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1 | /* |
2 | * Copyright (c) 1988 Mark Nudleman | |
3 | * Copyright (c) 1988 Regents of the University of California. | |
4 | * All rights reserved. | |
5 | * | |
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6 | * Redistribution and use in source and binary forms are permitted |
7 | * provided that the above copyright notice and this paragraph are | |
8 | * duplicated in all such forms and that any documentation, | |
9 | * advertising materials, and other materials related to such | |
10 | * distribution and use acknowledge that the software was developed | |
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11 | * by Mark Nudleman and the University of California, Berkeley. The |
12 | * name of Mark Nudleman or the | |
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13 | * University may not be used to endorse or promote products derived |
14 | * from this software without specific prior written permission. | |
15 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
16 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
17 | * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
18 | */ | |
19 | ||
20 | #ifndef lint | |
a942b40b | 21 | static char sccsid[] = "@(#)line.c 5.2 (Berkeley) %G%"; |
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22 | #endif /* not lint */ |
23 | ||
24 | /* | |
25 | * Routines to manipulate the "line buffer". | |
26 | * The line buffer holds a line of output as it is being built | |
27 | * in preparation for output to the screen. | |
28 | * We keep track of the PRINTABLE length of the line as it is being built. | |
29 | */ | |
30 | ||
31 | #include "less.h" | |
32 | ||
33 | static char linebuf[1024]; /* Buffer which holds the current output line */ | |
34 | static char *curr; /* Pointer into linebuf */ | |
35 | static int column; /* Printable length, accounting for | |
36 | backspaces, etc. */ | |
37 | /* | |
38 | * A ridiculously complex state machine takes care of backspaces | |
39 | * when in BS_SPECIAL mode. The complexity arises from the attempt | |
40 | * to deal with all cases, especially involving long lines with underlining, | |
41 | * boldfacing or whatever. There are still some cases which will break it. | |
42 | * | |
43 | * There are four states: | |
44 | * LN_NORMAL is the normal state (not in underline mode). | |
45 | * LN_UNDERLINE means we are in underline mode. We expect to get | |
46 | * either a sequence like "_\bX" or "X\b_" to continue | |
47 | * underline mode, or anything else to end underline mode. | |
48 | * LN_BOLDFACE means we are in boldface mode. We expect to get sequences | |
49 | * like "X\bX\b...X\bX" to continue boldface mode, or anything | |
50 | * else to end boldface mode. | |
51 | * LN_UL_X means we are one character after LN_UNDERLINE | |
52 | * (we have gotten the '_' in "_\bX" or the 'X' in "X\b_"). | |
53 | * LN_UL_XB means we are one character after LN_UL_X | |
54 | * (we have gotten the backspace in "_\bX" or "X\b_"; | |
55 | * we expect one more ordinary character, | |
56 | * which will put us back in state LN_UNDERLINE). | |
57 | * LN_BO_X means we are one character after LN_BOLDFACE | |
58 | * (we have gotten the 'X' in "X\bX"). | |
59 | * LN_BO_XB means we are one character after LN_BO_X | |
60 | * (we have gotten the backspace in "X\bX"; | |
61 | * we expect one more 'X' which will put us back | |
62 | * in LN_BOLDFACE). | |
63 | */ | |
64 | static int ln_state; /* Currently in normal/underline/bold/etc mode? */ | |
65 | #define LN_NORMAL 0 /* Not in underline, boldface or whatever mode */ | |
66 | #define LN_UNDERLINE 1 /* In underline, need next char */ | |
67 | #define LN_UL_X 2 /* In underline, got char, need \b */ | |
68 | #define LN_UL_XB 3 /* In underline, got char & \b, need one more */ | |
69 | #define LN_BOLDFACE 4 /* In boldface, need next char */ | |
70 | #define LN_BO_X 5 /* In boldface, got char, need \b */ | |
71 | #define LN_BO_XB 6 /* In boldface, got char & \b, need same char */ | |
72 | ||
73 | public char *line; /* Pointer to the current line. | |
74 | Usually points to linebuf. */ | |
75 | ||
76 | extern int bs_mode; | |
77 | extern int tabstop; | |
78 | extern int bo_width, be_width; | |
79 | extern int ul_width, ue_width; | |
80 | extern int sc_width, sc_height; | |
81 | ||
82 | /* | |
83 | * Rewind the line buffer. | |
84 | */ | |
85 | public void | |
86 | prewind() | |
87 | { | |
88 | line = curr = linebuf; | |
89 | ln_state = LN_NORMAL; | |
90 | column = 0; | |
91 | } | |
92 | ||
93 | /* | |
94 | * Append a character to the line buffer. | |
95 | * Expand tabs into spaces, handle underlining, boldfacing, etc. | |
96 | * Returns 0 if ok, 1 if couldn't fit in buffer. | |
97 | */ | |
98 | ||
99 | #define NEW_COLUMN(newcol) if ((newcol) + ((ln_state)?ue_width:0) > sc_width) \ | |
100 | return (1); else column = (newcol) | |
101 | ||
102 | public int | |
103 | pappend(c) | |
104 | int c; | |
105 | { | |
106 | if (c == '\0') | |
107 | { | |
108 | /* | |
109 | * Terminate any special modes, if necessary. | |
110 | * Append a '\0' to the end of the line. | |
111 | */ | |
112 | switch (ln_state) | |
113 | { | |
114 | case LN_UL_X: | |
115 | curr[0] = curr[-1]; | |
116 | curr[-1] = UE_CHAR; | |
117 | curr++; | |
118 | break; | |
119 | case LN_BO_X: | |
120 | curr[0] = curr[-1]; | |
121 | curr[-1] = BE_CHAR; | |
122 | curr++; | |
123 | break; | |
124 | case LN_UL_XB: | |
125 | case LN_UNDERLINE: | |
126 | *curr++ = UE_CHAR; | |
127 | break; | |
128 | case LN_BO_XB: | |
129 | case LN_BOLDFACE: | |
130 | *curr++ = BE_CHAR; | |
131 | break; | |
132 | } | |
133 | ln_state = LN_NORMAL; | |
134 | *curr = '\0'; | |
135 | return (0); | |
136 | } | |
137 | ||
138 | if (curr > linebuf + sizeof(linebuf) - 12) | |
139 | /* | |
140 | * Almost out of room in the line buffer. | |
141 | * Don't take any chances. | |
142 | * {{ Linebuf is supposed to be big enough that this | |
143 | * will never happen, but may need to be made | |
144 | * bigger for wide screens or lots of backspaces. }} | |
145 | */ | |
146 | return (1); | |
147 | ||
148 | if (bs_mode == BS_SPECIAL) | |
149 | { | |
150 | /* | |
151 | * Advance the state machine. | |
152 | */ | |
153 | switch (ln_state) | |
154 | { | |
155 | case LN_NORMAL: | |
156 | if (curr <= linebuf + 1 || curr[-1] != '\b') | |
157 | break; | |
158 | ||
159 | if (c == curr[-2]) | |
160 | goto enter_boldface; | |
161 | if (c == '_' || curr[-2] == '_') | |
162 | goto enter_underline; | |
163 | curr -= 2; | |
164 | break; | |
165 | ||
166 | enter_boldface: | |
167 | /* | |
168 | * We have "X\bX" (including the current char). | |
169 | * Switch into boldface mode. | |
170 | */ | |
171 | if (column + bo_width + be_width + 1 >= sc_width) | |
172 | /* | |
173 | * Not enough room left on the screen to | |
174 | * enter and exit boldface mode. | |
175 | */ | |
176 | return (1); | |
177 | ||
178 | if (bo_width > 0 && | |
179 | curr > linebuf + 2 && curr[-3] == ' ') | |
180 | { | |
181 | /* | |
182 | * Special case for magic cookie terminals: | |
183 | * if the previous char was a space, replace | |
184 | * it with the "enter boldface" sequence. | |
185 | */ | |
186 | curr[-3] = BO_CHAR; | |
187 | column += bo_width-1; | |
188 | } else | |
189 | { | |
190 | curr[-1] = curr[-2]; | |
191 | curr[-2] = BO_CHAR; | |
192 | column += bo_width; | |
193 | curr++; | |
194 | } | |
195 | goto ln_bo_xb_case; | |
196 | ||
197 | enter_underline: | |
198 | /* | |
199 | * We have either "_\bX" or "X\b_" (including | |
200 | * the current char). Switch into underline mode. | |
201 | */ | |
202 | if (column + ul_width + ue_width + 1 >= sc_width) | |
203 | /* | |
204 | * Not enough room left on the screen to | |
205 | * enter and exit underline mode. | |
206 | */ | |
207 | return (1); | |
208 | ||
209 | if (ul_width > 0 && | |
210 | curr > linebuf + 2 && curr[-3] == ' ') | |
211 | { | |
212 | /* | |
213 | * Special case for magic cookie terminals: | |
214 | * if the previous char was a space, replace | |
215 | * it with the "enter underline" sequence. | |
216 | */ | |
217 | curr[-3] = UL_CHAR; | |
218 | column += ul_width-1; | |
219 | } else | |
220 | { | |
221 | curr[-1] = curr[-2]; | |
222 | curr[-2] = UL_CHAR; | |
223 | column += ul_width; | |
224 | curr++; | |
225 | } | |
226 | goto ln_ul_xb_case; | |
227 | /*NOTREACHED*/ | |
228 | case LN_UL_XB: | |
229 | /* | |
230 | * Termination of a sequence "_\bX" or "X\b_". | |
231 | */ | |
232 | if (c != '_' && curr[-2] != '_' && c == curr[-2]) | |
233 | { | |
234 | /* | |
235 | * We seem to have run on from underlining | |
236 | * into boldfacing - this is a nasty fix, but | |
237 | * until this whole routine is rewritten as a | |
238 | * real DFA, ... well ... | |
239 | */ | |
240 | curr[0] = curr[-2]; | |
241 | curr[-2] = UE_CHAR; | |
242 | curr[-1] = BO_CHAR; | |
243 | curr += 2; /* char & non-existent backspace */ | |
244 | ln_state = LN_BO_XB; | |
245 | goto ln_bo_xb_case; | |
246 | } | |
247 | ln_ul_xb_case: | |
248 | if (c == '_') | |
249 | c = curr[-2]; | |
250 | curr -= 2; | |
251 | ln_state = LN_UNDERLINE; | |
252 | break; | |
253 | case LN_BO_XB: | |
254 | /* | |
255 | * Termination of a sequnce "X\bX". | |
256 | */ | |
257 | if (c != curr[-2] && (c == '_' || curr[-2] == '_')) | |
258 | { | |
259 | /* | |
260 | * We seem to have run on from | |
261 | * boldfacing into underlining. | |
262 | */ | |
263 | curr[0] = curr[-2]; | |
264 | curr[-2] = BE_CHAR; | |
265 | curr[-1] = UL_CHAR; | |
266 | curr += 2; /* char & non-existent backspace */ | |
267 | ln_state = LN_UL_XB; | |
268 | goto ln_ul_xb_case; | |
269 | } | |
270 | ln_bo_xb_case: | |
271 | curr -= 2; | |
272 | ln_state = LN_BOLDFACE; | |
273 | break; | |
274 | case LN_UNDERLINE: | |
275 | if (column + ue_width + bo_width + 1 + be_width >= sc_width) | |
276 | /* | |
277 | * We have just barely enough room to | |
278 | * exit underline mode and handle a possible | |
279 | * underline/boldface run on mixup. | |
280 | */ | |
281 | return (1); | |
282 | ln_state = LN_UL_X; | |
283 | break; | |
284 | case LN_BOLDFACE: | |
285 | if (c == '\b') | |
286 | { | |
287 | ln_state = LN_BO_XB; | |
288 | break; | |
289 | } | |
290 | if (column + be_width + ul_width + 1 + ue_width >= sc_width) | |
291 | /* | |
292 | * We have just barely enough room to | |
293 | * exit underline mode and handle a possible | |
294 | * underline/boldface run on mixup. | |
295 | */ | |
296 | return (1); | |
297 | ln_state = LN_BO_X; | |
298 | break; | |
299 | case LN_UL_X: | |
300 | if (c == '\b') | |
301 | ln_state = LN_UL_XB; | |
302 | else | |
303 | { | |
304 | /* | |
305 | * Exit underline mode. | |
306 | * We have to shuffle the chars a bit | |
307 | * to make this work. | |
308 | */ | |
309 | curr[0] = curr[-1]; | |
310 | curr[-1] = UE_CHAR; | |
311 | column += ue_width; | |
312 | if (ue_width > 0 && curr[0] == ' ') | |
313 | /* | |
314 | * Another special case for magic | |
315 | * cookie terminals: if the next | |
316 | * char is a space, replace it | |
317 | * with the "exit underline" sequence. | |
318 | */ | |
319 | column--; | |
320 | else | |
321 | curr++; | |
322 | ln_state = LN_NORMAL; | |
323 | } | |
324 | break; | |
325 | case LN_BO_X: | |
326 | if (c == '\b') | |
327 | ln_state = LN_BO_XB; | |
328 | else | |
329 | { | |
330 | /* | |
331 | * Exit boldface mode. | |
332 | * We have to shuffle the chars a bit | |
333 | * to make this work. | |
334 | */ | |
335 | curr[0] = curr[-1]; | |
336 | curr[-1] = BE_CHAR; | |
337 | column += be_width; | |
338 | if (be_width > 0 && curr[0] == ' ') | |
339 | /* | |
340 | * Another special case for magic | |
341 | * cookie terminals: if the next | |
342 | * char is a space, replace it | |
343 | * with the "exit boldface" sequence. | |
344 | */ | |
345 | column--; | |
346 | else | |
347 | curr++; | |
348 | ln_state = LN_NORMAL; | |
349 | } | |
350 | break; | |
351 | } | |
352 | } | |
353 | ||
354 | if (c == '\t') | |
355 | { | |
356 | /* | |
357 | * Expand a tab into spaces. | |
358 | */ | |
359 | do | |
360 | { | |
361 | NEW_COLUMN(column+1); | |
362 | } while ((column % tabstop) != 0); | |
363 | *curr++ = '\t'; | |
364 | return (0); | |
365 | } | |
366 | ||
367 | if (c == '\b') | |
368 | { | |
369 | if (bs_mode == BS_CONTROL) | |
370 | { | |
371 | /* | |
372 | * Treat backspace as a control char: output "^H". | |
373 | */ | |
374 | NEW_COLUMN(column+2); | |
375 | *curr++ = ('H' | 0200); | |
376 | } else | |
377 | { | |
378 | /* | |
379 | * Output a real backspace. | |
380 | */ | |
381 | column--; | |
382 | *curr++ = '\b'; | |
383 | } | |
384 | return (0); | |
385 | } | |
386 | ||
387 | if (control_char(c)) | |
388 | { | |
389 | /* | |
390 | * Put a "^X" into the buffer. | |
391 | * The 0200 bit is used to tell put_line() to prefix | |
392 | * the char with a ^. We don't actually put the ^ | |
393 | * in the buffer because we sometimes need to move | |
394 | * chars around, and such movement might separate | |
395 | * the ^ from its following character. | |
396 | * {{ This should be redone so that we can use an | |
397 | * 8 bit (e.g. international) character set. }} | |
398 | */ | |
399 | NEW_COLUMN(column+2); | |
400 | *curr++ = (carat_char(c) | 0200); | |
401 | return (0); | |
402 | } | |
403 | ||
404 | /* | |
405 | * Ordinary character. Just put it in the buffer. | |
406 | */ | |
407 | NEW_COLUMN(column+1); | |
408 | *curr++ = c; | |
409 | return (0); | |
410 | } | |
411 | ||
412 | /* | |
413 | * Analogous to forw_line(), but deals with "raw lines": | |
414 | * lines which are not split for screen width. | |
415 | * {{ This is supposed to be more efficient than forw_line(). }} | |
416 | */ | |
417 | public POSITION | |
418 | forw_raw_line(curr_pos) | |
419 | POSITION curr_pos; | |
420 | { | |
421 | register char *p; | |
422 | register int c; | |
423 | POSITION new_pos; | |
424 | ||
425 | if (curr_pos == NULL_POSITION || ch_seek(curr_pos) || | |
426 | (c = ch_forw_get()) == EOI) | |
427 | return (NULL_POSITION); | |
428 | ||
429 | p = linebuf; | |
430 | ||
431 | for (;;) | |
432 | { | |
433 | if (c == '\n' || c == EOI) | |
434 | { | |
435 | new_pos = ch_tell(); | |
436 | break; | |
437 | } | |
438 | if (p >= &linebuf[sizeof(linebuf)-1]) | |
439 | { | |
440 | /* | |
441 | * Overflowed the input buffer. | |
442 | * Pretend the line ended here. | |
443 | * {{ The line buffer is supposed to be big | |
444 | * enough that this never happens. }} | |
445 | */ | |
446 | new_pos = ch_tell() - 1; | |
447 | break; | |
448 | } | |
449 | *p++ = c; | |
450 | c = ch_forw_get(); | |
451 | } | |
452 | *p = '\0'; | |
453 | line = linebuf; | |
454 | return (new_pos); | |
455 | } | |
456 | ||
457 | /* | |
458 | * Analogous to back_line(), but deals with "raw lines". | |
459 | * {{ This is supposed to be more efficient than back_line(). }} | |
460 | */ | |
461 | public POSITION | |
462 | back_raw_line(curr_pos) | |
463 | POSITION curr_pos; | |
464 | { | |
465 | register char *p; | |
466 | register int c; | |
467 | POSITION new_pos; | |
468 | ||
469 | if (curr_pos == NULL_POSITION || curr_pos <= (POSITION)0 || | |
470 | ch_seek(curr_pos-1)) | |
471 | return (NULL_POSITION); | |
472 | ||
473 | p = &linebuf[sizeof(linebuf)]; | |
474 | *--p = '\0'; | |
475 | ||
476 | for (;;) | |
477 | { | |
478 | c = ch_back_get(); | |
479 | if (c == '\n') | |
480 | { | |
481 | /* | |
482 | * This is the newline ending the previous line. | |
483 | * We have hit the beginning of the line. | |
484 | */ | |
485 | new_pos = ch_tell() + 1; | |
486 | break; | |
487 | } | |
488 | if (c == EOI) | |
489 | { | |
490 | /* | |
491 | * We have hit the beginning of the file. | |
492 | * This must be the first line in the file. | |
493 | * This must, of course, be the beginning of the line. | |
494 | */ | |
495 | new_pos = (POSITION)0; | |
496 | break; | |
497 | } | |
498 | if (p <= linebuf) | |
499 | { | |
500 | /* | |
501 | * Overflowed the input buffer. | |
502 | * Pretend the line ended here. | |
503 | */ | |
504 | new_pos = ch_tell() + 1; | |
505 | break; | |
506 | } | |
507 | *--p = c; | |
508 | } | |
509 | line = p; | |
510 | return (new_pos); | |
511 | } |