code.delx.au - gnu-emacs/blob - lisp/emacs-lisp/debug.el

   1 ;;; debug.el --- debuggers and related commands for Emacs
   2
   3 ;; Copyright (C) 1985, 1986, 1994, 2001, 2003, 2005
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7 ;; Keywords: lisp, tools, maint
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; This is a major mode documented in the Emacs manual.
  29
  30 ;;; Code:
  31
  32 (require 'button)
  33
  34 (defgroup debugger nil
  35   "Debuggers and related commands for Emacs."
  36   :prefix "debugger-"
  37   :group 'debug)
  38
  39 (defcustom debugger-mode-hook nil
  40   "*Hooks run when `debugger-mode' is turned on."
  41   :type 'hook
  42   :group 'debugger
  43   :version "20.3")
  44
  45 (defcustom debugger-batch-max-lines 40
  46   "*Maximum lines to show in debugger buffer in a noninteractive Emacs.
  47 When the debugger is entered and Emacs is running in batch mode,
  48 if the backtrace text has more than this many lines,
  49 the middle is discarded, and just the beginning and end are displayed."
  50   :type 'integer
  51   :group 'debugger
  52   :version "21.1")
  53
  54 (defcustom debug-function-list nil
  55   "List of functions currently set for debug on entry."
  56   :type '(repeat function)
  57   :group 'debugger)
  58
  59 (defcustom debugger-step-after-exit nil
  60   "Non-nil means \"single-step\" after the debugger exits."
  61   :type 'boolean
  62   :group 'debugger)
  63
  64 (defvar debugger-value nil
  65   "This is the value for the debugger to return, when it returns.")
  66
  67 (defvar debugger-old-buffer nil
  68   "This is the buffer that was current when the debugger was entered.")
  69
  70 (defvar debugger-previous-backtrace nil
  71   "The contents of the previous backtrace (including text properties).
  72 This is to optimize `debugger-make-xrefs'.")
  73
  74 (defvar debugger-outer-match-data)
  75 (defvar debugger-outer-load-read-function)
  76 (defvar debugger-outer-overriding-local-map)
  77 (defvar debugger-outer-overriding-terminal-local-map)
  78 (defvar debugger-outer-track-mouse)
  79 (defvar debugger-outer-last-command)
  80 (defvar debugger-outer-this-command)
  81 ;; unread-command-char is obsolete,
  82 ;; but we still save and restore it
  83 ;; in case some user program still tries to set it.
  84 (defvar debugger-outer-unread-command-char)
  85 (defvar debugger-outer-unread-command-events)
  86 (defvar debugger-outer-unread-post-input-method-events)
  87 (defvar debugger-outer-last-input-event)
  88 (defvar debugger-outer-last-command-event)
  89 (defvar debugger-outer-last-nonmenu-event)
  90 (defvar debugger-outer-last-event-frame)
  91 (defvar debugger-outer-standard-input)
  92 (defvar debugger-outer-standard-output)
  93 (defvar debugger-outer-inhibit-redisplay)
  94 (defvar debugger-outer-cursor-in-echo-area)
  95
  96 ;;;###autoload
  97 (setq debugger 'debug)
  98 ;;;###autoload
  99 (defun debug (&rest debugger-args)
 100   "Enter debugger.  To return, type \\<debugger-mode-map>`\\[debugger-continue]'.
 101 Arguments are mainly for use when this is called from the internals
 102 of the evaluator.
 103
 104 You may call with no args, or you may pass nil as the first arg and
 105 any other args you like.  In that case, the list of args after the
 106 first will be printed into the backtrace buffer."
 107   (interactive)
 108   (if inhibit-redisplay
 109       ;; Don't really try to enter debugger within an eval from redisplay.
 110       debugger-value
 111     (unless noninteractive
 112       (message "Entering debugger..."))
 113     (let (debugger-value
 114           (debug-on-error nil)
 115           (debug-on-quit nil)
 116           (debugger-buffer (let ((default-major-mode 'fundamental-mode))
 117                              (get-buffer-create "*Backtrace*")))
 118           (debugger-old-buffer (current-buffer))
 119           (debugger-step-after-exit nil)
 120           ;; Don't keep reading from an executing kbd macro!
 121           (executing-kbd-macro nil)
 122           ;; Save the outer values of these vars for the `e' command
 123           ;; before we replace the values.
 124           (debugger-outer-match-data (match-data))
 125           (debugger-outer-load-read-function load-read-function)
 126           (debugger-outer-overriding-local-map overriding-local-map)
 127           (debugger-outer-overriding-terminal-local-map
 128            overriding-terminal-local-map)
 129           (debugger-outer-track-mouse track-mouse)
 130           (debugger-outer-last-command last-command)
 131           (debugger-outer-this-command this-command)
 132           (debugger-outer-unread-command-char
 133            (with-no-warnings unread-command-char))
 134           (debugger-outer-unread-command-events unread-command-events)
 135           (debugger-outer-unread-post-input-method-events
 136            unread-post-input-method-events)
 137           (debugger-outer-last-input-event last-input-event)
 138           (debugger-outer-last-command-event last-command-event)
 139           (debugger-outer-last-nonmenu-event last-nonmenu-event)
 140           (debugger-outer-last-event-frame last-event-frame)
 141           (debugger-outer-standard-input standard-input)
 142           (debugger-outer-standard-output standard-output)
 143           (debugger-outer-inhibit-redisplay inhibit-redisplay)
 144           (debugger-outer-cursor-in-echo-area cursor-in-echo-area))
 145       ;; Set this instead of binding it, so that `q'
 146       ;; will not restore it.
 147       (setq overriding-terminal-local-map nil)
 148       ;; Don't let these magic variables affect the debugger itself.
 149       (let ((last-command nil) this-command track-mouse
 150             unread-command-events
 151             unread-post-input-method-events
 152             last-input-event last-command-event last-nonmenu-event
 153             last-event-frame
 154             overriding-local-map
 155             load-read-function
 156             ;; If we are inside a minibuffer, allow nesting
 157             ;; so that we don't get an error from the `e' command.
 158             (enable-recursive-minibuffers
 159              (or enable-recursive-minibuffers (> (minibuffer-depth) 0)))
 160             (standard-input t) (standard-output t)
 161             inhibit-redisplay
 162             (cursor-in-echo-area nil))
 163         (unwind-protect
 164             (save-excursion
 165               (save-window-excursion
 166                 (with-no-warnings
 167                  (setq unread-command-char -1))
 168                 (pop-to-buffer debugger-buffer)
 169                 (debugger-mode)
 170                 (debugger-setup-buffer debugger-args)
 171                 (when noninteractive
 172                   ;; If the backtrace is long, save the beginning
 173                   ;; and the end, but discard the middle.
 174                   (when (> (count-lines (point-min) (point-max))
 175                            debugger-batch-max-lines)
 176                     (goto-char (point-min))
 177                     (forward-line (/ 2 debugger-batch-max-lines))
 178                     (let ((middlestart (point)))
 179                       (goto-char (point-max))
 180                       (forward-line (- (/ 2 debugger-batch-max-lines)
 181                                        debugger-batch-max-lines))
 182                       (delete-region middlestart (point)))
 183                     (insert "...\n"))
 184                   (goto-char (point-min))
 185                   (message "%s" (buffer-string))
 186                   (kill-emacs))
 187                 (if (eq (car debugger-args) 'debug)
 188                     ;; Skip the frames for backtrace-debug, byte-code, and debug.
 189                     (backtrace-debug 3 t))
 190                 (debugger-reenable)
 191                 (message "")
 192                 (let ((inhibit-trace t)
 193                       (standard-output nil)
 194                       (buffer-read-only t))
 195                   (message "")
 196                   ;; Make sure we unbind buffer-read-only in the right buffer.
 197                   (save-excursion
 198                     (recursive-edit)))))
 199           ;; Kill or at least neuter the backtrace buffer, so that users
 200           ;; don't try to execute debugger commands in an invalid context.
 201           (if (get-buffer-window debugger-buffer 0)
 202               ;; Still visible despite the save-window-excursion?  Maybe it
 203               ;; it's in a pop-up frame.  It would be annoying to delete and
 204               ;; recreate it every time the debugger stops, so instead we'll
 205               ;; erase it and hide it but keep it alive.
 206               (with-current-buffer debugger-buffer
 207                 (erase-buffer)
 208                 (fundamental-mode)
 209                 (with-selected-window (get-buffer-window debugger-buffer 0)
 210                   (bury-buffer)))
 211             (kill-buffer debugger-buffer))
 212           (set-match-data debugger-outer-match-data)))
 213       ;; Put into effect the modified values of these variables
 214       ;; in case the user set them with the `e' command.
 215       (setq load-read-function debugger-outer-load-read-function)
 216       (setq overriding-local-map debugger-outer-overriding-local-map)
 217       (setq overriding-terminal-local-map
 218             debugger-outer-overriding-terminal-local-map)
 219       (setq track-mouse debugger-outer-track-mouse)
 220       (setq last-command debugger-outer-last-command)
 221       (setq this-command debugger-outer-this-command)
 222       (with-no-warnings
 223        (setq unread-command-char debugger-outer-unread-command-char))
 224       (setq unread-command-events debugger-outer-unread-command-events)
 225       (setq unread-post-input-method-events
 226             debugger-outer-unread-post-input-method-events)
 227       (setq last-input-event debugger-outer-last-input-event)
 228       (setq last-command-event debugger-outer-last-command-event)
 229       (setq last-nonmenu-event debugger-outer-last-nonmenu-event)
 230       (setq last-event-frame debugger-outer-last-event-frame)
 231       (setq standard-input debugger-outer-standard-input)
 232       (setq standard-output debugger-outer-standard-output)
 233       (setq inhibit-redisplay debugger-outer-inhibit-redisplay)
 234       (setq cursor-in-echo-area debugger-outer-cursor-in-echo-area)
 235       (setq debug-on-next-call debugger-step-after-exit)
 236       debugger-value)))
 237 \f
 238 (defun debugger-setup-buffer (debugger-args)
 239   "Initialize the `*Backtrace*' buffer for entry to the debugger.
 240 That buffer should be current already."
 241   (setq buffer-read-only nil)
 242   (erase-buffer)
 243   (set-buffer-multibyte nil)
 244   (let ((standard-output (current-buffer))
 245         (print-escape-newlines t)
 246         (print-level 8)
 247         (print-length 50))
 248     (backtrace))
 249   (goto-char (point-min))
 250   (delete-region (point)
 251                  (progn
 252                    (search-forward "\n  debug(")
 253                    (forward-line 1)
 254                    (point)))
 255   (insert "Debugger entered")
 256   ;; lambda is for debug-on-call when a function call is next.
 257   ;; debug is for debug-on-entry function called.
 258   (cond ((memq (car debugger-args) '(lambda debug))
 259          (insert "--entering a function:\n")
 260          (if (eq (car debugger-args) 'debug)
 261              (progn
 262                (delete-char 1)
 263                (insert ?*)
 264                (beginning-of-line))))
 265         ;; Exiting a function.
 266         ((eq (car debugger-args) 'exit)
 267          (insert "--returning value: ")
 268          (setq debugger-value (nth 1 debugger-args))
 269          (prin1 debugger-value (current-buffer))
 270          (insert ?\n)
 271          (delete-char 1)
 272          (insert ? )
 273          (beginning-of-line))
 274         ;; Debugger entered for an error.
 275         ((eq (car debugger-args) 'error)
 276          (insert "--Lisp error: ")
 277          (prin1 (nth 1 debugger-args) (current-buffer))
 278          (insert ?\n))
 279         ;; debug-on-call, when the next thing is an eval.
 280         ((eq (car debugger-args) t)
 281          (insert "--beginning evaluation of function call form:\n"))
 282         ;; User calls debug directly.
 283         (t
 284          (insert ": ")
 285          (prin1 (if (eq (car debugger-args) 'nil)
 286                     (cdr debugger-args) debugger-args)
 287                 (current-buffer))
 288          (insert ?\n)))
 289   ;; After any frame that uses eval-buffer,
 290   ;; insert a line that states the buffer position it's reading at.
 291   (save-excursion
 292     (while (re-search-forward "^  eval-buffer(" nil t)
 293       (end-of-line)
 294       (insert (format "\n  ;;; Reading at buffer position %d"
 295                       (with-current-buffer (nth 2 (backtrace-frame (debugger-frame-number)))
 296                         (point))))))
 297   (debugger-make-xrefs))
 298
 299 (defun debugger-make-xrefs (&optional buffer)
 300   "Attach cross-references to symbol names in the `*Backtrace*' buffer."
 301   (interactive "b")
 302   (save-excursion
 303     (set-buffer (or buffer (current-buffer)))
 304     (setq buffer (current-buffer))
 305     (let ((buffer-read-only nil)
 306           (old-end (point-min)) (new-end (point-min)))
 307       ;; If we saved an old backtrace, find the common part
 308       ;; between the new and the old.
 309       ;; Compare line by line, starting from the end,
 310       ;; because that's the part that is likely to be unchanged.
 311       (if debugger-previous-backtrace
 312           (let (old-start new-start (all-match t))
 313             (goto-char (point-max))
 314             (with-temp-buffer
 315               (insert debugger-previous-backtrace)
 316               (while (and all-match (not (bobp)))
 317                 (setq old-end (point))
 318                 (forward-line -1)
 319                 (setq old-start (point))
 320                 (with-current-buffer buffer
 321                   (setq new-end (point))
 322                   (forward-line -1)
 323                   (setq new-start (point)))
 324                 (if (not (zerop
 325                           (compare-buffer-substrings
 326                            (current-buffer) old-start old-end
 327                            buffer new-start new-end)))
 328                     (setq all-match nil))))
 329             ;; Now new-end is the position of the start of the
 330             ;; unchanged part in the current buffer, and old-end is
 331             ;; the position of that same text in the saved old
 332             ;; backtrace.  But we must subtract (point-min) since strings are
 333             ;; indexed in origin 0.
 334
 335             ;; Replace the unchanged part of the backtrace
 336             ;; with the text from debugger-previous-backtrace,
 337             ;; since that already has the proper xrefs.
 338             ;; With this optimization, we only need to scan
 339             ;; the changed part of the backtrace.
 340             (delete-region new-end (point-max))
 341             (goto-char (point-max))
 342             (insert (substring debugger-previous-backtrace
 343                                (- old-end (point-min))))
 344             ;; Make the unchanged part of the backtrace inaccessible
 345             ;; so it won't be scanned.
 346             (narrow-to-region (point-min) new-end)))
 347
 348       ;; Scan the new part of the backtrace, inserting xrefs.
 349       (goto-char (point-min))
 350       (while (progn
 351                (skip-syntax-forward "^w_")
 352                (not (eobp)))
 353         (let* ((beg (point))
 354                (end (progn (skip-syntax-forward "w_") (point)))
 355                (sym (intern-soft (buffer-substring-no-properties
 356                                   beg end)))
 357                (file (and sym (symbol-file sym 'defun))))
 358           (when file
 359             (goto-char beg)
 360             ;; help-xref-button needs to operate on something matched
 361             ;; by a regexp, so set that up for it.
 362             (re-search-forward "\\(\\(\\sw\\|\\s_\\)+\\)")
 363             (help-xref-button 1 'help-function-def sym file)))
 364         (forward-line 1))
 365       (widen))
 366     (setq debugger-previous-backtrace (buffer-string))))
 367 \f
 368 (defun debugger-step-through ()
 369   "Proceed, stepping through subexpressions of this expression.
 370 Enter another debugger on next entry to eval, apply or funcall."
 371   (interactive)
 372   (setq debugger-step-after-exit t)
 373   (message "Proceeding, will debug on next eval or call.")
 374   (exit-recursive-edit))
 375
 376 (defun debugger-continue ()
 377   "Continue, evaluating this expression without stopping."
 378   (interactive)
 379   (unless debugger-may-continue
 380     (error "Cannot continue"))
 381   (message "Continuing.")
 382   (exit-recursive-edit))
 383
 384 (defun debugger-return-value (val)
 385   "Continue, specifying value to return.
 386 This is only useful when the value returned from the debugger
 387 will be used, such as in a debug on exit from a frame."
 388   (interactive "XReturn value (evaluated): ")
 389   (setq debugger-value val)
 390   (princ "Returning " t)
 391   (prin1 debugger-value)
 392   (exit-recursive-edit))
 393
 394 (defun debugger-jump ()
 395   "Continue to exit from this frame, with all debug-on-entry suspended."
 396   (interactive)
 397   (debugger-frame)
 398   ;; Turn off all debug-on-entry functions
 399   ;; but leave them in the list.
 400   (let ((list debug-function-list))
 401     (while list
 402       (fset (car list)
 403             (debug-on-entry-1 (car list) (symbol-function (car list)) nil))
 404       (setq list (cdr list))))
 405   (message "Continuing through this frame")
 406   (exit-recursive-edit))
 407
 408 (defun debugger-reenable ()
 409   "Turn all debug-on-entry functions back on."
 410   (let ((list debug-function-list))
 411     (while list
 412       (or (consp (symbol-function (car list)))
 413           (debug-convert-byte-code (car list)))
 414       (fset (car list)
 415             (debug-on-entry-1 (car list) (symbol-function (car list)) t))
 416       (setq list (cdr list)))))
 417
 418 (defun debugger-frame-number ()
 419   "Return number of frames in backtrace before the one point points at."
 420   (save-excursion
 421     (beginning-of-line)
 422     (let ((opoint (point))
 423           (count 0))
 424       (while (not (eq (cadr (backtrace-frame count)) 'debug))
 425         (setq count (1+ count)))
 426       (goto-char (point-min))
 427       (if (or (equal (buffer-substring (point) (+ (point) 6))
 428                      "Signal")
 429               (equal (buffer-substring (point) (+ (point) 6))
 430                      "Return"))
 431           (progn
 432             (search-forward ":")
 433             (forward-sexp 1)))
 434       (forward-line 1)
 435       (while (progn
 436                (forward-char 2)
 437                (if (= (following-char) ?\()
 438                    (forward-sexp 1)
 439                  (forward-sexp 2))
 440                (forward-line 1)
 441                (<= (point) opoint))
 442         (if (looking-at " *;;;")
 443             (forward-line 1))
 444         (setq count (1+ count)))
 445       count)))
 446
 447 (defun debugger-frame ()
 448   "Request entry to debugger when this frame exits.
 449 Applies to the frame whose line point is on in the backtrace."
 450   (interactive)
 451   (save-excursion
 452     (beginning-of-line)
 453     (if (looking-at " *;;;\\|[a-z]")
 454         (error "This line is not a function call")))
 455   (beginning-of-line)
 456   (backtrace-debug (debugger-frame-number) t)
 457   (if (= (following-char) ? )
 458       (let ((buffer-read-only nil))
 459         (delete-char 1)
 460         (insert ?*)))
 461   (beginning-of-line))
 462
 463 (defun debugger-frame-clear ()
 464   "Do not enter debugger when this frame exits.
 465 Applies to the frame whose line point is on in the backtrace."
 466   (interactive)
 467   (save-excursion
 468     (beginning-of-line)
 469     (if (looking-at " *;;;\\|[a-z]")
 470         (error "This line is not a function call")))
 471   (beginning-of-line)
 472   (backtrace-debug (debugger-frame-number) nil)
 473   (if (= (following-char) ?*)
 474       (let ((buffer-read-only nil))
 475         (delete-char 1)
 476         (insert ? )))
 477   (beginning-of-line))
 478
 479
 480
 481 (put 'debugger-env-macro 'lisp-indent-function 0)
 482 (defmacro debugger-env-macro (&rest body)
 483   "Run BODY in original environment."
 484   `(save-excursion
 485     (if (null (buffer-name debugger-old-buffer))
 486         ;; old buffer deleted
 487         (setq debugger-old-buffer (current-buffer)))
 488     (set-buffer debugger-old-buffer)
 489     (let ((load-read-function debugger-outer-load-read-function)
 490           (overriding-terminal-local-map
 491            debugger-outer-overriding-terminal-local-map)
 492           (overriding-local-map debugger-outer-overriding-local-map)
 493           (track-mouse debugger-outer-track-mouse)
 494           (last-command debugger-outer-last-command)
 495           (this-command debugger-outer-this-command)
 496           (unread-command-events debugger-outer-unread-command-events)
 497           (unread-post-input-method-events
 498            debugger-outer-unread-post-input-method-events)
 499           (last-input-event debugger-outer-last-input-event)
 500           (last-command-event debugger-outer-last-command-event)
 501           (last-nonmenu-event debugger-outer-last-nonmenu-event)
 502           (last-event-frame debugger-outer-last-event-frame)
 503           (standard-input debugger-outer-standard-input)
 504           (standard-output debugger-outer-standard-output)
 505           (inhibit-redisplay debugger-outer-inhibit-redisplay)
 506           (cursor-in-echo-area debugger-outer-cursor-in-echo-area))
 507       (set-match-data debugger-outer-match-data)
 508       (prog1
 509           (let ((save-ucc (with-no-warnings unread-command-char)))
 510             (unwind-protect
 511                 (progn
 512                   (with-no-warnings
 513                    (setq unread-command-char debugger-outer-unread-command-char))
 514                   (prog1 (progn ,@body)
 515                     (with-no-warnings
 516                      (setq debugger-outer-unread-command-char unread-command-char))))
 517               (with-no-warnings
 518                (setq unread-command-char save-ucc))))
 519         (setq debugger-outer-match-data (match-data))
 520         (setq debugger-outer-load-read-function load-read-function)
 521         (setq debugger-outer-overriding-terminal-local-map
 522               overriding-terminal-local-map)
 523         (setq debugger-outer-overriding-local-map overriding-local-map)
 524         (setq debugger-outer-track-mouse track-mouse)
 525         (setq debugger-outer-last-command last-command)
 526         (setq debugger-outer-this-command this-command)
 527         (setq debugger-outer-unread-command-events unread-command-events)
 528         (setq debugger-outer-unread-post-input-method-events
 529               unread-post-input-method-events)
 530         (setq debugger-outer-last-input-event last-input-event)
 531         (setq debugger-outer-last-command-event last-command-event)
 532         (setq debugger-outer-last-nonmenu-event last-nonmenu-event)
 533         (setq debugger-outer-last-event-frame last-event-frame)
 534         (setq debugger-outer-standard-input standard-input)
 535         (setq debugger-outer-standard-output standard-output)
 536         (setq debugger-outer-inhibit-redisplay inhibit-redisplay)
 537         (setq debugger-outer-cursor-in-echo-area cursor-in-echo-area)
 538         ))))
 539
 540 (defun debugger-eval-expression (exp)
 541   "Eval an expression, in an environment like that outside the debugger."
 542   (interactive
 543    (list (read-from-minibuffer "Eval: "
 544                                nil read-expression-map t
 545                                'read-expression-history)))
 546   (debugger-env-macro (eval-expression exp)))
 547 \f
 548 (defvar debugger-mode-map
 549   (let ((map (make-keymap)))
 550     (set-keymap-parent map button-buffer-map)
 551     (suppress-keymap map)
 552     (define-key map "-" 'negative-argument)
 553     (define-key map "b" 'debugger-frame)
 554     (define-key map "c" 'debugger-continue)
 555     (define-key map "j" 'debugger-jump)
 556     (define-key map "r" 'debugger-return-value)
 557     (define-key map "u" 'debugger-frame-clear)
 558     (define-key map "d" 'debugger-step-through)
 559     (define-key map "l" 'debugger-list-functions)
 560     (define-key map "h" 'describe-mode)
 561     (define-key map "q" 'top-level)
 562     (define-key map "e" 'debugger-eval-expression)
 563     (define-key map " " 'next-line)
 564     (define-key map "R" 'debugger-record-expression)
 565     (define-key map "\C-m" 'help-follow)
 566     (define-key map [mouse-2] 'push-button)
 567     map))
 568
 569 (defcustom debugger-record-buffer "*Debugger-record*"
 570   "*Buffer name for expression values, for \\[debugger-record-expression]."
 571   :type 'string
 572   :group 'debugger
 573   :version "20.3")
 574
 575 (defun debugger-record-expression  (exp)
 576   "Display a variable's value and record it in `*Backtrace-record*' buffer."
 577   (interactive
 578    (list (read-from-minibuffer
 579           "Record Eval: "
 580           nil
 581           read-expression-map t
 582           'read-expression-history)))
 583   (let* ((buffer (get-buffer-create debugger-record-buffer))
 584          (standard-output buffer))
 585     (princ (format "Debugger Eval (%s): " exp))
 586     (princ (debugger-eval-expression exp))
 587     (terpri))
 588
 589   (with-current-buffer (get-buffer debugger-record-buffer)
 590     (save-excursion
 591       (forward-line -1)
 592       (message
 593        (buffer-substring (point) (progn (end-of-line) (point)))))))
 594
 595 (put 'debugger-mode 'mode-class 'special)
 596
 597 (defun debugger-mode ()
 598   "Mode for backtrace buffers, selected in debugger.
 599 \\<debugger-mode-map>
 600 A line starts with `*' if exiting that frame will call the debugger.
 601 Type \\[debugger-frame] or \\[debugger-frame-clear] to set or remove the `*'.
 602
 603 When in debugger due to frame being exited,
 604 use the \\[debugger-return-value] command to override the value
 605 being returned from that frame.
 606
 607 Use \\[debug-on-entry] and \\[cancel-debug-on-entry] to control
 608 which functions will enter the debugger when called.
 609
 610 Complete list of commands:
 611 \\{debugger-mode-map}"
 612   (kill-all-local-variables)
 613   (setq major-mode 'debugger-mode)
 614   (setq mode-name "Debugger")
 615   (setq truncate-lines t)
 616   (set-syntax-table emacs-lisp-mode-syntax-table)
 617   (use-local-map debugger-mode-map)
 618   (run-mode-hooks 'debugger-mode-hook))
 619 \f
 620 ;;;###autoload
 621 (defun debug-on-entry (function)
 622   "Request FUNCTION to invoke debugger each time it is called.
 623 If you tell the debugger to continue, FUNCTION's execution proceeds.
 624 This works by modifying the definition of FUNCTION,
 625 which must be written in Lisp, not predefined.
 626 Use \\[cancel-debug-on-entry] to cancel the effect of this command.
 627 Redefining FUNCTION also cancels it."
 628   (interactive "aDebug on entry (to function): ")
 629   (debugger-reenable)
 630   ;; Handle a function that has been aliased to some other function.
 631   (if (and (subrp (symbol-function function))
 632            (eq (cdr (subr-arity (symbol-function function))) 'unevalled))
 633       (error "Function %s is a special form" function))
 634   (if (or (symbolp (symbol-function function))
 635           (subrp (symbol-function function)))
 636       ;; Create a wrapper in which we can then add the necessary debug call.
 637       (fset function `(lambda (&rest debug-on-entry-args)
 638                         ,(interactive-form (symbol-function function))
 639                         (apply ',(symbol-function function)
 640                                debug-on-entry-args))))
 641   (or (consp (symbol-function function))
 642       (debug-convert-byte-code function))
 643   (or (consp (symbol-function function))
 644       (error "Definition of %s is not a list" function))
 645   (fset function (debug-on-entry-1 function (symbol-function function) t))
 646   (or (memq function debug-function-list)
 647       (push function debug-function-list))
 648   function)
 649
 650 ;;;###autoload
 651 (defun cancel-debug-on-entry (&optional function)
 652   "Undo effect of \\[debug-on-entry] on FUNCTION.
 653 If argument is nil or an empty string, cancel for all functions."
 654   (interactive
 655    (list (let ((name
 656                 (completing-read "Cancel debug on entry (to function): "
 657                                  (mapcar 'symbol-name debug-function-list)
 658                                  nil t nil)))
 659            (if name (intern name)))))
 660   (debugger-reenable)
 661   (if (and function (not (string= function "")))
 662       (progn
 663         (let ((f (debug-on-entry-1 function (symbol-function function) nil)))
 664           (condition-case nil
 665               (if (and (equal (nth 1 f) '(&rest debug-on-entry-args))
 666                        (eq (car (nth 3 f)) 'apply))
 667                   ;; `f' is a wrapper introduced in debug-on-entry.
 668                   ;; Get rid of it since we don't need it any more.
 669                   (setq f (nth 1 (nth 1 (nth 3 f)))))
 670             (error nil))
 671           (fset function f))
 672         (setq debug-function-list (delq function debug-function-list))
 673         function)
 674     (message "Cancelling debug-on-entry for all functions")
 675     (mapcar 'cancel-debug-on-entry debug-function-list)))
 676
 677 (defun debug-convert-byte-code (function)
 678   (let ((defn (symbol-function function)))
 679     (if (not (consp defn))
 680         ;; Assume a compiled code object.
 681         (let* ((contents (append defn nil))
 682                (body
 683                 (list (list 'byte-code (nth 1 contents)
 684                             (nth 2 contents) (nth 3 contents)))))
 685           (if (nthcdr 5 contents)
 686               (setq body (cons (list 'interactive (nth 5 contents)) body)))
 687           (if (nth 4 contents)
 688               ;; Use `documentation' here, to get the actual string,
 689               ;; in case the compiled function has a reference
 690               ;; to the .elc file.
 691               (setq body (cons (documentation function) body)))
 692           (fset function (cons 'lambda (cons (car contents) body)))))))
 693
 694 (defun debug-on-entry-1 (function defn flag)
 695   (if (subrp defn)
 696       (error "%s is a built-in function" function)
 697     (if (eq (car defn) 'macro)
 698         (debug-on-entry-1 function (cdr defn) flag)
 699       (or (eq (car defn) 'lambda)
 700           (error "%s not user-defined Lisp function" function))
 701       (let ((tail (cddr defn)))
 702         ;; Skip the docstring.
 703         (if (stringp (car tail)) (setq tail (cdr tail)))
 704         ;; Skip the interactive form.
 705         (if (eq 'interactive (car-safe (car tail))) (setq tail (cdr tail)))
 706         (unless (eq flag (equal (car tail) '(debug 'debug)))
 707           ;; Add/remove debug statement as needed.
 708           (if (not flag)
 709               (progn (setcar tail (cadr tail))
 710                      (setcdr tail (cddr tail)))
 711             (setcdr tail (cons (car tail) (cdr tail)))
 712             (setcar tail '(debug 'debug))))
 713         defn))))
 714
 715 (defun debugger-list-functions ()
 716   "Display a list of all the functions now set to debug on entry."
 717   (interactive)
 718   (require 'help-mode)
 719   (help-setup-xref '(debugger-list-functions) (interactive-p))
 720   (with-output-to-temp-buffer (help-buffer)
 721     (with-current-buffer standard-output
 722       (if (null debug-function-list)
 723           (princ "No debug-on-entry functions now\n")
 724         (princ "Functions set to debug on entry:\n\n")
 725         (dolist (fun debug-function-list)
 726           (make-text-button (point) (progn (prin1 fun) (point))
 727                             'type 'help-function
 728                             'help-args (list fun))
 729           (terpri))
 730         (terpri)
 731         (princ "Note: if you have redefined a function, then it may no longer\n")
 732         (princ "be set to debug on entry, even if it is in the list.")))))
 733
 734 (provide 'debug)
 735
 736 ;; arch-tag: b6ec7047-f801-4103-9c63-d69322db9d3b
 737 ;;; debug.el ends here