scsh-0.5/env/read-command.scm

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1995-10-13 23:34:21 -04:00
; Copyright (c) 1993, 1994 Richard Kelsey and Jonathan Rees. See file COPYING.
; Read a command. No command name completion, yet.
(define (read-command prompt form-preferred? i-port)
(really-read-command prompt form-preferred? i-port no-more-commands))
(define (really-read-command prompt form-preferred? i-port more-commands)
(let ((o-port (command-output)))
(let prompt-loop ()
(if (and prompt (not (batch-mode?)))
(display prompt o-port))
(force-output o-port) ;foo
(let loop ()
(let ((c (peek-char i-port)))
(cond ((eof-object? c)
(read-char i-port))
((char-whitespace? c)
(read-char i-port)
(if (char=? c #\newline)
(prompt-loop)
(loop)))
((char=? c #\;) ;Comment
(gobble-line i-port)
(prompt-loop))
((char=? c command-prefix)
(read-char i-port)
(read-named-command i-port more-commands form-preferred?))
((or form-preferred?
(and (not (char-alphabetic? c))
(not (char-numeric? c))
(not (char=? c #\?))))
(read-evaluation-command i-port))
(else
(read-named-command i-port more-commands form-preferred?))))))))
(define (read-command-carefully prompt form-preferred? i-port . more-commands)
(call-with-current-continuation
(lambda (k)
(with-handler
(lambda (c punt)
(if (and (not (batch-mode?))
(or (read-error? c)
(read-command-error? c)))
(let ((port (last (condition-stuff c))))
(if (eq? port i-port)
(do ()
((or (not (char-ready? port))
(let ((c (read-char port)))
(or (eof-object? c) (char=? c #\newline)))))))
(display-condition c (command-output))
(k #f))
(punt)))
(lambda ()
(really-read-command prompt form-preferred? i-port
(if (null? more-commands)
no-more-commands
(car more-commands))))))))
(define (read-evaluation-command i-port)
(let ((form (read-form i-port)))
(if (eq? (skip-over horizontal-space? i-port) #\newline)
(read-char i-port))
(make-command 'run (list form))))
(define (no-more-commands name)
#f)
; Read a single form, allowing ## as a way to refer to last command
; output.
(define (read-form port)
(with-sharp-sharp (make-node (get-operator 'quote)
(list 'quote (focus-object)))
(lambda () (read port))))
; Read a command line: <name> <arg> ... <newline>
(define (read-named-command port more-commands form-preferred?)
(let ((c-name (read port)))
(let ((syntax (or (more-commands c-name)
(get-command-syntax c-name))))
(cond (syntax
(make-command c-name
(read-command-arguments syntax #f port
more-commands
form-preferred?)))
(else
(read-command-arguments '(&rest form) #f port #f #f) ; flush junk
(write-line "Unrecognized command name." (command-output))
#f)))))
(define (read-command-arguments ds opt? port more-commands form-preferred?)
(let recur ((ds ds) (opt? opt?))
(let ((c (skip-over horizontal-space? port)))
(cond ((and (not (null? ds))
(eq? (car ds) '&opt))
(recur (cdr ds) #t))
((or (eof-object? c)
(char=? c #\newline)
(if (char=? c #\;) ;Comment
(begin (gobble-line port)
#t)
#f))
(cond ((or (null? ds)
(eq? (car ds) '&rest)
opt?)
(read-char port)
'())
(else
(read-command-error port
"too few command arguments"))))
((null? ds)
(read-command-error port "too many command arguments"))
((eq? (car ds) '&rest)
(let ((arg (read-command-argument (cadr ds) port)))
(cons arg (recur ds #f))))
((eq? (car ds) 'command) ; must be the last argument
(if (not (null? (cdr ds)))
(error "invalid argument descriptions" ds))
(list (really-read-command #f form-preferred? port more-commands)))
(else
(let ((arg (read-command-argument (car ds) port)))
(cons arg (recur (cdr ds) opt?))))))))
(define (read-command-argument d port)
(if (procedure? d)
(d port)
(case d
((filename)
(read-string port char-whitespace?))
((expression form)
(read-form port))
((name)
(let ((thing (read port)))
(if (symbol? thing)
thing
(read-command-error port "invalid name" thing))))
(else (error "invalid argument description" d)))))
(define-condition-type 'read-command-error '(error))
(define read-command-error? (condition-predicate 'read-command-error))
(define (read-command-error port message . rest)
(apply signal 'read-command-error message (append rest (list port))))
; Utilities.
(define (horizontal-space? c)
(and (char-whitespace? c)
(not (char=? c #\newline))))
(define (read-string port delimiter?)
(let loop ((l '()))
(let ((c (peek-char port)))
(cond ((or (eof-object? c)
(delimiter? c))
(list->string (reverse l)))
(else
(loop (cons (read-char port) l)))))))
(define (skip-over pred port)
(let ((c (peek-char port)))
(cond ((eof-object? c) c)
((pred c) (read-char port) (skip-over pred port))
(else c))))
; ## should evaluate to the last REP-loop result.
(define-sharp-macro #\#
(lambda (c port)
(read-char port)
((fluid $sharp-sharp) port)))
(define $sharp-sharp
(make-fluid (lambda (port) (reading-error port "## in invalid context"))))
(define (with-sharp-sharp form body)
(let-fluid $sharp-sharp (lambda (port) form) body))
(define make-command cons) ;(name . args)
; (put 'with-sharp-sharp 'scheme-indent-hook 1)