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;;; Read-Eval-Print Loop
;; Copyright (C) 2001, 2009, 2010 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
;;; Code:
(define-module (system repl repl)
#:use-module (system base syntax)
#:use-module (system base pmatch)
#:use-module (system base compile)
#:use-module (system base language)
#:use-module (system vm vm)
#:use-module (system repl error-handling)
#:use-module (system repl common)
#:use-module (system repl command)
#:use-module (ice-9 control)
#:export (start-repl run-repl))
;;;
;;; Meta commands
;;;
(define meta-command-token (cons 'meta 'command))
(define (meta-reader read env)
(lambda read-args
(let ((port (if (pair? read-args) (car read-args) (current-input-port))))
(with-input-from-port port
(lambda ()
(let ((ch (next-char #t)))
(cond ((eof-object? ch)
;; apparently sometimes even if this is eof, read will
;; wait on somethingorother. strange.
ch)
((eqv? ch #\,)
(read-char port)
meta-command-token)
(else (read port env)))))))))
;; repl-reader is a function defined in boot-9.scm, and is replaced by
;; something else if readline has been activated. much of this hoopla is
;; to be able to re-use the existing readline machinery.
;;
;; Catches read errors, returning *unspecified* in that case.
(define (prompting-meta-read repl)
(catch #t
(lambda ()
(repl-reader (lambda () (repl-prompt repl))
(meta-reader (language-reader (repl-language repl))
(current-module))))
(lambda (key . args)
(case key
((quit)
(apply throw key args))
(else
(pmatch args
((,subr ,msg ,args . ,rest)
(format #t "Throw to key `~a' while reading expression:\n" key)
(display-error #f (current-output-port) subr msg args rest))
(else
(format #t "Throw to key `~a' with args `~s' while reading expression.\n"
key args)))
(force-output)
*unspecified*)))))
;;;
;;; The repl
;;;
(define* (start-repl #:optional (lang (current-language)) #:key debug)
(run-repl (make-repl lang debug)))
(define (run-repl repl)
(% (with-fluids ((*repl-stack*
(cons repl (or (fluid-ref *repl-stack*) '()))))
(if (null? (cdr (fluid-ref *repl-stack*)))
(repl-welcome repl))
(let prompt-loop ()
(let ((exp (prompting-meta-read repl)))
(cond
((eqv? exp *unspecified*)) ; read error, pass
((eq? exp meta-command-token)
(catch 'quit
(lambda () (meta-command repl))
(lambda (k . args)
(abort args))))
((eof-object? exp)
(newline)
(abort '()))
(else
;; since the input port is line-buffered, consume up to the
;; newline
(flush-to-newline)
(call-with-error-handling
(lambda ()
(catch 'quit
(lambda ()
(call-with-values
(lambda ()
(run-hook before-eval-hook exp)
(start-stack #t
(repl-eval repl (repl-parse repl exp))))
(lambda l
(for-each (lambda (v)
(repl-print repl v))
l))))
(lambda (k . args)
(abort args)))))))
(next-char #f) ;; consume trailing whitespace
(prompt-loop))))
(lambda (k status)
status)))
(define (next-char wait)
(if (or wait (char-ready?))
(let ((ch (peek-char)))
(cond ((eof-object? ch) ch)
((char-whitespace? ch) (read-char) (next-char wait))
(else ch)))
#f))
(define (flush-to-newline)
(if (char-ready?)
(let ((ch (peek-char)))
(if (and (not (eof-object? ch)) (char-whitespace? ch))
(begin
(read-char)
(if (not (char=? ch #\newline))
(flush-to-newline)))))))
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