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ccbbbe6d70
* module/system/repl/repl.scm (start-repl): (ice-9 history) integration via the before-eval-hook and the before-print-hook.
83 lines
3 KiB
Scheme
83 lines
3 KiB
Scheme
;;; Read-Eval-Print Loop
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;; Copyright (C) 2001 Free Software Foundation, Inc.
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;; This program is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;;
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;
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;; You should have received a copy of the GNU General Public License
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;; along with this program; see the file COPYING. If not, write to
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;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Code:
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(define-module (system repl repl)
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:use-syntax (system base syntax)
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:use-module (system base compile)
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:use-module (system base language)
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:use-module (system repl common)
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:use-module (system repl command)
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:use-module (system vm core)
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:use-module (ice-9 rdelim)
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:export (start-repl))
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(define meta-command-token (cons 'meta 'command))
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(define (meta-reader read)
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(lambda ()
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(if (eqv? (next-char #t) #\,)
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(begin (read-char) meta-command-token)
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(read))))
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;; repl-reader is a function defined in boot-9.scm, and is replaced by
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;; something else if readline has been activated. much of this hoopla is
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;; to be able to re-use the existing readline machinery.
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(define (prompting-meta-read repl)
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(let ((prompt (lambda () (repl-prompt repl)))
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(lread (language-reader (cenv-language (repl-env repl)))))
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(with-fluid* current-reader (meta-reader lread)
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(lambda () (repl-reader (lambda () (repl-prompt repl)))))))
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(define (start-repl lang)
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(let ((repl (make-repl lang)))
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(repl-welcome repl)
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(let prompt-loop ()
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(let ((exp (prompting-meta-read repl)))
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(cond
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((eq? exp meta-command-token)
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(meta-command repl (read-line)))
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((eof-object? exp)
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(throw 'quit))
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(else
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(catch 'vm-error
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(lambda ()
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(call-with-values (lambda ()
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(run-hook before-eval-hook exp)
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(repl-eval repl exp))
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(lambda l
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(for-each (lambda (v)
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(run-hook before-print-hook v)
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(repl-print repl v))
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l))))
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(lambda (key fun msg args)
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(display "ERROR: ")
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(apply format #t msg args)
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(newline)))))
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(next-char #f) ;; consume trailing whitespace
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(prompt-loop)))))
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(define (next-char wait)
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(if (or wait (char-ready?))
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(let ((ch (peek-char)))
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(cond ((eof-object? ch) (throw 'quit))
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((char-whitespace? ch) (read-char) (next-char wait))
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(else ch)))
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#f))
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