lisp/emacs-lisp/debug.el

   1 ;;; debug.el --- debuggers and related commands for Emacs
   2
   3 ;; Copyright (C) 1985, 1986, 1994 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: FSF
   6 ;; Keywords: lisp, tools, maint
   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 ;; This is a major mode documented in the Emacs manual.
  28
  29 ;;; Code:
  30
  31 (defvar debug-function-list nil
  32   "List of functions currently set for debug on entry.")
  33
  34 (defvar debugger-step-after-exit nil
  35   "Non-nil means \"single-step\" after the debugger exits.")
  36
  37 (defvar debugger-value nil
  38   "This is the value for the debugger to return, when it returns.")
  39
  40 (defvar debugger-old-buffer nil
  41   "This is the buffer that was current when the debugger was entered.")
  42
  43 (defvar debugger-outer-match-data)
  44 (defvar debugger-outer-load-read-function)
  45 (defvar debugger-outer-overriding-local-map)
  46 (defvar debugger-outer-track-mouse)
  47 (defvar debugger-outer-last-command)
  48 (defvar debugger-outer-this-command)
  49 (defvar debugger-outer-unread-command-char)
  50 (defvar debugger-outer-unread-command-events)
  51 (defvar debugger-outer-last-input-event)
  52 (defvar debugger-outer-last-command-event)
  53 (defvar debugger-outer-last-nonmenu-event)
  54 (defvar debugger-outer-last-event-frame)
  55 (defvar debugger-outer-standard-input)
  56 (defvar debugger-outer-standard-output)
  57 (defvar debugger-outer-cursor-in-echo-area)
  58
  59 ;;;###autoload
  60 (setq debugger 'debug)
  61 ;;;###autoload
  62 (defun debug (&rest debugger-args)
  63   "Enter debugger.  To return, type \\<debugger-mode-map>`\\[debugger-continue]'.
  64 Arguments are mainly for use when this is called from the internals
  65 of the evaluator.
  66
  67 You may call with no args, or you may pass nil as the first arg and
  68 any other args you like.  In that case, the list of args after the
  69 first will be printed into the backtrace buffer."
  70   (interactive)
  71   (message "Entering debugger...")
  72   (let (debugger-value
  73         (debug-on-error nil)
  74         (debug-on-quit nil)
  75         (debugger-buffer (let ((default-major-mode 'fundamental-mode))
  76                            (get-buffer-create "*Backtrace*")))
  77         (debugger-old-buffer (current-buffer))
  78         (debugger-step-after-exit nil)
  79         ;; Don't keep reading from an executing kbd macro!
  80         (executing-macro nil)
  81         ;; Save the outer values of these vars for the `e' command
  82         ;; before we replace the values.
  83         (debugger-outer-match-data (match-data))
  84         (debugger-outer-load-read-function load-read-function)
  85         (debugger-outer-overriding-local-map overriding-local-map)
  86         (debugger-outer-track-mouse track-mouse)
  87         (debugger-outer-last-command last-command)
  88         (debugger-outer-this-command this-command)
  89         (debugger-outer-unread-command-char unread-command-char)
  90         (debugger-outer-unread-command-events unread-command-events)
  91         (debugger-outer-last-input-event last-input-event)
  92         (debugger-outer-last-command-event last-command-event)
  93         (debugger-outer-last-nonmenu-event last-nonmenu-event)
  94         (debugger-outer-last-event-frame last-event-frame)
  95         (debugger-outer-standard-input standard-input)
  96         (debugger-outer-standard-output standard-output)
  97         (debugger-outer-cursor-in-echo-area cursor-in-echo-area))
  98     ;; Don't let these magic variables affect the debugger itself.
  99     (let ((last-command nil) this-command track-mouse
 100           (unread-command-char -1) unread-command-events
 101           last-input-event last-command-event last-nonmenu-event
 102           last-event-frame
 103           overriding-local-map
 104           load-read-function
 105           (standard-input t) (standard-output t)
 106           (cursor-in-echo-area nil))
 107       (unwind-protect
 108           (save-excursion
 109             (save-window-excursion
 110               (pop-to-buffer debugger-buffer)
 111               (erase-buffer)
 112               (let ((standard-output (current-buffer))
 113                     (print-escape-newlines t)
 114                     (print-length 50))
 115                 (backtrace))
 116               (goto-char (point-min))
 117               (debugger-mode)
 118               (delete-region (point)
 119                              (progn
 120                                (search-forward "\n  debug(")
 121                                (forward-line 1)
 122                                (point)))
 123               (debugger-reenable)
 124               ;; lambda is for debug-on-call when a function call is next.
 125               ;; debug is for debug-on-entry function called.
 126               (cond ((memq (car debugger-args) '(lambda debug))
 127                      (insert "Entering:\n")
 128                      (if (eq (car debugger-args) 'debug)
 129                          (progn
 130                            ;; Skip the frames for backtrace-debug, byte-code,
 131                            ;; and debug.
 132                            (backtrace-debug 3 t)
 133                            (delete-char 1)
 134                            (insert ?*)
 135                            (beginning-of-line))))
 136                     ;; Exiting a function.
 137                     ((eq (car debugger-args) 'exit)
 138                      (insert "Return value: ")
 139                      (setq debugger-value (nth 1 debugger-args))
 140                      (prin1 debugger-value (current-buffer))
 141                      (insert ?\n)
 142                      (delete-char 1)
 143                      (insert ? )
 144                      (beginning-of-line))
 145                     ;; Debugger entered for an error.
 146                     ((eq (car debugger-args) 'error)
 147                      (insert "Signaling: ")
 148                      (prin1 (nth 1 debugger-args) (current-buffer))
 149                      (insert ?\n))
 150                     ;; debug-on-call, when the next thing is an eval.
 151                     ((eq (car debugger-args) t)
 152                      (insert "Beginning evaluation of function call form:\n"))
 153                     ;; User calls debug directly.
 154                     (t
 155                      (prin1 (if (eq (car debugger-args) 'nil)
 156                                 (cdr debugger-args) debugger-args)
 157                             (current-buffer))
 158                      (insert ?\n)))
 159               (message "")
 160               (let ((inhibit-trace t)
 161                     (standard-output nil)
 162                     (buffer-read-only t))
 163                 (message "")
 164                 (recursive-edit))))
 165         ;; Kill or at least neuter the backtrace buffer, so that users
 166         ;; don't try to execute debugger commands in an invalid context.
 167         (if (get-buffer-window debugger-buffer 'visible)
 168             ;; Still visible despite the save-window-excursion?  Maybe it
 169             ;; it's in a pop-up frame.  It would be annoying to delete and
 170             ;; recreate it every time the debugger stops, so instead we'll
 171             ;; erase it but leave it visible.
 172             (save-excursion
 173               (set-buffer debugger-buffer)
 174               (erase-buffer)
 175               (fundamental-mode))
 176           (kill-buffer debugger-buffer))
 177         (store-match-data debugger-outer-match-data)))
 178     ;; Put into effect the modified values of these variables
 179     ;; in case the user set them with the `e' command.
 180     (setq load-read-function debugger-outer-load-read-function)
 181     (setq overriding-local-map debugger-outer-overriding-local-map)
 182     (setq track-mouse debugger-outer-track-mouse)
 183     (setq last-command debugger-outer-last-command)
 184     (setq this-command debugger-outer-this-command)
 185     (setq unread-command-char debugger-outer-unread-command-char)
 186     (setq unread-command-events debugger-outer-unread-command-events)
 187     (setq last-input-event debugger-outer-last-input-event)
 188     (setq last-command-event debugger-outer-last-command-event)
 189     (setq last-nonmenu-event debugger-outer-last-nonmenu-event)
 190     (setq last-event-frame debugger-outer-last-event-frame)
 191     (setq standard-input debugger-outer-standard-input)
 192     (setq standard-output debugger-outer-standard-output)
 193     (setq cursor-in-echo-area debugger-outer-cursor-in-echo-area)
 194     (setq debug-on-next-call debugger-step-after-exit)
 195     debugger-value))
 196 \f
 197 (defun debugger-step-through ()
 198   "Proceed, stepping through subexpressions of this expression.
 199 Enter another debugger on next entry to eval, apply or funcall."
 200   (interactive)
 201   (setq debugger-step-after-exit t)
 202   (message "Proceeding, will debug on next eval or call.")
 203   (exit-recursive-edit))
 204
 205 (defun debugger-continue ()
 206   "Continue, evaluating this expression without stopping."
 207   (interactive)
 208   (message "Continuing.")
 209   (exit-recursive-edit))
 210
 211 (defun debugger-return-value (val)
 212   "Continue, specifying value to return.
 213 This is only useful when the value returned from the debugger
 214 will be used, such as in a debug on exit from a frame."
 215   (interactive "XReturn value (evaluated): ")
 216   (setq debugger-value val)
 217   (princ "Returning " t)
 218   (prin1 debugger-value)
 219   (exit-recursive-edit))
 220
 221 (defun debugger-jump ()
 222   "Continue to exit from this frame, with all debug-on-entry suspended."
 223   (interactive)
 224   ;; Compensate for the two extra stack frames for debugger-jump.
 225   (let ((debugger-frame-offset (+ debugger-frame-offset 2)))
 226     (debugger-frame))
 227   ;; Turn off all debug-on-entry functions
 228   ;; but leave them in the list.
 229   (let ((list debug-function-list))
 230     (while list
 231       (fset (car list)
 232             (debug-on-entry-1 (car list) (symbol-function (car list)) nil))
 233       (setq list (cdr list))))
 234   (message "Continuing through this frame")
 235   (exit-recursive-edit))
 236
 237 (defun debugger-reenable ()
 238   "Turn all debug-on-entry functions back on."
 239   (let ((list debug-function-list))
 240     (while list
 241       (or (consp (symbol-function (car list)))
 242           (debug-convert-byte-code (car list)))
 243       (fset (car list)
 244             (debug-on-entry-1 (car list) (symbol-function (car list)) t))
 245       (setq list (cdr list)))))
 246
 247 (defun debugger-frame-number ()
 248   "Return number of frames in backtrace before the one point points at."
 249   (save-excursion
 250     (beginning-of-line)
 251     (let ((opoint (point))
 252           (count 0))
 253       (goto-char (point-min))
 254       (if (or (equal (buffer-substring (point) (+ (point) 6))
 255                      "Signal")
 256               (equal (buffer-substring (point) (+ (point) 6))
 257                      "Return"))
 258           (progn
 259             (search-forward ":")
 260             (forward-sexp 1)))
 261       (forward-line 1)
 262       (while (progn
 263                (forward-char 2)
 264                (if (= (following-char) ?\()
 265                    (forward-sexp 1)
 266                  (forward-sexp 2))
 267                (forward-line 1)
 268                (<= (point) opoint))
 269         (setq count (1+ count)))
 270       count)))
 271
 272 ;; Chosen empirically to account for all the frames
 273 ;; that will exist when debugger-frame is called
 274 ;; within the first one that appears in the backtrace buffer.
 275 ;; Assumes debugger-frame is called from a key;
 276 ;; will be wrong if it is called with Meta-x.
 277 (defconst debugger-frame-offset 8 "")
 278
 279 (defun debugger-frame ()
 280   "Request entry to debugger when this frame exits.
 281 Applies to the frame whose line point is on in the backtrace."
 282   (interactive)
 283   (beginning-of-line)
 284   (let ((level (debugger-frame-number)))
 285     (backtrace-debug (+ level debugger-frame-offset) t))
 286   (if (= (following-char) ? )
 287       (let ((buffer-read-only nil))
 288         (delete-char 1)
 289         (insert ?*)))
 290   (beginning-of-line))
 291
 292 (defun debugger-frame-clear ()
 293   "Do not enter to debugger when this frame exits.
 294 Applies to the frame whose line point is on in the backtrace."
 295   (interactive)
 296   (beginning-of-line)
 297   (let ((level (debugger-frame-number)))
 298     (backtrace-debug (+ level debugger-frame-offset) nil))
 299   (if (= (following-char) ?*)
 300       (let ((buffer-read-only nil))
 301         (delete-char 1)
 302         (insert ? )))
 303   (beginning-of-line))
 304
 305 (defun debugger-eval-expression (exp)
 306   "Eval an expression, in an environment like that outside the debugger."
 307   (interactive
 308    (list (read-from-minibuffer "Eval: "
 309                                nil read-expression-map t
 310                                'read-expression-history)))
 311   (save-excursion
 312     (if (null (buffer-name debugger-old-buffer))
 313         ;; old buffer deleted
 314         (setq debugger-old-buffer (current-buffer)))
 315     (set-buffer debugger-old-buffer)
 316     (let ((track-mouse debugger-outer-track-mouse)
 317           (last-command debugger-outer-last-command)
 318           (this-command debugger-outer-this-command)
 319           (unread-command-char debugger-outer-unread-command-char)
 320           (unread-command-events debugger-outer-unread-command-events)
 321           (last-input-event debugger-outer-last-input-event)
 322           (last-command-event debugger-outer-last-command-event)
 323           (last-nonmenu-event debugger-outer-last-nonmenu-event)
 324           (last-event-frame debugger-outer-last-event-frame)
 325           (standard-input debugger-outer-standard-input)
 326           (standard-output debugger-outer-standard-output)
 327           (cursor-in-echo-area debugger-outer-cursor-in-echo-area)
 328           (overriding-local-map debugger-outer-overriding-local-map)
 329           (load-read-function debugger-outer-load-read-function))
 330       (store-match-data debugger-outer-match-data)
 331       (prog1 (eval-expression exp)
 332         (setq debugger-outer-match-data (match-data))
 333         (setq debugger-outer-load-read-function load-read-function)
 334         (setq debugger-outer-overriding-local-map overriding-local-map)
 335         (setq debugger-outer-track-mouse track-mouse)
 336         (setq debugger-outer-last-command last-command)
 337         (setq debugger-outer-this-command this-command)
 338         (setq debugger-outer-unread-command-char unread-command-char)
 339         (setq debugger-outer-unread-command-events unread-command-events)
 340         (setq debugger-outer-last-input-event last-input-event)
 341         (setq debugger-outer-last-command-event last-command-event)
 342         (setq debugger-outer-last-nonmenu-event last-nonmenu-event)
 343         (setq debugger-outer-last-event-frame last-event-frame)
 344         (setq debugger-outer-standard-input standard-input)
 345         (setq debugger-outer-standard-output standard-output)
 346         (setq debugger-outer-cursor-in-echo-area cursor-in-echo-area)))))
 347 \f
 348 (defvar debugger-mode-map nil)
 349 (if debugger-mode-map
 350     nil
 351   (let ((loop ? ))
 352     (setq debugger-mode-map (make-keymap))
 353     (suppress-keymap debugger-mode-map)
 354     (define-key debugger-mode-map "-" 'negative-argument)
 355     (define-key debugger-mode-map "b" 'debugger-frame)
 356     (define-key debugger-mode-map "c" 'debugger-continue)
 357     (define-key debugger-mode-map "j" 'debugger-jump)
 358     (define-key debugger-mode-map "r" 'debugger-return-value)
 359     (define-key debugger-mode-map "u" 'debugger-frame-clear)
 360     (define-key debugger-mode-map "d" 'debugger-step-through)
 361     (define-key debugger-mode-map "l" 'debugger-list-functions)
 362     (define-key debugger-mode-map "h" 'describe-mode)
 363     (define-key debugger-mode-map "q" 'top-level)
 364     (define-key debugger-mode-map "e" 'debugger-eval-expression)
 365     (define-key debugger-mode-map " " 'next-line)))
 366
 367 (put 'debugger-mode 'mode-class 'special)
 368
 369 (defun debugger-mode ()
 370   "Mode for backtrace buffers, selected in debugger.
 371 \\<debugger-mode-map>
 372 A line starts with `*' if exiting that frame will call the debugger.
 373 Type \\[debugger-frame] or \\[debugger-frame-clear] to set or remove the `*'.
 374
 375 When in debugger due to frame being exited,
 376 use the \\[debugger-return-value] command to override the value
 377 being returned from that frame.
 378
 379 Use \\[debug-on-entry] and \\[cancel-debug-on-entry] to control
 380 which functions will enter the debugger when called.
 381
 382 Complete list of commands:
 383 \\{debugger-mode-map}"
 384   (kill-all-local-variables)
 385   (setq major-mode 'debugger-mode)
 386   (setq mode-name "Debugger")
 387   (setq truncate-lines t)
 388   (set-syntax-table emacs-lisp-mode-syntax-table)
 389   (use-local-map debugger-mode-map))
 390 \f
 391 ;;;###autoload
 392 (defun debug-on-entry (function)
 393   "Request FUNCTION to invoke debugger each time it is called.
 394 If you tell the debugger to continue, FUNCTION's execution proceeds.
 395 This works by modifying the definition of FUNCTION,
 396 which must be written in Lisp, not predefined.
 397 Use \\[cancel-debug-on-entry] to cancel the effect of this command.
 398 Redefining FUNCTION also cancels it."
 399   (interactive "aDebug on entry (to function): ")
 400   (debugger-reenable)
 401   (if (subrp (symbol-function function))
 402       (error "Function %s is a primitive" function))
 403   (or (consp (symbol-function function))
 404       (debug-convert-byte-code function))
 405   (or (consp (symbol-function function))
 406       (error "Definition of %s is not a list" function))
 407   (fset function (debug-on-entry-1 function (symbol-function function) t))
 408   (or (memq function debug-function-list)
 409       (setq debug-function-list (cons function debug-function-list)))
 410   function)
 411
 412 ;;;###autoload
 413 (defun cancel-debug-on-entry (&optional function)
 414   "Undo effect of \\[debug-on-entry] on FUNCTION.
 415 If argument is nil or an empty string, cancel for all functions."
 416   (interactive
 417    (list (let ((name
 418                 (completing-read "Cancel debug on entry (to function): "
 419                                  ;; Make an "alist" of the functions
 420                                  ;; that now have debug on entry.
 421                                  (mapcar 'list
 422                                          (mapcar 'symbol-name
 423                                                  debug-function-list))
 424                                  nil t nil)))
 425            (if name (intern name)))))
 426   (debugger-reenable)
 427   (if (and function (not (string= function "")))
 428       (progn
 429         (fset function
 430               (debug-on-entry-1 function (symbol-function function) nil))
 431         (setq debug-function-list (delq function debug-function-list))
 432         function)
 433     (message "Cancelling debug-on-entry for all functions")
 434     (mapcar 'cancel-debug-on-entry debug-function-list)))
 435
 436 (defun debug-convert-byte-code (function)
 437   (let ((defn (symbol-function function)))
 438     (if (not (consp defn))
 439         ;; Assume a compiled code object.
 440         (let* ((contents (append defn nil))
 441                (body
 442                 (list (list 'byte-code (nth 1 contents)
 443                             (nth 2 contents) (nth 3 contents)))))
 444           (if (nthcdr 5 contents)
 445               (setq body (cons (list 'interactive (nth 5 contents)) body)))
 446           (if (nth 4 contents)
 447               ;; Use `documentation' here, to get the actual string,
 448               ;; in case the compiled function has a reference
 449               ;; to the .elc file.
 450               (setq body (cons (documentation function) body)))
 451           (fset function (cons 'lambda (cons (car contents) body)))))))
 452
 453 (defun debug-on-entry-1 (function defn flag)
 454   (if (subrp defn)
 455       (error "%s is a built-in function" function)
 456     (if (eq (car defn) 'macro)
 457         (debug-on-entry-1 function (cdr defn) flag)
 458       (or (eq (car defn) 'lambda)
 459           (error "%s not user-defined Lisp function" function))
 460       (let (tail prec)
 461         (if (stringp (car (nthcdr 2 defn)))
 462             (setq tail (nthcdr 3 defn)
 463                   prec (list (car defn) (car (cdr defn))
 464                              (car (cdr (cdr defn)))))
 465           (setq tail (nthcdr 2 defn)
 466                 prec (list (car defn) (car (cdr defn)))))
 467         (if (eq flag (equal (car tail) '(debug 'debug)))
 468             defn
 469           (if flag
 470               (nconc prec (cons '(debug 'debug) tail))
 471             (nconc prec (cdr tail))))))))
 472
 473 (defun debugger-list-functions ()
 474   "Display a list of all the functions now set to debug on entry."
 475   (interactive)
 476   (with-output-to-temp-buffer "*Help*"
 477     (if (null debug-function-list)
 478         (princ "No debug-on-entry functions now\n")
 479       (princ "Functions set to debug on entry:\n\n")
 480       (let ((list debug-function-list))
 481         (while list
 482           (prin1 (car list))
 483           (terpri)
 484           (setq list (cdr list))))
 485       (princ "Note: if you have redefined a function, then it may no longer\n")
 486       (princ "be set to debug on entry, even if it is in the list."))
 487     (save-excursion
 488       (set-buffer standard-output)
 489       (help-mode))))
 490
 491 ;;; debug.el ends here