lisp/progmodes/scheme.el

   1 ;;; scheme.el --- Scheme mode, and its idiosyncratic commands.
   2
   3 ;; Copyright (C) 1986, 1987, 1988 Free Software Foundation, Inc.
   4
   5 ;; Author: Bill Rozas <jinz@prep.ai.mit.edu>
   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 ;; Adapted from Lisp mode by Bill Rozas, jinx@prep.
  27 ;; Initially a query replace of Lisp mode, except for the indentation
  28 ;; of special forms.  Probably the code should be merged at some point
  29 ;; so that there is sharing between both libraries.
  30
  31 ;;; Code:
  32 \f
  33 (defvar scheme-mode-syntax-table nil "")
  34 (if (not scheme-mode-syntax-table)
  35     (let ((i 0))
  36       (setq scheme-mode-syntax-table (make-syntax-table))
  37       (set-syntax-table scheme-mode-syntax-table)
  38
  39       ;; Default is atom-constituent.
  40       (while (< i 256)
  41         (modify-syntax-entry i "_   ")
  42         (setq i (1+ i)))
  43
  44       ;; Word components.
  45       (setq i ?0)
  46       (while (<= i ?9)
  47         (modify-syntax-entry i "w   ")
  48         (setq i (1+ i)))
  49       (setq i ?A)
  50       (while (<= i ?Z)
  51         (modify-syntax-entry i "w   ")
  52         (setq i (1+ i)))
  53       (setq i ?a)
  54       (while (<= i ?z)
  55         (modify-syntax-entry i "w   ")
  56         (setq i (1+ i)))
  57
  58       ;; Whitespace
  59       (modify-syntax-entry ?\t "    ")
  60       (modify-syntax-entry ?\n ">   ")
  61       (modify-syntax-entry ?\f "    ")
  62       (modify-syntax-entry ?\r "    ")
  63       (modify-syntax-entry ?  "    ")
  64
  65       ;; These characters are delimiters but otherwise undefined.
  66       ;; Brackets and braces balance for editing convenience.
  67       (modify-syntax-entry ?[ "(]  ")
  68       (modify-syntax-entry ?] ")[  ")
  69       (modify-syntax-entry ?{ "(}  ")
  70       (modify-syntax-entry ?} "){  ")
  71       (modify-syntax-entry ?\| "  23")
  72
  73       ;; Other atom delimiters
  74       (modify-syntax-entry ?\( "()  ")
  75       (modify-syntax-entry ?\) ")(  ")
  76       (modify-syntax-entry ?\; "<   ")
  77       (modify-syntax-entry ?\" "\"    ")
  78       (modify-syntax-entry ?' "  p")
  79       (modify-syntax-entry ?` "  p")
  80
  81       ;; Special characters
  82       (modify-syntax-entry ?, "_ p")
  83       (modify-syntax-entry ?@ "_ p")
  84       (modify-syntax-entry ?# "_ p14")
  85       (modify-syntax-entry ?\\ "\\   ")))
  86 \f
  87 (defvar scheme-mode-abbrev-table nil "")
  88 (define-abbrev-table 'scheme-mode-abbrev-table ())
  89
  90 (defun scheme-mode-variables ()
  91   (set-syntax-table scheme-mode-syntax-table)
  92   (setq local-abbrev-table scheme-mode-abbrev-table)
  93   (make-local-variable 'paragraph-start)
  94   (setq paragraph-start (concat "^$\\|" page-delimiter))
  95   (make-local-variable 'paragraph-separate)
  96   (setq paragraph-separate paragraph-start)
  97   (make-local-variable 'paragraph-ignore-fill-prefix)
  98   (setq paragraph-ignore-fill-prefix t)
  99   (make-local-variable 'indent-line-function)
 100   (setq indent-line-function 'scheme-indent-line)
 101   (make-local-variable 'comment-start)
 102   (setq comment-start ";")
 103   (make-local-variable 'comment-start-skip)
 104   (setq comment-start-skip ";+[ \t]*")
 105   (make-local-variable 'comment-column)
 106   (setq comment-column 40)
 107   (make-local-variable 'comment-indent-function)
 108   (setq comment-indent-function 'scheme-comment-indent)
 109   (setq mode-line-process '("" scheme-mode-line-process)))
 110
 111 (defvar scheme-mode-line-process "")
 112
 113 (defun scheme-mode-commands (map)
 114   (define-key map "\t" 'scheme-indent-line)
 115   (define-key map "\177" 'backward-delete-char-untabify)
 116   (define-key map "\e\C-q" 'scheme-indent-sexp))
 117
 118 (defvar scheme-mode-map nil)
 119 (if (not scheme-mode-map)
 120     (progn
 121       (setq scheme-mode-map (make-sparse-keymap))
 122       (scheme-mode-commands scheme-mode-map)))
 123 \f
 124 ;;;###autoload
 125 (defun scheme-mode ()
 126   "Major mode for editing Scheme code.
 127 Editing commands are similar to those of lisp-mode.
 128
 129 In addition, if an inferior Scheme process is running, some additional
 130 commands will be defined, for evaluating expressions and controlling
 131 the interpreter, and the state of the process will be displayed in the
 132 modeline of all Scheme buffers.  The names of commands that interact
 133 with the Scheme process start with \"xscheme-\".  For more information
 134 see the documentation for xscheme-interaction-mode.
 135
 136 Commands:
 137 Delete converts tabs to spaces as it moves back.
 138 Blank lines separate paragraphs.  Semicolons start comments.
 139 \\{scheme-mode-map}
 140 Entry to this mode calls the value of scheme-mode-hook
 141 if that value is non-nil."
 142   (interactive)
 143   (kill-all-local-variables)
 144   (scheme-mode-initialize)
 145   (scheme-mode-variables)
 146   (run-hooks 'scheme-mode-hook))
 147
 148 (defun scheme-mode-initialize ()
 149   (use-local-map scheme-mode-map)
 150   (setq major-mode 'scheme-mode)
 151   (setq mode-name "Scheme"))
 152
 153 (defvar scheme-mit-dialect t
 154   "If non-nil, scheme mode is specialized for MIT Scheme.
 155 Set this to nil if you normally use another dialect.")
 156 \f
 157 (defun scheme-comment-indent (&optional pos)
 158   (save-excursion
 159     (if pos (goto-char pos))
 160     (cond ((looking-at ";;;") (current-column))
 161           ((looking-at ";;")
 162            (let ((tem (calculate-scheme-indent)))
 163              (if (listp tem) (car tem) tem)))
 164           (t
 165            (skip-chars-backward " \t")
 166            (max (if (bolp) 0 (1+ (current-column)))
 167                 comment-column)))))
 168
 169 (defvar scheme-indent-offset nil "")
 170 (defvar scheme-indent-function 'scheme-indent-function "")
 171
 172 (defun scheme-indent-line (&optional whole-exp)
 173   "Indent current line as Scheme code.
 174 With argument, indent any additional lines of the same expression
 175 rigidly along with this one."
 176   (interactive "P")
 177   (let ((indent (calculate-scheme-indent)) shift-amt beg end
 178         (pos (- (point-max) (point))))
 179     (beginning-of-line)
 180     (setq beg (point))
 181     (skip-chars-forward " \t")
 182     (if (looking-at "[ \t]*;;;")
 183         ;; Don't alter indentation of a ;;; comment line.
 184         nil
 185       (if (listp indent) (setq indent (car indent)))
 186       (setq shift-amt (- indent (current-column)))
 187       (if (zerop shift-amt)
 188           nil
 189         (delete-region beg (point))
 190         (indent-to indent))
 191       ;; If initial point was within line's indentation,
 192       ;; position after the indentation.  Else stay at same point in text.
 193       (if (> (- (point-max) pos) (point))
 194           (goto-char (- (point-max) pos)))
 195       ;; If desired, shift remaining lines of expression the same amount.
 196       (and whole-exp (not (zerop shift-amt))
 197            (save-excursion
 198              (goto-char beg)
 199              (forward-sexp 1)
 200              (setq end (point))
 201              (goto-char beg)
 202              (forward-line 1)
 203              (setq beg (point))
 204              (> end beg))
 205            (indent-code-rigidly beg end shift-amt)))))
 206 \f
 207 (defun calculate-scheme-indent (&optional parse-start)
 208   "Return appropriate indentation for current line as scheme code.
 209 In usual case returns an integer: the column to indent to.
 210 Can instead return a list, whose car is the column to indent to.
 211 This means that following lines at the same level of indentation
 212 should not necessarily be indented the same way.
 213 The second element of the list is the buffer position
 214 of the start of the containing expression."
 215   (save-excursion
 216     (beginning-of-line)
 217     (let ((indent-point (point)) state paren-depth desired-indent (retry t)
 218           last-sexp containing-sexp first-sexp-list-p)
 219       (if parse-start
 220           (goto-char parse-start)
 221         (beginning-of-defun))
 222       ;; Find outermost containing sexp
 223       (while (< (point) indent-point)
 224         (setq state (parse-partial-sexp (point) indent-point 0)))
 225       ;; Find innermost containing sexp
 226       (while (and retry (setq paren-depth (car state)) (> paren-depth 0))
 227         (setq retry nil)
 228         (setq last-sexp (nth 2 state))
 229         (setq containing-sexp (car (cdr state)))
 230         ;; Position following last unclosed open.
 231         (goto-char (1+ containing-sexp))
 232         ;; Is there a complete sexp since then?
 233         (if (and last-sexp (> last-sexp (point)))
 234             ;; Yes, but is there a containing sexp after that?
 235             (let ((peek (parse-partial-sexp last-sexp indent-point 0)))
 236               (if (setq retry (car (cdr peek))) (setq state peek))))
 237         (if (not retry)
 238             ;; Innermost containing sexp found
 239             (progn
 240               (goto-char (1+ containing-sexp))
 241               (if (not last-sexp)
 242                   ;; indent-point immediately follows open paren.
 243                   ;; Don't call hook.
 244                   (setq desired-indent (current-column))
 245                 ;; Move to first sexp after containing open paren
 246                 (parse-partial-sexp (point) last-sexp 0 t)
 247                 (setq first-sexp-list-p (looking-at "\\s("))
 248                 (cond
 249                  ((> (save-excursion (forward-line 1) (point))
 250                      last-sexp)
 251                   ;; Last sexp is on same line as containing sexp.
 252                   ;; It's almost certainly a function call.
 253                   (parse-partial-sexp (point) last-sexp 0 t)
 254                   (if (/= (point) last-sexp)
 255                       ;; Indent beneath first argument or, if only one sexp
 256                       ;; on line, indent beneath that.
 257                       (progn (forward-sexp 1)
 258                              (parse-partial-sexp (point) last-sexp 0 t)))
 259                   (backward-prefix-chars))
 260                  (t
 261                   ;; Indent beneath first sexp on same line as last-sexp.
 262                   ;; Again, it's almost certainly a function call.
 263                   (goto-char last-sexp)
 264                   (beginning-of-line)
 265                   (parse-partial-sexp (point) last-sexp 0 t)
 266                   (backward-prefix-chars)))))))
 267       ;; If looking at a list, don't call hook.
 268       (if first-sexp-list-p
 269           (setq desired-indent (current-column)))
 270       ;; Point is at the point to indent under unless we are inside a string.
 271       ;; Call indentation hook except when overriden by scheme-indent-offset
 272       ;; or if the desired indentation has already been computed.
 273       (cond ((car (nthcdr 3 state))
 274              ;; Inside a string, don't change indentation.
 275              (goto-char indent-point)
 276              (skip-chars-forward " \t")
 277              (setq desired-indent (current-column)))
 278             ((and (integerp scheme-indent-offset) containing-sexp)
 279              ;; Indent by constant offset
 280              (goto-char containing-sexp)
 281              (setq desired-indent (+ scheme-indent-offset (current-column))))
 282             ((not (or desired-indent
 283                       (and (boundp 'scheme-indent-function)
 284                            scheme-indent-function
 285                            (not retry)
 286                            (setq desired-indent
 287                                  (funcall scheme-indent-function
 288                                           indent-point state)))))
 289              ;; Use default indentation if not computed yet
 290              (setq desired-indent (current-column))))
 291       desired-indent)))
 292 \f
 293 (defun scheme-indent-function (indent-point state)
 294   (let ((normal-indent (current-column)))
 295     (save-excursion
 296       (goto-char (1+ (car (cdr state))))
 297       (re-search-forward "\\sw\\|\\s_")
 298       (if (/= (point) (car (cdr state)))
 299           (let ((function (buffer-substring (progn (forward-char -1) (point))
 300                                             (progn (forward-sexp 1) (point))))
 301                 method)
 302             ;; Who cares about this, really?
 303             ;(if (not (string-match "\\\\\\||" function)))
 304             (setq function (downcase function))
 305             (setq method (get (intern-soft function) 'scheme-indent-function))
 306             (cond ((integerp method)
 307                    (scheme-indent-specform method state indent-point))
 308                   (method
 309                    (funcall method state indent-point))
 310                   ((and (> (length function) 3)
 311                         (string-equal (substring function 0 3) "def"))
 312                    (scheme-indent-defform state indent-point))))))))
 313
 314 (defvar scheme-body-indent 2 "")
 315 \f
 316 (defun scheme-indent-specform (count state indent-point)
 317   (let ((containing-form-start (car (cdr state))) (i count)
 318         body-indent containing-form-column)
 319     ;; Move to the start of containing form, calculate indentation
 320     ;; to use for non-distinguished forms (> count), and move past the
 321     ;; function symbol.  scheme-indent-function guarantees that there is at
 322     ;; least one word or symbol character following open paren of containing
 323     ;; form.
 324     (goto-char containing-form-start)
 325     (setq containing-form-column (current-column))
 326     (setq body-indent (+ scheme-body-indent containing-form-column))
 327     (forward-char 1)
 328     (forward-sexp 1)
 329     ;; Now find the start of the last form.
 330     (parse-partial-sexp (point) indent-point 1 t)
 331     (while (and (< (point) indent-point)
 332                 (condition-case nil
 333                     (progn
 334                       (setq count (1- count))
 335                       (forward-sexp 1)
 336                       (parse-partial-sexp (point) indent-point 1 t))
 337                   (error nil))))
 338     ;; Point is sitting on first character of last (or count) sexp.
 339     (cond ((> count 0)
 340            ;; A distinguished form.  Use double scheme-body-indent.
 341            (list (+ containing-form-column (* 2 scheme-body-indent))
 342                  containing-form-start))
 343           ;; A non-distinguished form. Use body-indent if there are no
 344           ;; distinguished forms and this is the first undistinguished
 345           ;; form, or if this is the first undistinguished form and
 346           ;; the preceding distinguished form has indentation at least
 347           ;; as great as body-indent.
 348           ((and (= count 0)
 349                 (or (= i 0)
 350                     (<= body-indent normal-indent)))
 351            body-indent)
 352           (t
 353            normal-indent))))
 354
 355 (defun scheme-indent-defform (state indent-point)
 356   (goto-char (car (cdr state)))
 357   (forward-line 1)
 358   (if (> (point) (car (cdr (cdr state))))
 359       (progn
 360         (goto-char (car (cdr state)))
 361         (+ scheme-body-indent (current-column)))))
 362 \f
 363 ;;; Let is different in Scheme
 364
 365 (defun would-be-symbol (string)
 366   (not (string-equal (substring string 0 1) "(")))
 367
 368 (defun next-sexp-as-string ()
 369   ;; Assumes that protected by a save-excursion
 370   (forward-sexp 1)
 371   (let ((the-end (point)))
 372     (backward-sexp 1)
 373     (buffer-substring (point) the-end)))
 374
 375 ;; This is correct but too slow.
 376 ;; The one below works almost always.
 377 ;;(defun scheme-let-indent (state indent-point)
 378 ;;  (if (would-be-symbol (next-sexp-as-string))
 379 ;;      (scheme-indent-specform 2 state indent-point)
 380 ;;      (scheme-indent-specform 1 state indent-point)))
 381
 382 (defun scheme-let-indent (state indent-point)
 383   (skip-chars-forward " \t")
 384   (if (looking-at "[a-zA-Z0-9+-*/?!@$%^&_:~]")
 385       (scheme-indent-specform 2 state indent-point)
 386       (scheme-indent-specform 1 state indent-point)))
 387
 388 ;; (put 'begin 'scheme-indent-function 0), say, causes begin to be indented
 389 ;; like defun if the first form is placed on the next line, otherwise
 390 ;; it is indented like any other form (i.e. forms line up under first).
 391
 392 (put 'begin 'scheme-indent-function 0)
 393 (put 'case 'scheme-indent-function 1)
 394 (put 'delay 'scheme-indent-function 0)
 395 (put 'do 'scheme-indent-function 2)
 396 (put 'lambda 'scheme-indent-function 1)
 397 (put 'let 'scheme-indent-function 'scheme-let-indent)
 398 (put 'let* 'scheme-indent-function 1)
 399 (put 'letrec 'scheme-indent-function 1)
 400 (put 'sequence 'scheme-indent-function 0)
 401
 402 (put 'call-with-input-file 'scheme-indent-function 1)
 403 (put 'with-input-from-file 'scheme-indent-function 1)
 404 (put 'with-input-from-port 'scheme-indent-function 1)
 405 (put 'call-with-output-file 'scheme-indent-function 1)
 406 (put 'with-output-to-file 'scheme-indent-function 1)
 407 (put 'with-output-to-port 'scheme-indent-function 1)
 408 \f
 409 ;;;; MIT Scheme specific indentation.
 410
 411 (if scheme-mit-dialect
 412     (progn
 413       (put 'fluid-let 'scheme-indent-function 1)
 414       (put 'in-package 'scheme-indent-function 1)
 415       (put 'let-syntax 'scheme-indent-function 1)
 416       (put 'local-declare 'scheme-indent-function 1)
 417       (put 'macro 'scheme-indent-function 1)
 418       (put 'make-environment 'scheme-indent-function 0)
 419       (put 'named-lambda 'scheme-indent-function 1)
 420       (put 'using-syntax 'scheme-indent-function 1)
 421
 422       (put 'with-input-from-string 'scheme-indent-function 1)
 423       (put 'with-output-to-string 'scheme-indent-function 0)
 424       (put 'with-values 'scheme-indent-function 1)
 425
 426       (put 'syntax-table-define 'scheme-indent-function 2)
 427       (put 'list-transform-positive 'scheme-indent-function 1)
 428       (put 'list-transform-negative 'scheme-indent-function 1)
 429       (put 'list-search-positive 'scheme-indent-function 1)
 430       (put 'list-search-negative 'scheme-indent-function 1)
 431
 432       (put 'access-components 'scheme-indent-function 1)
 433       (put 'assignment-components 'scheme-indent-function 1)
 434       (put 'combination-components 'scheme-indent-function 1)
 435       (put 'comment-components 'scheme-indent-function 1)
 436       (put 'conditional-components 'scheme-indent-function 1)
 437       (put 'disjunction-components 'scheme-indent-function 1)
 438       (put 'declaration-components 'scheme-indent-function 1)
 439       (put 'definition-components 'scheme-indent-function 1)
 440       (put 'delay-components 'scheme-indent-function 1)
 441       (put 'in-package-components 'scheme-indent-function 1)
 442       (put 'lambda-components 'scheme-indent-function 1)
 443       (put 'lambda-components* 'scheme-indent-function 1)
 444       (put 'lambda-components** 'scheme-indent-function 1)
 445       (put 'open-block-components 'scheme-indent-function 1)
 446       (put 'pathname-components 'scheme-indent-function 1)
 447       (put 'procedure-components 'scheme-indent-function 1)
 448       (put 'sequence-components 'scheme-indent-function 1)
 449       (put 'unassigned\?-components 'scheme-indent-function 1)
 450       (put 'unbound\?-components 'scheme-indent-function 1)
 451       (put 'variable-components 'scheme-indent-function 1)))
 452 \f
 453 (defun scheme-indent-sexp ()
 454   "Indent each line of the list starting just after point."
 455   (interactive)
 456   (let ((indent-stack (list nil)) (next-depth 0) bol
 457         outer-loop-done inner-loop-done state this-indent)
 458     (save-excursion (forward-sexp 1))
 459     (save-excursion
 460       (setq outer-loop-done nil)
 461       (while (not outer-loop-done)
 462         (setq last-depth next-depth
 463               innerloop-done nil)
 464         (while (and (not innerloop-done)
 465                     (not (setq outer-loop-done (eobp))))
 466           (setq state (parse-partial-sexp (point) (progn (end-of-line) (point))
 467                                           nil nil state))
 468           (setq next-depth (car state))
 469           (if (car (nthcdr 4 state))
 470               (progn (indent-for-comment)
 471                      (end-of-line)
 472                      (setcar (nthcdr 4 state) nil)))
 473           (if (car (nthcdr 3 state))
 474               (progn
 475                 (forward-line 1)
 476                 (setcar (nthcdr 5 state) nil))
 477             (setq innerloop-done t)))
 478         (if (setq outer-loop-done (<= next-depth 0))
 479             nil
 480           (while (> last-depth next-depth)
 481             (setq indent-stack (cdr indent-stack)
 482                   last-depth (1- last-depth)))
 483           (while (< last-depth next-depth)
 484             (setq indent-stack (cons nil indent-stack)
 485                   last-depth (1+ last-depth)))
 486           (forward-line 1)
 487           (setq bol (point))
 488           (skip-chars-forward " \t")
 489           (if (or (eobp) (looking-at "[;\n]"))
 490               nil
 491             (if (and (car indent-stack)
 492                      (>= (car indent-stack) 0))
 493                 (setq this-indent (car indent-stack))
 494               (let ((val (calculate-scheme-indent
 495                           (if (car indent-stack) (- (car indent-stack))))))
 496                 (if (integerp val)
 497                     (setcar indent-stack
 498                             (setq this-indent val))
 499                   (setcar indent-stack (- (car (cdr val))))
 500                   (setq this-indent (car val)))))
 501             (if (/= (current-column) this-indent)
 502                 (progn (delete-region bol (point))
 503                        (indent-to this-indent)))))))))
 504
 505 (provide 'scheme)
 506
 507 ;;; scheme.el ends here