lisp/progmodes/cc-guess.el

   1 ;;; cc-guess.el --- guess indentation values by scanning existing code
   2
   3 ;; Copyright (C) 1985, 1987, 1992-2006, 2011-2014 Free Software
   4 ;; Foundation, Inc.
   5
   6 ;; Author:     1994-1995 Barry A. Warsaw
   7 ;;             2011-     Masatake YAMATO
   8 ;; Maintainer: bug-cc-mode@gnu.org
   9 ;; Created:    August 1994, split from cc-mode.el
  10 ;; Version:    See cc-mode.el
  11 ;; Keywords:   c languages oop
  12
  13 ;; This file is part of GNU Emacs.
  14
  15 ;; GNU Emacs is free software: you can redistribute it and/or modify
  16 ;; it under the terms of the GNU General Public License as published by
  17 ;; the Free Software Foundation, either version 3 of the License, or
  18 ;; (at your option) any later version.
  19
  20 ;; GNU Emacs is distributed in the hope that it will be useful,
  21 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  22 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23 ;; GNU General Public License for more details.
  24
  25 ;; You should have received a copy of the GNU General Public License
  26 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  27
  28 ;;; Commentary:
  29 ;;
  30 ;; This file contains routines that help guess the cc-mode style in a
  31 ;; particular region/buffer.  Here style means `c-offsets-alist' and
  32 ;; `c-basic-offset'.
  33 ;;
  34 ;; The main entry point of this program is `c-guess' command but there
  35 ;; are some variants.
  36 ;;
  37 ;; Suppose the major mode for the current buffer is one of the modes
  38 ;; provided by cc-mode. `c-guess' guesses the indentation style by
  39 ;; examining the indentation in the region between beginning of buffer
  40 ;; and `c-guess-region-max'.
  41
  42 ;; and installs the guessed style. The name for installed style is given
  43 ;; by `c-guess-style-name'.
  44 ;;
  45 ;; `c-guess-buffer' does the same but in the whole buffer.
  46 ;; `c-guess-region' does the same but in the region between the point
  47 ;; and the mark.  `c-guess-no-install', `c-guess-buffer-no-install'
  48 ;; and `c-guess-region-no-install' guess the indentation style but
  49 ;; don't install it. You can review a guessed style with `c-guess-view'.
  50 ;; After reviewing, use `c-guess-install' to install the style
  51 ;; if you prefer it.
  52 ;;
  53 ;; If you want to reuse the guessed style in another buffer,
  54 ;; run `c-set-style' command with the name of the guessed style:
  55 ;; "*c-guess*:<name-of-file-which-examined-when-guessing>".
  56 ;; Once the guessed style is installed explicitly with `c-guess-install'
  57 ;; or implicitly with `c-guess', `c-guess-buffer', or `c-guess-region',
  58 ;; a style name is given by `c-guess-style-name' with the above form.
  59 ;;
  60 ;; If you want to reuse the guessed style in future emacs sessions,
  61 ;; you may want to put it to your .emacs. `c-guess-view' is for
  62 ;; you. It emits emacs lisp code which defines the last guessed
  63 ;; style, in a temporary buffer. You can put the emitted code into
  64 ;; your .emacs. This command was suggested by Alan Mackenzie.
  65
  66 ;;; Code:
  67
  68 (eval-when-compile
  69   (let ((load-path
  70          (if (and (boundp 'byte-compile-dest-file)
  71                   (stringp byte-compile-dest-file))
  72              (cons (file-name-directory byte-compile-dest-file) load-path)
  73            load-path)))
  74     (load "cc-bytecomp" nil t)))
  75
  76 (cc-require 'cc-defs)
  77 (cc-require 'cc-engine)
  78 (cc-require 'cc-styles)
  79
  80 \f
  81
  82 (defcustom c-guess-offset-threshold 10
  83   "Threshold of acceptable offsets when examining indent information.
  84 Discard an examined offset if its absolute value is greater than this.
  85
  86 The offset of a line included in the indent information returned by
  87 `c-guess-basic-syntax'."
  88   :version "24.1"
  89   :type 'integer
  90   :group 'c)
  91
  92 (defcustom c-guess-region-max 50000
  93   "The maximum region size for examining indent information with `c-guess'.
  94 It takes a long time to examine indent information from a large region;
  95 this option helps you limit that time. `nil' means no limit."
  96   :version "24.1"
  97   :type 'integer
  98   :group 'c)
  99
 100 \f
 101 ;;;###autoload
 102 (defvar c-guess-guessed-offsets-alist nil
 103   "Currently guessed offsets-alist.")
 104 ;;;###autoload
 105 (defvar c-guess-guessed-basic-offset nil
 106   "Currently guessed basic-offset.")
 107
 108 (defvar c-guess-accumulator nil)
 109 ;; Accumulated examined indent information.  Information is represented
 110 ;; in a list.  Each element in it has following structure:
 111 ;;
 112 ;; (syntactic-symbol ((indentation-offset1 . number-of-times1)
 113 ;;                    (indentation-offset2 . number-of-times2)
 114 ;;                    ...))
 115 ;;
 116 ;; This structure is built by `c-guess-accumulate-offset'.
 117 ;;
 118 ;; Here we call the pair (indentation-offset1 . number-of-times1) a
 119 ;; counter.  `c-guess-sort-accumulator' sorts the order of
 120 ;; counters by number-of-times.
 121 ;; Use `c-guess-dump-accumulator' to see the value.
 122
 123 (defconst c-guess-conversions
 124   '((c . c-lineup-C-comments)
 125     (inher-cont . c-lineup-multi-inher)
 126     (string . -1000)
 127     (comment-intro . c-lineup-comment)
 128     (arglist-cont-nonempty . c-lineup-arglist)
 129     (arglist-close . c-lineup-close-paren)
 130     (cpp-macro . -1000)))
 131
 132
 133 ;;;###autoload
 134 (defun c-guess (&optional accumulate)
 135   "Guess the style in the region up to `c-guess-region-max', and install it.
 136
 137 The style is given a name based on the file's absolute file name.
 138
 139 If given a prefix argument (or if the optional argument ACCUMULATE is
 140 non-nil) then the previous guess is extended, otherwise a new guess is
 141 made from scratch."
 142   (interactive "P")
 143   (c-guess-region (point-min)
 144                    (min (point-max) (or c-guess-region-max
 145                                         (point-max)))
 146                    accumulate))
 147
 148 ;;;###autoload
 149 (defun c-guess-no-install (&optional accumulate)
 150   "Guess the style in the region up to `c-guess-region-max'; don't install it.
 151
 152 If given a prefix argument (or if the optional argument ACCUMULATE is
 153 non-nil) then the previous guess is extended, otherwise a new guess is
 154 made from scratch."
 155   (interactive "P")
 156   (c-guess-region-no-install (point-min)
 157                               (min (point-max) (or c-guess-region-max
 158                                                    (point-max)))
 159                               accumulate))
 160
 161 ;;;###autoload
 162 (defun c-guess-buffer (&optional accumulate)
 163   "Guess the style on the whole current buffer, and install it.
 164
 165 The style is given a name based on the file's absolute file name.
 166
 167 If given a prefix argument (or if the optional argument ACCUMULATE is
 168 non-nil) then the previous guess is extended, otherwise a new guess is
 169 made from scratch."
 170   (interactive "P")
 171   (c-guess-region (point-min)
 172                    (point-max)
 173                    accumulate))
 174
 175 ;;;###autoload
 176 (defun c-guess-buffer-no-install (&optional accumulate)
 177   "Guess the style on the whole current buffer; don't install it.
 178
 179 If given a prefix argument (or if the optional argument ACCUMULATE is
 180 non-nil) then the previous guess is extended, otherwise a new guess is
 181 made from scratch."
 182   (interactive "P")
 183   (c-guess-region-no-install (point-min)
 184                               (point-max)
 185                               accumulate))
 186
 187 ;;;###autoload
 188 (defun c-guess-region (start end &optional accumulate)
 189   "Guess the style on the region and install it.
 190
 191 The style is given a name based on the file's absolute file name.
 192
 193 If given a prefix argument (or if the optional argument ACCUMULATE is
 194 non-nil) then the previous guess is extended, otherwise a new guess is
 195 made from scratch."
 196   (interactive "r\nP")
 197   (c-guess-region-no-install start end accumulate)
 198   (c-guess-install))
 199
 200
 201 (defsubst c-guess-empty-line-p ()
 202   (eq (line-beginning-position)
 203       (line-end-position)))
 204
 205 ;;;###autoload
 206 (defun c-guess-region-no-install (start end &optional accumulate)
 207   "Guess the style on the region; don't install it.
 208
 209 Every line of code in the region is examined and values for the following two
 210 variables are guessed:
 211
 212 * `c-basic-offset', and
 213 * the indentation values of the various syntactic symbols in
 214   `c-offsets-alist'.
 215
 216 The guessed values are put into `c-guess-guessed-basic-offset' and
 217 `c-guess-guessed-offsets-alist'.
 218
 219 Frequencies of use are taken into account when guessing, so minor
 220 inconsistencies in the indentation style shouldn't produce wrong guesses.
 221
 222 If given a prefix argument (or if the optional argument ACCUMULATE is
 223 non-nil) then the previous examination is extended, otherwise a new
 224 guess is made from scratch.
 225
 226 Note that the larger the region to guess in, the slower the guessing.
 227 So you can limit the region with `c-guess-region-max'."
 228   (interactive "r\nP")
 229   (let ((accumulator (when accumulate c-guess-accumulator)))
 230     (setq c-guess-accumulator (c-guess-examine start end accumulator))
 231     (let ((pair (c-guess-guess c-guess-accumulator)))
 232       (setq c-guess-guessed-basic-offset (car pair)
 233             c-guess-guessed-offsets-alist (cdr pair)))))
 234
 235
 236 (defun c-guess-examine (start end accumulator)
 237   (let ((reporter (when (fboundp 'make-progress-reporter)
 238                     (make-progress-reporter "Examining Indentation "
 239                                             start
 240                                             end))))
 241     (save-excursion
 242       (goto-char start)
 243       (while (< (point) end)
 244         (unless (c-guess-empty-line-p)
 245           (mapc (lambda (s)
 246                   (setq accumulator (or (c-guess-accumulate accumulator s)
 247                                         accumulator)))
 248                 (c-save-buffer-state () (c-guess-basic-syntax))))
 249         (when reporter (progress-reporter-update reporter (point)))
 250         (forward-line 1)))
 251     (when reporter (progress-reporter-done reporter)))
 252   (c-guess-sort-accumulator accumulator))
 253
 254 (defun c-guess-guess (accumulator)
 255   ;; Guess basic-offset and offsets-alist from ACCUMULATOR,
 256   ;; then return them as a cons: (basic-offset . offsets-alist).
 257   ;; See the comments at `c-guess-accumulator' about the format
 258   ;; ACCUMULATOR.
 259   (let* ((basic-offset (c-guess-make-basic-offset accumulator))
 260          (typical-offsets-alist (c-guess-make-offsets-alist
 261                                  accumulator))
 262          (symbolic-offsets-alist (c-guess-symbolize-offsets-alist
 263                                   typical-offsets-alist
 264                                   basic-offset))
 265          (merged-offsets-alist (c-guess-merge-offsets-alists
 266                                 (copy-tree c-guess-conversions)
 267                                 symbolic-offsets-alist)))
 268     (cons basic-offset merged-offsets-alist)))
 269
 270 (defun c-guess-current-offset (relpos)
 271   ;; Calculate relative indentation (point) to RELPOS.
 272   (- (progn (back-to-indentation)
 273             (current-column))
 274      (save-excursion
 275        (goto-char relpos)
 276        (current-column))))
 277
 278 (defun c-guess-accumulate (accumulator syntax-element)
 279   ;; Add SYNTAX-ELEMENT to ACCUMULATOR.
 280   (let ((symbol (car syntax-element))
 281         (relpos (cadr syntax-element)))
 282     (when (numberp relpos)
 283       (let ((offset (c-guess-current-offset relpos)))
 284         (when (< (abs offset) c-guess-offset-threshold)
 285           (c-guess-accumulate-offset accumulator
 286                                       symbol
 287                                       offset))))))
 288
 289 (defun c-guess-accumulate-offset (accumulator symbol offset)
 290   ;; Added SYMBOL and OFFSET to ACCUMULATOR.  See
 291   ;; `c-guess-accumulator' about the structure of ACCUMULATOR.
 292   (let* ((entry    (assoc symbol accumulator))
 293          (counters (cdr entry))
 294          counter)
 295     (if entry
 296         (progn
 297           (setq counter (assoc offset counters))
 298           (if counter
 299               (setcdr counter (1+ (cdr counter)))
 300             (setq counters (cons (cons offset 1) counters))
 301             (setcdr entry counters))
 302           accumulator)
 303       (cons (cons symbol (cons (cons offset 1) nil)) accumulator))))
 304
 305 (defun c-guess-sort-accumulator (accumulator)
 306   ;; Sort each element of ACCUMULATOR by the number-of-times.  See
 307   ;; `c-guess-accumulator' for more details.
 308   (mapcar
 309    (lambda (entry)
 310      (let ((symbol (car entry))
 311            (counters (cdr entry)))
 312        (cons symbol (sort counters
 313                           (lambda (a b)
 314                             (if (> (cdr a) (cdr b))
 315                                 t
 316                               (and
 317                                (eq (cdr a) (cdr b))
 318                                (< (car a) (car b)))))))))
 319    accumulator))
 320
 321 (defun c-guess-make-offsets-alist (accumulator)
 322   ;; Throw away the rare cases in accumulator and make an offsets-alist structure.
 323   (mapcar
 324    (lambda (entry)
 325      (cons (car entry)
 326            (car (car (cdr entry)))))
 327    accumulator))
 328
 329 (defun c-guess-merge-offsets-alists (strong weak)
 330   ;; Merge two offsets-alists into one.
 331   ;; When two offsets-alists have the same symbol
 332   ;; entry, give STRONG priority over WEAK.
 333   (mapc
 334    (lambda (weak-elt)
 335      (unless (assoc (car weak-elt) strong)
 336        (setq strong (cons weak-elt strong))))
 337    weak)
 338   strong)
 339
 340 (defun c-guess-make-basic-offset (accumulator)
 341   ;; As candidate for `c-basic-offset', find the most frequently appearing
 342   ;; indentation-offset in ACCUMULATOR.
 343   (let* (;; Drop the value related to `c' syntactic-symbol.
 344          ;; (`c': Inside a multiline C style block comment.)
 345          ;; The impact for values of `c' is too large for guessing
 346          ;; `basic-offset' if the target source file is small and its license
 347          ;; notice is at top of the file.
 348          (accumulator (assq-delete-all 'c (copy-tree accumulator)))
 349          ;; Drop syntactic-symbols from ACCUMULATOR.
 350          (alist (apply #'append (mapcar (lambda (elts)
 351                                           (mapcar (lambda (elt)
 352                                                     (cons (abs (car elt))
 353                                                           (cdr elt)))
 354                                                   (cdr elts)))
 355                                         accumulator)))
 356          ;; Gather all indentation-offsets other than 0.
 357          ;; 0 is meaningless as `basic-offset'.
 358          (offset-list (delete 0
 359                               (delete-dups (mapcar
 360                                             (lambda (elt) (car elt))
 361                                             alist))))
 362          ;; Sum of number-of-times for offset:
 363          ;;  (offset . sum)
 364          (summed (mapcar (lambda (offset)
 365                            (cons offset
 366                                  (apply #'+
 367                                         (mapcar (lambda (a)
 368                                                   (if (eq (car a) offset)
 369                                                       (cdr a)
 370                                                     0))
 371                                                 alist))))
 372                          offset-list)))
 373     ;;
 374     ;; Find the majority.
 375     ;;
 376     (let ((majority '(nil . 0)))
 377       (while summed
 378         (when (< (cdr majority) (cdr (car summed)))
 379           (setq majority (car summed)))
 380         (setq summed (cdr summed)))
 381       (car majority))))
 382
 383 (defun c-guess-symbolize-offsets-alist (offsets-alist basic-offset)
 384   ;; Convert the representation of OFFSETS-ALIST to an alist using
 385   ;; `+', `-', `++', `--', `*', or `/'. These symbols represent
 386   ;; a value relative to BASIC-OFFSET.  Their meaning can be found
 387   ;; in the CC Mode manual.
 388   (mapcar
 389    (lambda (elt)
 390      (let ((s (car elt))
 391            (v (cdr elt)))
 392        (cond
 393         ((integerp v)
 394          (cons s (c-guess-symbolize-integer v
 395                                              basic-offset)))
 396         (t elt))))
 397    offsets-alist))
 398
 399 (defun c-guess-symbolize-integer (int basic-offset)
 400   (let ((aint (abs int)))
 401     (cond
 402      ((eq int basic-offset) '+)
 403      ((eq aint basic-offset) '-)
 404      ((eq int (* 2 basic-offset)) '++)
 405      ((eq aint (* 2 basic-offset)) '--)
 406      ((eq (* 2 int) basic-offset) '*)
 407      ((eq (* 2 aint) basic-offset) '-)
 408      (t int))))
 409
 410 (defun c-guess-style-name ()
 411   ;; Make a style name for the guessed style.
 412   (format "*c-guess*:%s" (buffer-file-name)))
 413
 414 (defun c-guess-make-style (basic-offset offsets-alist)
 415   (when basic-offset
 416     ;; Make a style from guessed values.
 417     (let*       ((offsets-alist (c-guess-merge-offsets-alists
 418                                  offsets-alist
 419                                  c-offsets-alist)))
 420       `((c-basic-offset . ,basic-offset)
 421         (c-offsets-alist . ,offsets-alist)))))
 422
 423 ;;;###autoload
 424 (defun c-guess-install (&optional style-name)
 425   "Install the latest guessed style into the current buffer.
 426 \(This guessed style is a combination of `c-guess-guessed-basic-offset',
 427 `c-guess-guessed-offsets-alist' and `c-offsets-alist'.)
 428
 429 The style is entered into CC Mode's style system by
 430 `c-add-style'.  Its name is either STYLE-NAME, or a name based on
 431 the absolute file name of the file if STYLE-NAME is nil."
 432   (interactive "sNew style name (empty for default name): ")
 433   (let* ((style (c-guess-make-style c-guess-guessed-basic-offset
 434                                     c-guess-guessed-offsets-alist)))
 435     (if style
 436         (let ((style-name (or (if (equal style-name "")
 437                                   nil
 438                                 style-name)
 439                               (c-guess-style-name))))
 440           (c-add-style style-name style t)
 441           (message "Style \"%s\" is installed" style-name))
 442       (error "Not yet guessed"))))
 443
 444 (defun c-guess-dump-accumulator ()
 445   "Show `c-guess-accumulator'."
 446   (interactive)
 447   (with-output-to-temp-buffer "*Accumulated Examined Indent Information*"
 448     (pp c-guess-accumulator)))
 449
 450 (defun c-guess-reset-accumulator ()
 451   "Reset `c-guess-accumulator'."
 452   (interactive)
 453   (setq c-guess-accumulator nil))
 454
 455 (defun c-guess-dump-guessed-values ()
 456   "Show `c-guess-guessed-basic-offset' and `c-guess-guessed-offsets-alist'."
 457   (interactive)
 458   (with-output-to-temp-buffer "*Guessed Values*"
 459     (princ "basic-offset: \n\t")
 460     (pp c-guess-guessed-basic-offset)
 461     (princ "\n\n")
 462     (princ "offsets-alist: \n")
 463     (pp c-guess-guessed-offsets-alist)
 464     ))
 465
 466 (defun c-guess-dump-guessed-style (&optional printer)
 467   "Show the guessed style.
 468 `pp' is used to print the style but if PRINTER is given,
 469 PRINTER is used instead. If PRINTER is not `nil', it
 470 is called with one argument, the guessed style."
 471   (interactive)
 472   (let ((style (c-guess-make-style c-guess-guessed-basic-offset
 473                                    c-guess-guessed-offsets-alist)))
 474     (if style
 475         (with-output-to-temp-buffer "*Guessed Style*"
 476           (funcall (if printer printer 'pp) style))
 477       (error "Not yet guessed"))))
 478
 479 (defun c-guess-guessed-syntactic-symbols ()
 480   ;; Return syntactic symbols in c-guess-guessed-offsets-alist
 481   ;; but not in c-guess-conversions.
 482   (let ((alist c-guess-guessed-offsets-alist)
 483         elt
 484         (symbols nil))
 485     (while alist
 486       (setq elt (car alist)
 487             alist (cdr alist))
 488       (unless (assq (car elt) c-guess-conversions)
 489         (setq symbols (cons (car elt)
 490                             symbols))))
 491     symbols))
 492
 493 (defun c-guess-view-reorder-offsets-alist-in-style (style guessed-syntactic-symbols)
 494   ;; Reorder the `c-offsets-alist' field of STYLE.
 495   ;; If an entry in `c-offsets-alist' holds a guessed value, move it to
 496   ;; front in the field. In addition alphabetical sort by entry name is done.
 497   (setq style (copy-tree style))
 498   (let ((offsets-alist-cell (assq 'c-offsets-alist style))
 499         (guessed-syntactic-symbols (c-guess-guessed-syntactic-symbols)))
 500     (setcdr offsets-alist-cell
 501             (sort (cdr offsets-alist-cell)
 502                   (lambda (a b)
 503                     (let ((a-guessed? (memq (car a) guessed-syntactic-symbols))
 504                           (b-guessed? (memq (car b) guessed-syntactic-symbols)))
 505                       (cond
 506                        ((or (and a-guessed? b-guessed?)
 507                             (not (or a-guessed? b-guessed?)))
 508                         (string-lessp (symbol-name (car a))
 509                                       (symbol-name (car b))))
 510                        (a-guessed? t)
 511                        (b-guessed? nil)))))))
 512   style)
 513
 514 (defun c-guess-view-mark-guessed-entries (guessed-syntactic-symbols)
 515   ;; Put " ; Guess value" markers on all entries which hold
 516   ;; guessed values.
 517   ;; `c-basic-offset' is always considered as holding a guessed value.
 518   (let ((needs-markers (cons 'c-basic-offset
 519                              guessed-syntactic-symbols)))
 520     (while needs-markers
 521       (goto-char (point-min))
 522       (when (search-forward (concat "("
 523                                     (symbol-name (car needs-markers))
 524                                     " ") nil t)
 525         (move-end-of-line 1)
 526         (comment-dwim nil)
 527         (insert " Guessed value"))
 528       (setq needs-markers
 529             (cdr needs-markers)))))
 530
 531 (defun c-guess-view (&optional with-name)
 532   "Emit emacs lisp code which defines the last guessed style.
 533 So you can put the code into .emacs if you prefer the
 534 guessed code.
 535 \"STYLE NAME HERE\" is used as the name for the style in the
 536 emitted code. If WITH-NAME is given, it is used instead.
 537 WITH-NAME is expected as a string but if this function
 538 called interactively with prefix argument, the value for
 539 WITH-NAME is asked to the user."
 540   (interactive "P")
 541   (let* ((temporary-style-name (cond
 542                                 ((stringp with-name) with-name)
 543                                 (with-name (read-from-minibuffer
 544                                             "New style name: "))
 545                                 (t
 546                                  "STYLE NAME HERE")))
 547          (guessed-style-name (c-guess-style-name))
 548          (current-style-name c-indentation-style)
 549          (parent-style-name (if (string-equal guessed-style-name
 550                                               current-style-name)
 551                                 ;; The guessed style is already installed.
 552                                 ;; It cannot be used as the parent style.
 553                                 ;; Use the default style for the current
 554                                 ;; major mode as the parent style.
 555                                 (cc-choose-style-for-mode
 556                                  major-mode
 557                                  c-default-style)
 558                               ;; The guessed style is not installed yet.
 559                               current-style-name)))
 560     (c-guess-dump-guessed-style
 561      (lambda (style)
 562        (let ((guessed-syntactic-symbols (c-guess-guessed-syntactic-symbols)))
 563          (pp `(c-add-style ,temporary-style-name
 564                            ',(cons parent-style-name
 565                                    (c-guess-view-reorder-offsets-alist-in-style
 566                                     style
 567                                     guessed-syntactic-symbols))))
 568          (with-current-buffer standard-output
 569            (lisp-interaction-mode)
 570            (c-guess-view-mark-guessed-entries
 571             guessed-syntactic-symbols)
 572            (buffer-enable-undo)))))))
 573
 574 \f
 575 (cc-provide 'cc-guess)
 576 ;;; cc-guess.el ends here