1;;; debug.el --- debuggers and related commands for Emacs
2
3;; Copyright (C) 1985, 1986, 1994, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 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., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27
28;; This is a major mode documented in the Emacs Lisp 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.
47When the debugger is entered and Emacs is running in batch mode,
48if the backtrace text has more than this many lines,
49the middle is discarded, and just the beginning and end are displayed."
50  :type 'integer
51  :group 'debugger
52  :version "21.1")
53
54(defvar debug-function-list nil
55  "List of functions currently set for debug on entry.")
56
57(defvar debugger-step-after-exit nil
58  "Non-nil means \"single-step\" after the debugger exits.")
59
60(defvar debugger-value nil
61  "This is the value for the debugger to return, when it returns.")
62
63(defvar debugger-old-buffer nil
64  "This is the buffer that was current when the debugger was entered.")
65
66(defvar debugger-previous-backtrace nil
67  "The contents of the previous backtrace (including text properties).
68This is to optimize `debugger-make-xrefs'.")
69
70(defvar debugger-outer-match-data)
71(defvar debugger-outer-load-read-function)
72(defvar debugger-outer-overriding-local-map)
73(defvar debugger-outer-overriding-terminal-local-map)
74(defvar debugger-outer-track-mouse)
75(defvar debugger-outer-last-command)
76(defvar debugger-outer-this-command)
77;; unread-command-char is obsolete,
78;; but we still save and restore it
79;; in case some user program still tries to set it.
80(defvar debugger-outer-unread-command-char)
81(defvar debugger-outer-unread-command-events)
82(defvar debugger-outer-unread-post-input-method-events)
83(defvar debugger-outer-last-input-event)
84(defvar debugger-outer-last-command-event)
85(defvar debugger-outer-last-nonmenu-event)
86(defvar debugger-outer-last-event-frame)
87(defvar debugger-outer-standard-input)
88(defvar debugger-outer-standard-output)
89(defvar debugger-outer-inhibit-redisplay)
90(defvar debugger-outer-cursor-in-echo-area)
91(defvar debugger-will-be-back nil
92  "Non-nil if we expect to get back in the debugger soon.")
93
94(defvar inhibit-debug-on-entry nil
95  "Non-nil means that debug-on-entry is disabled.")
96
97(defvar debugger-jumping-flag nil
98  "Non-nil means that debug-on-entry is disabled.
99This variable is used by `debugger-jump', `debugger-step-through',
100and `debugger-reenable' to temporarily disable debug-on-entry.")
101
102(defvar inhibit-trace)                  ;Not yet implemented.
103
104;;;###autoload
105(setq debugger 'debug)
106;;;###autoload
107(defun debug (&rest debugger-args)
108  "Enter debugger.  To return, type \\<debugger-mode-map>`\\[debugger-continue]'.
109Arguments are mainly for use when this is called from the internals
110of the evaluator.
111
112You may call with no args, or you may pass nil as the first arg and
113any other args you like.  In that case, the list of args after the
114first will be printed into the backtrace buffer."
115  (interactive)
116  (if inhibit-redisplay
117      ;; Don't really try to enter debugger within an eval from redisplay.
118      debugger-value
119    (unless noninteractive
120      (message "Entering debugger..."))
121    (let (debugger-value
122	  (debug-on-error nil)
123	  (debug-on-quit nil)
124	  (debugger-buffer (let ((default-major-mode 'fundamental-mode))
125			     (get-buffer-create "*Backtrace*")))
126	  (debugger-old-buffer (current-buffer))
127	  (debugger-step-after-exit nil)
128          (debugger-will-be-back nil)
129	  ;; Don't keep reading from an executing kbd macro!
130	  (executing-kbd-macro nil)
131	  ;; Save the outer values of these vars for the `e' command
132	  ;; before we replace the values.
133	  (debugger-outer-match-data (match-data))
134	  (debugger-outer-load-read-function load-read-function)
135	  (debugger-outer-overriding-local-map overriding-local-map)
136	  (debugger-outer-overriding-terminal-local-map
137	   overriding-terminal-local-map)
138	  (debugger-outer-track-mouse track-mouse)
139	  (debugger-outer-last-command last-command)
140	  (debugger-outer-this-command this-command)
141	  (debugger-outer-unread-command-char
142	   (with-no-warnings unread-command-char))
143	  (debugger-outer-unread-command-events unread-command-events)
144	  (debugger-outer-unread-post-input-method-events
145	   unread-post-input-method-events)
146	  (debugger-outer-last-input-event last-input-event)
147	  (debugger-outer-last-command-event last-command-event)
148	  (debugger-outer-last-nonmenu-event last-nonmenu-event)
149	  (debugger-outer-last-event-frame last-event-frame)
150	  (debugger-outer-standard-input standard-input)
151	  (debugger-outer-standard-output standard-output)
152	  (debugger-outer-inhibit-redisplay inhibit-redisplay)
153	  (debugger-outer-cursor-in-echo-area cursor-in-echo-area)
154	  (debugger-with-timeout-suspend (with-timeout-suspend)))
155      ;; Set this instead of binding it, so that `q'
156      ;; will not restore it.
157      (setq overriding-terminal-local-map nil)
158      ;; Don't let these magic variables affect the debugger itself.
159      (let ((last-command nil) this-command track-mouse
160	    (inhibit-trace t)
161	    (inhibit-debug-on-entry t)
162	    unread-command-events
163	    unread-post-input-method-events
164	    last-input-event last-command-event last-nonmenu-event
165	    last-event-frame
166	    overriding-local-map
167	    load-read-function
168	    ;; If we are inside a minibuffer, allow nesting
169	    ;; so that we don't get an error from the `e' command.
170	    (enable-recursive-minibuffers
171	     (or enable-recursive-minibuffers (> (minibuffer-depth) 0)))
172	    (standard-input t) (standard-output t)
173	    inhibit-redisplay
174	    (cursor-in-echo-area nil))
175	(unwind-protect
176	    (save-excursion
177	      (save-window-excursion
178		(with-no-warnings
179		  (setq unread-command-char -1))
180		(when (eq (car debugger-args) 'debug)
181		  ;; Skip the frames for backtrace-debug, byte-code,
182		  ;; and implement-debug-on-entry.
183		  (backtrace-debug 4 t)
184		  ;; Place an extra debug-on-exit for macro's.
185		  (when (eq 'lambda (car-safe (cadr (backtrace-frame 4))))
186		    (backtrace-debug 5 t)))
187                (pop-to-buffer debugger-buffer)
188		(debugger-mode)
189		(debugger-setup-buffer debugger-args)
190		(when noninteractive
191		  ;; If the backtrace is long, save the beginning
192		  ;; and the end, but discard the middle.
193		  (when (> (count-lines (point-min) (point-max))
194			   debugger-batch-max-lines)
195		    (goto-char (point-min))
196		    (forward-line (/ 2 debugger-batch-max-lines))
197		    (let ((middlestart (point)))
198		      (goto-char (point-max))
199		      (forward-line (- (/ 2 debugger-batch-max-lines)
200				       debugger-batch-max-lines))
201		      (delete-region middlestart (point)))
202		    (insert "...\n"))
203		  (goto-char (point-min))
204		  (message "%s" (buffer-string))
205		  (kill-emacs))
206		(message "")
207		(let ((standard-output nil)
208		      (buffer-read-only t))
209		  (message "")
210		  ;; Make sure we unbind buffer-read-only in the right buffer.
211		  (save-excursion
212		    (recursive-edit)))))
213	  ;; Kill or at least neuter the backtrace buffer, so that users
214	  ;; don't try to execute debugger commands in an invalid context.
215	  (if (get-buffer-window debugger-buffer 0)
216	      ;; Still visible despite the save-window-excursion?  Maybe it
217	      ;; it's in a pop-up frame.  It would be annoying to delete and
218	      ;; recreate it every time the debugger stops, so instead we'll
219	      ;; erase it (and maybe hide it) but keep it alive.
220	      (with-current-buffer debugger-buffer
221		(erase-buffer)
222		(fundamental-mode)
223		(with-selected-window (get-buffer-window debugger-buffer 0)
224                  (when (and (window-dedicated-p (selected-window))
225                             (not debugger-will-be-back))
226                    ;; If the window is not dedicated, burying the buffer
227                    ;; will mean that the frame created for it is left
228                    ;; around showing some random buffer, and next time we
229                    ;; pop to the debugger buffer we'll create yet
230                    ;; another frame.
231                    ;; If debugger-will-be-back is non-nil, the frame
232                    ;; would need to be de-iconified anyway immediately
233                    ;; after when we re-enter the debugger, so iconifying it
234                    ;; here would cause flashing.
235                    ;; Use quit-window rather than bury-buffer to quieten
236                    ;; Drew Adams.  --Stef
237                    (quit-window))))
238	    (kill-buffer debugger-buffer))
239	  (with-timeout-unsuspend debugger-with-timeout-suspend)
240	  (set-match-data debugger-outer-match-data)))
241      ;; Put into effect the modified values of these variables
242      ;; in case the user set them with the `e' command.
243      (setq load-read-function debugger-outer-load-read-function)
244      (setq overriding-local-map debugger-outer-overriding-local-map)
245      (setq overriding-terminal-local-map
246	    debugger-outer-overriding-terminal-local-map)
247      (setq track-mouse debugger-outer-track-mouse)
248      (setq last-command debugger-outer-last-command)
249      (setq this-command debugger-outer-this-command)
250      (with-no-warnings
251	(setq unread-command-char debugger-outer-unread-command-char))
252      (setq unread-command-events debugger-outer-unread-command-events)
253      (setq unread-post-input-method-events
254	    debugger-outer-unread-post-input-method-events)
255      (setq last-input-event debugger-outer-last-input-event)
256      (setq last-command-event debugger-outer-last-command-event)
257      (setq last-nonmenu-event debugger-outer-last-nonmenu-event)
258      (setq last-event-frame debugger-outer-last-event-frame)
259      (setq standard-input debugger-outer-standard-input)
260      (setq standard-output debugger-outer-standard-output)
261      (setq inhibit-redisplay debugger-outer-inhibit-redisplay)
262      (setq cursor-in-echo-area debugger-outer-cursor-in-echo-area)
263      (setq debug-on-next-call debugger-step-after-exit)
264      debugger-value)))
265
266(defun debugger-setup-buffer (debugger-args)
267  "Initialize the `*Backtrace*' buffer for entry to the debugger.
268That buffer should be current already."
269  (setq buffer-read-only nil)
270  (erase-buffer)
271  (set-buffer-multibyte nil)
272  (let ((standard-output (current-buffer))
273	(print-escape-newlines t)
274	(print-level 8)
275	(print-length 50))
276    (backtrace))
277  (goto-char (point-min))
278  (delete-region (point)
279		 (progn
280		   (search-forward "\n  debug(")
281		   (forward-line (if (eq (car debugger-args) 'debug)
282				     2	; Remove implement-debug-on-entry frame.
283				   1))
284		   (point)))
285  (insert "Debugger entered")
286  ;; lambda is for debug-on-call when a function call is next.
287  ;; debug is for debug-on-entry function called.
288  (cond ((memq (car debugger-args) '(lambda debug))
289	 (insert "--entering a function:\n"))
290	;; Exiting a function.
291	((eq (car debugger-args) 'exit)
292	 (insert "--returning value: ")
293	 (setq debugger-value (nth 1 debugger-args))
294	 (prin1 debugger-value (current-buffer))
295	 (insert ?\n)
296	 (delete-char 1)
297	 (insert ? )
298	 (beginning-of-line))
299	;; Debugger entered for an error.
300	((eq (car debugger-args) 'error)
301	 (insert "--Lisp error: ")
302	 (prin1 (nth 1 debugger-args) (current-buffer))
303	 (insert ?\n))
304	;; debug-on-call, when the next thing is an eval.
305	((eq (car debugger-args) t)
306	 (insert "--beginning evaluation of function call form:\n"))
307	;; User calls debug directly.
308	(t
309	 (insert ": ")
310	 (prin1 (if (eq (car debugger-args) 'nil)
311		    (cdr debugger-args) debugger-args)
312		(current-buffer))
313	 (insert ?\n)))
314  ;; After any frame that uses eval-buffer,
315  ;; insert a line that states the buffer position it's reading at.
316  (save-excursion
317    (let ((tem eval-buffer-list))
318      (while (and tem
319		  (re-search-forward "^  eval-\\(buffer\\|region\\)(" nil t))
320	(end-of-line)
321	(insert (format "  ; Reading at buffer position %d"
322			;; This will get the wrong result
323			;; if there are two nested eval-region calls
324			;; for the same buffer.  That's not a very useful case.
325			(with-current-buffer (car tem)
326			  (point))))
327	(pop tem))))
328  (debugger-make-xrefs))
329
330(defun debugger-make-xrefs (&optional buffer)
331  "Attach cross-references to function names in the `*Backtrace*' buffer."
332  (interactive "b")
333  (save-excursion
334    (set-buffer (or buffer (current-buffer)))
335    (setq buffer (current-buffer))
336    (let ((inhibit-read-only t)
337	  (old-end (point-min)) (new-end (point-min)))
338      ;; If we saved an old backtrace, find the common part
339      ;; between the new and the old.
340      ;; Compare line by line, starting from the end,
341      ;; because that's the part that is likely to be unchanged.
342      (if debugger-previous-backtrace
343	  (let (old-start new-start (all-match t))
344	    (goto-char (point-max))
345	    (with-temp-buffer
346	      (insert debugger-previous-backtrace)
347	      (while (and all-match (not (bobp)))
348		(setq old-end (point))
349		(forward-line -1)
350		(setq old-start (point))
351		(with-current-buffer buffer
352		  (setq new-end (point))
353		  (forward-line -1)
354		  (setq new-start (point)))
355		(if (not (zerop
356                          (let ((case-fold-search nil))
357                            (compare-buffer-substrings
358                             (current-buffer) old-start old-end
359                             buffer new-start new-end))))
360		    (setq all-match nil))))
361	    ;; Now new-end is the position of the start of the
362	    ;; unchanged part in the current buffer, and old-end is
363	    ;; the position of that same text in the saved old
364	    ;; backtrace.  But we must subtract (point-min) since strings are
365	    ;; indexed in origin 0.
366
367	    ;; Replace the unchanged part of the backtrace
368	    ;; with the text from debugger-previous-backtrace,
369	    ;; since that already has the proper xrefs.
370	    ;; With this optimization, we only need to scan
371	    ;; the changed part of the backtrace.
372	    (delete-region new-end (point-max))
373	    (goto-char (point-max))
374	    (insert (substring debugger-previous-backtrace
375			       (- old-end (point-min))))
376	    ;; Make the unchanged part of the backtrace inaccessible
377	    ;; so it won't be scanned.
378	    (narrow-to-region (point-min) new-end)))
379
380      ;; Scan the new part of the backtrace, inserting xrefs.
381      (goto-char (point-min))
382      (while (progn
383	       (goto-char (+ (point) 2))
384	       (skip-syntax-forward "^w_")
385	       (not (eobp)))
386	(let* ((beg (point))
387	       (end (progn (skip-syntax-forward "w_") (point)))
388	       (sym (intern-soft (buffer-substring-no-properties
389				  beg end)))
390	       (file (and sym (symbol-file sym 'defun))))
391	  (when file
392	    (goto-char beg)
393	    ;; help-xref-button needs to operate on something matched
394	    ;; by a regexp, so set that up for it.
395	    (re-search-forward "\\(\\sw\\|\\s_\\)+")
396	    (help-xref-button 0 'help-function-def sym file)))
397	(forward-line 1))
398      (widen))
399    (setq debugger-previous-backtrace (buffer-string))))
400
401(defun debugger-step-through ()
402  "Proceed, stepping through subexpressions of this expression.
403Enter another debugger on next entry to eval, apply or funcall."
404  (interactive)
405  (setq debugger-step-after-exit t)
406  (setq debugger-jumping-flag t)
407  (setq debugger-will-be-back t)
408  (add-hook 'post-command-hook 'debugger-reenable)
409  (message "Proceeding, will debug on next eval or call.")
410  (exit-recursive-edit))
411
412(defun debugger-continue ()
413  "Continue, evaluating this expression without stopping."
414  (interactive)
415  (unless debugger-may-continue
416    (error "Cannot continue"))
417  (message "Continuing.")
418  (save-excursion
419    ;; Check to see if we've flagged some frame for debug-on-exit, in which
420    ;; case we'll probably come back to the debugger soon.
421    (goto-char (point-min))
422    (if (re-search-forward "^\\* " nil t)
423        (setq debugger-will-be-back t)))
424  (exit-recursive-edit))
425
426(defun debugger-return-value (val)
427  "Continue, specifying value to return.
428This is only useful when the value returned from the debugger
429will be used, such as in a debug on exit from a frame."
430  (interactive "XReturn value (evaluated): ")
431  (setq debugger-value val)
432  (princ "Returning " t)
433  (prin1 debugger-value)
434  (save-excursion
435    ;; Check to see if we've flagged some frame for debug-on-exit, in which
436    ;; case we'll probably come back to the debugger soon.
437    (goto-char (point-min))
438    (if (re-search-forward "^\\* " nil t)
439        (setq debugger-will-be-back t)))
440  (exit-recursive-edit))
441
442(defun debugger-jump ()
443  "Continue to exit from this frame, with all debug-on-entry suspended."
444  (interactive)
445  (debugger-frame)
446  (setq debugger-jumping-flag t)
447  (add-hook 'post-command-hook 'debugger-reenable)
448  (message "Continuing through this frame")
449  (setq debugger-will-be-back t)
450  (exit-recursive-edit))
451
452(defun debugger-reenable ()
453  "Turn all debug-on-entry functions back on.
454This function is put on `post-command-hook' by `debugger-jump' and
455removes itself from that hook."
456  (setq debugger-jumping-flag nil)
457  (remove-hook 'post-command-hook 'debugger-reenable))
458
459(defun debugger-frame-number ()
460  "Return number of frames in backtrace before the one point points at."
461  (save-excursion
462    (beginning-of-line)
463    (let ((opoint (point))
464	  (count 0))
465      (while (not (eq (cadr (backtrace-frame count)) 'debug))
466	(setq count (1+ count)))
467      ;; Skip implement-debug-on-entry frame.
468      (when (eq 'implement-debug-on-entry (cadr (backtrace-frame (1+ count))))
469	(setq count (1+ count)))
470      (goto-char (point-min))
471      (when (looking-at "Debugger entered--\\(Lisp error\\|returning value\\):")
472	(goto-char (match-end 0))
473	(forward-sexp 1))
474      (forward-line 1)
475      (while (progn
476	       (forward-char 2)
477	       (if (= (following-char) ?\()
478		   (forward-sexp 1)
479		 (forward-sexp 2))
480	       (forward-line 1)
481	       (<= (point) opoint))
482	(if (looking-at " *;;;")
483	    (forward-line 1))
484	(setq count (1+ count)))
485      count)))
486
487(defun debugger-frame ()
488  "Request entry to debugger when this frame exits.
489Applies to the frame whose line point is on in the backtrace."
490  (interactive)
491  (save-excursion
492    (beginning-of-line)
493    (if (looking-at " *;;;\\|[a-z]")
494	(error "This line is not a function call")))
495  (beginning-of-line)
496  (backtrace-debug (debugger-frame-number) t)
497  (if (= (following-char) ? )
498      (let ((inhibit-read-only t))
499	(delete-char 1)
500	(insert ?*)))
501  (beginning-of-line))
502
503(defun debugger-frame-clear ()
504  "Do not enter debugger when this frame exits.
505Applies to the frame whose line point is on in the backtrace."
506  (interactive)
507  (save-excursion
508    (beginning-of-line)
509    (if (looking-at " *;;;\\|[a-z]")
510	(error "This line is not a function call")))
511  (beginning-of-line)
512  (backtrace-debug (debugger-frame-number) nil)
513  (if (= (following-char) ?*)
514      (let ((inhibit-read-only t))
515	(delete-char 1)
516	(insert ? )))
517  (beginning-of-line))
518
519(put 'debugger-env-macro 'lisp-indent-function 0)
520(defmacro debugger-env-macro (&rest body)
521  "Run BODY in original environment."
522  `(save-excursion
523    (if (null (buffer-name debugger-old-buffer))
524        ;; old buffer deleted
525        (setq debugger-old-buffer (current-buffer)))
526    (set-buffer debugger-old-buffer)
527    (let ((load-read-function debugger-outer-load-read-function)
528          (overriding-terminal-local-map
529           debugger-outer-overriding-terminal-local-map)
530          (overriding-local-map debugger-outer-overriding-local-map)
531          (track-mouse debugger-outer-track-mouse)
532          (last-command debugger-outer-last-command)
533          (this-command debugger-outer-this-command)
534          (unread-command-events debugger-outer-unread-command-events)
535          (unread-post-input-method-events
536           debugger-outer-unread-post-input-method-events)
537          (last-input-event debugger-outer-last-input-event)
538          (last-command-event debugger-outer-last-command-event)
539          (last-nonmenu-event debugger-outer-last-nonmenu-event)
540          (last-event-frame debugger-outer-last-event-frame)
541          (standard-input debugger-outer-standard-input)
542          (standard-output debugger-outer-standard-output)
543          (inhibit-redisplay debugger-outer-inhibit-redisplay)
544          (cursor-in-echo-area debugger-outer-cursor-in-echo-area))
545      (set-match-data debugger-outer-match-data)
546      (prog1
547	  (let ((save-ucc (with-no-warnings unread-command-char)))
548	    (unwind-protect
549		(progn
550		  (with-no-warnings
551		    (setq unread-command-char debugger-outer-unread-command-char))
552		  (prog1 (progn ,@body)
553		    (with-no-warnings
554		      (setq debugger-outer-unread-command-char unread-command-char))))
555	      (with-no-warnings
556		(setq unread-command-char save-ucc))))
557        (setq debugger-outer-match-data (match-data))
558        (setq debugger-outer-load-read-function load-read-function)
559        (setq debugger-outer-overriding-terminal-local-map
560              overriding-terminal-local-map)
561        (setq debugger-outer-overriding-local-map overriding-local-map)
562        (setq debugger-outer-track-mouse track-mouse)
563        (setq debugger-outer-last-command last-command)
564        (setq debugger-outer-this-command this-command)
565        (setq debugger-outer-unread-command-events unread-command-events)
566        (setq debugger-outer-unread-post-input-method-events
567              unread-post-input-method-events)
568        (setq debugger-outer-last-input-event last-input-event)
569        (setq debugger-outer-last-command-event last-command-event)
570        (setq debugger-outer-last-nonmenu-event last-nonmenu-event)
571        (setq debugger-outer-last-event-frame last-event-frame)
572        (setq debugger-outer-standard-input standard-input)
573        (setq debugger-outer-standard-output standard-output)
574        (setq debugger-outer-inhibit-redisplay inhibit-redisplay)
575        (setq debugger-outer-cursor-in-echo-area cursor-in-echo-area)
576        ))))
577
578(defun debugger-eval-expression (exp)
579  "Eval an expression, in an environment like that outside the debugger."
580  (interactive
581   (list (read-from-minibuffer "Eval: "
582			       nil read-expression-map t
583			       'read-expression-history)))
584  (debugger-env-macro (eval-expression exp)))
585
586(defvar debugger-mode-map
587  (let ((map (make-keymap)))
588    (set-keymap-parent map button-buffer-map)
589    (suppress-keymap map)
590    (define-key map "-" 'negative-argument)
591    (define-key map "b" 'debugger-frame)
592    (define-key map "c" 'debugger-continue)
593    (define-key map "j" 'debugger-jump)
594    (define-key map "r" 'debugger-return-value)
595    (define-key map "u" 'debugger-frame-clear)
596    (define-key map "d" 'debugger-step-through)
597    (define-key map "l" 'debugger-list-functions)
598    (define-key map "h" 'describe-mode)
599    (define-key map "q" 'top-level)
600    (define-key map "e" 'debugger-eval-expression)
601    (define-key map " " 'next-line)
602    (define-key map "R" 'debugger-record-expression)
603    (define-key map "\C-m" 'debug-help-follow)
604    (define-key map [mouse-2] 'push-button)
605    map))
606
607(put 'debugger-mode 'mode-class 'special)
608
609(defun debugger-mode ()
610  "Mode for backtrace buffers, selected in debugger.
611\\<debugger-mode-map>
612A line starts with `*' if exiting that frame will call the debugger.
613Type \\[debugger-frame] or \\[debugger-frame-clear] to set or remove the `*'.
614
615When in debugger due to frame being exited,
616use the \\[debugger-return-value] command to override the value
617being returned from that frame.
618
619Use \\[debug-on-entry] and \\[cancel-debug-on-entry] to control
620which functions will enter the debugger when called.
621
622Complete list of commands:
623\\{debugger-mode-map}"
624  (kill-all-local-variables)
625  (setq major-mode 'debugger-mode)
626  (setq mode-name "Debugger")
627  (setq truncate-lines t)
628  (set-syntax-table emacs-lisp-mode-syntax-table)
629  (use-local-map debugger-mode-map)
630  (run-mode-hooks 'debugger-mode-hook))
631
632(defcustom debugger-record-buffer "*Debugger-record*"
633  "*Buffer name for expression values, for \\[debugger-record-expression]."
634  :type 'string
635  :group 'debugger
636  :version "20.3")
637
638(defun debugger-record-expression  (exp)
639  "Display a variable's value and record it in `*Backtrace-record*' buffer."
640  (interactive
641   (list (read-from-minibuffer
642	  "Record Eval: "
643	  nil
644	  read-expression-map t
645	  'read-expression-history)))
646  (let* ((buffer (get-buffer-create debugger-record-buffer))
647	 (standard-output buffer))
648    (princ (format "Debugger Eval (%s): " exp))
649    (princ (debugger-eval-expression exp))
650    (terpri))
651
652  (with-current-buffer (get-buffer debugger-record-buffer)
653    (message "%s"
654	     (buffer-substring (line-beginning-position 0)
655			       (line-end-position 0)))))
656
657(defun debug-help-follow (&optional pos)
658  "Follow cross-reference at POS, defaulting to point.
659
660For the cross-reference format, see `help-make-xrefs'."
661  (interactive "d")
662  (require 'help-mode)
663  ;; Ideally we'd just do (call-interactively 'help-follow) except that this
664  ;; assumes we're already in a *Help* buffer and reuses it, so it ends up
665  ;; incorrectly "reusing" the *Backtrace* buffer to show the help info.
666  (unless pos
667    (setq pos (point)))
668  (unless (push-button pos)
669    ;; check if the symbol under point is a function or variable
670    (let ((sym
671	   (intern
672	    (save-excursion
673	      (goto-char pos) (skip-syntax-backward "w_")
674	      (buffer-substring (point)
675				(progn (skip-syntax-forward "w_")
676				       (point)))))))
677      (when (or (boundp sym) (fboundp sym) (facep sym))
678        (help-xref-interned sym)))))
679
680;; When you change this, you may also need to change the number of
681;; frames that the debugger skips.
682(defun implement-debug-on-entry ()
683  "Conditionally call the debugger.
684A call to this function is inserted by `debug-on-entry' to cause
685functions to break on entry."
686  (if (or inhibit-debug-on-entry debugger-jumping-flag)
687      nil
688    (funcall debugger 'debug)))
689
690(defun debugger-special-form-p (symbol)
691  "Return whether SYMBOL is a special form."
692  (and (fboundp symbol)
693       (subrp (symbol-function symbol))
694       (eq (cdr (subr-arity (symbol-function symbol))) 'unevalled)))
695
696;;;###autoload
697(defun debug-on-entry (function)
698  "Request FUNCTION to invoke debugger each time it is called.
699
700When called interactively, prompt for FUNCTION in the minibuffer.
701
702This works by modifying the definition of FUNCTION.  If you tell the
703debugger to continue, FUNCTION's execution proceeds.  If FUNCTION is a
704normal function or a macro written in Lisp, you can also step through
705its execution.  FUNCTION can also be a primitive that is not a special
706form, in which case stepping is not possible.  Break-on-entry for
707primitive functions only works when that function is called from Lisp.
708
709Use \\[cancel-debug-on-entry] to cancel the effect of this command.
710Redefining FUNCTION also cancels it."
711  (interactive
712   (let ((fn (function-called-at-point)) val)
713     (when (debugger-special-form-p fn)
714       (setq fn nil))
715     (setq val (completing-read
716		(if fn
717		    (format "Debug on entry to function (default %s): " fn)
718		  "Debug on entry to function: ")
719		obarray
720		#'(lambda (symbol)
721		    (and (fboundp symbol)
722			 (not (debugger-special-form-p symbol))))
723		t nil nil (symbol-name fn)))
724     (list (if (equal val "") fn (intern val)))))
725  (when (debugger-special-form-p function)
726    (error "Function %s is a special form" function))
727  (if (or (symbolp (symbol-function function))
728	  (subrp (symbol-function function)))
729      ;; The function is built-in or aliased to another function.
730      ;; Create a wrapper in which we can add the debug call.
731      (fset function `(lambda (&rest debug-on-entry-args)
732			,(interactive-form (symbol-function function))
733			(apply ',(symbol-function function)
734			       debug-on-entry-args)))
735    (when (eq (car-safe (symbol-function function)) 'autoload)
736      ;; The function is autoloaded.  Load its real definition.
737      (load (cadr (symbol-function function)) nil noninteractive nil t))
738    (when (or (not (consp (symbol-function function)))
739	      (and (eq (car (symbol-function function)) 'macro)
740		   (not (consp (cdr (symbol-function function))))))
741      ;; The function is byte-compiled.  Create a wrapper in which
742      ;; we can add the debug call.
743      (debug-convert-byte-code function)))
744  (unless (consp (symbol-function function))
745    (error "Definition of %s is not a list" function))
746  (fset function (debug-on-entry-1 function t))
747  (unless (memq function debug-function-list)
748    (push function debug-function-list))
749  function)
750
751;;;###autoload
752(defun cancel-debug-on-entry (&optional function)
753  "Undo effect of \\[debug-on-entry] on FUNCTION.
754If FUNCTION is nil, cancel debug-on-entry for all functions.
755When called interactively, prompt for FUNCTION in the minibuffer.
756To specify a nil argument interactively, exit with an empty minibuffer."
757  (interactive
758   (list (let ((name
759		(completing-read
760		 "Cancel debug on entry to function (default all functions): "
761		 (mapcar 'symbol-name debug-function-list) nil t)))
762	   (when name
763	     (unless (string= name "")
764	       (intern name))))))
765  (if (and function
766	   (not (string= function ""))) ; Pre 22.1 compatibility test.
767      (progn
768	(let ((defn (debug-on-entry-1 function nil)))
769	  (condition-case nil
770	      (when (and (equal (nth 1 defn) '(&rest debug-on-entry-args))
771			 (eq (car (nth 3 defn)) 'apply))
772		;; `defn' is a wrapper introduced in debug-on-entry.
773		;; Get rid of it since we don't need it any more.
774		(setq defn (nth 1 (nth 1 (nth 3 defn)))))
775	    (error nil))
776	  (fset function defn))
777	(setq debug-function-list (delq function debug-function-list))
778	function)
779    (message "Cancelling debug-on-entry for all functions")
780    (mapcar 'cancel-debug-on-entry debug-function-list)))
781
782(defun debug-convert-byte-code (function)
783  (let* ((defn (symbol-function function))
784	 (macro (eq (car-safe defn) 'macro)))
785    (when macro (setq defn (cdr defn)))
786    (unless (consp defn)
787      ;; Assume a compiled code object.
788      (let* ((contents (append defn nil))
789	     (body
790	      (list (list 'byte-code (nth 1 contents)
791			  (nth 2 contents) (nth 3 contents)))))
792	(if (nthcdr 5 contents)
793	    (setq body (cons (list 'interactive (nth 5 contents)) body)))
794	(if (nth 4 contents)
795	    ;; Use `documentation' here, to get the actual string,
796	    ;; in case the compiled function has a reference
797	    ;; to the .elc file.
798	    (setq body (cons (documentation function) body)))
799	(setq defn (cons 'lambda (cons (car contents) body))))
800      (when macro (setq defn (cons 'macro defn)))
801      (fset function defn))))
802
803(defun debug-on-entry-1 (function flag)
804  (let* ((defn (symbol-function function))
805	 (tail defn))
806    (when (eq (car-safe tail) 'macro)
807      (setq tail (cdr tail)))
808    (if (not (eq (car-safe tail) 'lambda))
809	;; Only signal an error when we try to set debug-on-entry.
810	;; When we try to clear debug-on-entry, we are now done.
811	(when flag
812	  (error "%s is not a user-defined Lisp function" function))
813      (setq tail (cdr tail))
814      ;; Skip the docstring.
815      (when (and (stringp (cadr tail)) (cddr tail))
816	(setq tail (cdr tail)))
817      ;; Skip the interactive form.
818      (when (eq 'interactive (car-safe (cadr tail)))
819	(setq tail (cdr tail)))
820      (unless (eq flag (equal (cadr tail) '(implement-debug-on-entry)))
821	;; Add/remove debug statement as needed.
822	(if flag
823	    (setcdr tail (cons '(implement-debug-on-entry) (cdr tail)))
824	  (setcdr tail (cddr tail)))))
825    defn))
826
827(defun debugger-list-functions ()
828  "Display a list of all the functions now set to debug on entry."
829  (interactive)
830  (require 'help-mode)
831  (help-setup-xref '(debugger-list-functions) (interactive-p))
832  (with-output-to-temp-buffer (help-buffer)
833    (with-current-buffer standard-output
834      (if (null debug-function-list)
835	  (princ "No debug-on-entry functions now\n")
836	(princ "Functions set to debug on entry:\n\n")
837	(dolist (fun debug-function-list)
838	  (make-text-button (point) (progn (prin1 fun) (point))
839			    'type 'help-function
840			    'help-args (list fun))
841	  (terpri))
842	(terpri)
843	(princ "Note: if you have redefined a function, then it may no longer\n")
844	(princ "be set to debug on entry, even if it is in the list.")))))
845
846(provide 'debug)
847
848;; arch-tag: b6ec7047-f801-4103-9c63-d69322db9d3b
849;;; debug.el ends here
850