summaryrefslogtreecommitdiff
path: root/module/system/repl/repl.scm
blob: 93f20c5ab08199f8bf8c3ae3c9019e527d4c6daf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
;;; Read-Eval-Print Loop

;; Copyright (C) 2001 Free Software Foundation, Inc.

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.
;; 
;; This program 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 General Public License for more details.
;; 
;; You should have received a copy of the GNU General Public License
;; along with this program; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Code:

(define-module (system repl repl)
  #:use-syntax (system base syntax)
  #:use-module (system base pmatch)
  #:use-module (system base compile)
  #:use-module (system base language)
  #:use-module (system repl common)
  #:use-module (system repl command)
  #:use-module (system vm vm)
  #:use-module (system vm debug)
  #:use-module (ice-9 rdelim)
  #:export (start-repl call-with-backtrace))

(define meta-command-token (cons 'meta 'command))

(define (meta-reader read)
  (lambda read-args
    (with-input-from-port
        (if (pair? read-args) (car read-args) (current-input-port))
      (lambda ()
        (if (eqv? (next-char #t) #\,)
            (begin (read-char) meta-command-token)
            (read))))))
        
;; 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.
(define (prompting-meta-read repl)
  (let ((prompt (lambda () (repl-prompt repl)))
        (lread (language-reader (repl-language repl))))
    (with-fluid* current-reader (meta-reader lread)
      (lambda () (repl-reader (lambda () (repl-prompt repl)))))))

(define (default-catch-handler . args)
  (pmatch args
    ((quit . _)
     (apply throw args))
    ((,key ,subr ,msg ,args . ,rest)
     (let ((cep (current-error-port)))
       (cond ((not (stack? (fluid-ref the-last-stack))))
             ((memq 'backtrace (debug-options-interface))
              (let ((highlights (if (or (eq? key 'wrong-type-arg)
                                        (eq? key 'out-of-range))
                                    (car rest)
                                    '())))
                (run-hook before-backtrace-hook)
                (newline cep)
                (display "Backtrace:\n")
                (display-backtrace (fluid-ref the-last-stack) cep
                                   #f #f highlights)
                (newline cep)
                (run-hook after-backtrace-hook))))
       (run-hook before-error-hook)
       (display-error (fluid-ref the-last-stack) cep subr msg args rest)
       (run-hook after-error-hook)
       (set! stack-saved? #f)
       (force-output cep)))
    (else
     (format (current-error-port) "\nERROR: uncaught throw to `~a', args: ~a\n"
             (car args) (cdr args)))))

(define (call-with-backtrace thunk)
  (catch #t
         (lambda () (%start-stack #t thunk))
         default-catch-handler
         pre-unwind-handler-dispatch))

(define-macro (with-backtrace form)
  `(call-with-backtrace (lambda () ,form)))

(define (start-repl lang)
  (let ((repl (make-repl lang))
        (status #f))
    (repl-welcome repl)
    (let prompt-loop ()
      (let ((exp (with-backtrace (prompting-meta-read repl))))
        (cond
         ((eqv? exp (if #f #f))) ; read error, pass
         ((eq? exp meta-command-token)
          (with-backtrace (meta-command repl (read-line))))
         ((eof-object? exp)
          (newline)
          (set! status '()))
         (else
          (with-backtrace
           (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)
                                    (run-hook before-print-hook v)
                                    (repl-print repl v))
                                  l))))
                  (lambda (k . args)
                    (set! status args))))))
        (or status
            (begin
              (next-char #f) ;; consume trailing whitespace
              (prompt-loop)))))))

(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))