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e8af40ee | 1 | ;;; cwarn.el --- highlight suspicious C and C++ constructions |
2936437d | 2 | |
ba318903 | 3 | ;; Copyright (C) 1999-2014 Free Software Foundation, Inc. |
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4 | |
5 | ;; Author: Anders Lindgren <andersl@andersl.com> | |
6 | ;; Keywords: c, languages, faces | |
7 | ;; X-Url: http://www.andersl.com/emacs | |
bd78fa1d | 8 | ;; Version: 1.3.1 |
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9 | |
10 | ;; This file is part of GNU Emacs. | |
11 | ||
b1fc2b50 | 12 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
2936437d | 13 | ;; it under the terms of the GNU General Public License as published by |
b1fc2b50 GM |
14 | ;; the Free Software Foundation, either version 3 of the License, or |
15 | ;; (at your option) any later version. | |
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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 | |
b1fc2b50 | 23 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
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24 | |
25 | ;;; Commentary: | |
26 | ||
27 | ;;{{{ Documentation | |
28 | ||
29 | ;; Description: | |
30 | ;; | |
31 | ;; CWarn is a package that highlights suspicious C and C++ constructions. | |
32 | ;; | |
33 | ;; For example, take a look at the following piece of C code: | |
34 | ;; | |
35 | ;; if (x = 0); | |
36 | ;; foo(); | |
37 | ;; | |
38 | ;; The code contains two, possibly fatal, bugs. The first is that the | |
39 | ;; assignment operator "=" is used as part of the test; the user | |
0b05c8ca | 40 | ;; probably meant to use the comparison operator "==". |
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41 | ;; |
42 | ;; The second problem is that an extra semicolon is placed after | |
43 | ;; closing parenthesis of the test expression. This makes the body of | |
44 | ;; the if statement to be an empty statement, not the call to the | |
45 | ;; function "foo", as the user probably intended. | |
46 | ;; | |
47 | ;; This package is capable of highlighting the following C and C++ | |
48 | ;; constructions: | |
49 | ;; | |
50 | ;; * Assignments inside expressions, including variations like "+=". | |
51 | ;; * Semicolon following immediately after `if', `for', and `while' | |
52 | ;; (except, of course, after a `do .. while' statement). | |
53 | ;; * C++ functions with reference parameters. | |
54 | ;; | |
55 | ;; Note that none of the constructions highlighted (especially not C++ | |
0b05c8ca | 56 | ;; reference parameters) are considered errors by the language |
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57 | ;; definitions. |
58 | ||
59 | ;; Usage: | |
60 | ;; | |
61 | ;; CWarn is implemented as two minor modes: `cwarn-mode' and | |
62 | ;; `global-cwarn-mode'. The former can be applied to individual buffers | |
63 | ;; and the latter to all buffers. | |
64 | ;; | |
65 | ;; Activate this package by Customize, or by placing the following line | |
66 | ;; into the appropriate init file: | |
67 | ;; | |
68 | ;; (global-cwarn-mode 1) | |
69 | ;; | |
70 | ;; Also, `font-lock-mode' or `global-font-lock-mode' must be enabled. | |
71 | ||
72 | ;; Afterthought: | |
73 | ;; | |
74 | ;; After using this package for several weeks it feels as though I | |
75 | ;; find stupid typo-style bugs while editing rather than at compile- | |
76 | ;; or run-time, if I ever find them. | |
77 | ;; | |
78 | ;; On the other hand, I find myself using assignments inside | |
79 | ;; expressions much more often than I used to do. The reason is that | |
80 | ;; there is no risk of interpreting an assignment operator as a | |
81 | ;; comparison ("hey, the assignment operator is red, duh!"). | |
82 | ||
83 | ;; Reporting bugs: | |
84 | ;; | |
85 | ;; Out of the last ten bugs you found, how many did you report? | |
86 | ;; | |
87 | ;; When reporting a bug, please: | |
88 | ;; | |
89 | ;; * Send a mail the maintainer of the package, or to the author | |
90 | ;; if no maintainer exists. | |
91 | ;; * Include the name of the package in the title of the mail, to | |
92 | ;; simplify for the recipient. | |
93 | ;; * State exactly what you did, what happened, and what you expected | |
94 | ;; to see when you found the bug. | |
95 | ;; * If the bug cause an error, set the variable `debug-on-error' to t, | |
0b05c8ca | 96 | ;; repeat the operations that triggered the error and include |
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97 | ;; the backtrace in the letter. |
98 | ;; * If possible, include an example that activates the bug. | |
99 | ;; * Should you speculate about the cause of the problem, please | |
100 | ;; state explicitly that you are guessing. | |
101 | ||
102 | ;;}}} | |
103 | ||
104 | ;;; Code: | |
105 | ||
106 | ;;{{{ Dependencies | |
107 | ||
2936437d GM |
108 | (require 'custom) |
109 | (require 'font-lock) | |
110 | (require 'cc-mode) | |
111 | ||
112 | ;;}}} | |
113 | ;;{{{ Variables | |
114 | ||
115 | (defgroup cwarn nil | |
116 | "Highlight suspicious C and C++ constructions." | |
9a513aba | 117 | :version "21.1" |
2936437d GM |
118 | :group 'faces) |
119 | ||
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120 | (defcustom cwarn-configuration |
121 | '((c-mode (not reference)) | |
122 | (c++-mode t)) | |
47893581 | 123 | "List of items each describing which features are enable for a mode. |
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124 | Each item is on the form (mode featurelist), where featurelist can be |
125 | on one of three forms: | |
126 | ||
127 | * A list of enabled features. | |
128 | * A list starting with the atom `not' followed by the features | |
129 | which are not enabled. | |
130 | * The atom t, that represent that all features are enabled. | |
131 | ||
132 | See variable `cwarn-font-lock-feature-keywords-alist' for available | |
133 | features." | |
9a513aba | 134 | :type '(repeat sexp) |
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135 | :group 'cwarn) |
136 | ||
137 | (defcustom cwarn-font-lock-feature-keywords-alist | |
138 | '((assign . cwarn-font-lock-assignment-keywords) | |
139 | (semicolon . cwarn-font-lock-semicolon-keywords) | |
140 | (reference . cwarn-font-lock-reference-keywords)) | |
9a513aba | 141 | "An alist mapping a CWarn feature to font-lock keywords. |
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142 | The keywords could either a font-lock keyword list or a symbol. |
143 | If it is a symbol it is assumed to be a variable containing a font-lock | |
144 | keyword list." | |
9a513aba DL |
145 | :type '(alist :key-type (choice (const assign) |
146 | (const semicolon) | |
147 | (const reference)) | |
04808157 | 148 | :value-type (sexp :tag "Value")) |
2936437d GM |
149 | :group 'cwarn) |
150 | ||
151 | (defcustom cwarn-verbose t | |
47893581 | 152 | "When nil, CWarn mode will not generate any messages. |
2936437d GM |
153 | |
154 | Currently, messages are generated when the mode is activated and | |
155 | deactivated." | |
156 | :group 'cwarn | |
157 | :type 'boolean) | |
158 | ||
159 | (defcustom cwarn-mode-text " CWarn" | |
47893581 | 160 | "String to display in the mode line when CWarn mode is active. |
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161 | |
162 | \(When the string is not empty, make sure that it has a leading space.)" | |
163 | :tag "CWarn mode text" ; To separate it from `global-...' | |
164 | :group 'cwarn | |
165 | :type 'string) | |
166 | ||
2936437d | 167 | (defcustom cwarn-load-hook nil |
47893581 | 168 | "Functions to run when CWarn mode is first loaded." |
2936437d GM |
169 | :tag "Load Hook" |
170 | :group 'cwarn | |
171 | :type 'hook) | |
172 | ||
173 | ;;}}} | |
174 | ;;{{{ The modes | |
175 | ||
176 | ;;;###autoload | |
0b05c8ca | 177 | (define-minor-mode cwarn-mode |
9a513aba | 178 | "Minor mode that highlights suspicious C and C++ constructions. |
2936437d | 179 | |
1902a98c EZ |
180 | Suspicious constructs are highlighted using `font-lock-warning-face'. |
181 | ||
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182 | Note, in addition to enabling this minor mode, the major mode must |
183 | be included in the variable `cwarn-configuration'. By default C and | |
184 | C++ modes are included. | |
185 | ||
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186 | With a prefix argument ARG, enable the mode if ARG is positive, |
187 | and disable it otherwise. If called from Lisp, enable the mode | |
188 | if ARG is omitted or nil." | |
1f644ce3 | 189 | :group 'cwarn :lighter cwarn-mode-text |
0b05c8ca SM |
190 | (cwarn-font-lock-keywords cwarn-mode) |
191 | (if font-lock-mode (font-lock-fontify-buffer))) | |
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192 | |
193 | ;;;###autoload | |
59f7af81 | 194 | (define-obsolete-function-alias 'turn-on-cwarn-mode 'cwarn-mode "24.1") |
2936437d | 195 | |
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196 | ;;}}} |
197 | ;;{{{ Help functions | |
198 | ||
199 | (defun cwarn-is-enabled (mode &optional feature) | |
200 | "Non-nil if CWarn FEATURE is enabled for MODE. | |
cd1181db | 201 | FEATURE is an atom representing one construction to highlight. |
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202 | |
203 | Check if any feature is enabled for MODE if no feature is specified. | |
204 | ||
205 | The valid features are described by the variable | |
206 | `cwarn-font-lock-feature-keywords-alist'." | |
cd1181db JB |
207 | (let ((mode-configuration (assq mode cwarn-configuration))) |
208 | (and mode-configuration | |
2936437d | 209 | (or (null feature) |
cd1181db | 210 | (let ((list-or-t (nth 1 mode-configuration))) |
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211 | (or (eq list-or-t t) |
212 | (if (eq (car-safe list-or-t) 'not) | |
213 | (not (memq feature (cdr list-or-t))) | |
214 | (memq feature list-or-t)))))))) | |
215 | ||
216 | (defun cwarn-inside-macro () | |
217 | "True if point is inside a C macro definition." | |
218 | (save-excursion | |
219 | (beginning-of-line) | |
220 | (while (eq (char-before (1- (point))) ?\\) | |
221 | (forward-line -1)) | |
222 | (back-to-indentation) | |
223 | (eq (char-after) ?#))) | |
224 | ||
0b05c8ca | 225 | (defun cwarn-font-lock-keywords (addp) |
cd1181db | 226 | "Install/remove keywords into current buffer. |
0b05c8ca | 227 | If ADDP is non-nil, install else remove." |
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228 | (dolist (pair cwarn-font-lock-feature-keywords-alist) |
229 | (let ((feature (car pair)) | |
230 | (keywords (cdr pair))) | |
231 | (if (not (listp keywords)) | |
232 | (setq keywords (symbol-value keywords))) | |
0b05c8ca SM |
233 | (if (cwarn-is-enabled major-mode feature) |
234 | (funcall (if addp 'font-lock-add-keywords 'font-lock-remove-keywords) | |
235 | nil keywords))))) | |
2936437d | 236 | |
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237 | ;;}}} |
238 | ;;{{{ Font-lock keywords and match functions | |
239 | ||
240 | ;; This section contains font-lock keywords. A font lock keyword can | |
241 | ;; either contain a regular expression or a match function. All | |
242 | ;; keywords defined here use match functions since the C and C++ | |
243 | ;; constructions highlighted by CWarn are too complex to be matched by | |
244 | ;; regular expressions. | |
245 | ;; | |
246 | ;; A match function should act like a normal forward search. They | |
247 | ;; should return non-nil if they found a candidate and the match data | |
248 | ;; should correspond to the highlight part of the font-lock keyword. | |
0b05c8ca | 249 | ;; The functions should not generate errors, in that case font-lock |
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250 | ;; will fail to highlight the buffer. A match function takes one |
251 | ;; argument, LIMIT, that represent the end of area to be searched. | |
252 | ;; | |
253 | ;; The variable `cwarn-font-lock-feature-keywords-alist' contains a | |
254 | ;; mapping from CWarn features to the font-lock keywords defined | |
255 | ;; below. | |
256 | ||
0b05c8ca SM |
257 | (defmacro cwarn-font-lock-match (re &rest body) |
258 | "Match RE but only if BODY holds." | |
259 | `(let ((res nil)) | |
260 | (while | |
261 | (progn | |
262 | (setq res (re-search-forward ,re limit t)) | |
263 | (and res | |
264 | (save-excursion | |
265 | (when (match-beginning 1) (goto-char (match-beginning 1))) | |
266 | (condition-case nil ; In case something barfs. | |
267 | (not (save-match-data | |
268 | ,@body)) | |
269 | (error t)))))) | |
270 | res)) | |
271 | ||
2936437d GM |
272 | ;;{{{ Assignment in expressions |
273 | ||
274 | (defconst cwarn-font-lock-assignment-keywords | |
275 | '((cwarn-font-lock-match-assignment-in-expression | |
276 | (1 font-lock-warning-face)))) | |
277 | ||
278 | (defun cwarn-font-lock-match-assignment-in-expression (limit) | |
279 | "Match assignments inside expressions." | |
0b05c8ca SM |
280 | (cwarn-font-lock-match |
281 | "[^!<>=]\\(\\([-+*/%&^|]\\|<<\\|>>\\)?=\\)[^=]" | |
282 | (backward-up-list 1) | |
283 | (and (memq (following-char) '(?\( ?\[)) | |
284 | (not (progn | |
285 | (skip-chars-backward " ") | |
286 | (skip-chars-backward "a-zA-Z0-9_") | |
287 | (or | |
288 | ;; Default parameter of function. | |
289 | (c-at-toplevel-p) | |
290 | (looking-at "for\\>"))))))) | |
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291 | |
292 | ;;}}} | |
293 | ;;{{{ Semicolon | |
294 | ||
295 | (defconst cwarn-font-lock-semicolon-keywords | |
296 | '((cwarn-font-lock-match-dangerous-semicolon (0 font-lock-warning-face)))) | |
297 | ||
298 | (defun cwarn-font-lock-match-dangerous-semicolon (limit) | |
299 | "Match semicolons directly after `for', `while', and `if'. | |
0b05c8ca SM |
300 | The semicolon after a `do { ... } while (x);' construction is not matched." |
301 | (cwarn-font-lock-match | |
302 | ";" | |
303 | (backward-sexp 2) ; Expression and keyword. | |
304 | (or (looking-at "\\(for\\|if\\)\\>") | |
305 | (and (looking-at "while\\>") | |
306 | (condition-case nil | |
307 | (progn | |
308 | (backward-sexp 2) ; Body and "do". | |
309 | (not (looking-at "do\\>"))) | |
310 | (error t)))))) | |
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311 | |
312 | ;;}}} | |
313 | ;;{{{ Reference | |
314 | ||
315 | (defconst cwarn-font-lock-reference-keywords | |
316 | '((cwarn-font-lock-match-reference (1 font-lock-warning-face)))) | |
317 | ||
318 | (defun cwarn-font-lock-match-reference (limit) | |
319 | "Font-lock matcher for C++ reference parameters." | |
0b05c8ca SM |
320 | (cwarn-font-lock-match |
321 | "[^&]\\(&\\)[^&=]" | |
322 | (backward-up-list 1) | |
323 | (and (eq (following-char) ?\() | |
324 | (not (cwarn-inside-macro)) | |
325 | (c-at-toplevel-p)))) | |
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326 | |
327 | ;;}}} | |
328 | ||
329 | ;;}}} | |
330 | ;;{{{ The end | |
331 | ||
0b05c8ca SM |
332 | (defun turn-on-cwarn-mode-if-enabled () |
333 | "Turn on CWarn mode in the current buffer if applicable. | |
334 | The mode is turned if some feature is enabled for the current | |
335 | `major-mode' in `cwarn-configuration'." | |
47893581 | 336 | (when (cwarn-is-enabled major-mode) (cwarn-mode 1))) |
0b05c8ca SM |
337 | |
338 | ;;;###autoload | |
b6a856a6 | 339 | (define-globalized-minor-mode global-cwarn-mode |
e72b3747 | 340 | cwarn-mode turn-on-cwarn-mode-if-enabled) |
2936437d GM |
341 | |
342 | (provide 'cwarn) | |
343 | ||
344 | (run-hooks 'cwarn-load-hook) | |
345 | ||
2936437d GM |
346 | ;;}}} |
347 | ||
348 | ;;; cwarn.el ends here |