t2203: abstract away SHA-1-specific constants
[git] / ws.c
1 /*
2  * Whitespace rules
3  *
4  * Copyright (c) 2007 Junio C Hamano
5  */
6
7 #include "cache.h"
8 #include "attr.h"
9
10 static struct whitespace_rule {
11         const char *rule_name;
12         unsigned rule_bits;
13         unsigned loosens_error:1,
14                 exclude_default:1;
15 } whitespace_rule_names[] = {
16         { "trailing-space", WS_TRAILING_SPACE, 0 },
17         { "space-before-tab", WS_SPACE_BEFORE_TAB, 0 },
18         { "indent-with-non-tab", WS_INDENT_WITH_NON_TAB, 0 },
19         { "cr-at-eol", WS_CR_AT_EOL, 1 },
20         { "blank-at-eol", WS_BLANK_AT_EOL, 0 },
21         { "blank-at-eof", WS_BLANK_AT_EOF, 0 },
22         { "tab-in-indent", WS_TAB_IN_INDENT, 0, 1 },
23 };
24
25 unsigned parse_whitespace_rule(const char *string)
26 {
27         unsigned rule = WS_DEFAULT_RULE;
28
29         while (string) {
30                 int i;
31                 size_t len;
32                 const char *ep;
33                 int negated = 0;
34
35                 string = string + strspn(string, ", \t\n\r");
36                 ep = strchrnul(string, ',');
37                 len = ep - string;
38
39                 if (*string == '-') {
40                         negated = 1;
41                         string++;
42                         len--;
43                 }
44                 if (!len)
45                         break;
46                 for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++) {
47                         if (strncmp(whitespace_rule_names[i].rule_name,
48                                     string, len))
49                                 continue;
50                         if (negated)
51                                 rule &= ~whitespace_rule_names[i].rule_bits;
52                         else
53                                 rule |= whitespace_rule_names[i].rule_bits;
54                         break;
55                 }
56                 if (strncmp(string, "tabwidth=", 9) == 0) {
57                         unsigned tabwidth = atoi(string + 9);
58                         if (0 < tabwidth && tabwidth < 0100) {
59                                 rule &= ~WS_TAB_WIDTH_MASK;
60                                 rule |= tabwidth;
61                         }
62                         else
63                                 warning("tabwidth %.*s out of range",
64                                         (int)(len - 9), string + 9);
65                 }
66                 string = ep;
67         }
68
69         if (rule & WS_TAB_IN_INDENT && rule & WS_INDENT_WITH_NON_TAB)
70                 die("cannot enforce both tab-in-indent and indent-with-non-tab");
71         return rule;
72 }
73
74 unsigned whitespace_rule(const char *pathname)
75 {
76         static struct attr_check *attr_whitespace_rule;
77
78         if (!attr_whitespace_rule)
79                 attr_whitespace_rule = attr_check_initl("whitespace", NULL);
80
81         if (!git_check_attr(pathname, attr_whitespace_rule)) {
82                 const char *value;
83
84                 value = attr_whitespace_rule->items[0].value;
85                 if (ATTR_TRUE(value)) {
86                         /* true (whitespace) */
87                         unsigned all_rule = ws_tab_width(whitespace_rule_cfg);
88                         int i;
89                         for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++)
90                                 if (!whitespace_rule_names[i].loosens_error &&
91                                     !whitespace_rule_names[i].exclude_default)
92                                         all_rule |= whitespace_rule_names[i].rule_bits;
93                         return all_rule;
94                 } else if (ATTR_FALSE(value)) {
95                         /* false (-whitespace) */
96                         return ws_tab_width(whitespace_rule_cfg);
97                 } else if (ATTR_UNSET(value)) {
98                         /* reset to default (!whitespace) */
99                         return whitespace_rule_cfg;
100                 } else {
101                         /* string */
102                         return parse_whitespace_rule(value);
103                 }
104         } else {
105                 return whitespace_rule_cfg;
106         }
107 }
108
109 /* The returned string should be freed by the caller. */
110 char *whitespace_error_string(unsigned ws)
111 {
112         struct strbuf err = STRBUF_INIT;
113         if ((ws & WS_TRAILING_SPACE) == WS_TRAILING_SPACE)
114                 strbuf_addstr(&err, "trailing whitespace");
115         else {
116                 if (ws & WS_BLANK_AT_EOL)
117                         strbuf_addstr(&err, "trailing whitespace");
118                 if (ws & WS_BLANK_AT_EOF) {
119                         if (err.len)
120                                 strbuf_addstr(&err, ", ");
121                         strbuf_addstr(&err, "new blank line at EOF");
122                 }
123         }
124         if (ws & WS_SPACE_BEFORE_TAB) {
125                 if (err.len)
126                         strbuf_addstr(&err, ", ");
127                 strbuf_addstr(&err, "space before tab in indent");
128         }
129         if (ws & WS_INDENT_WITH_NON_TAB) {
130                 if (err.len)
131                         strbuf_addstr(&err, ", ");
132                 strbuf_addstr(&err, "indent with spaces");
133         }
134         if (ws & WS_TAB_IN_INDENT) {
135                 if (err.len)
136                         strbuf_addstr(&err, ", ");
137                 strbuf_addstr(&err, "tab in indent");
138         }
139         return strbuf_detach(&err, NULL);
140 }
141
142 /* If stream is non-NULL, emits the line after checking. */
143 static unsigned ws_check_emit_1(const char *line, int len, unsigned ws_rule,
144                                 FILE *stream, const char *set,
145                                 const char *reset, const char *ws)
146 {
147         unsigned result = 0;
148         int written = 0;
149         int trailing_whitespace = -1;
150         int trailing_newline = 0;
151         int trailing_carriage_return = 0;
152         int i;
153
154         /* Logic is simpler if we temporarily ignore the trailing newline. */
155         if (len > 0 && line[len - 1] == '\n') {
156                 trailing_newline = 1;
157                 len--;
158         }
159         if ((ws_rule & WS_CR_AT_EOL) &&
160             len > 0 && line[len - 1] == '\r') {
161                 trailing_carriage_return = 1;
162                 len--;
163         }
164
165         /* Check for trailing whitespace. */
166         if (ws_rule & WS_BLANK_AT_EOL) {
167                 for (i = len - 1; i >= 0; i--) {
168                         if (isspace(line[i])) {
169                                 trailing_whitespace = i;
170                                 result |= WS_BLANK_AT_EOL;
171                         }
172                         else
173                                 break;
174                 }
175         }
176
177         if (trailing_whitespace == -1)
178                 trailing_whitespace = len;
179
180         /* Check indentation */
181         for (i = 0; i < trailing_whitespace; i++) {
182                 if (line[i] == ' ')
183                         continue;
184                 if (line[i] != '\t')
185                         break;
186                 if ((ws_rule & WS_SPACE_BEFORE_TAB) && written < i) {
187                         result |= WS_SPACE_BEFORE_TAB;
188                         if (stream) {
189                                 fputs(ws, stream);
190                                 fwrite(line + written, i - written, 1, stream);
191                                 fputs(reset, stream);
192                                 fwrite(line + i, 1, 1, stream);
193                         }
194                 } else if (ws_rule & WS_TAB_IN_INDENT) {
195                         result |= WS_TAB_IN_INDENT;
196                         if (stream) {
197                                 fwrite(line + written, i - written, 1, stream);
198                                 fputs(ws, stream);
199                                 fwrite(line + i, 1, 1, stream);
200                                 fputs(reset, stream);
201                         }
202                 } else if (stream) {
203                         fwrite(line + written, i - written + 1, 1, stream);
204                 }
205                 written = i + 1;
206         }
207
208         /* Check for indent using non-tab. */
209         if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= ws_tab_width(ws_rule)) {
210                 result |= WS_INDENT_WITH_NON_TAB;
211                 if (stream) {
212                         fputs(ws, stream);
213                         fwrite(line + written, i - written, 1, stream);
214                         fputs(reset, stream);
215                 }
216                 written = i;
217         }
218
219         if (stream) {
220                 /*
221                  * Now the rest of the line starts at "written".
222                  * The non-highlighted part ends at "trailing_whitespace".
223                  */
224
225                 /* Emit non-highlighted (middle) segment. */
226                 if (trailing_whitespace - written > 0) {
227                         fputs(set, stream);
228                         fwrite(line + written,
229                             trailing_whitespace - written, 1, stream);
230                         fputs(reset, stream);
231                 }
232
233                 /* Highlight errors in trailing whitespace. */
234                 if (trailing_whitespace != len) {
235                         fputs(ws, stream);
236                         fwrite(line + trailing_whitespace,
237                             len - trailing_whitespace, 1, stream);
238                         fputs(reset, stream);
239                 }
240                 if (trailing_carriage_return)
241                         fputc('\r', stream);
242                 if (trailing_newline)
243                         fputc('\n', stream);
244         }
245         return result;
246 }
247
248 void ws_check_emit(const char *line, int len, unsigned ws_rule,
249                    FILE *stream, const char *set,
250                    const char *reset, const char *ws)
251 {
252         (void)ws_check_emit_1(line, len, ws_rule, stream, set, reset, ws);
253 }
254
255 unsigned ws_check(const char *line, int len, unsigned ws_rule)
256 {
257         return ws_check_emit_1(line, len, ws_rule, NULL, NULL, NULL, NULL);
258 }
259
260 int ws_blank_line(const char *line, int len, unsigned ws_rule)
261 {
262         /*
263          * We _might_ want to treat CR differently from other
264          * whitespace characters when ws_rule has WS_CR_AT_EOL, but
265          * for now we just use this stupid definition.
266          */
267         while (len-- > 0) {
268                 if (!isspace(*line))
269                         return 0;
270                 line++;
271         }
272         return 1;
273 }
274
275 /* Copy the line onto the end of the strbuf while fixing whitespaces */
276 void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule, int *error_count)
277 {
278         /*
279          * len is number of bytes to be copied from src, starting
280          * at src.  Typically src[len-1] is '\n', unless this is
281          * the incomplete last line.
282          */
283         int i;
284         int add_nl_to_tail = 0;
285         int add_cr_to_tail = 0;
286         int fixed = 0;
287         int last_tab_in_indent = -1;
288         int last_space_in_indent = -1;
289         int need_fix_leading_space = 0;
290
291         /*
292          * Strip trailing whitespace
293          */
294         if (ws_rule & WS_BLANK_AT_EOL) {
295                 if (0 < len && src[len - 1] == '\n') {
296                         add_nl_to_tail = 1;
297                         len--;
298                         if (0 < len && src[len - 1] == '\r') {
299                                 add_cr_to_tail = !!(ws_rule & WS_CR_AT_EOL);
300                                 len--;
301                         }
302                 }
303                 if (0 < len && isspace(src[len - 1])) {
304                         while (0 < len && isspace(src[len-1]))
305                                 len--;
306                         fixed = 1;
307                 }
308         }
309
310         /*
311          * Check leading whitespaces (indent)
312          */
313         for (i = 0; i < len; i++) {
314                 char ch = src[i];
315                 if (ch == '\t') {
316                         last_tab_in_indent = i;
317                         if ((ws_rule & WS_SPACE_BEFORE_TAB) &&
318                             0 <= last_space_in_indent)
319                             need_fix_leading_space = 1;
320                 } else if (ch == ' ') {
321                         last_space_in_indent = i;
322                         if ((ws_rule & WS_INDENT_WITH_NON_TAB) &&
323                             ws_tab_width(ws_rule) <= i - last_tab_in_indent)
324                                 need_fix_leading_space = 1;
325                 } else
326                         break;
327         }
328
329         if (need_fix_leading_space) {
330                 /* Process indent ourselves */
331                 int consecutive_spaces = 0;
332                 int last = last_tab_in_indent + 1;
333
334                 if (ws_rule & WS_INDENT_WITH_NON_TAB) {
335                         /* have "last" point at one past the indent */
336                         if (last_tab_in_indent < last_space_in_indent)
337                                 last = last_space_in_indent + 1;
338                         else
339                                 last = last_tab_in_indent + 1;
340                 }
341
342                 /*
343                  * between src[0..last-1], strip the funny spaces,
344                  * updating them to tab as needed.
345                  */
346                 for (i = 0; i < last; i++) {
347                         char ch = src[i];
348                         if (ch != ' ') {
349                                 consecutive_spaces = 0;
350                                 strbuf_addch(dst, ch);
351                         } else {
352                                 consecutive_spaces++;
353                                 if (consecutive_spaces == ws_tab_width(ws_rule)) {
354                                         strbuf_addch(dst, '\t');
355                                         consecutive_spaces = 0;
356                                 }
357                         }
358                 }
359                 while (0 < consecutive_spaces--)
360                         strbuf_addch(dst, ' ');
361                 len -= last;
362                 src += last;
363                 fixed = 1;
364         } else if ((ws_rule & WS_TAB_IN_INDENT) && last_tab_in_indent >= 0) {
365                 /* Expand tabs into spaces */
366                 int start = dst->len;
367                 int last = last_tab_in_indent + 1;
368                 for (i = 0; i < last; i++) {
369                         if (src[i] == '\t')
370                                 do {
371                                         strbuf_addch(dst, ' ');
372                                 } while ((dst->len - start) % ws_tab_width(ws_rule));
373                         else
374                                 strbuf_addch(dst, src[i]);
375                 }
376                 len -= last;
377                 src += last;
378                 fixed = 1;
379         }
380
381         strbuf_add(dst, src, len);
382         if (add_cr_to_tail)
383                 strbuf_addch(dst, '\r');
384         if (add_nl_to_tail)
385                 strbuf_addch(dst, '\n');
386         if (fixed && error_count)
387                 (*error_count)++;
388 }