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   ;; Look within the line for a ; following an even number of backslashes
 108   ;; after either a non-backslash or the line beginning.
 109   (setq comment-start-skip "\\(\\(^\\|[^\\\\\n]\\)\\(\\\\\\\\\\)*\\);+[ \t]*")
 110   (make-local-variable 'comment-column)
 111   (setq comment-column 40)
 112   (make-local-variable 'comment-indent-function)
 113   (setq comment-indent-function 'scheme-comment-indent)
 114   (make-local-variable 'parse-sexp-ignore-comments)
 115   (setq parse-sexp-ignore-comments t)
 116   (setq mode-line-process '("" scheme-mode-line-process)))
 117
 118 (defvar scheme-mode-line-process "")
 119
 120 (defun scheme-mode-commands (map)
 121   (define-key map "\t" 'scheme-indent-line)
 122   (define-key map "\177" 'backward-delete-char-untabify)
 123   (define-key map "\e\C-q" 'scheme-indent-sexp))
 124
 125 (defvar scheme-mode-map nil)
 126 (if (not scheme-mode-map)
 127     (progn
 128       (setq scheme-mode-map (make-sparse-keymap))
 129       (scheme-mode-commands scheme-mode-map)))
 130 \f
 131 ;;;###autoload
 132 (defun scheme-mode ()
 133   "Major mode for editing Scheme code.
 134 Editing commands are similar to those of lisp-mode.
 135
 136 In addition, if an inferior Scheme process is running, some additional
 137 commands will be defined, for evaluating expressions and controlling
 138 the interpreter, and the state of the process will be displayed in the
 139 modeline of all Scheme buffers.  The names of commands that interact
 140 with the Scheme process start with \"xscheme-\".  For more information
 141 see the documentation for xscheme-interaction-mode.
 142
 143 Commands:
 144 Delete converts tabs to spaces as it moves back.
 145 Blank lines separate paragraphs.  Semicolons start comments.
 146 \\{scheme-mode-map}
 147 Entry to this mode calls the value of scheme-mode-hook
 148 if that value is non-nil."
 149   (interactive)
 150   (kill-all-local-variables)
 151   (scheme-mode-initialize)
 152   (scheme-mode-variables)
 153   (run-hooks 'scheme-mode-hook))
 154
 155 (defun scheme-mode-initialize ()
 156   (use-local-map scheme-mode-map)
 157   (setq major-mode 'scheme-mode)
 158   (setq mode-name "Scheme"))
 159
 160 (defvar scheme-mit-dialect t
 161   "If non-nil, scheme mode is specialized for MIT Scheme.
 162 Set this to nil if you normally use another dialect.")
 163 \f
 164 (defun scheme-comment-indent (&optional pos)
 165   (save-excursion
 166     (if pos (goto-char pos))
 167     (cond ((looking-at ";;;") (current-column))
 168           ((looking-at ";;")
 169            (let ((tem (calculate-scheme-indent)))
 170              (if (listp tem) (car tem) tem)))
 171           (t
 172            (skip-chars-backward " \t")
 173            (max (if (bolp) 0 (1+ (current-column)))
 174                 comment-column)))))
 175
 176 (defvar scheme-indent-offset nil "")
 177 (defvar scheme-indent-function 'scheme-indent-function "")
 178
 179 (defun scheme-indent-line (&optional whole-exp)
 180   "Indent current line as Scheme code.
 181 With argument, indent any additional lines of the same expression
 182 rigidly along with this one."
 183   (interactive "P")
 184   (let ((indent (calculate-scheme-indent)) shift-amt beg end
 185         (pos (- (point-max) (point))))
 186     (beginning-of-line)
 187     (setq beg (point))
 188     (skip-chars-forward " \t")
 189     (if (looking-at "[ \t]*;;;")
 190         ;; Don't alter indentation of a ;;; comment line.
 191         nil
 192       (if (listp indent) (setq indent (car indent)))
 193       (setq shift-amt (- indent (current-column)))
 194       (if (zerop shift-amt)
 195           nil
 196         (delete-region beg (point))
 197         (indent-to indent))
 198       ;; If initial point was within line's indentation,
 199       ;; position after the indentation.  Else stay at same point in text.
 200       (if (> (- (point-max) pos) (point))
 201           (goto-char (- (point-max) pos)))
 202       ;; If desired, shift remaining lines of expression the same amount.
 203       (and whole-exp (not (zerop shift-amt))
 204            (save-excursion
 205              (goto-char beg)
 206              (forward-sexp 1)
 207              (setq end (point))
 208              (goto-char beg)
 209              (forward-line 1)
 210              (setq beg (point))
 211              (> end beg))
 212            (indent-code-rigidly beg end shift-amt)))))
 213 \f
 214 (defun calculate-scheme-indent (&optional parse-start)
 215   "Return appropriate indentation for current line as scheme code.
 216 In usual case returns an integer: the column to indent to.
 217 Can instead return a list, whose car is the column to indent to.
 218 This means that following lines at the same level of indentation
 219 should not necessarily be indented the same way.
 220 The second element of the list is the buffer position
 221 of the start of the containing expression."
 222   (save-excursion
 223     (beginning-of-line)
 224     (let ((indent-point (point)) state paren-depth desired-indent (retry t)
 225           last-sexp containing-sexp first-sexp-list-p)
 226       (if parse-start
 227           (goto-char parse-start)
 228         (beginning-of-defun))
 229       ;; Find outermost containing sexp
 230       (while (< (point) indent-point)
 231         (setq state (parse-partial-sexp (point) indent-point 0)))
 232       ;; Find innermost containing sexp
 233       (while (and retry (setq paren-depth (car state)) (> paren-depth 0))
 234         (setq retry nil)
 235         (setq last-sexp (nth 2 state))
 236         (setq containing-sexp (car (cdr state)))
 237         ;; Position following last unclosed open.
 238         (goto-char (1+ containing-sexp))
 239         ;; Is there a complete sexp since then?
 240         (if (and last-sexp (> last-sexp (point)))
 241             ;; Yes, but is there a containing sexp after that?
 242             (let ((peek (parse-partial-sexp last-sexp indent-point 0)))
 243               (if (setq retry (car (cdr peek))) (setq state peek))))
 244         (if (not retry)
 245             ;; Innermost containing sexp found
 246             (progn
 247               (goto-char (1+ containing-sexp))
 248               (if (not last-sexp)
 249                   ;; indent-point immediately follows open paren.
 250                   ;; Don't call hook.
 251                   (setq desired-indent (current-column))
 252                 ;; Move to first sexp after containing open paren
 253                 (parse-partial-sexp (point) last-sexp 0 t)
 254                 (setq first-sexp-list-p (looking-at "\\s("))
 255                 (cond
 256                  ((> (save-excursion (forward-line 1) (point))
 257                      last-sexp)
 258                   ;; Last sexp is on same line as containing sexp.
 259                   ;; It's almost certainly a function call.
 260                   (parse-partial-sexp (point) last-sexp 0 t)
 261                   (if (/= (point) last-sexp)
 262                       ;; Indent beneath first argument or, if only one sexp
 263                       ;; on line, indent beneath that.
 264                       (progn (forward-sexp 1)
 265                              (parse-partial-sexp (point) last-sexp 0 t)))
 266                   (backward-prefix-chars))
 267                  (t
 268                   ;; Indent beneath first sexp on same line as last-sexp.
 269                   ;; Again, it's almost certainly a function call.
 270                   (goto-char last-sexp)
 271                   (beginning-of-line)
 272                   (parse-partial-sexp (point) last-sexp 0 t)
 273                   (backward-prefix-chars)))))))
 274       ;; If looking at a list, don't call hook.
 275       (if first-sexp-list-p
 276           (setq desired-indent (current-column)))
 277       ;; Point is at the point to indent under unless we are inside a string.
 278       ;; Call indentation hook except when overridden by scheme-indent-offset
 279       ;; or if the desired indentation has already been computed.
 280       (cond ((car (nthcdr 3 state))
 281              ;; Inside a string, don't change indentation.
 282              (goto-char indent-point)
 283              (skip-chars-forward " \t")
 284              (setq desired-indent (current-column)))
 285             ((and (integerp scheme-indent-offset) containing-sexp)
 286              ;; Indent by constant offset
 287              (goto-char containing-sexp)
 288              (setq desired-indent (+ scheme-indent-offset (current-column))))
 289             ((not (or desired-indent
 290                       (and (boundp 'scheme-indent-function)
 291                            scheme-indent-function
 292                            (not retry)
 293                            (setq desired-indent
 294                                  (funcall scheme-indent-function
 295                                           indent-point state)))))
 296              ;; Use default indentation if not computed yet
 297              (setq desired-indent (current-column))))
 298       desired-indent)))
 299 \f
 300 (defun scheme-indent-function (indent-point state)
 301   (let ((normal-indent (current-column)))
 302     (save-excursion
 303       (goto-char (1+ (car (cdr state))))
 304       (re-search-forward "\\sw\\|\\s_")
 305       (if (/= (point) (car (cdr state)))
 306           (let ((function (buffer-substring (progn (forward-char -1) (point))
 307                                             (progn (forward-sexp 1) (point))))
 308                 method)
 309             ;; Who cares about this, really?
 310             ;(if (not (string-match "\\\\\\||" function)))
 311             (setq function (downcase function))
 312             (setq method (get (intern-soft function) 'scheme-indent-function))
 313             (cond ((integerp method)
 314                    (scheme-indent-specform method state indent-point))
 315                   (method
 316                    (funcall method state indent-point))
 317                   ((and (> (length function) 3)
 318                         (string-equal (substring function 0 3) "def"))
 319                    (scheme-indent-defform state indent-point))))))))
 320
 321 (defvar scheme-body-indent 2 "")
 322 \f
 323 (defun scheme-indent-specform (count state indent-point)
 324   (let ((containing-form-start (car (cdr state))) (i count)
 325         body-indent containing-form-column)
 326     ;; Move to the start of containing form, calculate indentation
 327     ;; to use for non-distinguished forms (> count), and move past the
 328     ;; function symbol.  scheme-indent-function guarantees that there is at
 329     ;; least one word or symbol character following open paren of containing
 330     ;; form.
 331     (goto-char containing-form-start)
 332     (setq containing-form-column (current-column))
 333     (setq body-indent (+ scheme-body-indent containing-form-column))
 334     (forward-char 1)
 335     (forward-sexp 1)
 336     ;; Now find the start of the last form.
 337     (parse-partial-sexp (point) indent-point 1 t)
 338     (while (and (< (point) indent-point)
 339                 (condition-case nil
 340                     (progn
 341                       (setq count (1- count))
 342                       (forward-sexp 1)
 343                       (parse-partial-sexp (point) indent-point 1 t))
 344                   (error nil))))
 345     ;; Point is sitting on first character of last (or count) sexp.
 346     (cond ((> count 0)
 347            ;; A distinguished form.  Use double scheme-body-indent.
 348            (list (+ containing-form-column (* 2 scheme-body-indent))
 349                  containing-form-start))
 350           ;; A non-distinguished form. Use body-indent if there are no
 351           ;; distinguished forms and this is the first undistinguished
 352           ;; form, or if this is the first undistinguished form and
 353           ;; the preceding distinguished form has indentation at least
 354           ;; as great as body-indent.
 355           ((and (= count 0)
 356                 (or (= i 0)
 357                     (<= body-indent normal-indent)))
 358            body-indent)
 359           (t
 360            normal-indent))))
 361
 362 (defun scheme-indent-defform (state indent-point)
 363   (goto-char (car (cdr state)))
 364   (forward-line 1)
 365   (if (> (point) (car (cdr (cdr state))))
 366       (progn
 367         (goto-char (car (cdr state)))
 368         (+ scheme-body-indent (current-column)))))
 369 \f
 370 ;;; Let is different in Scheme
 371
 372 (defun would-be-symbol (string)
 373   (not (string-equal (substring string 0 1) "(")))
 374
 375 (defun next-sexp-as-string ()
 376   ;; Assumes that protected by a save-excursion
 377   (forward-sexp 1)
 378   (let ((the-end (point)))
 379     (backward-sexp 1)
 380     (buffer-substring (point) the-end)))
 381
 382 ;; This is correct but too slow.
 383 ;; The one below works almost always.
 384 ;;(defun scheme-let-indent (state indent-point)
 385 ;;  (if (would-be-symbol (next-sexp-as-string))
 386 ;;      (scheme-indent-specform 2 state indent-point)
 387 ;;      (scheme-indent-specform 1 state indent-point)))
 388
 389 (defun scheme-let-indent (state indent-point)
 390   (skip-chars-forward " \t")
 391   (if (looking-at "[-a-zA-Z0-9+*/?!@$%^&_:~]")
 392       (scheme-indent-specform 2 state indent-point)
 393       (scheme-indent-specform 1 state indent-point)))
 394
 395 ;; (put 'begin 'scheme-indent-function 0), say, causes begin to be indented
 396 ;; like defun if the first form is placed on the next line, otherwise
 397 ;; it is indented like any other form (i.e. forms line up under first).
 398
 399 (put 'begin 'scheme-indent-function 0)
 400 (put 'case 'scheme-indent-function 1)
 401 (put 'delay 'scheme-indent-function 0)
 402 (put 'do 'scheme-indent-function 2)
 403 (put 'lambda 'scheme-indent-function 1)
 404 (put 'let 'scheme-indent-function 'scheme-let-indent)
 405 (put 'let* 'scheme-indent-function 1)
 406 (put 'letrec 'scheme-indent-function 1)
 407 (put 'sequence 'scheme-indent-function 0)
 408
 409 (put 'call-with-input-file 'scheme-indent-function 1)
 410 (put 'with-input-from-file 'scheme-indent-function 1)
 411 (put 'with-input-from-port 'scheme-indent-function 1)
 412 (put 'call-with-output-file 'scheme-indent-function 1)
 413 (put 'with-output-to-file 'scheme-indent-function 1)
 414 (put 'with-output-to-port 'scheme-indent-function 1)
 415 \f
 416 ;;;; MIT Scheme specific indentation.
 417
 418 (if scheme-mit-dialect
 419     (progn
 420       (put 'fluid-let 'scheme-indent-function 1)
 421       (put 'in-package 'scheme-indent-function 1)
 422       (put 'let-syntax 'scheme-indent-function 1)
 423       (put 'local-declare 'scheme-indent-function 1)
 424       (put 'macro 'scheme-indent-function 1)
 425       (put 'make-environment 'scheme-indent-function 0)
 426       (put 'named-lambda 'scheme-indent-function 1)
 427       (put 'using-syntax 'scheme-indent-function 1)
 428
 429       (put 'with-input-from-string 'scheme-indent-function 1)
 430       (put 'with-output-to-string 'scheme-indent-function 0)
 431       (put 'with-values 'scheme-indent-function 1)
 432
 433       (put 'syntax-table-define 'scheme-indent-function 2)
 434       (put 'list-transform-positive 'scheme-indent-function 1)
 435       (put 'list-transform-negative 'scheme-indent-function 1)
 436       (put 'list-search-positive 'scheme-indent-function 1)
 437       (put 'list-search-negative 'scheme-indent-function 1)
 438
 439       (put 'access-components 'scheme-indent-function 1)
 440       (put 'assignment-components 'scheme-indent-function 1)
 441       (put 'combination-components 'scheme-indent-function 1)
 442       (put 'comment-components 'scheme-indent-function 1)
 443       (put 'conditional-components 'scheme-indent-function 1)
 444       (put 'disjunction-components 'scheme-indent-function 1)
 445       (put 'declaration-components 'scheme-indent-function 1)
 446       (put 'definition-components 'scheme-indent-function 1)
 447       (put 'delay-components 'scheme-indent-function 1)
 448       (put 'in-package-components 'scheme-indent-function 1)
 449       (put 'lambda-components 'scheme-indent-function 1)
 450       (put 'lambda-components* 'scheme-indent-function 1)
 451       (put 'lambda-components** 'scheme-indent-function 1)
 452       (put 'open-block-components 'scheme-indent-function 1)
 453       (put 'pathname-components 'scheme-indent-function 1)
 454       (put 'procedure-components 'scheme-indent-function 1)
 455       (put 'sequence-components 'scheme-indent-function 1)
 456       (put 'unassigned\?-components 'scheme-indent-function 1)
 457       (put 'unbound\?-components 'scheme-indent-function 1)
 458       (put 'variable-components 'scheme-indent-function 1)))
 459 \f
 460 (defun scheme-indent-sexp ()
 461   "Indent each line of the list starting just after point."
 462   (interactive)
 463   (let ((indent-stack (list nil)) (next-depth 0) bol
 464         outer-loop-done inner-loop-done state this-indent)
 465     (save-excursion (forward-sexp 1))
 466     (save-excursion
 467       (setq outer-loop-done nil)
 468       (while (not outer-loop-done)
 469         (setq last-depth next-depth
 470               innerloop-done nil)
 471         (while (and (not innerloop-done)
 472                     (not (setq outer-loop-done (eobp))))
 473           (setq state (parse-partial-sexp (point) (progn (end-of-line) (point))
 474                                           nil nil state))
 475           (setq next-depth (car state))
 476           (if (car (nthcdr 4 state))
 477               (progn (indent-for-comment)
 478                      (end-of-line)
 479                      (setcar (nthcdr 4 state) nil)))
 480           (if (car (nthcdr 3 state))
 481               (progn
 482                 (forward-line 1)
 483                 (setcar (nthcdr 5 state) nil))
 484             (setq innerloop-done t)))
 485         (if (setq outer-loop-done (<= next-depth 0))
 486             nil
 487           (while (> last-depth next-depth)
 488             (setq indent-stack (cdr indent-stack)
 489                   last-depth (1- last-depth)))
 490           (while (< last-depth next-depth)
 491             (setq indent-stack (cons nil indent-stack)
 492                   last-depth (1+ last-depth)))
 493           (forward-line 1)
 494           (setq bol (point))
 495           (skip-chars-forward " \t")
 496           (if (or (eobp) (looking-at "[;\n]"))
 497               nil
 498             (if (and (car indent-stack)
 499                      (>= (car indent-stack) 0))
 500                 (setq this-indent (car indent-stack))
 501               (let ((val (calculate-scheme-indent
 502                           (if (car indent-stack) (- (car indent-stack))))))
 503                 (if (integerp val)
 504                     (setcar indent-stack
 505                             (setq this-indent val))
 506                   (if (cdr val)
 507                       (setcar indent-stack (- (car (cdr val)))))
 508                   (setq this-indent (car val)))))
 509             (if (/= (current-column) this-indent)
 510                 (progn (delete-region bol (point))
 511                        (indent-to this-indent)))))))))
 512
 513 (provide 'scheme)
 514
 515 ;;; scheme.el ends here