoder-codec t)
+           (eq? (native-eol-style)
+                (transcoder-eol-style t))
+           (eq? (error-handling-mode replace)
+                (transcoder-error-handling-mode t))))))
 
 ;;; Local Variables:
 ;;; mode: scheme
-- 
tg: (9421ef5..) t/rnrs-transcoders (depends on: t/rnrs-io-current-ports)

Regards, Rotty
-- 
Andreas Rottmann -- <http://rotty.yi.org/>