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Make (ice-9 buffered-input) more general

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This commit is contained in:
Neil Jerram 2001-03-10 14:07:19 +00:00
parent 97d0e20b2e
commit 451d273ac9
2 changed files with 44 additions and 17 deletions
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9
ice-9/ChangeLog
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@ -1,3 +1,12 @@
2001-03-10 Neil Jerram <neil@ossau.uklinux.net>
* buffered-input.scm (make-buffered-input-port): New, more general
buffered input procedure. Does not assume that a newline
character should be interpolated between chunks of input returned
by the reader proc.
(make-line-buffered-input-port): Redefine in terms of
make-buffered-input-port.
2001-03-09 Keisuke Nishida <kxn30@po.cwru.edu>
* match.scm: Don't export defstruct. Use (unquote defstruct) instead.

52
ice-9/buffered-input.scm
View file

@ -18,7 +18,8 @@
;;;; Boston, MA 02111-1307 USA
(define-module (ice-9 buffered-input)
#:export (make-line-buffered-input-port
#:export (make-buffered-input-port
make-line-buffered-input-port
set-buffered-input-continuation?!))
;; @code{buffered-input-continuation?} is a property of the ports
@ -29,20 +30,18 @@
(define (set-buffered-input-continuation?! port val)
"Set the read continuation flag for @var{port} to @var{val}.
See @code{make-line-buffered-input-port} for the meaning and use of
this flag."
See @code{make-buffered-input-port} for the meaning and use of this
flag."
(set! (buffered-input-continuation? port) val))
(define (make-line-buffered-input-port reader)
(define (make-buffered-input-port reader)
"Construct a line-buffered input port from the specified @var{reader}.
@var{reader} should be a procedure of one argument that somehow reads
a line of input and returns it as a string @emph{without} the
terminating newline character.
a chunk of input and returns it as a string.
The port created by @code{make-line-buffered-input-port} automatically
adds a newline character after each string returned by @var{reader};
this makes these ports useful for reading strings that extend across
more than one input line.
The port created by @code{make-buffered-input-port} does @emph{not}
interpolate any additional characters between the strings returned by
@var{reader}.
@var{reader} should take a boolean @var{continuation?} argument.
@var{continuation?} indicates whether @var{reader} is being called to
@ -54,12 +53,12 @@ use the @var{continuation?} argument to determine what prompt to
display to the user.
The new/continuation distinction is largely an application-level
concept, and @code{set-buffered-input-continuation?!} allows an
application some control over when a read operation is considered to
be new. But note that if there is data already buffered in the port
when a new read operation starts, this data will be read before the
first call to @var{reader}, and so @var{reader} will be called with
@var{continuation?} set to @code{#t}."
concept: @code{set-buffered-input-continuation?!} allows an
application to specify when a read operation is considered to be new.
But note that if there is non-whitespace data already buffered in the
port when a new read operation starts, this data will be read before
the first call to @var{reader}, and so @var{reader} will be called
with @var{continuation?} set to @code{#t}."
(let ((read-string "")
(string-index -1))
(letrec ((get-character
@ -69,7 +68,7 @@ first call to @var{reader}, and so @var{reader} will be called with
read-string)
((>= string-index (string-length read-string))
(set! string-index -1)
#\nl)
(get-character))
((= string-index -1)
(set! read-string (reader (buffered-input-continuation? port)))
(set! string-index 0)
@ -87,4 +86,23 @@ first call to @var{reader}, and so @var{reader} will be called with
(set! (buffered-input-continuation? port) #f)
port)))
(define (make-line-buffered-input-port reader)
"Construct a line-buffered input port from the specified @var{reader}.
@var{reader} should be a procedure of one argument that somehow reads
a line of input and returns it as a string @emph{without} the
terminating newline character.
The port created by @code{make-line-buffered-input-port} automatically
interpolates a newline character after each string returned by
@var{reader}.
@var{reader} should take a boolean @var{continuation?} argument. For
the meaning and use of this argument, see
@code{make-buffered-input-port}."
(make-buffered-input-port (lambda (continuation?)
(let ((str (reader continuation?)))
(if (eof-object? str)
str
(string-append str "\n"))))))
;;; buffered-input.scm ends here