lisp/progmodes/scheme.el

   1 ;;; scheme.el --- Scheme mode, and its idiosyncratic commands.
   2
   3 ;; Author: Bill Rozas <jinz@prep.ai.mit.edu>
   4 ;; Last-Modified: 16 Mar 1992
   5
   6 ;;; $Header: scheme.el,v 1.7 88/07/15 20:20:00 GMT cph Exp $
   7
   8 ;; Copyright (C) 1986, 1987, 1988 Free Software Foundation, Inc.
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  24 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; Adapted from Lisp mode by Bill Rozas, jinx@prep.
  29 ;; Initially a query replace of Lisp mode, except for the indentation
  30 ;; of special forms.  Probably the code should be merged at some point
  31 ;; so that there is sharing between both libraries.
  32
  33 ;;; Code:
  34 \f
  35 (defvar scheme-mode-syntax-table nil "")
  36 (if (not scheme-mode-syntax-table)
  37     (let ((i 0))
  38       (setq scheme-mode-syntax-table (make-syntax-table))
  39       (set-syntax-table scheme-mode-syntax-table)
  40
  41       ;; Default is atom-constituent.
  42       (while (< i 256)
  43         (modify-syntax-entry i "_   ")
  44         (setq i (1+ i)))
  45
  46       ;; Word components.
  47       (setq i ?0)
  48       (while (<= i ?9)
  49         (modify-syntax-entry i "w   ")
  50         (setq i (1+ i)))
  51       (setq i ?A)
  52       (while (<= i ?Z)
  53         (modify-syntax-entry i "w   ")
  54         (setq i (1+ i)))
  55       (setq i ?a)
  56       (while (<= i ?z)
  57         (modify-syntax-entry i "w   ")
  58         (setq i (1+ i)))
  59
  60       ;; Whitespace
  61       (modify-syntax-entry ?\t "    ")
  62       (modify-syntax-entry ?\n ">   ")
  63       (modify-syntax-entry ?\f "    ")
  64       (modify-syntax-entry ?\r "    ")
  65       (modify-syntax-entry ?  "    ")
  66
  67       ;; These characters are delimiters but otherwise undefined.
  68       ;; Brackets and braces balance for editing convenience.
  69       (modify-syntax-entry ?[ "(]  ")
  70       (modify-syntax-entry ?] ")[  ")
  71       (modify-syntax-entry ?{ "(}  ")
  72       (modify-syntax-entry ?} "){  ")
  73       (modify-syntax-entry ?\| "  23")
  74
  75       ;; Other atom delimiters
  76       (modify-syntax-entry ?\( "()  ")
  77       (modify-syntax-entry ?\) ")(  ")
  78       (modify-syntax-entry ?\; "<   ")
  79       (modify-syntax-entry ?\" "\"    ")
  80       (modify-syntax-entry ?' "  p")
  81       (modify-syntax-entry ?` "  p")
  82
  83       ;; Special characters
  84       (modify-syntax-entry ?, "_ p")
  85       (modify-syntax-entry ?@ "_ p")
  86       (modify-syntax-entry ?# "_ p14")
  87       (modify-syntax-entry ?\\ "\\   ")))
  88 \f
  89 (defvar scheme-mode-abbrev-table nil "")
  90 (define-abbrev-table 'scheme-mode-abbrev-table ())
  91
  92 (defun scheme-mode-variables ()
  93   (set-syntax-table scheme-mode-syntax-table)
  94   (setq local-abbrev-table scheme-mode-abbrev-table)
  95   (make-local-variable 'paragraph-start)
  96   (setq paragraph-start (concat "^$\\|" page-delimiter))
  97   (make-local-variable 'paragraph-separate)
  98   (setq paragraph-separate paragraph-start)
  99   (make-local-variable 'paragraph-ignore-fill-prefix)
 100   (setq paragraph-ignore-fill-prefix t)
 101   (make-local-variable 'indent-line-function)
 102   (setq indent-line-function 'scheme-indent-line)
 103   (make-local-variable 'comment-start)
 104   (setq comment-start ";")
 105   (make-local-variable 'comment-start-skip)
 106   (setq comment-start-skip ";+[ \t]*")
 107   (make-local-variable 'comment-column)
 108   (setq comment-column 40)
 109   (make-local-variable 'comment-indent-hook)
 110   (setq comment-indent-hook 'scheme-comment-indent)
 111   (setq mode-line-process '("" scheme-mode-line-process)))
 112
 113 (defvar scheme-mode-line-process "")
 114
 115 (defun scheme-mode-commands (map)
 116   (define-key map "\t" 'scheme-indent-line)
 117   (define-key map "\177" 'backward-delete-char-untabify)
 118   (define-key map "\e\C-q" 'scheme-indent-sexp))
 119
 120 (defvar scheme-mode-map nil)
 121 (if (not scheme-mode-map)
 122     (progn
 123       (setq scheme-mode-map (make-sparse-keymap))
 124       (scheme-mode-commands scheme-mode-map)))
 125 \f
 126 ;;;###autoload
 127 (defun scheme-mode ()
 128   "Major mode for editing Scheme code.
 129 Editing commands are similar to those of lisp-mode.
 130
 131 In addition, if an inferior Scheme process is running, some additional
 132 commands will be defined, for evaluating expressions and controlling
 133 the interpreter, and the state of the process will be displayed in the
 134 modeline of all Scheme buffers.  The names of commands that interact
 135 with the Scheme process start with \"xscheme-\".  For more information
 136 see the documentation for xscheme-interaction-mode.
 137
 138 Commands:
 139 Delete converts tabs to spaces as it moves back.
 140 Blank lines separate paragraphs.  Semicolons start comments.
 141 \\{scheme-mode-map}
 142 Entry to this mode calls the value of scheme-mode-hook
 143 if that value is non-nil."
 144   (interactive)
 145   (kill-all-local-variables)
 146   (scheme-mode-initialize)
 147   (scheme-mode-variables)
 148   (run-hooks 'scheme-mode-hook))
 149
 150 (defun scheme-mode-initialize ()
 151   (use-local-map scheme-mode-map)
 152   (setq major-mode 'scheme-mode)
 153   (setq mode-name "Scheme"))
 154
 155 (defvar scheme-mit-dialect t
 156   "If non-nil, scheme mode is specialized for MIT Scheme.
 157 Set this to nil if you normally use another dialect.")
 158 \f
 159 (defun scheme-comment-indent (&optional pos)
 160   (save-excursion
 161     (if pos (goto-char pos))
 162     (cond ((looking-at ";;;") (current-column))
 163           ((looking-at ";;")
 164            (let ((tem (calculate-scheme-indent)))
 165              (if (listp tem) (car tem) tem)))
 166           (t
 167            (skip-chars-backward " \t")
 168            (max (if (bolp) 0 (1+ (current-column)))
 169                 comment-column)))))
 170
 171 (defvar scheme-indent-offset nil "")
 172 (defvar scheme-indent-function 'scheme-indent-function "")
 173
 174 (defun scheme-indent-line (&optional whole-exp)
 175   "Indent current line as Scheme code.
 176 With argument, indent any additional lines of the same expression
 177 rigidly along with this one."
 178   (interactive "P")
 179   (let ((indent (calculate-scheme-indent)) shift-amt beg end
 180         (pos (- (point-max) (point))))
 181     (beginning-of-line)
 182     (setq beg (point))
 183     (skip-chars-forward " \t")
 184     (if (looking-at "[ \t]*;;;")
 185         ;; Don't alter indentation of a ;;; comment line.
 186         nil
 187       (if (listp indent) (setq indent (car indent)))
 188       (setq shift-amt (- indent (current-column)))
 189       (if (zerop shift-amt)
 190           nil
 191         (delete-region beg (point))
 192         (indent-to indent))
 193       ;; If initial point was within line's indentation,
 194       ;; position after the indentation.  Else stay at same point in text.
 195       (if (> (- (point-max) pos) (point))
 196           (goto-char (- (point-max) pos)))
 197       ;; If desired, shift remaining lines of expression the same amount.
 198       (and whole-exp (not (zerop shift-amt))
 199            (save-excursion
 200              (goto-char beg)
 201              (forward-sexp 1)
 202              (setq end (point))
 203              (goto-char beg)
 204              (forward-line 1)
 205              (setq beg (point))
 206              (> end beg))
 207            (indent-code-rigidly beg end shift-amt)))))
 208 \f
 209 (defun calculate-scheme-indent (&optional parse-start)
 210   "Return appropriate indentation for current line as scheme code.
 211 In usual case returns an integer: the column to indent to.
 212 Can instead return a list, whose car is the column to indent to.
 213 This means that following lines at the same level of indentation
 214 should not necessarily be indented the same way.
 215 The second element of the list is the buffer position
 216 of the start of the containing expression."
 217   (save-excursion
 218     (beginning-of-line)
 219     (let ((indent-point (point)) state paren-depth desired-indent (retry t)
 220           last-sexp containing-sexp first-sexp-list-p)
 221       (if parse-start
 222           (goto-char parse-start)
 223         (beginning-of-defun))
 224       ;; Find outermost containing sexp
 225       (while (< (point) indent-point)
 226         (setq state (parse-partial-sexp (point) indent-point 0)))
 227       ;; Find innermost containing sexp
 228       (while (and retry (setq paren-depth (car state)) (> paren-depth 0))
 229         (setq retry nil)
 230         (setq last-sexp (nth 2 state))
 231         (setq containing-sexp (car (cdr state)))
 232         ;; Position following last unclosed open.
 233         (goto-char (1+ containing-sexp))
 234         ;; Is there a complete sexp since then?
 235         (if (and last-sexp (> last-sexp (point)))
 236             ;; Yes, but is there a containing sexp after that?
 237             (let ((peek (parse-partial-sexp last-sexp indent-point 0)))
 238               (if (setq retry (car (cdr peek))) (setq state peek))))
 239         (if (not retry)
 240             ;; Innermost containing sexp found
 241             (progn
 242               (goto-char (1+ containing-sexp))
 243               (if (not last-sexp)
 244                   ;; indent-point immediately follows open paren.
 245                   ;; Don't call hook.
 246                   (setq desired-indent (current-column))
 247                 ;; Move to first sexp after containing open paren
 248                 (parse-partial-sexp (point) last-sexp 0 t)
 249                 (setq first-sexp-list-p (looking-at "\\s("))
 250                 (cond
 251                  ((> (save-excursion (forward-line 1) (point))
 252                      last-sexp)
 253                   ;; Last sexp is on same line as containing sexp.
 254                   ;; It's almost certainly a function call.
 255                   (parse-partial-sexp (point) last-sexp 0 t)
 256                   (if (/= (point) last-sexp)
 257                       ;; Indent beneath first argument or, if only one sexp
 258                       ;; on line, indent beneath that.
 259                       (progn (forward-sexp 1)
 260                              (parse-partial-sexp (point) last-sexp 0 t)))
 261                   (backward-prefix-chars))
 262                  (t
 263                   ;; Indent beneath first sexp on same line as last-sexp.
 264                   ;; Again, it's almost certainly a function call.
 265                   (goto-char last-sexp)
 266                   (beginning-of-line)
 267                   (parse-partial-sexp (point) last-sexp 0 t)
 268                   (backward-prefix-chars)))))))
 269       ;; If looking at a list, don't call hook.
 270       (if first-sexp-list-p
 271           (setq desired-indent (current-column)))
 272       ;; Point is at the point to indent under unless we are inside a string.
 273       ;; Call indentation hook except when overriden by scheme-indent-offset
 274       ;; or if the desired indentation has already been computed.
 275       (cond ((car (nthcdr 3 state))
 276              ;; Inside a string, don't change indentation.
 277              (goto-char indent-point)
 278              (skip-chars-forward " \t")
 279              (setq desired-indent (current-column)))
 280             ((and (integerp scheme-indent-offset) containing-sexp)
 281              ;; Indent by constant offset
 282              (goto-char containing-sexp)
 283              (setq desired-indent (+ scheme-indent-offset (current-column))))
 284             ((not (or desired-indent
 285                       (and (boundp 'scheme-indent-function)
 286                            scheme-indent-function
 287                            (not retry)
 288                            (setq desired-indent
 289                                  (funcall scheme-indent-function
 290                                           indent-point state)))))
 291              ;; Use default indentation if not computed yet
 292              (setq desired-indent (current-column))))
 293       desired-indent)))
 294 \f
 295 (defun scheme-indent-function (indent-point state)
 296   (let ((normal-indent (current-column)))
 297     (save-excursion
 298       (goto-char (1+ (car (cdr state))))
 299       (re-search-forward "\\sw\\|\\s_")
 300       (if (/= (point) (car (cdr state)))
 301           (let ((function (buffer-substring (progn (forward-char -1) (point))
 302                                             (progn (forward-sexp 1) (point))))
 303                 method)
 304             ;; Who cares about this, really?
 305             ;(if (not (string-match "\\\\\\||" function)))
 306             (setq function (downcase function))
 307             (setq method (get (intern-soft function) 'scheme-indent-function))
 308             (cond ((integerp method)
 309                    (scheme-indent-specform method state indent-point))
 310                   (method
 311                    (funcall method state indent-point))
 312                   ((and (> (length function) 3)
 313                         (string-equal (substring function 0 3) "def"))
 314                    (scheme-indent-defform state indent-point))))))))
 315
 316 (defvar scheme-body-indent 2 "")
 317 \f
 318 (defun scheme-indent-specform (count state indent-point)
 319   (let ((containing-form-start (car (cdr state))) (i count)
 320         body-indent containing-form-column)
 321     ;; Move to the start of containing form, calculate indentation
 322     ;; to use for non-distinguished forms (> count), and move past the
 323     ;; function symbol.  scheme-indent-function guarantees that there is at
 324     ;; least one word or symbol character following open paren of containing
 325     ;; form.
 326     (goto-char containing-form-start)
 327     (setq containing-form-column (current-column))
 328     (setq body-indent (+ scheme-body-indent containing-form-column))
 329     (forward-char 1)
 330     (forward-sexp 1)
 331     ;; Now find the start of the last form.
 332     (parse-partial-sexp (point) indent-point 1 t)
 333     (while (and (< (point) indent-point)
 334                 (condition-case nil
 335                     (progn
 336                       (setq count (1- count))
 337                       (forward-sexp 1)
 338                       (parse-partial-sexp (point) indent-point 1 t))
 339                   (error nil))))
 340     ;; Point is sitting on first character of last (or count) sexp.
 341     (cond ((> count 0)
 342            ;; A distinguished form.  Use double scheme-body-indent.
 343            (list (+ containing-form-column (* 2 scheme-body-indent))
 344                  containing-form-start))
 345           ;; A non-distinguished form. Use body-indent if there are no
 346           ;; distinguished forms and this is the first undistinguished
 347           ;; form, or if this is the first undistinguished form and
 348           ;; the preceding distinguished form has indentation at least
 349           ;; as great as body-indent.
 350           ((and (= count 0)
 351                 (or (= i 0)
 352                     (<= body-indent normal-indent)))
 353            body-indent)
 354           (t
 355            normal-indent))))
 356
 357 (defun scheme-indent-defform (state indent-point)
 358   (goto-char (car (cdr state)))
 359   (forward-line 1)
 360   (if (> (point) (car (cdr (cdr state))))
 361       (progn
 362         (goto-char (car (cdr state)))
 363         (+ scheme-body-indent (current-column)))))
 364 \f
 365 ;;; Let is different in Scheme
 366
 367 (defun would-be-symbol (string)
 368   (not (string-equal (substring string 0 1) "(")))
 369
 370 (defun next-sexp-as-string ()
 371   ;; Assumes that protected by a save-excursion
 372   (forward-sexp 1)
 373   (let ((the-end (point)))
 374     (backward-sexp 1)
 375     (buffer-substring (point) the-end)))
 376
 377 ;; This is correct but too slow.
 378 ;; The one below works almost always.
 379 ;;(defun scheme-let-indent (state indent-point)
 380 ;;  (if (would-be-symbol (next-sexp-as-string))
 381 ;;      (scheme-indent-specform 2 state indent-point)
 382 ;;      (scheme-indent-specform 1 state indent-point)))
 383
 384 (defun scheme-let-indent (state indent-point)
 385   (skip-chars-forward " \t")
 386   (if (looking-at "[a-zA-Z0-9+-*/?!@$%^&_:~]")
 387       (scheme-indent-specform 2 state indent-point)
 388       (scheme-indent-specform 1 state indent-point)))
 389
 390 ;; (put 'begin 'scheme-indent-function 0), say, causes begin to be indented
 391 ;; like defun if the first form is placed on the next line, otherwise
 392 ;; it is indented like any other form (i.e. forms line up under first).
 393
 394 (put 'begin 'scheme-indent-function 0)
 395 (put 'case 'scheme-indent-function 1)
 396 (put 'delay 'scheme-indent-function 0)
 397 (put 'do 'scheme-indent-function 2)
 398 (put 'lambda 'scheme-indent-function 1)
 399 (put 'let 'scheme-indent-function 'scheme-let-indent)
 400 (put 'let* 'scheme-indent-function 1)
 401 (put 'letrec 'scheme-indent-function 1)
 402 (put 'sequence 'scheme-indent-function 0)
 403
 404 (put 'call-with-input-file 'scheme-indent-function 1)
 405 (put 'with-input-from-file 'scheme-indent-function 1)
 406 (put 'with-input-from-port 'scheme-indent-function 1)
 407 (put 'call-with-output-file 'scheme-indent-function 1)
 408 (put 'with-output-to-file 'scheme-indent-function 1)
 409 (put 'with-output-to-port 'scheme-indent-function 1)
 410 \f
 411 ;;;; MIT Scheme specific indentation.
 412
 413 (if scheme-mit-dialect
 414     (progn
 415       (put 'fluid-let 'scheme-indent-function 1)
 416       (put 'in-package 'scheme-indent-function 1)
 417       (put 'let-syntax 'scheme-indent-function 1)
 418       (put 'local-declare 'scheme-indent-function 1)
 419       (put 'macro 'scheme-indent-function 1)
 420       (put 'make-environment 'scheme-indent-function 0)
 421       (put 'named-lambda 'scheme-indent-function 1)
 422       (put 'using-syntax 'scheme-indent-function 1)
 423
 424       (put 'with-input-from-string 'scheme-indent-function 1)
 425       (put 'with-output-to-string 'scheme-indent-function 0)
 426       (put 'with-values 'scheme-indent-function 1)
 427
 428       (put 'syntax-table-define 'scheme-indent-function 2)
 429       (put 'list-transform-positive 'scheme-indent-function 1)
 430       (put 'list-transform-negative 'scheme-indent-function 1)
 431       (put 'list-search-positive 'scheme-indent-function 1)
 432       (put 'list-search-negative 'scheme-indent-function 1)
 433
 434       (put 'access-components 'scheme-indent-function 1)
 435       (put 'assignment-components 'scheme-indent-function 1)
 436       (put 'combination-components 'scheme-indent-function 1)
 437       (put 'comment-components 'scheme-indent-function 1)
 438       (put 'conditional-components 'scheme-indent-function 1)
 439       (put 'disjunction-components 'scheme-indent-function 1)
 440       (put 'declaration-components 'scheme-indent-function 1)
 441       (put 'definition-components 'scheme-indent-function 1)
 442       (put 'delay-components 'scheme-indent-function 1)
 443       (put 'in-package-components 'scheme-indent-function 1)
 444       (put 'lambda-components 'scheme-indent-function 1)
 445       (put 'lambda-components* 'scheme-indent-function 1)
 446       (put 'lambda-components** 'scheme-indent-function 1)
 447       (put 'open-block-components 'scheme-indent-function 1)
 448       (put 'pathname-components 'scheme-indent-function 1)
 449       (put 'procedure-components 'scheme-indent-function 1)
 450       (put 'sequence-components 'scheme-indent-function 1)
 451       (put 'unassigned\?-components 'scheme-indent-function 1)
 452       (put 'unbound\?-components 'scheme-indent-function 1)
 453       (put 'variable-components 'scheme-indent-function 1)))
 454 \f
 455 (defun scheme-indent-sexp ()
 456   "Indent each line of the list starting just after point."
 457   (interactive)
 458   (let ((indent-stack (list nil)) (next-depth 0) bol
 459         outer-loop-done inner-loop-done state this-indent)
 460     (save-excursion (forward-sexp 1))
 461     (save-excursion
 462       (setq outer-loop-done nil)
 463       (while (not outer-loop-done)
 464         (setq last-depth next-depth
 465               innerloop-done nil)
 466         (while (and (not innerloop-done)
 467                     (not (setq outer-loop-done (eobp))))
 468           (setq state (parse-partial-sexp (point) (progn (end-of-line) (point))
 469                                           nil nil state))
 470           (setq next-depth (car state))
 471           (if (car (nthcdr 4 state))
 472               (progn (indent-for-comment)
 473                      (end-of-line)
 474                      (setcar (nthcdr 4 state) nil)))
 475           (if (car (nthcdr 3 state))
 476               (progn
 477                 (forward-line 1)
 478                 (setcar (nthcdr 5 state) nil))
 479             (setq innerloop-done t)))
 480         (if (setq outer-loop-done (<= next-depth 0))
 481             nil
 482           (while (> last-depth next-depth)
 483             (setq indent-stack (cdr indent-stack)
 484                   last-depth (1- last-depth)))
 485           (while (< last-depth next-depth)
 486             (setq indent-stack (cons nil indent-stack)
 487                   last-depth (1+ last-depth)))
 488           (forward-line 1)
 489           (setq bol (point))
 490           (skip-chars-forward " \t")
 491           (if (or (eobp) (looking-at "[;\n]"))
 492               nil
 493             (if (and (car indent-stack)
 494                      (>= (car indent-stack) 0))
 495                 (setq this-indent (car indent-stack))
 496               (let ((val (calculate-scheme-indent
 497                           (if (car indent-stack) (- (car indent-stack))))))
 498                 (if (integerp val)
 499                     (setcar indent-stack
 500                             (setq this-indent val))
 501                   (setcar indent-stack (- (car (cdr val))))
 502                   (setq this-indent (car val)))))
 503             (if (/= (current-column) this-indent)
 504                 (progn (delete-region bol (point))
 505                        (indent-to this-indent)))))))))
 506
 507 (provide 'scheme)
 508
 509 ;;; scheme.el ends here