lisp/emacs-lisp/debug.el

   1 ;; Debuggers and related commands for Emacs
   2 ;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
   3
   4 ;; This file is part of GNU Emacs.
   5
   6 ;; GNU Emacs is free software; you can redistribute it and/or modify
   7 ;; it under the terms of the GNU General Public License as published by
   8 ;; the Free Software Foundation; either version 1, or (at your option)
   9 ;; any later version.
  10
  11 ;; GNU Emacs is distributed in the hope that it will be useful,
  12 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 ;; GNU General Public License for more details.
  15
  16 ;; You should have received a copy of the GNU General Public License
  17 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  18 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20
  21 (defvar debug-function-list nil
  22   "List of functions currently set for debug on entry.")
  23
  24 ;;;###autoload
  25 (setq debugger 'debug)
  26 ;;;###autoload
  27 (defun debug (&rest debugger-args)
  28   "Enter debugger.  Returns if user says \"continue\".
  29 Arguments are mainly for use when this is called from the internals
  30 of the evaluator.
  31
  32 You may call with no args, or you may pass nil as the first arg and
  33 any other args you like.  In that case, the list of args after the
  34 first will be printed into the backtrace buffer."
  35   (message "Entering debugger...")
  36   (let (debugger-value
  37         (debugger-match-data (match-data))
  38         (debug-on-error nil)
  39         (debug-on-quit nil)
  40         (debugger-buffer (let ((default-major-mode 'fundamental-mode))
  41                            (generate-new-buffer "*Backtrace*")))
  42         (debugger-old-buffer (current-buffer))
  43         (debugger-step-after-exit nil)
  44         ;; Don't keep reading from an executing kbd macro!
  45         (executing-macro nil)
  46         (cursor-in-echo-area nil))
  47     (unwind-protect
  48         (save-excursion
  49           (save-window-excursion
  50             (pop-to-buffer debugger-buffer)
  51             (erase-buffer)
  52             (let ((standard-output (current-buffer))
  53                   (print-escape-newlines t)
  54                   (print-length 50))
  55               (backtrace))
  56             (goto-char (point-min))
  57             (debugger-mode)
  58             (delete-region (point)
  59                            (progn
  60                              (search-forward "\n  debug(")
  61                              (forward-line 1)
  62                              (point)))
  63             (debugger-reenable)
  64             (cond ((memq (car debugger-args) '(lambda debug))
  65                    (insert "Entering:\n")
  66                    (if (eq (car debugger-args) 'debug)
  67                        (progn
  68                          (backtrace-debug 4 t)
  69                          (delete-char 1)
  70                          (insert ?*)
  71                          (beginning-of-line))))
  72                   ((eq (car debugger-args) 'exit)
  73                    (insert "Return value: ")
  74                    (setq debugger-value (nth 1 debugger-args))
  75                    (prin1 debugger-value (current-buffer))
  76                    (insert ?\n)
  77                    (delete-char 1)
  78                    (insert ? )
  79                    (beginning-of-line))
  80                   ((eq (car debugger-args) 'error)
  81                    (insert "Signalling: ")
  82                    (prin1 (nth 1 debugger-args) (current-buffer))
  83                    (insert ?\n))
  84                   ((eq (car debugger-args) t)
  85                    (insert "Beginning evaluation of function call form:\n"))
  86                   (t
  87                    (prin1 (if (eq (car debugger-args) 'nil)
  88                               (cdr debugger-args) debugger-args)
  89                           (current-buffer))
  90                    (insert ?\n)))
  91             (message "")
  92             (let ((inhibit-trace t)
  93                   (standard-output nil)
  94                   (buffer-read-only t))
  95               (message "")
  96               (recursive-edit))))
  97       ;; So that users do not try to execute debugger commands
  98       ;;  in an invalid context
  99       (kill-buffer debugger-buffer)
 100       (store-match-data debugger-match-data))
 101     (setq debug-on-next-call debugger-step-after-exit)
 102     debugger-value))
 103 \f
 104 (defun debugger-step-through ()
 105   "Proceed, stepping through subexpressions of this expression.
 106 Enter another debugger on next entry to eval, apply or funcall."
 107   (interactive)
 108   (setq debugger-step-after-exit t)
 109   (message "Proceeding, will debug on next eval or call.")
 110   (exit-recursive-edit))
 111
 112 (defun debugger-continue ()
 113   "Continue, evaluating this expression without stopping."
 114   (interactive)
 115   (message "Continuing.")
 116   (exit-recursive-edit))
 117
 118 (defun debugger-return-value (val)
 119   "Continue, specifying value to return.
 120 This is only useful when the value returned from the debugger
 121 will be used, such as in a debug on exit from a frame."
 122   (interactive "XReturn value (evaluated): ")
 123   (setq debugger-value val)
 124   (princ "Returning " t)
 125   (prin1 debugger-value)
 126   (exit-recursive-edit))
 127
 128 (defun debugger-jump ()
 129   "Continue to exit from this frame, with all debug-on-entry suspended."
 130   (interactive)
 131   ;; Compensate for the two extra stack frames for debugger-jump.
 132   (let ((debugger-frame-offset (+ debugger-frame-offset 2)))
 133     (debugger-frame))
 134   ;; Turn off all debug-on-entry functions
 135   ;; but leave them in the list.
 136   (let ((list debug-function-list))
 137     (while list
 138       (fset (car list)
 139             (debug-on-entry-1 (car list) (symbol-function (car list)) nil))
 140       (setq list (cdr list))))
 141   (message "Continuing through this frame")
 142   (exit-recursive-edit))
 143
 144 (defun debugger-reenable ()
 145   "Turn all debug-on-entry functions back on."
 146   (let ((list debug-function-list))
 147     (while list
 148       (or (consp (symbol-function (car list)))
 149           (debug-convert-byte-code (car list)))
 150       (fset (car list)
 151             (debug-on-entry-1 (car list) (symbol-function (car list)) t))
 152       (setq list (cdr list)))))
 153
 154 (defun debugger-frame-number ()
 155   "Return number of frames in backtrace before the one point points at."
 156   (save-excursion
 157     (beginning-of-line)
 158     (let ((opoint (point))
 159           (count 0))
 160       (goto-char (point-min))
 161       (if (or (equal (buffer-substring (point) (+ (point) 6))
 162                      "Signal")
 163               (equal (buffer-substring (point) (+ (point) 6))
 164                      "Return"))
 165           (progn
 166             (search-forward ":")
 167             (forward-sexp 1)))
 168       (forward-line 1)
 169       (while (progn
 170                (forward-char 2)
 171                (if (= (following-char) ?\()
 172                    (forward-sexp 1)
 173                  (forward-sexp 2))
 174                (forward-line 1)
 175                (<= (point) opoint))
 176         (setq count (1+ count)))
 177       count)))
 178
 179 ;; Chosen empirically to account for all the frames
 180 ;; that will exist when debugger-frame is called
 181 ;; within the first one that appears in the backtrace buffer.
 182 ;; Assumes debugger-frame is called from a key;
 183 ;; will be wrong if it is called with Meta-x.
 184 (defconst debugger-frame-offset 8 "")
 185
 186 (defun debugger-frame ()
 187   "Request entry to debugger when this frame exits.
 188 Applies to the frame whose line point is on in the backtrace."
 189   (interactive)
 190   (beginning-of-line)
 191   (let ((level (debugger-frame-number)))
 192     (backtrace-debug (+ level debugger-frame-offset) t))
 193   (if (= (following-char) ? )
 194       (let ((buffer-read-only nil))
 195         (delete-char 1)
 196         (insert ?*)))
 197   (beginning-of-line))
 198
 199 (defun debugger-frame-clear ()
 200   "Do not enter to debugger when this frame exits.
 201 Applies to the frame whose line point is on in the backtrace."
 202   (interactive)
 203   (beginning-of-line)
 204   (let ((level (debugger-frame-number)))
 205     (backtrace-debug (+ level debugger-frame-offset) nil))
 206   (if (= (following-char) ?*)
 207       (let ((buffer-read-only nil))
 208         (delete-char 1)
 209         (insert ? )))
 210   (beginning-of-line))
 211
 212 (defun debugger-eval-expression (exp)
 213   (interactive "xEval: ")
 214   (save-excursion
 215     (if (null (buffer-name debugger-old-buffer))
 216         ;; old buffer deleted
 217         (setq debugger-old-buffer (current-buffer)))
 218     (set-buffer debugger-old-buffer)
 219     (eval-expression exp)))
 220 \f
 221 (defvar debugger-mode-map nil)
 222 (if debugger-mode-map
 223     nil
 224   (let ((loop ? ))
 225     (setq debugger-mode-map (make-keymap))
 226     (suppress-keymap debugger-mode-map)
 227     (define-key debugger-mode-map "-" 'negative-argument)
 228     (define-key debugger-mode-map "b" 'debugger-frame)
 229     (define-key debugger-mode-map "c" 'debugger-continue)
 230     (define-key debugger-mode-map "j" 'debugger-jump)
 231     (define-key debugger-mode-map "r" 'debugger-return-value)
 232     (define-key debugger-mode-map "u" 'debugger-frame-clear)
 233     (define-key debugger-mode-map "d" 'debugger-step-through)
 234     (define-key debugger-mode-map "l" 'debugger-list-functions)
 235     (define-key debugger-mode-map "h" 'describe-mode)
 236     (define-key debugger-mode-map "q" 'top-level)
 237     (define-key debugger-mode-map "e" 'debugger-eval-expression)
 238     (define-key debugger-mode-map " " 'next-line)))
 239
 240 (put 'debugger-mode 'mode-class 'special)
 241
 242 (defun debugger-mode ()
 243   "Mode for backtrace buffers, selected in debugger.
 244 \\<debugger-mode-map>
 245 A line starts with `*' if exiting that frame will call the debugger.
 246 Type \\[debugger-frame] or \\[debugger-frame-clear] to set or remove the `*'.
 247
 248 When in debugger due to frame being exited,
 249 use the \\[debugger-return-value] command to override the value
 250 being returned from that frame.
 251
 252 Use \\[debug-on-entry] and \\[cancel-debug-on-entry] to control
 253 which functions will enter the debugger when called.
 254
 255 Complete list of commands:
 256 \\{debugger-mode-map}"
 257   (kill-all-local-variables)
 258   (setq major-mode 'debugger-mode)
 259   (setq mode-name "Debugger")
 260   (setq truncate-lines t)
 261   (set-syntax-table emacs-lisp-mode-syntax-table)
 262   (use-local-map debugger-mode-map))
 263 \f
 264 ;;;###autoload
 265 (defun debug-on-entry (function)
 266   "Request FUNCTION to invoke debugger each time it is called.
 267 If the user continues, FUNCTION's execution proceeds.
 268 Works by modifying the definition of FUNCTION,
 269 which must be written in Lisp, not predefined.
 270 Use \\[cancel-debug-on-entry] to cancel the effect of this command.
 271 Redefining FUNCTION also does that."
 272   (interactive "aDebug on entry (to function): ")
 273   (debugger-reenable)
 274   (if (subrp (symbol-function function))
 275       (error "Function %s is a primitive" function))
 276   (or (consp (symbol-function function))
 277       (debug-convert-byte-code function))
 278   (or (consp (symbol-function function))
 279       (error "Definition of %s is not a list" function))
 280   (fset function (debug-on-entry-1 function (symbol-function function) t))
 281   (or (memq function debug-function-list)
 282       (setq debug-function-list (cons function debug-function-list)))
 283   function)
 284
 285 ;;;###autoload
 286 (defun cancel-debug-on-entry (&optional function)
 287   "Undo effect of \\[debug-on-entry] on FUNCTION.
 288 If argument is nil or an empty string, cancel for all functions."
 289   (interactive "aCancel debug on entry (to function): ")
 290   (debugger-reenable)
 291   (if (and function (not (string= function "")))
 292       (progn
 293         (fset function
 294               (debug-on-entry-1 function (symbol-function function) nil))
 295         (setq debug-function-list (delq function debug-function-list))
 296         function)
 297     (message "Cancelling debug-on-entry for all functions")
 298     (mapcar 'cancel-debug-on-entry debug-function-list)))
 299
 300 (defun debug-convert-byte-code (function)
 301   (let ((defn (symbol-function function)))
 302     (if (not (consp defn))
 303         ;; Assume a compiled code object.
 304         (let* ((contents (append defn nil))
 305                (body
 306                 (list (list 'byte-code (nth 1 contents)
 307                             (nth 2 contents) (nth 3 contents)))))
 308           (if (nthcdr 5 contents)
 309               (setq body (cons (list 'interactive (nth 5 contents)) body)))
 310           (if (nth 4 contents)
 311               (setq body (cons (nth 4 contents) body)))
 312           (fset function (cons 'lambda (cons (car contents) body)))))))
 313
 314 (defun debug-on-entry-1 (function defn flag)
 315   (if (subrp defn)
 316       (error "%s is a built-in function" function)
 317     (if (eq (car defn) 'macro)
 318         (debug-on-entry-1 function (cdr defn) flag)
 319       (or (eq (car defn) 'lambda)
 320           (error "%s not user-defined Lisp function" function))
 321       (let (tail prec)
 322         (if (stringp (car (nthcdr 2 defn)))
 323             (setq tail (nthcdr 3 defn)
 324                   prec (list (car defn) (car (cdr defn))
 325                              (car (cdr (cdr defn)))))
 326           (setq tail (nthcdr 2 defn)
 327                 prec (list (car defn) (car (cdr defn)))))
 328         (if (eq flag (equal (car tail) '(debug 'debug)))
 329             defn
 330           (if flag
 331               (nconc prec (cons '(debug 'debug) tail))
 332             (nconc prec (cdr tail))))))))
 333
 334 (defun debugger-list-functions ()
 335   "Display a list of all the functions now set to debug on entry."
 336   (interactive)
 337   (with-output-to-temp-buffer "*Help*"
 338     (if (null debug-function-list)
 339         (princ "No debug-on-entry functions now\n")
 340       (princ "Functions set to debug on entry:\n\n")
 341       (let ((list debug-function-list))
 342         (while list
 343           (prin1 (car list))
 344           (terpri)
 345           (setq list (cdr list))))
 346       (princ "Note: if you have redefined a function, then it may no longer\n")
 347       (princ "be set to debug on entry, even if it is in the list."))))