1 /*
2 * Copyright (c) 1993-1994 by Xerox Corporation. All rights reserved.
3 *
4 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
6 *
7 * Permission is hereby granted to use or copy this program
8 * for any purpose, provided the above notices are retained on all copies.
9 * Permission to modify the code and to distribute modified code is granted,
10 * provided the above notices are retained, and a notice that the code was
11 * modified is included with the above copyright notice.
12 *
13 * Author: Hans-J. Boehm (boehm@parc.xerox.com)
14 */
15 /* Boehm, October 3, 1994 5:19 pm PDT */
16 # include "gc.h"
17 # include "cord.h"
18 # include <stdlib.h>
19 # include <stdio.h>
20 # include <string.h>
21
22 /* An implementation of the cord primitives. These are the only */
23 /* Functions that understand the representation. We perform only */
24 /* minimal checks on arguments to these functions. Out of bounds */
25 /* arguments to the iteration functions may result in client functions */
26 /* invoked on garbage data. In most cases, client functions should be */
27 /* programmed defensively enough that this does not result in memory */
28 /* smashes. */
29
30 typedef void (* oom_fn)(void);
31
32 oom_fn CORD_oom_fn = (oom_fn) 0;
33
34 # define OUT_OF_MEMORY { if (CORD_oom_fn != (oom_fn) 0) (*CORD_oom_fn)(); \
35 ABORT("Out of memory\n"); }
36 # define ABORT(msg) { fprintf(stderr, "%s\n", msg); abort(); }
37
38 typedef unsigned long word;
39
40 typedef union {
41 struct Concatenation {
42 char null;
43 char header;
44 char depth; /* concatenation nesting depth. */
45 unsigned char left_len;
46 /* Length of left child if it is sufficiently */
47 /* short; 0 otherwise. */
48 # define MAX_LEFT_LEN 255
49 word len;
50 CORD left; /* length(left) > 0 */
51 CORD right; /* length(right) > 0 */
52 } concatenation;
53 struct Function {
54 char null;
55 char header;
56 char depth; /* always 0 */
57 char left_len; /* always 0 */
58 word len;
59 CORD_fn fn;
60 void * client_data;
61 } function;
62 struct Generic {
63 char null;
64 char header;
65 char depth;
66 char left_len;
67 word len;
68 } generic;
69 char string[1];
70 } CordRep;
71
72 # define CONCAT_HDR 1
73
74 # define FN_HDR 4
75 # define SUBSTR_HDR 6
76 /* Substring nodes are a special case of function nodes. */
77 /* The client_data field is known to point to a substr_args */
78 /* structure, and the function is either CORD_apply_access_fn */
79 /* or CORD_index_access_fn. */
80
81 /* The following may be applied only to function and concatenation nodes: */
82 #define IS_CONCATENATION(s) (((CordRep *)s)->generic.header == CONCAT_HDR)
83
84 #define IS_FUNCTION(s) ((((CordRep *)s)->generic.header & FN_HDR) != 0)
85
86 #define IS_SUBSTR(s) (((CordRep *)s)->generic.header == SUBSTR_HDR)
87
88 #define LEN(s) (((CordRep *)s) -> generic.len)
89 #define DEPTH(s) (((CordRep *)s) -> generic.depth)
90 #define GEN_LEN(s) (CORD_IS_STRING(s) ? strlen(s) : LEN(s))
91
92 #define LEFT_LEN(c) ((c) -> left_len != 0? \
93 (c) -> left_len \
94 : (CORD_IS_STRING((c) -> left) ? \
95 (c) -> len - GEN_LEN((c) -> right) \
96 : LEN((c) -> left)))
97
98 #define SHORT_LIMIT (sizeof(CordRep) - 1)
99 /* Cords shorter than this are C strings */
100
101
102 /* Dump the internal representation of x to stdout, with initial */
103 /* indentation level n. */
CORD_dump_inner(CORD x,unsigned n)104 void CORD_dump_inner(CORD x, unsigned n)
105 {
106 register size_t i;
107
108 for (i = 0; i < (size_t)n; i++) {
109 fputs(" ", stdout);
110 }
111 if (x == 0) {
112 fputs("NIL\n", stdout);
113 } else if (CORD_IS_STRING(x)) {
114 for (i = 0; i <= SHORT_LIMIT; i++) {
115 if (x[i] == '\0') break;
116 putchar(x[i]);
117 }
118 if (x[i] != '\0') fputs("...", stdout);
119 putchar('\n');
120 } else if (IS_CONCATENATION(x)) {
121 register struct Concatenation * conc =
122 &(((CordRep *)x) -> concatenation);
123 printf("Concatenation: %p (len: %d, depth: %d)\n",
124 x, (int)(conc -> len), (int)(conc -> depth));
125 CORD_dump_inner(conc -> left, n+1);
126 CORD_dump_inner(conc -> right, n+1);
127 } else /* function */{
128 register struct Function * func =
129 &(((CordRep *)x) -> function);
130 if (IS_SUBSTR(x)) printf("(Substring) ");
131 printf("Function: %p (len: %d): ", x, (int)(func -> len));
132 for (i = 0; i < 20 && i < func -> len; i++) {
133 putchar((*(func -> fn))(i, func -> client_data));
134 }
135 if (i < func -> len) fputs("...", stdout);
136 putchar('\n');
137 }
138 }
139
140 /* Dump the internal representation of x to stdout */
CORD_dump(CORD x)141 void CORD_dump(CORD x)
142 {
143 CORD_dump_inner(x, 0);
144 fflush(stdout);
145 }
146
CORD_cat_char_star(CORD x,const char * y,size_t leny)147 CORD CORD_cat_char_star(CORD x, const char * y, size_t leny)
148 {
149 register size_t result_len;
150 register size_t lenx;
151 register int depth;
152
153 if (x == CORD_EMPTY) return(y);
154 if (leny == 0) return(x);
155 if (CORD_IS_STRING(x)) {
156 lenx = strlen(x);
157 result_len = lenx + leny;
158 if (result_len <= SHORT_LIMIT) {
159 register char * result = GC_MALLOC_ATOMIC(result_len+1);
160
161 if (result == 0) OUT_OF_MEMORY;
162 memcpy(result, x, lenx);
163 memcpy(result + lenx, y, leny);
164 result[result_len] = '\0';
165 return((CORD) result);
166 } else {
167 depth = 1;
168 }
169 } else {
170 register CORD right;
171 register CORD left;
172 register char * new_right;
173 register size_t right_len;
174
175 lenx = LEN(x);
176
177 if (leny <= SHORT_LIMIT/2
178 && IS_CONCATENATION(x)
179 && CORD_IS_STRING(right = ((CordRep *)x) -> concatenation.right)) {
180 /* Merge y into right part of x. */
181 if (!CORD_IS_STRING(left = ((CordRep *)x) -> concatenation.left)) {
182 right_len = lenx - LEN(left);
183 } else if (((CordRep *)x) -> concatenation.left_len != 0) {
184 right_len = lenx - ((CordRep *)x) -> concatenation.left_len;
185 } else {
186 right_len = strlen(right);
187 }
188 result_len = right_len + leny; /* length of new_right */
189 if (result_len <= SHORT_LIMIT) {
190 new_right = GC_MALLOC_ATOMIC(result_len + 1);
191 memcpy(new_right, right, right_len);
192 memcpy(new_right + right_len, y, leny);
193 new_right[result_len] = '\0';
194 y = new_right;
195 leny = result_len;
196 x = left;
197 lenx -= right_len;
198 /* Now fall through to concatenate the two pieces: */
199 }
200 if (CORD_IS_STRING(x)) {
201 depth = 1;
202 } else {
203 depth = DEPTH(x) + 1;
204 }
205 } else {
206 depth = DEPTH(x) + 1;
207 }
208 result_len = lenx + leny;
209 }
210 {
211 /* The general case; lenx, result_len is known: */
212 register struct Concatenation * result;
213
214 result = GC_NEW(struct Concatenation);
215 if (result == 0) OUT_OF_MEMORY;
216 result->header = CONCAT_HDR;
217 result->depth = depth;
218 if (lenx <= MAX_LEFT_LEN) result->left_len = lenx;
219 result->len = result_len;
220 result->left = x;
221 result->right = y;
222 if (depth >= MAX_DEPTH) {
223 return(CORD_balance((CORD)result));
224 } else {
225 return((CORD) result);
226 }
227 }
228 }
229
230
CORD_cat(CORD x,CORD y)231 CORD CORD_cat(CORD x, CORD y)
232 {
233 register size_t result_len;
234 register int depth;
235 register size_t lenx;
236
237 if (x == CORD_EMPTY) return(y);
238 if (y == CORD_EMPTY) return(x);
239 if (CORD_IS_STRING(y)) {
240 return(CORD_cat_char_star(x, y, strlen(y)));
241 } else if (CORD_IS_STRING(x)) {
242 lenx = strlen(x);
243 depth = DEPTH(y) + 1;
244 } else {
245 register int depthy = DEPTH(y);
246
247 lenx = LEN(x);
248 depth = DEPTH(x) + 1;
249 if (depthy >= depth) depth = depthy + 1;
250 }
251 result_len = lenx + LEN(y);
252 {
253 register struct Concatenation * result;
254
255 result = GC_NEW(struct Concatenation);
256 if (result == 0) OUT_OF_MEMORY;
257 result->header = CONCAT_HDR;
258 result->depth = depth;
259 if (lenx <= MAX_LEFT_LEN) result->left_len = lenx;
260 result->len = result_len;
261 result->left = x;
262 result->right = y;
263 if (depth >= MAX_DEPTH) {
264 return(CORD_balance((CORD)result));
265 } else {
266 return((CORD) result);
267 }
268 }
269 }
270
271
272
CORD_from_fn(CORD_fn fn,void * client_data,size_t len)273 CORD CORD_from_fn(CORD_fn fn, void * client_data, size_t len)
274 {
275 if (len <= 0) return(0);
276 if (len <= SHORT_LIMIT) {
277 register char * result;
278 register size_t i;
279 char buf[SHORT_LIMIT+1];
280 register char c;
281
282 for (i = 0; i < len; i++) {
283 c = (*fn)(i, client_data);
284 if (c == '\0') goto gen_case;
285 buf[i] = c;
286 }
287 buf[i] = '\0';
288 result = GC_MALLOC_ATOMIC(len+1);
289 if (result == 0) OUT_OF_MEMORY;
290 strcpy(result, buf);
291 result[len] = '\0';
292 return((CORD) result);
293 }
294 gen_case:
295 {
296 register struct Function * result;
297
298 result = GC_NEW(struct Function);
299 if (result == 0) OUT_OF_MEMORY;
300 result->header = FN_HDR;
301 /* depth is already 0 */
302 result->len = len;
303 result->fn = fn;
304 result->client_data = client_data;
305 return((CORD) result);
306 }
307 }
308
CORD_len(CORD x)309 size_t CORD_len(CORD x)
310 {
311 if (x == 0) {
312 return(0);
313 } else {
314 return(GEN_LEN(x));
315 }
316 }
317
318 struct substr_args {
319 CordRep * sa_cord;
320 size_t sa_index;
321 };
322
CORD_index_access_fn(size_t i,void * client_data)323 char CORD_index_access_fn(size_t i, void * client_data)
324 {
325 register struct substr_args *descr = (struct substr_args *)client_data;
326
327 return(((char *)(descr->sa_cord))[i + descr->sa_index]);
328 }
329
CORD_apply_access_fn(size_t i,void * client_data)330 char CORD_apply_access_fn(size_t i, void * client_data)
331 {
332 register struct substr_args *descr = (struct substr_args *)client_data;
333 register struct Function * fn_cord = &(descr->sa_cord->function);
334
335 return((*(fn_cord->fn))(i + descr->sa_index, fn_cord->client_data));
336 }
337
338 /* A version of CORD_substr that simply returns a function node, thus */
339 /* postponing its work. The fourth argument is a function that may */
340 /* be used for efficient access to the ith character. */
341 /* Assumes i >= 0 and i + n < length(x). */
CORD_substr_closure(CORD x,size_t i,size_t n,CORD_fn f)342 CORD CORD_substr_closure(CORD x, size_t i, size_t n, CORD_fn f)
343 {
344 register struct substr_args * sa = GC_NEW(struct substr_args);
345 CORD result;
346
347 if (sa == 0) OUT_OF_MEMORY;
348 sa->sa_cord = (CordRep *)x;
349 sa->sa_index = i;
350 result = CORD_from_fn(f, (void *)sa, n);
351 ((CordRep *)result) -> function.header = SUBSTR_HDR;
352 return (result);
353 }
354
355 # define SUBSTR_LIMIT (10 * SHORT_LIMIT)
356 /* Substrings of function nodes and flat strings shorter than */
357 /* this are flat strings. Othewise we use a functional */
358 /* representation, which is significantly slower to access. */
359
360 /* A version of CORD_substr that assumes i >= 0, n > 0, and i + n < length(x).*/
CORD_substr_checked(CORD x,size_t i,size_t n)361 CORD CORD_substr_checked(CORD x, size_t i, size_t n)
362 {
363 if (CORD_IS_STRING(x)) {
364 if (n > SUBSTR_LIMIT) {
365 return(CORD_substr_closure(x, i, n, CORD_index_access_fn));
366 } else {
367 register char * result = GC_MALLOC_ATOMIC(n+1);
368
369 if (result == 0) OUT_OF_MEMORY;
370 strncpy(result, x+i, n);
371 result[n] = '\0';
372 return(result);
373 }
374 } else if (IS_CONCATENATION(x)) {
375 register struct Concatenation * conc
376 = &(((CordRep *)x) -> concatenation);
377 register size_t left_len;
378 register size_t right_len;
379
380 left_len = LEFT_LEN(conc);
381 right_len = conc -> len - left_len;
382 if (i >= left_len) {
383 if (n == right_len) return(conc -> right);
384 return(CORD_substr_checked(conc -> right, i - left_len, n));
385 } else if (i+n <= left_len) {
386 if (n == left_len) return(conc -> left);
387 return(CORD_substr_checked(conc -> left, i, n));
388 } else {
389 /* Need at least one character from each side. */
390 register CORD left_part;
391 register CORD right_part;
392 register size_t left_part_len = left_len - i;
393
394 if (i == 0) {
395 left_part = conc -> left;
396 } else {
397 left_part = CORD_substr_checked(conc -> left, i, left_part_len);
398 }
399 if (i + n == right_len + left_len) {
400 right_part = conc -> right;
401 } else {
402 right_part = CORD_substr_checked(conc -> right, 0,
403 n - left_part_len);
404 }
405 return(CORD_cat(left_part, right_part));
406 }
407 } else /* function */ {
408 if (n > SUBSTR_LIMIT) {
409 if (IS_SUBSTR(x)) {
410 /* Avoid nesting substring nodes. */
411 register struct Function * f = &(((CordRep *)x) -> function);
412 register struct substr_args *descr =
413 (struct substr_args *)(f -> client_data);
414
415 return(CORD_substr_closure((CORD)descr->sa_cord,
416 i + descr->sa_index,
417 n, f -> fn));
418 } else {
419 return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
420 }
421 } else {
422 char * result;
423 register struct Function * f = &(((CordRep *)x) -> function);
424 char buf[SUBSTR_LIMIT+1];
425 register char * p = buf;
426 register char c;
427 register int j;
428 register int lim = i + n;
429
430 for (j = i; j < lim; j++) {
431 c = (*(f -> fn))(j, f -> client_data);
432 if (c == '\0') {
433 return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
434 }
435 *p++ = c;
436 }
437 *p = '\0';
438 result = GC_MALLOC_ATOMIC(n+1);
439 if (result == 0) OUT_OF_MEMORY;
440 strcpy(result, buf);
441 return(result);
442 }
443 }
444 }
445
CORD_substr(CORD x,size_t i,size_t n)446 CORD CORD_substr(CORD x, size_t i, size_t n)
447 {
448 register size_t len = CORD_len(x);
449
450 if (i >= len || n <= 0) return(0);
451 /* n < 0 is impossible in a correct C implementation, but */
452 /* quite possible under SunOS 4.X. */
453 if (i + n > len) n = len - i;
454 # ifndef __STDC__
455 if (i < 0) ABORT("CORD_substr: second arg. negative");
456 /* Possible only if both client and C implementation are buggy. */
457 /* But empirically this happens frequently. */
458 # endif
459 return(CORD_substr_checked(x, i, n));
460 }
461
462 /* See cord.h for definition. We assume i is in range. */
CORD_iter5(CORD x,size_t i,CORD_iter_fn f1,CORD_batched_iter_fn f2,void * client_data)463 int CORD_iter5(CORD x, size_t i, CORD_iter_fn f1,
464 CORD_batched_iter_fn f2, void * client_data)
465 {
466 if (x == 0) return(0);
467 if (CORD_IS_STRING(x)) {
468 register const char *p = x+i;
469
470 if (*p == '\0') ABORT("2nd arg to CORD_iter5 too big");
471 if (f2 != CORD_NO_FN) {
472 return((*f2)(p, client_data));
473 } else {
474 while (*p) {
475 if ((*f1)(*p, client_data)) return(1);
476 p++;
477 }
478 return(0);
479 }
480 } else if (IS_CONCATENATION(x)) {
481 register struct Concatenation * conc
482 = &(((CordRep *)x) -> concatenation);
483
484
485 if (i > 0) {
486 register size_t left_len = LEFT_LEN(conc);
487
488 if (i >= left_len) {
489 return(CORD_iter5(conc -> right, i - left_len, f1, f2,
490 client_data));
491 }
492 }
493 if (CORD_iter5(conc -> left, i, f1, f2, client_data)) {
494 return(1);
495 }
496 return(CORD_iter5(conc -> right, 0, f1, f2, client_data));
497 } else /* function */ {
498 register struct Function * f = &(((CordRep *)x) -> function);
499 register size_t j;
500 register size_t lim = f -> len;
501
502 for (j = i; j < lim; j++) {
503 if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
504 return(1);
505 }
506 }
507 return(0);
508 }
509 }
510
511 #undef CORD_iter
CORD_iter(CORD x,CORD_iter_fn f1,void * client_data)512 int CORD_iter(CORD x, CORD_iter_fn f1, void * client_data)
513 {
514 return(CORD_iter5(x, 0, f1, CORD_NO_FN, client_data));
515 }
516
CORD_riter4(CORD x,size_t i,CORD_iter_fn f1,void * client_data)517 int CORD_riter4(CORD x, size_t i, CORD_iter_fn f1, void * client_data)
518 {
519 if (x == 0) return(0);
520 if (CORD_IS_STRING(x)) {
521 register const char *p = x + i;
522 register char c;
523
524 for(;;) {
525 c = *p;
526 if (c == '\0') ABORT("2nd arg to CORD_riter4 too big");
527 if ((*f1)(c, client_data)) return(1);
528 if (p == x) break;
529 p--;
530 }
531 return(0);
532 } else if (IS_CONCATENATION(x)) {
533 register struct Concatenation * conc
534 = &(((CordRep *)x) -> concatenation);
535 register CORD left_part = conc -> left;
536 register size_t left_len;
537
538 left_len = LEFT_LEN(conc);
539 if (i >= left_len) {
540 if (CORD_riter4(conc -> right, i - left_len, f1, client_data)) {
541 return(1);
542 }
543 return(CORD_riter4(left_part, left_len - 1, f1, client_data));
544 } else {
545 return(CORD_riter4(left_part, i, f1, client_data));
546 }
547 } else /* function */ {
548 register struct Function * f = &(((CordRep *)x) -> function);
549 register size_t j;
550
551 for (j = i; ; j--) {
552 if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
553 return(1);
554 }
555 if (j == 0) return(0);
556 }
557 }
558 }
559
CORD_riter(CORD x,CORD_iter_fn f1,void * client_data)560 int CORD_riter(CORD x, CORD_iter_fn f1, void * client_data)
561 {
562 return(CORD_riter4(x, CORD_len(x) - 1, f1, client_data));
563 }
564
565 /*
566 * The following functions are concerned with balancing cords.
567 * Strategy:
568 * Scan the cord from left to right, keeping the cord scanned so far
569 * as a forest of balanced trees of exponentialy decreasing length.
570 * When a new subtree needs to be added to the forest, we concatenate all
571 * shorter ones to the new tree in the appropriate order, and then insert
572 * the result into the forest.
573 * Crucial invariants:
574 * 1. The concatenation of the forest (in decreasing order) with the
575 * unscanned part of the rope is equal to the rope being balanced.
576 * 2. All trees in the forest are balanced.
577 * 3. forest[i] has depth at most i.
578 */
579
580 typedef struct {
581 CORD c;
582 size_t len; /* Actual length of c */
583 } ForestElement;
584
585 static size_t min_len [ MAX_DEPTH ];
586
587 static int min_len_init = 0;
588
589 int CORD_max_len;
590
591 typedef ForestElement Forest [ MAX_DEPTH ];
592 /* forest[i].len >= fib(i+1) */
593 /* The string is the concatenation */
594 /* of the forest in order of DECREASING */
595 /* indices. */
596
CORD_init_min_len()597 void CORD_init_min_len()
598 {
599 register int i;
600 register size_t last, previous, current;
601
602 min_len[0] = previous = 1;
603 min_len[1] = last = 2;
604 for (i = 2; i < MAX_DEPTH; i++) {
605 current = last + previous;
606 if (current < last) /* overflow */ current = last;
607 min_len[i] = current;
608 previous = last;
609 last = current;
610 }
611 CORD_max_len = last - 1;
612 min_len_init = 1;
613 }
614
615
CORD_init_forest(ForestElement * forest,size_t max_len)616 void CORD_init_forest(ForestElement * forest, size_t max_len)
617 {
618 register int i;
619
620 for (i = 0; i < MAX_DEPTH; i++) {
621 forest[i].c = 0;
622 if (min_len[i] > max_len) return;
623 }
624 ABORT("Cord too long");
625 }
626
627 /* Add a leaf to the appropriate level in the forest, cleaning */
628 /* out lower levels as necessary. */
629 /* Also works if x is a balanced tree of concatenations; however */
630 /* in this case an extra concatenation node may be inserted above x; */
631 /* This node should not be counted in the statement of the invariants. */
CORD_add_forest(ForestElement * forest,CORD x,size_t len)632 void CORD_add_forest(ForestElement * forest, CORD x, size_t len)
633 {
634 register int i = 0;
635 register CORD sum = CORD_EMPTY;
636 register size_t sum_len = 0;
637
638 while (len > min_len[i + 1]) {
639 if (forest[i].c != 0) {
640 sum = CORD_cat(forest[i].c, sum);
641 sum_len += forest[i].len;
642 forest[i].c = 0;
643 }
644 i++;
645 }
646 /* Sum has depth at most 1 greter than what would be required */
647 /* for balance. */
648 sum = CORD_cat(sum, x);
649 sum_len += len;
650 /* If x was a leaf, then sum is now balanced. To see this */
651 /* consider the two cases in which forest[i-1] either is or is */
652 /* not empty. */
653 while (sum_len >= min_len[i]) {
654 if (forest[i].c != 0) {
655 sum = CORD_cat(forest[i].c, sum);
656 sum_len += forest[i].len;
657 /* This is again balanced, since sum was balanced, and has */
658 /* allowable depth that differs from i by at most 1. */
659 forest[i].c = 0;
660 }
661 i++;
662 }
663 i--;
664 forest[i].c = sum;
665 forest[i].len = sum_len;
666 }
667
CORD_concat_forest(ForestElement * forest,size_t expected_len)668 CORD CORD_concat_forest(ForestElement * forest, size_t expected_len)
669 {
670 register int i = 0;
671 CORD sum = 0;
672 size_t sum_len = 0;
673
674 while (sum_len != expected_len) {
675 if (forest[i].c != 0) {
676 sum = CORD_cat(forest[i].c, sum);
677 sum_len += forest[i].len;
678 }
679 i++;
680 }
681 return(sum);
682 }
683
684 /* Insert the frontier of x into forest. Balanced subtrees are */
685 /* treated as leaves. This potentially adds one to the depth */
686 /* of the final tree. */
CORD_balance_insert(CORD x,size_t len,ForestElement * forest)687 void CORD_balance_insert(CORD x, size_t len, ForestElement * forest)
688 {
689 register int depth;
690
691 if (CORD_IS_STRING(x)) {
692 CORD_add_forest(forest, x, len);
693 } else if (IS_CONCATENATION(x)
694 && ((depth = DEPTH(x)) >= MAX_DEPTH
695 || len < min_len[depth])) {
696 register struct Concatenation * conc
697 = &(((CordRep *)x) -> concatenation);
698 size_t left_len = LEFT_LEN(conc);
699
700 CORD_balance_insert(conc -> left, left_len, forest);
701 CORD_balance_insert(conc -> right, len - left_len, forest);
702 } else /* function or balanced */ {
703 CORD_add_forest(forest, x, len);
704 }
705 }
706
707
CORD_balance(CORD x)708 CORD CORD_balance(CORD x)
709 {
710 Forest forest;
711 register size_t len;
712
713 if (x == 0) return(0);
714 if (CORD_IS_STRING(x)) return(x);
715 if (!min_len_init) CORD_init_min_len();
716 len = LEN(x);
717 CORD_init_forest(forest, len);
718 CORD_balance_insert(x, len, forest);
719 return(CORD_concat_forest(forest, len));
720 }
721
722
723 /* Position primitives */
724
725 /* Private routines to deal with the hard cases only: */
726
727 /* P contains a prefix of the path to cur_pos. Extend it to a full */
728 /* path and set up leaf info. */
729 /* Return 0 if past the end of cord, 1 o.w. */
CORD__extend_path(register CORD_pos p)730 void CORD__extend_path(register CORD_pos p)
731 {
732 register struct CORD_pe * current_pe = &(p[0].path[p[0].path_len]);
733 register CORD top = current_pe -> pe_cord;
734 register size_t pos = p[0].cur_pos;
735 register size_t top_pos = current_pe -> pe_start_pos;
736 register size_t top_len = GEN_LEN(top);
737
738 /* Fill in the rest of the path. */
739 while(!CORD_IS_STRING(top) && IS_CONCATENATION(top)) {
740 register struct Concatenation * conc =
741 &(((CordRep *)top) -> concatenation);
742 register size_t left_len;
743
744 left_len = LEFT_LEN(conc);
745 current_pe++;
746 if (pos >= top_pos + left_len) {
747 current_pe -> pe_cord = top = conc -> right;
748 current_pe -> pe_start_pos = top_pos = top_pos + left_len;
749 top_len -= left_len;
750 } else {
751 current_pe -> pe_cord = top = conc -> left;
752 current_pe -> pe_start_pos = top_pos;
753 top_len = left_len;
754 }
755 p[0].path_len++;
756 }
757 /* Fill in leaf description for fast access. */
758 if (CORD_IS_STRING(top)) {
759 p[0].cur_leaf = top;
760 p[0].cur_start = top_pos;
761 p[0].cur_end = top_pos + top_len;
762 } else {
763 p[0].cur_end = 0;
764 }
765 if (pos >= top_pos + top_len) p[0].path_len = CORD_POS_INVALID;
766 }
767
CORD__pos_fetch(register CORD_pos p)768 char CORD__pos_fetch(register CORD_pos p)
769 {
770 /* Leaf is a function node */
771 struct CORD_pe * pe = &((p)[0].path[(p)[0].path_len]);
772 CORD leaf = pe -> pe_cord;
773 register struct Function * f = &(((CordRep *)leaf) -> function);
774
775 if (!IS_FUNCTION(leaf)) ABORT("CORD_pos_fetch: bad leaf");
776 return ((*(f -> fn))(p[0].cur_pos - pe -> pe_start_pos, f -> client_data));
777 }
778
CORD__next(register CORD_pos p)779 void CORD__next(register CORD_pos p)
780 {
781 register size_t cur_pos = p[0].cur_pos + 1;
782 register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
783 register CORD leaf = current_pe -> pe_cord;
784
785 /* Leaf is not a string or we're at end of leaf */
786 p[0].cur_pos = cur_pos;
787 if (!CORD_IS_STRING(leaf)) {
788 /* Function leaf */
789 register struct Function * f = &(((CordRep *)leaf) -> function);
790 register size_t start_pos = current_pe -> pe_start_pos;
791 register size_t end_pos = start_pos + f -> len;
792
793 if (cur_pos < end_pos) {
794 /* Fill cache and return. */
795 register size_t i;
796 register size_t limit = cur_pos + FUNCTION_BUF_SZ;
797 register CORD_fn fn = f -> fn;
798 register void * client_data = f -> client_data;
799
800 if (limit > end_pos) {
801 limit = end_pos;
802 }
803 for (i = cur_pos; i < limit; i++) {
804 p[0].function_buf[i - cur_pos] =
805 (*fn)(i - start_pos, client_data);
806 }
807 p[0].cur_start = cur_pos;
808 p[0].cur_leaf = p[0].function_buf;
809 p[0].cur_end = limit;
810 return;
811 }
812 }
813 /* End of leaf */
814 /* Pop the stack until we find two concatenation nodes with the */
815 /* same start position: this implies we were in left part. */
816 {
817 while (p[0].path_len > 0
818 && current_pe[0].pe_start_pos != current_pe[-1].pe_start_pos) {
819 p[0].path_len--;
820 current_pe--;
821 }
822 if (p[0].path_len == 0) {
823 p[0].path_len = CORD_POS_INVALID;
824 return;
825 }
826 }
827 p[0].path_len--;
828 CORD__extend_path(p);
829 }
830
CORD__prev(register CORD_pos p)831 void CORD__prev(register CORD_pos p)
832 {
833 register struct CORD_pe * pe = &(p[0].path[p[0].path_len]);
834
835 if (p[0].cur_pos == 0) {
836 p[0].path_len = CORD_POS_INVALID;
837 return;
838 }
839 p[0].cur_pos--;
840 if (p[0].cur_pos >= pe -> pe_start_pos) return;
841
842 /* Beginning of leaf */
843
844 /* Pop the stack until we find two concatenation nodes with the */
845 /* different start position: this implies we were in right part. */
846 {
847 register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
848
849 while (p[0].path_len > 0
850 && current_pe[0].pe_start_pos == current_pe[-1].pe_start_pos) {
851 p[0].path_len--;
852 current_pe--;
853 }
854 }
855 p[0].path_len--;
856 CORD__extend_path(p);
857 }
858
859 #undef CORD_pos_fetch
860 #undef CORD_next
861 #undef CORD_prev
862 #undef CORD_pos_to_index
863 #undef CORD_pos_to_cord
864 #undef CORD_pos_valid
865
CORD_pos_fetch(register CORD_pos p)866 char CORD_pos_fetch(register CORD_pos p)
867 {
868 if (p[0].cur_start <= p[0].cur_pos && p[0].cur_pos < p[0].cur_end) {
869 return(p[0].cur_leaf[p[0].cur_pos - p[0].cur_start]);
870 } else {
871 return(CORD__pos_fetch(p));
872 }
873 }
874
CORD_next(CORD_pos p)875 void CORD_next(CORD_pos p)
876 {
877 if (p[0].cur_pos < p[0].cur_end - 1) {
878 p[0].cur_pos++;
879 } else {
880 CORD__next(p);
881 }
882 }
883
CORD_prev(CORD_pos p)884 void CORD_prev(CORD_pos p)
885 {
886 if (p[0].cur_end != 0 && p[0].cur_pos > p[0].cur_start) {
887 p[0].cur_pos--;
888 } else {
889 CORD__prev(p);
890 }
891 }
892
CORD_pos_to_index(CORD_pos p)893 size_t CORD_pos_to_index(CORD_pos p)
894 {
895 return(p[0].cur_pos);
896 }
897
CORD_pos_to_cord(CORD_pos p)898 CORD CORD_pos_to_cord(CORD_pos p)
899 {
900 return(p[0].path[0].pe_cord);
901 }
902
CORD_pos_valid(CORD_pos p)903 int CORD_pos_valid(CORD_pos p)
904 {
905 return(p[0].path_len != CORD_POS_INVALID);
906 }
907
CORD_set_pos(CORD_pos p,CORD x,size_t i)908 void CORD_set_pos(CORD_pos p, CORD x, size_t i)
909 {
910 if (x == CORD_EMPTY) {
911 p[0].path_len = CORD_POS_INVALID;
912 return;
913 }
914 p[0].path[0].pe_cord = x;
915 p[0].path[0].pe_start_pos = 0;
916 p[0].path_len = 0;
917 p[0].cur_pos = i;
918 CORD__extend_path(p);
919 }
920