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 the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; Adapted from Lisp mode by Bill Rozas, jinx@prep.
  28 ;; Initially a query replace of Lisp mode, except for the indentation
  29 ;; of special forms.  Probably the code should be merged at some point
  30 ;; so that there is sharing between both libraries.
  31
  32 ;;; Code:
  33 \f
  34 (defvar scheme-mode-syntax-table nil "")
  35 (if (not scheme-mode-syntax-table)
  36     (let ((i 0))
  37       (setq scheme-mode-syntax-table (make-syntax-table))
  38       (set-syntax-table scheme-mode-syntax-table)
  39
  40       ;; Default is atom-constituent.
  41       (while (< i 256)
  42         (modify-syntax-entry i "_   ")
  43         (setq i (1+ i)))
  44
  45       ;; Word components.
  46       (setq i ?0)
  47       (while (<= i ?9)
  48         (modify-syntax-entry i "w   ")
  49         (setq i (1+ i)))
  50       (setq i ?A)
  51       (while (<= i ?Z)
  52         (modify-syntax-entry i "w   ")
  53         (setq i (1+ i)))
  54       (setq i ?a)
  55       (while (<= i ?z)
  56         (modify-syntax-entry i "w   ")
  57         (setq i (1+ i)))
  58
  59       ;; Whitespace
  60       (modify-syntax-entry ?\t "    ")
  61       (modify-syntax-entry ?\n ">   ")
  62       (modify-syntax-entry ?\f "    ")
  63       (modify-syntax-entry ?\r "    ")
  64       (modify-syntax-entry ?  "    ")
  65
  66       ;; These characters are delimiters but otherwise undefined.
  67       ;; Brackets and braces balance for editing convenience.
  68       (modify-syntax-entry ?[ "(]  ")
  69       (modify-syntax-entry ?] ")[  ")
  70       (modify-syntax-entry ?{ "(}  ")
  71       (modify-syntax-entry ?} "){  ")
  72       (modify-syntax-entry ?\| "  23")
  73
  74       ;; Other atom delimiters
  75       (modify-syntax-entry ?\( "()  ")
  76       (modify-syntax-entry ?\) ")(  ")
  77       (modify-syntax-entry ?\; "<   ")
  78       (modify-syntax-entry ?\" "\"    ")
  79       (modify-syntax-entry ?' "  p")
  80       (modify-syntax-entry ?` "  p")
  81
  82       ;; Special characters
  83       (modify-syntax-entry ?, "_ p")
  84       (modify-syntax-entry ?@ "_ p")
  85       (modify-syntax-entry ?# "_ p14")
  86       (modify-syntax-entry ?\\ "\\   ")))
  87 \f
  88 (defvar scheme-mode-abbrev-table nil "")
  89 (define-abbrev-table 'scheme-mode-abbrev-table ())
  90
  91 (defun scheme-mode-variables ()
  92   (set-syntax-table scheme-mode-syntax-table)
  93   (setq local-abbrev-table scheme-mode-abbrev-table)
  94   (make-local-variable 'paragraph-start)
  95   (setq paragraph-start (concat "$\\|" page-delimiter))
  96   (make-local-variable 'paragraph-separate)
  97   (setq paragraph-separate paragraph-start)
  98   (make-local-variable 'paragraph-ignore-fill-prefix)
  99   (setq paragraph-ignore-fill-prefix t)
 100   (make-local-variable 'indent-line-function)
 101   (setq indent-line-function 'scheme-indent-line)
 102   (make-local-variable 'parse-sexp-ignore-comments)
 103   (setq parse-sexp-ignore-comments t)
 104   (make-local-variable 'comment-start)
 105   (setq comment-start ";")
 106   (make-local-variable 'comment-start-skip)
 107   (setq comment-start-skip ";+[ \t]*")
 108   (make-local-variable 'comment-column)
 109   (setq comment-column 40)
 110   (make-local-variable 'comment-indent-function)
 111   (setq comment-indent-function 'scheme-comment-indent)
 112   (make-local-variable 'parse-sexp-ignore-comments)
 113   (setq parse-sexp-ignore-comments t)
 114   (setq mode-line-process '("" scheme-mode-line-process)))
 115
 116 (defvar scheme-mode-line-process "")
 117
 118 (defun scheme-mode-commands (map)
 119   (define-key map "\t" 'scheme-indent-line)
 120   (define-key map "\177" 'backward-delete-char-untabify)
 121   (define-key map "\e\C-q" 'scheme-indent-sexp))
 122
 123 (defvar scheme-mode-map nil)
 124 (if (not scheme-mode-map)
 125     (progn
 126       (setq scheme-mode-map (make-sparse-keymap))
 127       (scheme-mode-commands scheme-mode-map)))
 128 \f
 129 ;;;###autoload
 130 (defun scheme-mode ()
 131   "Major mode for editing Scheme code.
 132 Editing commands are similar to those of lisp-mode.
 133
 134 In addition, if an inferior Scheme process is running, some additional
 135 commands will be defined, for evaluating expressions and controlling
 136 the interpreter, and the state of the process will be displayed in the
 137 modeline of all Scheme buffers.  The names of commands that interact
 138 with the Scheme process start with \"xscheme-\".  For more information
 139 see the documentation for xscheme-interaction-mode.
 140
 141 Commands:
 142 Delete converts tabs to spaces as it moves back.
 143 Blank lines separate paragraphs.  Semicolons start comments.
 144 \\{scheme-mode-map}
 145 Entry to this mode calls the value of scheme-mode-hook
 146 if that value is non-nil."
 147   (interactive)
 148   (kill-all-local-variables)
 149   (scheme-mode-initialize)
 150   (scheme-mode-variables)
 151   (run-hooks 'scheme-mode-hook))
 152
 153 (defun scheme-mode-initialize ()
 154   (use-local-map scheme-mode-map)
 155   (setq major-mode 'scheme-mode)
 156   (setq mode-name "Scheme"))
 157
 158 (defvar scheme-mit-dialect t
 159   "If non-nil, scheme mode is specialized for MIT Scheme.
 160 Set this to nil if you normally use another dialect.")
 161 \f
 162 (defun scheme-comment-indent (&optional pos)
 163   (save-excursion
 164     (if pos (goto-char pos))
 165     (cond ((looking-at ";;;") (current-column))
 166           ((looking-at ";;")
 167            (let ((tem (calculate-scheme-indent)))
 168              (if (listp tem) (car tem) tem)))
 169           (t
 170            (skip-chars-backward " \t")
 171            (max (if (bolp) 0 (1+ (current-column)))
 172                 comment-column)))))
 173
 174 (defvar scheme-indent-offset nil "")
 175 (defvar scheme-indent-function 'scheme-indent-function "")
 176
 177 (defun scheme-indent-line (&optional whole-exp)
 178   "Indent current line as Scheme code.
 179 With argument, indent any additional lines of the same expression
 180 rigidly along with this one."
 181   (interactive "P")
 182   (let ((indent (calculate-scheme-indent)) shift-amt beg end
 183         (pos (- (point-max) (point))))
 184     (beginning-of-line)
 185     (setq beg (point))
 186     (skip-chars-forward " \t")
 187     (if (looking-at "[ \t]*;;;")
 188         ;; Don't alter indentation of a ;;; comment line.
 189         nil
 190       (if (listp indent) (setq indent (car indent)))
 191       (setq shift-amt (- indent (current-column)))
 192       (if (zerop shift-amt)
 193           nil
 194         (delete-region beg (point))
 195         (indent-to indent))
 196       ;; If initial point was within line's indentation,
 197       ;; position after the indentation.  Else stay at same point in text.
 198       (if (> (- (point-max) pos) (point))
 199           (goto-char (- (point-max) pos)))
 200       ;; If desired, shift remaining lines of expression the same amount.
 201       (and whole-exp (not (zerop shift-amt))
 202            (save-excursion
 203              (goto-char beg)
 204              (forward-sexp 1)
 205              (setq end (point))
 206              (goto-char beg)
 207              (forward-line 1)
 208              (setq beg (point))
 209              (> end beg))
 210            (indent-code-rigidly beg end shift-amt)))))
 211 \f
 212 (defun calculate-scheme-indent (&optional parse-start)
 213   "Return appropriate indentation for current line as scheme code.
 214 In usual case returns an integer: the column to indent to.
 215 Can instead return a list, whose car is the column to indent to.
 216 This means that following lines at the same level of indentation
 217 should not necessarily be indented the same way.
 218 The second element of the list is the buffer position
 219 of the start of the containing expression."
 220   (save-excursion
 221     (beginning-of-line)
 222     (let ((indent-point (point)) state paren-depth desired-indent (retry t)
 223           last-sexp containing-sexp first-sexp-list-p)
 224       (if parse-start
 225           (goto-char parse-start)
 226         (beginning-of-defun))
 227       ;; Find outermost containing sexp
 228       (while (< (point) indent-point)
 229         (setq state (parse-partial-sexp (point) indent-point 0)))
 230       ;; Find innermost containing sexp
 231       (while (and retry (setq paren-depth (car state)) (> paren-depth 0))
 232         (setq retry nil)
 233         (setq last-sexp (nth 2 state))
 234         (setq containing-sexp (car (cdr state)))
 235         ;; Position following last unclosed open.
 236         (goto-char (1+ containing-sexp))
 237         ;; Is there a complete sexp since then?
 238         (if (and last-sexp (> last-sexp (point)))
 239             ;; Yes, but is there a containing sexp after that?
 240             (let ((peek (parse-partial-sexp last-sexp indent-point 0)))
 241               (if (setq retry (car (cdr peek))) (setq state peek))))
 242         (if (not retry)
 243             ;; Innermost containing sexp found
 244             (progn
 245               (goto-char (1+ containing-sexp))
 246               (if (not last-sexp)
 247                   ;; indent-point immediately follows open paren.
 248                   ;; Don't call hook.
 249                   (setq desired-indent (current-column))
 250                 ;; Move to first sexp after containing open paren
 251                 (parse-partial-sexp (point) last-sexp 0 t)
 252                 (setq first-sexp-list-p (looking-at "\\s("))
 253                 (cond
 254                  ((> (save-excursion (forward-line 1) (point))
 255                      last-sexp)
 256                   ;; Last sexp is on same line as containing sexp.
 257                   ;; It's almost certainly a function call.
 258                   (parse-partial-sexp (point) last-sexp 0 t)
 259                   (if (/= (point) last-sexp)
 260                       ;; Indent beneath first argument or, if only one sexp
 261                       ;; on line, indent beneath that.
 262                       (progn (forward-sexp 1)
 263                              (parse-partial-sexp (point) last-sexp 0 t)))
 264                   (backward-prefix-chars))
 265                  (t
 266                   ;; Indent beneath first sexp on same line as last-sexp.
 267                   ;; Again, it's almost certainly a function call.
 268                   (goto-char last-sexp)
 269                   (beginning-of-line)
 270                   (parse-partial-sexp (point) last-sexp 0 t)
 271                   (backward-prefix-chars)))))))
 272       ;; If looking at a list, don't call hook.
 273       (if first-sexp-list-p
 274           (setq desired-indent (current-column)))
 275       ;; Point is at the point to indent under unless we are inside a string.
 276       ;; Call indentation hook except when overridden by scheme-indent-offset
 277       ;; or if the desired indentation has already been computed.
 278       (cond ((car (nthcdr 3 state))
 279              ;; Inside a string, don't change indentation.
 280              (goto-char indent-point)
 281              (skip-chars-forward " \t")
 282              (setq desired-indent (current-column)))
 283             ((and (integerp scheme-indent-offset) containing-sexp)
 284              ;; Indent by constant offset
 285              (goto-char containing-sexp)
 286              (setq desired-indent (+ scheme-indent-offset (current-column))))
 287             ((not (or desired-indent
 288                       (and (boundp 'scheme-indent-function)
 289                            scheme-indent-function
 290                            (not retry)
 291                            (setq desired-indent
 292                                  (funcall scheme-indent-function
 293                                           indent-point state)))))
 294              ;; Use default indentation if not computed yet
 295              (setq desired-indent (current-column))))
 296       desired-indent)))
 297 \f
 298 (defun scheme-indent-function (indent-point state)
 299   (let ((normal-indent (current-column)))
 300     (save-excursion
 301       (goto-char (1+ (car (cdr state))))
 302       (re-search-forward "\\sw\\|\\s_")
 303       (if (/= (point) (car (cdr state)))
 304           (let ((function (buffer-substring (progn (forward-char -1) (point))
 305                                             (progn (forward-sexp 1) (point))))
 306                 method)
 307             ;; Who cares about this, really?
 308             ;(if (not (string-match "\\\\\\||" function)))
 309             (setq function (downcase function))
 310             (setq method (get (intern-soft function) 'scheme-indent-function))
 311             (cond ((integerp method)
 312                    (scheme-indent-specform method state indent-point))
 313                   (method
 314                    (funcall method state indent-point))
 315                   ((and (> (length function) 3)
 316                         (string-equal (substring function 0 3) "def"))
 317                    (scheme-indent-defform state indent-point))))))))
 318
 319 (defvar scheme-body-indent 2 "")
 320 \f
 321 (defun scheme-indent-specform (count state indent-point)
 322   (let ((containing-form-start (car (cdr state))) (i count)
 323         body-indent containing-form-column)
 324     ;; Move to the start of containing form, calculate indentation
 325     ;; to use for non-distinguished forms (> count), and move past the
 326     ;; function symbol.  scheme-indent-function guarantees that there is at
 327     ;; least one word or symbol character following open paren of containing
 328     ;; form.
 329     (goto-char containing-form-start)
 330     (setq containing-form-column (current-column))
 331     (setq body-indent (+ scheme-body-indent containing-form-column))
 332     (forward-char 1)
 333     (forward-sexp 1)
 334     ;; Now find the start of the last form.
 335     (parse-partial-sexp (point) indent-point 1 t)
 336     (while (and (< (point) indent-point)
 337                 (condition-case nil
 338                     (progn
 339                       (setq count (1- count))
 340                       (forward-sexp 1)
 341                       (parse-partial-sexp (point) indent-point 1 t))
 342                   (error nil))))
 343     ;; Point is sitting on first character of last (or count) sexp.
 344     (cond ((> count 0)
 345            ;; A distinguished form.  Use double scheme-body-indent.
 346            (list (+ containing-form-column (* 2 scheme-body-indent))
 347                  containing-form-start))
 348           ;; A non-distinguished form. Use body-indent if there are no
 349           ;; distinguished forms and this is the first undistinguished
 350           ;; form, or if this is the first undistinguished form and
 351           ;; the preceding distinguished form has indentation at least
 352           ;; as great as body-indent.
 353           ((and (= count 0)
 354                 (or (= i 0)
 355                     (<= body-indent normal-indent)))
 356            body-indent)
 357           (t
 358            normal-indent))))
 359
 360 (defun scheme-indent-defform (state indent-point)
 361   (goto-char (car (cdr state)))
 362   (forward-line 1)
 363   (if (> (point) (car (cdr (cdr state))))
 364       (progn
 365         (goto-char (car (cdr state)))
 366         (+ scheme-body-indent (current-column)))))
 367 \f
 368 ;;; Let is different in Scheme
 369
 370 (defun would-be-symbol (string)
 371   (not (string-equal (substring string 0 1) "(")))
 372
 373 (defun next-sexp-as-string ()
 374   ;; Assumes that protected by a save-excursion
 375   (forward-sexp 1)
 376   (let ((the-end (point)))
 377     (backward-sexp 1)
 378     (buffer-substring (point) the-end)))
 379
 380 ;; This is correct but too slow.
 381 ;; The one below works almost always.
 382 ;;(defun scheme-let-indent (state indent-point)
 383 ;;  (if (would-be-symbol (next-sexp-as-string))
 384 ;;      (scheme-indent-specform 2 state indent-point)
 385 ;;      (scheme-indent-specform 1 state indent-point)))
 386
 387 (defun scheme-let-indent (state indent-point)
 388   (skip-chars-forward " \t")
 389   (if (looking-at "[-a-zA-Z0-9+*/?!@$%^&_:~]")
 390       (scheme-indent-specform 2 state indent-point)
 391       (scheme-indent-specform 1 state indent-point)))
 392
 393 ;; (put 'begin 'scheme-indent-function 0), say, causes begin to be indented
 394 ;; like defun if the first form is placed on the next line, otherwise
 395 ;; it is indented like any other form (i.e. forms line up under first).
 396
 397 (put 'begin 'scheme-indent-function 0)
 398 (put 'case 'scheme-indent-function 1)
 399 (put 'delay 'scheme-indent-function 0)
 400 (put 'do 'scheme-indent-function 2)
 401 (put 'lambda 'scheme-indent-function 1)
 402 (put 'let 'scheme-indent-function 'scheme-let-indent)
 403 (put 'let* 'scheme-indent-function 1)
 404 (put 'letrec 'scheme-indent-function 1)
 405 (put 'sequence 'scheme-indent-function 0)
 406
 407 (put 'call-with-input-file 'scheme-indent-function 1)
 408 (put 'with-input-from-file 'scheme-indent-function 1)
 409 (put 'with-input-from-port 'scheme-indent-function 1)
 410 (put 'call-with-output-file 'scheme-indent-function 1)
 411 (put 'with-output-to-file 'scheme-indent-function 1)
 412 (put 'with-output-to-port 'scheme-indent-function 1)
 413 \f
 414 ;;;; MIT Scheme specific indentation.
 415
 416 (if scheme-mit-dialect
 417     (progn
 418       (put 'fluid-let 'scheme-indent-function 1)
 419       (put 'in-package 'scheme-indent-function 1)
 420       (put 'let-syntax 'scheme-indent-function 1)
 421       (put 'local-declare 'scheme-indent-function 1)
 422       (put 'macro 'scheme-indent-function 1)
 423       (put 'make-environment 'scheme-indent-function 0)
 424       (put 'named-lambda 'scheme-indent-function 1)
 425       (put 'using-syntax 'scheme-indent-function 1)
 426
 427       (put 'with-input-from-string 'scheme-indent-function 1)
 428       (put 'with-output-to-string 'scheme-indent-function 0)
 429       (put 'with-values 'scheme-indent-function 1)
 430
 431       (put 'syntax-table-define 'scheme-indent-function 2)
 432       (put 'list-transform-positive 'scheme-indent-function 1)
 433       (put 'list-transform-negative 'scheme-indent-function 1)
 434       (put 'list-search-positive 'scheme-indent-function 1)
 435       (put 'list-search-negative 'scheme-indent-function 1)
 436
 437       (put 'access-components 'scheme-indent-function 1)
 438       (put 'assignment-components 'scheme-indent-function 1)
 439       (put 'combination-components 'scheme-indent-function 1)
 440       (put 'comment-components 'scheme-indent-function 1)
 441       (put 'conditional-components 'scheme-indent-function 1)
 442       (put 'disjunction-components 'scheme-indent-function 1)
 443       (put 'declaration-components 'scheme-indent-function 1)
 444       (put 'definition-components 'scheme-indent-function 1)
 445       (put 'delay-components 'scheme-indent-function 1)
 446       (put 'in-package-components 'scheme-indent-function 1)
 447       (put 'lambda-components 'scheme-indent-function 1)
 448       (put 'lambda-components* 'scheme-indent-function 1)
 449       (put 'lambda-components** 'scheme-indent-function 1)
 450       (put 'open-block-components 'scheme-indent-function 1)
 451       (put 'pathname-components 'scheme-indent-function 1)
 452       (put 'procedure-components 'scheme-indent-function 1)
 453       (put 'sequence-components 'scheme-indent-function 1)
 454       (put 'unassigned\?-components 'scheme-indent-function 1)
 455       (put 'unbound\?-components 'scheme-indent-function 1)
 456       (put 'variable-components 'scheme-indent-function 1)))
 457 \f
 458 (defun scheme-indent-sexp ()
 459   "Indent each line of the list starting just after point."
 460   (interactive)
 461   (let ((indent-stack (list nil)) (next-depth 0) bol
 462         outer-loop-done inner-loop-done state this-indent)
 463     (save-excursion (forward-sexp 1))
 464     (save-excursion
 465       (setq outer-loop-done nil)
 466       (while (not outer-loop-done)
 467         (setq last-depth next-depth
 468               innerloop-done nil)
 469         (while (and (not innerloop-done)
 470                     (not (setq outer-loop-done (eobp))))
 471           (setq state (parse-partial-sexp (point) (progn (end-of-line) (point))
 472                                           nil nil state))
 473           (setq next-depth (car state))
 474           (if (car (nthcdr 4 state))
 475               (progn (indent-for-comment)
 476                      (end-of-line)
 477                      (setcar (nthcdr 4 state) nil)))
 478           (if (car (nthcdr 3 state))
 479               (progn
 480                 (forward-line 1)
 481                 (setcar (nthcdr 5 state) nil))
 482             (setq innerloop-done t)))
 483         (if (setq outer-loop-done (<= next-depth 0))
 484             nil
 485           (while (> last-depth next-depth)
 486             (setq indent-stack (cdr indent-stack)
 487                   last-depth (1- last-depth)))
 488           (while (< last-depth next-depth)
 489             (setq indent-stack (cons nil indent-stack)
 490                   last-depth (1+ last-depth)))
 491           (forward-line 1)
 492           (setq bol (point))
 493           (skip-chars-forward " \t")
 494           (if (or (eobp) (looking-at "[;\n]"))
 495               nil
 496             (if (and (car indent-stack)
 497                      (>= (car indent-stack) 0))
 498                 (setq this-indent (car indent-stack))
 499               (let ((val (calculate-scheme-indent
 500                           (if (car indent-stack) (- (car indent-stack))))))
 501                 (if (integerp val)
 502                     (setcar indent-stack
 503                             (setq this-indent val))
 504                   (if (cdr val)
 505                       (setcar indent-stack (- (car (cdr val)))))
 506                   (setq this-indent (car val)))))
 507             (if (/= (current-column) this-indent)
 508                 (progn (delete-region bol (point))
 509                        (indent-to this-indent)))))))))
 510
 511 (provide 'scheme)
 512
 513 ;;; scheme.el ends here