lisp/emacs-lisp/trace.el

   1 ;;; trace.el --- tracing facility for Emacs Lisp functions
   2
   3 ;; Copyright (C) 1993, 1998, 2000, 2005  Free Software Foundation, Inc.
   4
   5 ;; Author: Hans Chalupsky <hans@cs.buffalo.edu>
   6 ;; Maintainer: FSF
   7 ;; Created: 15 Dec 1992
   8 ;; Keywords: tools, lisp
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software; you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation; either version 2, or (at your option)
  15 ;; any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, USA.
  26
  27 ;; LCD Archive Entry:
  28 ;; trace|Hans Chalupsky|hans@cs.buffalo.edu|
  29 ;; Tracing facility for Emacs Lisp functions|
  30 ;; 1993/05/18 00:41:16|2.0|~/packages/trace.el.Z|
  31
  32
  33 ;;; Commentary:
  34
  35 ;; Introduction:
  36 ;; =============
  37 ;; A simple trace package that utilizes advice.el. It generates trace
  38 ;; information in a Lisp-style fashion and inserts it into a trace output
  39 ;; buffer. Tracing can be done in the background (or silently) so that
  40 ;; generation of trace output won't interfere with what you are currently
  41 ;; doing.
  42
  43 ;; Requirement:
  44 ;; ============
  45 ;; trace.el needs advice.el version 2.0 or later which you can get from the
  46 ;; same place from where you got trace.el.
  47
  48 ;; Restrictions:
  49 ;; =============
  50 ;; - Traced subrs when called interactively will always show nil as the
  51 ;;   value of their arguments.
  52 ;; - Only functions/macros/subrs that are called via their function cell will
  53 ;;   generate trace output, hence, you won't get trace output for:
  54 ;;   + Subrs called directly from other subrs/C-code
  55 ;;   + Compiled calls to subrs that have special byte-codes associated
  56 ;;     with them (e.g., car, cdr, ...)
  57 ;;   + Macros that were expanded during compilation
  58 ;; - All the restrictions that apply to advice.el
  59
  60 ;; Installation:
  61 ;; =============
  62 ;; Put this file together with advice.el (version 2.0 or later) somewhere
  63 ;; into your Emacs `load-path', byte-compile it/them for efficiency, and
  64 ;; put the following autoload declarations into your .emacs
  65 ;;
  66 ;;    (autoload 'trace-function "trace" "Trace a function" t)
  67 ;;    (autoload 'trace-function-background "trace" "Trace a function" t)
  68 ;;
  69 ;; or explicitly load it with (require 'trace) or (load "trace").
  70
  71 ;; Usage:
  72 ;; ======
  73 ;; - To trace a function say `M-x trace-function' which will ask you for the
  74 ;;   name of the function/subr/macro to trace, as well as for the buffer
  75 ;;   into which trace output should go.
  76 ;; - If you want to trace a function that switches buffers or does other
  77 ;;   display oriented stuff use `M-x trace-function-background' which will
  78 ;;   generate the trace output silently in the background without popping
  79 ;;   up windows and doing other irritating stuff.
  80 ;; - To untrace a function say `M-x untrace-function'.
  81 ;; - To untrace all currently traced functions say `M-x untrace-all'.
  82
  83 ;; Examples:
  84 ;; =========
  85 ;;
  86 ;;  (defun fact (n)
  87 ;;    (if (= n 0) 1
  88 ;;      (* n (fact (1- n)))))
  89 ;;  fact
  90 ;;
  91 ;;  (trace-function 'fact)
  92 ;;  fact
  93 ;;
  94 ;;  Now, evaluating this...
  95 ;;
  96 ;;  (fact 4)
  97 ;;  24
  98 ;;
  99 ;;  ...will generate the following in *trace-buffer*:
 100 ;;
 101 ;;  1 -> fact: n=4
 102 ;;  | 2 -> fact: n=3
 103 ;;  | | 3 -> fact: n=2
 104 ;;  | | | 4 -> fact: n=1
 105 ;;  | | | | 5 -> fact: n=0
 106 ;;  | | | | 5 <- fact: 1
 107 ;;  | | | 4 <- fact: 1
 108 ;;  | | 3 <- fact: 2
 109 ;;  | 2 <- fact: 6
 110 ;;  1 <- fact: 24
 111 ;;
 112 ;;
 113 ;;  (defun ack (x y z)
 114 ;;    (if (= x 0)
 115 ;;        (+ y z)
 116 ;;      (if (and (<= x 2) (= z 0))
 117 ;;          (1- x)
 118 ;;        (if (and (> x 2) (= z 0))
 119 ;;            y
 120 ;;          (ack (1- x) y (ack x y (1- z)))))))
 121 ;;  ack
 122 ;;
 123 ;;  (trace-function 'ack)
 124 ;;  ack
 125 ;;
 126 ;;  Try this for some interesting trace output:
 127 ;;
 128 ;;  (ack 3 3 1)
 129 ;;  27
 130 ;;
 131 ;;
 132 ;; The following does something similar to the functionality of the package
 133 ;; log-message.el by Robert Potter, which is giving you a chance to look at
 134 ;; messages that might have whizzed by too quickly (you won't see subr
 135 ;; generated messages though):
 136 ;;
 137 ;; (trace-function-background 'message "*Message Log*")
 138
 139
 140 ;;; Change Log:
 141
 142 ;; Revision 2.0 1993/05/18 00:41:16 hans
 143 ;;      * Adapted for advice.el 2.0; it now also works
 144 ;;        for GNU Emacs-19 and Lemacs
 145 ;;      * Separate function `trace-function-background'
 146 ;;      * Separate pieces of advice for foreground and background tracing
 147 ;;      * Less insane handling of interactive trace buffer specification
 148 ;;      * String arguments and values are now printed properly
 149 ;;
 150 ;; Revision 1.1 1992/12/15 22:45:15 hans
 151 ;;      * Created, first public release
 152
 153
 154 ;;; Code:
 155
 156 (require 'advice)
 157
 158 (defgroup trace nil
 159   "Tracing facility for Emacs Lisp functions"
 160   :prefix "trace-"
 161   :group 'lisp)
 162
 163 ;;;###autoload
 164 (defcustom trace-buffer "*trace-output*"
 165   "*Trace output will by default go to that buffer."
 166   :type 'string
 167   :group 'trace)
 168
 169 ;; Current level of traced function invocation:
 170 (defvar trace-level 0)
 171
 172 ;; Semi-cryptic name used for a piece of trace advice:
 173 (defvar trace-advice-name 'trace-function\ )
 174
 175 ;; Used to separate new trace output from previous traced runs:
 176 (defvar trace-separator (format "%s\n" (make-string 70 ?=)))
 177
 178 (defvar inhibit-trace nil
 179   "If non-nil, all tracing is temporarily inhibited.")
 180
 181 (defun trace-entry-message (function level argument-bindings)
 182   ;; Generates a string that describes that FUNCTION has been entered at
 183   ;; trace LEVEL with ARGUMENT-BINDINGS.
 184   (format "%s%s%d -> %s: %s\n"
 185           (mapconcat 'char-to-string (make-string (1- level) ?|) " ")
 186           (if (> level 1) " " "")
 187           level
 188           function
 189           (mapconcat (lambda (binding)
 190                        (concat
 191                         (symbol-name (ad-arg-binding-field binding 'name))
 192                         "="
 193                         ;; do this so we'll see strings:
 194                         (prin1-to-string
 195                          (ad-arg-binding-field binding 'value))))
 196                      argument-bindings
 197                      " ")))
 198
 199 (defun trace-exit-message (function level value)
 200   ;; Generates a string that describes that FUNCTION has been exited at
 201   ;; trace LEVEL and that it returned VALUE.
 202   (format "%s%s%d <- %s: %s\n"
 203           (mapconcat 'char-to-string (make-string (1- level) ?|) " ")
 204           (if (> level 1) " " "")
 205           level
 206           function
 207           ;; do this so we'll see strings:
 208           (prin1-to-string value)))
 209
 210 (defun trace-make-advice (function buffer background)
 211   ;; Builds the piece of advice to be added to FUNCTION's advice info
 212   ;; so that it will generate the proper trace output in BUFFER
 213   ;; (quietly if BACKGROUND is t).
 214   (ad-make-advice
 215    trace-advice-name nil t
 216    `(advice
 217      lambda ()
 218      (let ((trace-level (1+ trace-level))
 219            (trace-buffer (get-buffer-create ,buffer)))
 220        (unless inhibit-trace
 221          (with-current-buffer trace-buffer
 222            ,(unless background '(pop-to-buffer trace-buffer))
 223            (goto-char (point-max))
 224            ;; Insert a separator from previous trace output:
 225            (if (= trace-level 1) (insert trace-separator))
 226            (insert
 227             (trace-entry-message
 228              ',function trace-level ad-arg-bindings))))
 229        ad-do-it
 230        (unless inhibit-trace
 231          (with-current-buffer trace-buffer
 232            ,(unless background '(pop-to-buffer trace-buffer))
 233            (goto-char (point-max))
 234            (insert
 235             (trace-exit-message
 236              ',function trace-level ad-return-value))))))))
 237
 238 (defun trace-function-internal (function buffer background)
 239   ;; Adds trace advice for FUNCTION and activates it.
 240   (ad-add-advice
 241    function
 242    (trace-make-advice function (or buffer trace-buffer) background)
 243    'around 'last)
 244   (ad-activate function nil))
 245
 246 (defun trace-is-traced (function)
 247   (ad-find-advice function 'around trace-advice-name))
 248
 249 ;;;###autoload
 250 (defun trace-function (function &optional buffer)
 251   "Traces FUNCTION with trace output going to BUFFER.
 252 For every call of FUNCTION Lisp-style trace messages that display argument
 253 and return values will be inserted into BUFFER.  This function generates the
 254 trace advice for FUNCTION and activates it together with any other advice
 255 there might be!! The trace BUFFER will popup whenever FUNCTION is called.
 256 Do not use this to trace functions that switch buffers or do any other
 257 display oriented stuff, use `trace-function-background' instead."
 258   (interactive
 259    (list
 260     (intern (completing-read "Trace function: " obarray 'fboundp t))
 261     (read-buffer "Output to buffer: " trace-buffer)))
 262   (trace-function-internal function buffer nil))
 263
 264 ;;;###autoload
 265 (defun trace-function-background (function &optional buffer)
 266   "Traces FUNCTION with trace output going quietly to BUFFER.
 267 For every call of FUNCTION Lisp-style trace messages that display argument
 268 and return values will be inserted into BUFFER.  This function generates the
 269 trace advice for FUNCTION and activates it together with any other advice
 270 there might be!! Trace output will quietly go to BUFFER without changing
 271 the window or buffer configuration at all."
 272   (interactive
 273    (list
 274     (intern
 275      (completing-read "Trace function in background: " obarray 'fboundp t))
 276     (read-buffer "Output to buffer: " trace-buffer)))
 277   (trace-function-internal function buffer t))
 278
 279 (defun untrace-function (function)
 280   "Untraces FUNCTION and possibly activates all remaining advice.
 281 Activation is performed with `ad-update', hence remaining advice will get
 282 activated only if the advice of FUNCTION is currently active.  If FUNCTION
 283 was not traced this is a noop."
 284   (interactive
 285    (list (ad-read-advised-function "Untrace function: " 'trace-is-traced)))
 286   (when (trace-is-traced function)
 287     (ad-remove-advice function 'around trace-advice-name)
 288     (ad-update function)))
 289
 290 (defun untrace-all ()
 291   "Untraces all currently traced functions."
 292   (interactive)
 293   (ad-do-advised-functions (function)
 294     (untrace-function function)))
 295
 296 (provide 'trace)
 297
 298 ;; arch-tag: cfd170a7-4932-4331-8c8b-b7151942e5a1
 299 ;;; trace.el ends here