lisp/xscheme.el

   1 ;;; xscheme.el --- run Scheme under Emacs
   2
   3 ;; Copyright (C) 1986, 1987, 1989, 1990 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: languages, lisp
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; A major mode for editing Scheme and interacting with MIT's C-Scheme.
  27 ;;
  28 ;; Requires C-Scheme release 5 or later
  29 ;; Changes to Control-G handler require runtime version 13.85 or later
  30
  31 ;;; Code:
  32
  33 (require 'scheme)
  34 \f
  35 (defvar scheme-program-name "scheme"
  36   "*Program invoked by the `run-scheme' command.")
  37
  38 (defvar scheme-band-name nil
  39   "*Band loaded by the `run-scheme' command.")
  40
  41 (defvar scheme-program-arguments nil
  42   "*Arguments passed to the Scheme program by the `run-scheme' command.")
  43
  44 (defvar xscheme-allow-pipelined-evaluation t
  45   "If non-nil, an expression may be transmitted while another is evaluating.
  46 Otherwise, attempting to evaluate an expression before the previous expression
  47 has finished evaluating will signal an error.")
  48
  49 (defvar xscheme-startup-message
  50   "This is the Scheme process buffer.
  51 Type \\[advertised-xscheme-send-previous-expression] to evaluate the expression before point.
  52 Type \\[xscheme-send-control-g-interrupt] to abort evaluation.
  53 Type \\[describe-mode] for more information.
  54
  55 "
  56   "String to insert into Scheme process buffer first time it is started.
  57 Is processed with `substitute-command-keys' first.")
  58
  59 (defvar xscheme-signal-death-message nil
  60   "If non-nil, causes a message to be generated when the Scheme process dies.")
  61
  62 (defun xscheme-evaluation-commands (keymap)
  63   (define-key keymap "\e\C-x" 'xscheme-send-definition)
  64   (define-key keymap "\C-x\C-e" 'advertised-xscheme-send-previous-expression)
  65   (define-key keymap "\eo" 'xscheme-send-buffer)
  66   (define-key keymap "\ez" 'xscheme-send-definition)
  67   (define-key keymap "\e\C-m" 'xscheme-send-previous-expression)
  68   (define-key keymap "\e\C-z" 'xscheme-send-region))
  69
  70 (defun xscheme-interrupt-commands (keymap)
  71   (define-key keymap "\C-c\C-s" 'xscheme-select-process-buffer)
  72   (define-key keymap "\C-c\C-b" 'xscheme-send-breakpoint-interrupt)
  73   (define-key keymap "\C-c\C-c" 'xscheme-send-control-g-interrupt)
  74   (define-key keymap "\C-c\C-u" 'xscheme-send-control-u-interrupt)
  75   (define-key keymap "\C-c\C-x" 'xscheme-send-control-x-interrupt))
  76
  77 (xscheme-evaluation-commands scheme-mode-map)
  78 (xscheme-interrupt-commands scheme-mode-map)
  79 \f
  80 (defun run-scheme (command-line)
  81   "Run MIT Scheme in an inferior process.
  82 Output goes to the buffer `*scheme*'.
  83 With argument, asks for a command line."
  84   (interactive
  85    (list (let ((default
  86                  (or xscheme-process-command-line
  87                      (xscheme-default-command-line))))
  88            (if current-prefix-arg
  89                (read-string "Run Scheme: " default)
  90                default))))
  91   (setq xscheme-process-command-line command-line)
  92   (pop-to-buffer (xscheme-start-process command-line)))
  93
  94 (defun reset-scheme ()
  95   "Reset the Scheme process."
  96   (interactive)
  97   (let ((process (get-process "scheme")))
  98     (cond ((or (not process)
  99                (not (eq (process-status process) 'run))
 100                (yes-or-no-p
 101 "The Scheme process is running, are you SURE you want to reset it? "))
 102            (message "Resetting Scheme process...")
 103            (if process (kill-process process t))
 104            (xscheme-start-process xscheme-process-command-line)
 105            (message "Resetting Scheme process...done")))))
 106
 107 (defun xscheme-default-command-line ()
 108   (concat scheme-program-name " -emacs"
 109           (if scheme-program-arguments
 110               (concat " " scheme-program-arguments)
 111               "")
 112           (if scheme-band-name
 113               (concat " -band " scheme-band-name)
 114               "")))
 115 \f
 116 ;;;; Interaction Mode
 117
 118 (defun scheme-interaction-mode ()
 119   "Major mode for interacting with the inferior Scheme process.
 120 Like  scheme-mode  except that:
 121
 122 \\[advertised-xscheme-send-previous-expression] sends the expression before point to the Scheme process as input
 123 \\[xscheme-yank-previous-send] yanks the expression most recently sent to Scheme
 124
 125 All output from the Scheme process is written in the Scheme process
 126 buffer, which is initially named \"*scheme*\".  The result of
 127 evaluating a Scheme expression is also printed in the process buffer,
 128 preceded by the string \";Value: \" to highlight it.  If the process
 129 buffer is not visible at that time, the value will also be displayed
 130 in the minibuffer.  If an error occurs, the process buffer will
 131 automatically pop up to show you the error message.
 132
 133 While the Scheme process is running, the modelines of all buffers in
 134 scheme-mode are modified to show the state of the process.  The
 135 possible states and their meanings are:
 136
 137 input           waiting for input
 138 run             evaluating
 139 gc              garbage collecting
 140
 141 The process buffer's modeline contains additional information where
 142 the buffer's name is normally displayed: the command interpreter level
 143 and type.
 144
 145 Scheme maintains a stack of command interpreters.  Every time an error
 146 or breakpoint occurs, the current command interpreter is pushed on the
 147 command interpreter stack, and a new command interpreter is started.
 148 One example of why this is done is so that an error that occurs while
 149 you are debugging another error will not destroy the state of the
 150 initial error, allowing you to return to it after the second error has
 151 been fixed.
 152
 153 The command interpreter level indicates how many interpreters are in
 154 the command interpreter stack.  It is initially set to one, and it is
 155 incremented every time that stack is pushed, and decremented every
 156 time it is popped.  The following commands are useful for manipulating
 157 the command interpreter stack:
 158
 159 \\[xscheme-send-breakpoint-interrupt]   pushes the stack once
 160 \\[xscheme-send-control-u-interrupt]    pops the stack once
 161 \\[xscheme-send-control-g-interrupt]    pops everything off
 162 \\[xscheme-send-control-x-interrupt]    aborts evaluation, doesn't affect stack
 163
 164 Some possible command interpreter types and their meanings are:
 165
 166 [Evaluator]     read-eval-print loop for evaluating expressions
 167 [Debugger]      single character commands for debugging errors
 168 [Where]         single character commands for examining environments
 169
 170 Starting with release 6.2 of Scheme, the latter two types of command
 171 interpreters will change the major mode of the Scheme process buffer
 172 to scheme-debugger-mode , in which the evaluation commands are
 173 disabled, and the keys which normally self insert instead send
 174 themselves to the Scheme process.  The command character ? will list
 175 the available commands.
 176
 177 For older releases of Scheme, the major mode will be be
 178 scheme-interaction-mode , and the command characters must be sent as
 179 if they were expressions.
 180
 181 Commands:
 182 Delete converts tabs to spaces as it moves back.
 183 Blank lines separate paragraphs.  Semicolons start comments.
 184 \\{scheme-interaction-mode-map}
 185
 186 Entry to this mode calls the value of scheme-interaction-mode-hook
 187 with no args, if that value is non-nil.
 188  Likewise with the value of scheme-mode-hook.
 189  scheme-interaction-mode-hook is called after scheme-mode-hook."
 190   (interactive)
 191   (kill-all-local-variables)
 192   (scheme-interaction-mode-initialize)
 193   (scheme-mode-variables)
 194   (make-local-variable 'xscheme-previous-send)
 195   (run-hooks 'scheme-mode-hook 'scheme-interaction-mode-hook))
 196
 197 (defun scheme-interaction-mode-initialize ()
 198   (use-local-map scheme-interaction-mode-map)
 199   (setq major-mode 'scheme-interaction-mode)
 200   (setq mode-name "Scheme Interaction"))
 201
 202 (defun scheme-interaction-mode-commands (keymap)
 203   (define-key keymap "\C-c\C-m" 'xscheme-send-current-line)
 204   (define-key keymap "\C-c\C-p" 'xscheme-send-proceed)
 205   (define-key keymap "\C-c\C-y" 'xscheme-yank-previous-send))
 206
 207 (defvar scheme-interaction-mode-map nil)
 208 (if (not scheme-interaction-mode-map)
 209     (progn
 210       (setq scheme-interaction-mode-map (make-keymap))
 211       (scheme-mode-commands scheme-interaction-mode-map)
 212       (xscheme-interrupt-commands scheme-interaction-mode-map)
 213       (xscheme-evaluation-commands scheme-interaction-mode-map)
 214       (scheme-interaction-mode-commands scheme-interaction-mode-map)))
 215
 216 (defun xscheme-enter-interaction-mode ()
 217   (save-excursion
 218     (set-buffer (xscheme-process-buffer))
 219     (if (not (eq major-mode 'scheme-interaction-mode))
 220         (if (eq major-mode 'scheme-debugger-mode)
 221             (scheme-interaction-mode-initialize)
 222             (scheme-interaction-mode)))))
 223
 224 (fset 'advertised-xscheme-send-previous-expression
 225       'xscheme-send-previous-expression)
 226 \f
 227 ;;;; Debugger Mode
 228
 229 (defun scheme-debugger-mode ()
 230   "Major mode for executing the Scheme debugger.
 231 Like  scheme-mode  except that the evaluation commands
 232 are disabled, and characters that would normally be self inserting are
 233 sent to the Scheme process instead.  Typing ?  will show you which
 234 characters perform useful functions.
 235
 236 Commands:
 237 \\{scheme-debugger-mode-map}"
 238   (error "Illegal entry to scheme-debugger-mode"))
 239
 240 (defun scheme-debugger-mode-initialize ()
 241   (use-local-map scheme-debugger-mode-map)
 242   (setq major-mode 'scheme-debugger-mode)
 243   (setq mode-name "Scheme Debugger"))
 244
 245 (defun scheme-debugger-mode-commands (keymap)
 246   (let ((char ? ))
 247     (while (< char 127)
 248       (define-key keymap (char-to-string char) 'scheme-debugger-self-insert)
 249       (setq char (1+ char)))))
 250
 251 (defvar scheme-debugger-mode-map nil)
 252 (if (not scheme-debugger-mode-map)
 253     (progn
 254       (setq scheme-debugger-mode-map (make-keymap))
 255       (scheme-mode-commands scheme-debugger-mode-map)
 256       (xscheme-interrupt-commands scheme-debugger-mode-map)
 257       (scheme-debugger-mode-commands scheme-debugger-mode-map)))
 258
 259 (defun scheme-debugger-self-insert ()
 260   "Transmit this character to the Scheme process."
 261   (interactive)
 262   (xscheme-send-char last-command-char))
 263
 264 (defun xscheme-enter-debugger-mode (prompt-string)
 265   (save-excursion
 266     (set-buffer (xscheme-process-buffer))
 267     (if (not (eq major-mode 'scheme-debugger-mode))
 268         (progn
 269           (if (not (eq major-mode 'scheme-interaction-mode))
 270               (scheme-interaction-mode))
 271           (scheme-debugger-mode-initialize)))))
 272
 273 (defun xscheme-debugger-mode-p ()
 274   (let ((buffer (xscheme-process-buffer)))
 275     (and buffer
 276          (save-excursion
 277            (set-buffer buffer)
 278            (eq major-mode 'scheme-debugger-mode)))))
 279 \f
 280 ;;;; Evaluation Commands
 281
 282 (defun xscheme-send-string (&rest strings)
 283   "Send the string arguments to the Scheme process.
 284 The strings are concatenated and terminated by a newline."
 285   (cond ((not (xscheme-process-running-p))
 286          (if (yes-or-no-p "The Scheme process has died.  Reset it? ")
 287              (progn
 288                (reset-scheme)
 289                (xscheme-wait-for-process)
 290                (goto-char (point-max))
 291                (apply 'insert-before-markers strings)
 292                (xscheme-send-string-1 strings))))
 293         ((xscheme-debugger-mode-p) (error "No sends allowed in debugger mode"))
 294         ((and (not xscheme-allow-pipelined-evaluation)
 295               xscheme-running-p)
 296          (error "No sends allowed while Scheme running"))
 297         (t (xscheme-send-string-1 strings))))
 298
 299 (defun xscheme-send-string-1 (strings)
 300   (let ((string (apply 'concat strings)))
 301     (xscheme-send-string-2 string)
 302     (if (eq major-mode 'scheme-interaction-mode)
 303         (setq xscheme-previous-send string))))
 304
 305 (defun xscheme-send-string-2 (string)
 306   (let ((process (get-process "scheme")))
 307     (send-string process (concat string "\n"))
 308     (if (xscheme-process-buffer-current-p)
 309         (set-marker (process-mark process) (point)))))
 310
 311 (defun xscheme-yank-previous-send ()
 312   "Insert the most recent expression at point."
 313   (interactive)
 314   (push-mark)
 315   (insert xscheme-previous-send))
 316
 317 (defun xscheme-select-process-buffer ()
 318   "Select the Scheme process buffer and move to its output point."
 319   (interactive)
 320   (let ((process (or (get-process "scheme") (error "No scheme process"))))
 321     (let ((buffer (or (process-buffer process) (error "No process buffer"))))
 322       (let ((window (get-buffer-window buffer)))
 323         (if window
 324             (select-window window)
 325             (switch-to-buffer buffer))
 326         (goto-char (process-mark process))))))
 327 \f
 328 (defun xscheme-send-region (start end)
 329   "Send the current region to the Scheme process.
 330 The region is sent terminated by a newline."
 331   (interactive "r")
 332   (if (xscheme-process-buffer-current-p)
 333       (progn (goto-char end)
 334              (set-marker (process-mark (get-process "scheme")) end)))
 335   (xscheme-send-string (buffer-substring start end)))
 336
 337 (defun xscheme-send-definition ()
 338   "Send the current definition to the Scheme process.
 339 If the current line begins with a non-whitespace character,
 340 parse an expression from the beginning of the line and send that instead."
 341   (interactive)
 342   (let ((start nil) (end nil))
 343     (save-excursion
 344       (end-of-defun)
 345       (setq end (point))
 346       (if (re-search-backward "^\\s(" nil t)
 347           (setq start (point))
 348           (error "Can't find definition")))
 349     (xscheme-send-region start end)))
 350
 351 (defun xscheme-send-next-expression ()
 352   "Send the expression to the right of `point' to the Scheme process."
 353   (interactive)
 354   (let ((start (point)))
 355     (xscheme-send-region start (save-excursion (forward-sexp) (point)))))
 356
 357 (defun xscheme-send-previous-expression ()
 358   "Send the expression to the left of `point' to the Scheme process."
 359   (interactive)
 360   (let ((end (point)))
 361     (xscheme-send-region (save-excursion (backward-sexp) (point)) end)))
 362 \f
 363 (defun xscheme-send-current-line ()
 364   "Send the current line to the Scheme process.
 365 Useful for working with debugging Scheme under adb."
 366   (interactive)
 367   (let ((line
 368          (save-excursion
 369            (beginning-of-line)
 370            (let ((start (point)))
 371              (end-of-line)
 372              (buffer-substring start (point))))))
 373     (end-of-line)
 374     (insert ?\n)
 375     (xscheme-send-string-2 line)))
 376
 377 (defun xscheme-send-buffer ()
 378   "Send the current buffer to the Scheme process."
 379   (interactive)
 380   (if (xscheme-process-buffer-current-p)
 381       (error "Not allowed to send this buffer's contents to Scheme"))
 382   (xscheme-send-region (point-min) (point-max)))
 383
 384 (defun xscheme-send-char (char)
 385   "Prompt for a character and send it to the Scheme process."
 386   (interactive "cCharacter to send: ")
 387   (send-string "scheme" (char-to-string char)))
 388 \f
 389 ;;;; Interrupts
 390
 391 (defun xscheme-send-breakpoint-interrupt ()
 392   "Cause the Scheme process to enter a breakpoint."
 393   (interactive)
 394   (xscheme-send-interrupt ?b nil))
 395
 396 (defun xscheme-send-proceed ()
 397   "Cause the Scheme process to proceed from a breakpoint."
 398   (interactive)
 399   (send-string "scheme" "(proceed)\n"))
 400
 401 (defun xscheme-send-control-g-interrupt ()
 402   "Cause the Scheme processor to halt and flush input.
 403 Control returns to the top level rep loop."
 404   (interactive)
 405   (let ((inhibit-quit t))
 406     (cond ((not xscheme-control-g-synchronization-p)
 407            (interrupt-process "scheme"))
 408           (xscheme-control-g-disabled-p
 409            (message "Relax..."))
 410           (t
 411            (setq xscheme-control-g-disabled-p t)
 412            (message "Sending C-G interrupt to Scheme...")
 413            (interrupt-process "scheme")
 414            (send-string "scheme" (char-to-string 0))))))
 415
 416 (defun xscheme-send-control-u-interrupt ()
 417   "Cause the Scheme process to halt, returning to previous rep loop."
 418   (interactive)
 419   (xscheme-send-interrupt ?u t))
 420
 421 (defun xscheme-send-control-x-interrupt ()
 422   "Cause the Scheme process to halt, returning to current rep loop."
 423   (interactive)
 424   (xscheme-send-interrupt ?x t))
 425
 426 ;;; This doesn't really work right -- Scheme just gobbles the first
 427 ;;; character in the input.  There is no way for us to guarantee that
 428 ;;; the argument to this procedure is the first char unless we put
 429 ;;; some kind of marker in the input stream.
 430
 431 (defun xscheme-send-interrupt (char mark-p)
 432   "Send a ^A type interrupt to the Scheme process."
 433   (interactive "cInterrupt character to send: ")
 434   (quit-process "scheme")
 435   (send-string "scheme" (char-to-string char))
 436   (if (and mark-p xscheme-control-g-synchronization-p)
 437       (send-string "scheme" (char-to-string 0))))
 438 \f
 439 ;;;; Internal Variables
 440
 441 (defvar xscheme-process-command-line nil
 442   "Command used to start the most recent Scheme process.")
 443
 444 (defvar xscheme-previous-send ""
 445   "Most recent expression transmitted to the Scheme process.")
 446
 447 (defvar xscheme-process-filter-state 'idle
 448   "State of scheme process escape reader state machine:
 449 idle                   waiting for an escape sequence
 450 reading-type           received an altmode but nothing else
 451 reading-string         reading prompt string")
 452
 453 (defvar xscheme-running-p nil
 454   "This variable, if nil, indicates that the scheme process is
 455 waiting for input.  Otherwise, it is busy evaluating something.")
 456
 457 (defconst xscheme-control-g-synchronization-p t
 458   "If non-nil, insert markers in the scheme input stream to indicate when
 459 control-g interrupts were signaled.  Do not allow more control-g's to be
 460 signaled until the scheme process acknowledges receipt.")
 461
 462 (defvar xscheme-control-g-disabled-p nil
 463   "This variable, if non-nil, indicates that a control-g is being processed
 464 by the scheme process, so additional control-g's are to be ignored.")
 465
 466 (defvar xscheme-allow-output-p t
 467   "This variable, if nil, prevents output from the scheme process
 468 from being inserted into the process-buffer.")
 469
 470 (defvar xscheme-prompt ""
 471   "The current scheme prompt string.")
 472
 473 (defvar xscheme-string-accumulator ""
 474   "Accumulator for the string being received from the scheme process.")
 475
 476 (defvar xscheme-string-receiver nil
 477   "Procedure to send the string argument from the scheme process.")
 478
 479 (defvar xscheme-start-hook nil
 480   "If non-nil, a procedure to call when the Scheme process is started.
 481 When called, the current buffer will be the Scheme process-buffer.")
 482
 483 (defvar xscheme-runlight-string nil)
 484 (defvar xscheme-mode-string nil)
 485 (defvar xscheme-filter-input nil)
 486 \f
 487 ;;;; Basic Process Control
 488
 489 (defun xscheme-start-process (command-line)
 490   (let ((buffer (get-buffer-create "*scheme*")))
 491     (let ((process (get-buffer-process buffer)))
 492       (save-excursion
 493         (set-buffer buffer)
 494         (if (and process (memq (process-status process) '(run stop)))
 495             (set-marker (process-mark process) (point-max))
 496             (progn (if process (delete-process process))
 497                    (goto-char (point-max))
 498                    (scheme-interaction-mode)
 499                    (if (bobp)
 500                        (insert-before-markers
 501                         (substitute-command-keys xscheme-startup-message)))
 502                    (setq process
 503                          (let ((process-connection-type nil))
 504                            (apply 'start-process
 505                                   (cons "scheme"
 506                                         (cons buffer
 507                                               (xscheme-parse-command-line
 508                                                command-line))))))
 509                    (set-marker (process-mark process) (point-max))
 510                    (xscheme-process-filter-initialize t)
 511                    (xscheme-modeline-initialize)
 512                    (set-process-sentinel process 'xscheme-process-sentinel)
 513                    (set-process-filter process 'xscheme-process-filter)
 514                    (run-hooks 'xscheme-start-hook)))))
 515     buffer))
 516
 517 (defun xscheme-parse-command-line (string)
 518   (setq string (substitute-in-file-name string))
 519   (let ((start 0)
 520         (result '()))
 521     (while start
 522       (let ((index (string-match "[ \t]" string start)))
 523         (setq start
 524               (cond ((not index)
 525                      (setq result
 526                            (cons (substring string start)
 527                                  result))
 528                      nil)
 529                     ((= index start)
 530                      (string-match "[^ \t]" string start))
 531                     (t
 532                      (setq result
 533                            (cons (substring string start index)
 534                                  result))
 535                      (1+ index))))))
 536     (nreverse result)))
 537 \f
 538 (defun xscheme-wait-for-process ()
 539   (sleep-for 2)
 540   (while xscheme-running-p
 541     (sleep-for 1)))
 542
 543 (defun xscheme-process-running-p ()
 544   "True iff there is a Scheme process whose status is `run'."
 545   (let ((process (get-process "scheme")))
 546     (and process
 547          (eq (process-status process) 'run))))
 548
 549 (defun xscheme-process-buffer ()
 550   (let ((process (get-process "scheme")))
 551     (and process (process-buffer process))))
 552
 553 (defun xscheme-process-buffer-window ()
 554   (let ((buffer (xscheme-process-buffer)))
 555     (and buffer (get-buffer-window buffer))))
 556
 557 (defun xscheme-process-buffer-current-p ()
 558   "True iff the current buffer is the Scheme process buffer."
 559   (eq (xscheme-process-buffer) (current-buffer)))
 560 \f
 561 ;;;; Process Filter
 562
 563 (defun xscheme-process-sentinel (proc reason)
 564   (xscheme-process-filter-initialize (eq reason 'run))
 565   (if (eq reason 'run)
 566       (xscheme-modeline-initialize)
 567       (progn
 568        (setq scheme-mode-line-process "")
 569        (setq xscheme-mode-string "no process")))
 570   (if (and (not (memq reason '(run stop)))
 571            xscheme-signal-death-message)
 572       (progn (beep)
 573              (message
 574 "The Scheme process has died!  Do M-x reset-scheme to restart it"))))
 575
 576 (defun xscheme-process-filter-initialize (running-p)
 577   (setq xscheme-process-filter-state 'idle)
 578   (setq xscheme-running-p running-p)
 579   (setq xscheme-control-g-disabled-p nil)
 580   (setq xscheme-allow-output-p t)
 581   (setq xscheme-prompt "")
 582   (setq scheme-mode-line-process '(": " xscheme-runlight-string)))
 583
 584 (defun xscheme-process-filter (proc string)
 585   (let ((xscheme-filter-input string))
 586     (while xscheme-filter-input
 587       (cond ((eq xscheme-process-filter-state 'idle)
 588              (let ((start (string-match "\e" xscheme-filter-input)))
 589                (if start
 590                    (progn
 591                      (xscheme-process-filter-output
 592                       (substring xscheme-filter-input 0 start))
 593                      (setq xscheme-filter-input
 594                            (substring xscheme-filter-input (1+ start)))
 595                      (setq xscheme-process-filter-state 'reading-type))
 596                    (let ((string xscheme-filter-input))
 597                      (setq xscheme-filter-input nil)
 598                      (xscheme-process-filter-output string)))))
 599             ((eq xscheme-process-filter-state 'reading-type)
 600              (if (zerop (length xscheme-filter-input))
 601                  (setq xscheme-filter-input nil)
 602                  (let ((char (aref xscheme-filter-input 0)))
 603                    (setq xscheme-filter-input
 604                          (substring xscheme-filter-input 1))
 605                    (let ((entry (assoc char xscheme-process-filter-alist)))
 606                      (if entry
 607                          (funcall (nth 2 entry) (nth 1 entry))
 608                          (progn
 609                            (xscheme-process-filter-output ?\e char)
 610                            (setq xscheme-process-filter-state 'idle)))))))
 611             ((eq xscheme-process-filter-state 'reading-string)
 612              (let ((start (string-match "\e" xscheme-filter-input)))
 613                (if start
 614                    (let ((string
 615                           (concat xscheme-string-accumulator
 616                                   (substring xscheme-filter-input 0 start))))
 617                      (setq xscheme-filter-input
 618                            (substring xscheme-filter-input (1+ start)))
 619                      (setq xscheme-process-filter-state 'idle)
 620                      (funcall xscheme-string-receiver string))
 621                    (progn
 622                      (setq xscheme-string-accumulator
 623                            (concat xscheme-string-accumulator
 624                                    xscheme-filter-input))
 625                      (setq xscheme-filter-input nil)))))
 626             (t
 627              (error "Scheme process filter -- bad state"))))))
 628 \f
 629 ;;;; Process Filter Output
 630
 631 (defun xscheme-process-filter-output (&rest args)
 632   (if xscheme-allow-output-p
 633       (let ((string (apply 'concat args)))
 634         (save-excursion
 635           (xscheme-goto-output-point)
 636           (while (string-match "\\(\007\\|\f\\)" string)
 637             (let ((start (match-beginning 0))
 638                   (end (match-end 0)))
 639               (insert-before-markers (substring string 0 start))
 640               (if (= ?\f (aref string start))
 641                   (progn
 642                     (if (not (bolp))
 643                         (insert-before-markers ?\n))
 644                     (insert-before-markers ?\f))
 645                   (beep))
 646               (setq string (substring string (1+ start)))))
 647           (insert-before-markers string)))))
 648
 649 (defun xscheme-guarantee-newlines (n)
 650   (if xscheme-allow-output-p
 651       (save-excursion
 652         (xscheme-goto-output-point)
 653         (let ((stop nil))
 654           (while (and (not stop)
 655                       (bolp))
 656             (setq n (1- n))
 657             (if (bobp)
 658                 (setq stop t)
 659                 (backward-char))))
 660         (xscheme-goto-output-point)
 661         (while (> n 0)
 662           (insert-before-markers ?\n)
 663           (setq n (1- n))))))
 664
 665 (defun xscheme-goto-output-point ()
 666   (let ((process (get-process "scheme")))
 667     (set-buffer (process-buffer process))
 668     (goto-char (process-mark process))))
 669
 670 (defun xscheme-modeline-initialize ()
 671   (setq xscheme-runlight-string "")
 672   (setq xscheme-mode-string "")
 673   (setq mode-line-buffer-identification '("Scheme: " xscheme-mode-string)))
 674
 675 (defun xscheme-set-runlight (runlight)
 676   (setq xscheme-runlight-string runlight)
 677   (force-mode-line-update t))
 678 \f
 679 ;;;; Process Filter Operations
 680
 681 (defvar xscheme-process-filter-alist
 682   '((?D xscheme-enter-debugger-mode
 683         xscheme-process-filter:string-action)
 684     (?E xscheme-eval
 685         xscheme-process-filter:string-action)
 686     (?P xscheme-set-prompt-variable
 687         xscheme-process-filter:string-action)
 688     (?R xscheme-enter-interaction-mode
 689         xscheme-process-filter:simple-action)
 690     (?b xscheme-start-gc
 691         xscheme-process-filter:simple-action)
 692     (?e xscheme-finish-gc
 693         xscheme-process-filter:simple-action)
 694     (?f xscheme-exit-input-wait
 695         xscheme-process-filter:simple-action)
 696     (?g xscheme-enable-control-g
 697         xscheme-process-filter:simple-action)
 698     (?i xscheme-prompt-for-expression
 699         xscheme-process-filter:string-action)
 700     (?m xscheme-message
 701         xscheme-process-filter:string-action)
 702     (?n xscheme-prompt-for-confirmation
 703         xscheme-process-filter:string-action)
 704     (?o xscheme-output-goto
 705         xscheme-process-filter:simple-action)
 706     (?p xscheme-set-prompt
 707         xscheme-process-filter:string-action)
 708     (?s xscheme-enter-input-wait
 709         xscheme-process-filter:simple-action)
 710     (?v xscheme-write-value
 711         xscheme-process-filter:string-action)
 712     (?w xscheme-cd
 713         xscheme-process-filter:string-action)
 714     (?z xscheme-display-process-buffer
 715         xscheme-process-filter:simple-action)
 716     (?c xscheme-unsolicited-read-char
 717         xscheme-process-filter:simple-action))
 718   "Table used to decide how to handle process filter commands.
 719 Value is a list of entries, each entry is a list of three items.
 720
 721 The first item is the character that the process filter dispatches on.
 722 The second item is the action to be taken, a function.
 723 The third item is the handler for the entry, a function.
 724
 725 When the process filter sees a command whose character matches a
 726 particular entry, it calls the handler with two arguments: the action
 727 and the string containing the rest of the process filter's input
 728 stream.  It is the responsibility of the handler to invoke the action
 729 with the appropriate arguments, and to reenter the process filter with
 730 the remaining input.")
 731 \f
 732 (defun xscheme-process-filter:simple-action (action)
 733   (setq xscheme-process-filter-state 'idle)
 734   (funcall action))
 735
 736 (defun xscheme-process-filter:string-action (action)
 737   (setq xscheme-string-receiver action)
 738   (setq xscheme-string-accumulator "")
 739   (setq xscheme-process-filter-state 'reading-string))
 740
 741 (defconst xscheme-runlight:running "run"
 742   "The character displayed when the Scheme process is running.")
 743
 744 (defconst xscheme-runlight:input "input"
 745   "The character displayed when the Scheme process is waiting for input.")
 746
 747 (defconst xscheme-runlight:gc "gc"
 748   "The character displayed when the Scheme process is garbage collecting.")
 749
 750 (defun xscheme-start-gc ()
 751   (xscheme-set-runlight xscheme-runlight:gc))
 752
 753 (defun xscheme-finish-gc ()
 754   (xscheme-set-runlight
 755    (if xscheme-running-p xscheme-runlight:running xscheme-runlight:input)))
 756
 757 (defun xscheme-enter-input-wait ()
 758   (xscheme-set-runlight xscheme-runlight:input)
 759   (setq xscheme-running-p nil))
 760
 761 (defun xscheme-exit-input-wait ()
 762   (xscheme-set-runlight xscheme-runlight:running)
 763   (setq xscheme-running-p t))
 764
 765 (defun xscheme-enable-control-g ()
 766   (setq xscheme-control-g-disabled-p nil))
 767
 768 (defun xscheme-display-process-buffer ()
 769   (let ((window (or (xscheme-process-buffer-window)
 770                     (display-buffer (xscheme-process-buffer)))))
 771     (save-window-excursion
 772       (select-window window)
 773       (xscheme-goto-output-point)
 774       (if (xscheme-debugger-mode-p)
 775           (xscheme-enter-interaction-mode)))))
 776
 777 (defun xscheme-unsolicited-read-char ()
 778   nil)
 779 \f
 780 (defun xscheme-eval (string)
 781   (eval (car (read-from-string string))))
 782
 783 (defun xscheme-message (string)
 784   (if (not (zerop (length string)))
 785       (xscheme-write-message-1 string (format ";%s" string))))
 786
 787 (defun xscheme-write-value (string)
 788   (if (zerop (length string))
 789       (xscheme-write-message-1 "(no value)" ";No value")
 790       (xscheme-write-message-1 string (format ";Value: %s" string))))
 791
 792 (defun xscheme-write-message-1 (message-string output-string)
 793   (let* ((process (get-process "scheme"))
 794          (window (get-buffer-window (process-buffer process))))
 795     (if (or (not window)
 796             (not (pos-visible-in-window-p (process-mark process)
 797                                           window)))
 798         (message "%s" message-string)))
 799   (xscheme-guarantee-newlines 1)
 800   (xscheme-process-filter-output output-string))
 801
 802 (defun xscheme-set-prompt-variable (string)
 803   (setq xscheme-prompt string))
 804
 805 (defun xscheme-set-prompt (string)
 806   (setq xscheme-prompt string)
 807   (xscheme-guarantee-newlines 2)
 808   (setq xscheme-mode-string (xscheme-coerce-prompt string))
 809   (force-mode-line-update t))
 810
 811 (defun xscheme-output-goto ()
 812   (xscheme-goto-output-point)
 813   (xscheme-guarantee-newlines 2))
 814
 815 (defun xscheme-coerce-prompt (string)
 816   (if (string-match "^[0-9]+ " string)
 817       (let ((end (match-end 0)))
 818         (concat (substring string 0 end)
 819                 (let ((prompt (substring string end)))
 820                   (let ((entry (assoc prompt xscheme-prompt-alist)))
 821                     (if entry
 822                         (cdr entry)
 823                         prompt)))))
 824       string))
 825
 826 (defvar xscheme-prompt-alist
 827   '(("[Normal REPL]" . "[Evaluator]")
 828     ("[Error REPL]" . "[Evaluator]")
 829     ("[Breakpoint REPL]" . "[Evaluator]")
 830     ("[Debugger REPL]" . "[Evaluator]")
 831     ("[Visiting environment]" . "[Evaluator]")
 832     ("[Environment Inspector]" . "[Where]"))
 833   "An alist which maps the Scheme command interpreter type to a print string.")
 834
 835 (defun xscheme-cd (directory-string)
 836   (save-excursion
 837     (set-buffer (xscheme-process-buffer))
 838     (cd directory-string)))
 839 \f
 840 (defun xscheme-prompt-for-confirmation (prompt-string)
 841   (xscheme-send-char (if (y-or-n-p prompt-string) ?y ?n)))
 842
 843 (defun xscheme-prompt-for-expression (prompt-string)
 844   (xscheme-send-string-2
 845    (read-from-minibuffer prompt-string nil xscheme-prompt-for-expression-map)))
 846
 847 (defvar xscheme-prompt-for-expression-map nil)
 848 (if (not xscheme-prompt-for-expression-map)
 849     (progn
 850       (setq xscheme-prompt-for-expression-map
 851             (copy-keymap minibuffer-local-map))
 852       (substitute-key-definition 'exit-minibuffer
 853                                  'xscheme-prompt-for-expression-exit
 854                                  xscheme-prompt-for-expression-map)))
 855
 856 (defun xscheme-prompt-for-expression-exit ()
 857   (interactive)
 858   (if (eq (xscheme-region-expression-p (point-min) (point-max)) 'one)
 859       (exit-minibuffer)
 860       (error "input must be a single, complete expression")))
 861
 862 (defun xscheme-region-expression-p (start end)
 863   (save-excursion
 864     (let ((old-syntax-table (syntax-table)))
 865       (unwind-protect
 866           (progn
 867             (set-syntax-table scheme-mode-syntax-table)
 868             (let ((state (parse-partial-sexp start end)))
 869               (and (zerop (car state))  ;depth = 0
 870                    (nth 2 state)        ;last-sexp exists, i.e. >= 1 sexps
 871                    (let ((state (parse-partial-sexp start (nth 2 state))))
 872                      (if (nth 2 state) 'many 'one)))))
 873         (set-syntax-table old-syntax-table)))))
 874
 875 (provide 'xscheme)
 876
 877 ;;; xscheme.el ends here