2 * Copyright (c) 1993-1994 by Xerox Corporation. All rights reserved.
4 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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.
13 * Author: Hans-J. Boehm (boehm@parc.xerox.com)
15 /* Boehm, October 3, 1994 5:19 pm PDT */
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 */
30 typedef void (* oom_fn)(void);
32 oom_fn CORD_oom_fn = (oom_fn) 0;
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(); }
38 typedef unsigned long word;
41 struct Concatenation {
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
50 CORD left; /* length(left) > 0 */
51 CORD right; /* length(right) > 0 */
56 char depth; /* always 0 */
57 char left_len; /* always 0 */
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. */
81 /* The following may be applied only to function and concatenation nodes: */
82 #define IS_CONCATENATION(s) (((CordRep *)s)->generic.header == CONCAT_HDR)
84 #define IS_FUNCTION(s) ((((CordRep *)s)->generic.header & FN_HDR) != 0)
86 #define IS_SUBSTR(s) (((CordRep *)s)->generic.header == SUBSTR_HDR)
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))
92 #define LEFT_LEN(c) ((c) -> left_len != 0? \
94 : (CORD_IS_STRING((c) -> left) ? \
95 (c) -> len - GEN_LEN((c) -> right) \
98 #define SHORT_LIMIT (sizeof(CordRep) - 1)
99 /* Cords shorter than this are C strings */
102 /* Dump the internal representation of x to stdout, with initial */
103 /* indentation level n. */
104 void CORD_dump_inner(CORD x, unsigned n)
108 for (i = 0; i < (size_t)n; i++) {
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;
118 if (x[i] != '\0') fputs("...", stdout);
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));
135 if (i < func -> len) fputs("...", stdout);
140 /* Dump the internal representation of x to stdout */
141 void CORD_dump(CORD x)
143 CORD_dump_inner(x, 0);
147 CORD CORD_cat_char_star(CORD x, const char * y, size_t leny)
149 register size_t result_len;
150 register size_t lenx;
153 if (x == CORD_EMPTY) return(y);
154 if (leny == 0) return(x);
155 if (CORD_IS_STRING(x)) {
157 result_len = lenx + leny;
158 if (result_len <= SHORT_LIMIT) {
159 register char * result = GC_MALLOC_ATOMIC(result_len+1);
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);
172 register char * new_right;
173 register size_t right_len;
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;
186 right_len = strlen(right);
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';
198 /* Now fall through to concatenate the two pieces: */
200 if (CORD_IS_STRING(x)) {
203 depth = DEPTH(x) + 1;
206 depth = DEPTH(x) + 1;
208 result_len = lenx + leny;
211 /* The general case; lenx, result_len is known: */
212 register struct Concatenation * result;
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;
222 if (depth > MAX_DEPTH) {
223 return(CORD_balance((CORD)result));
225 return((CORD) result);
231 CORD CORD_cat(CORD x, CORD y)
233 register size_t result_len;
235 register size_t lenx;
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)) {
243 depth = DEPTH(y) + 1;
245 register int depthy = DEPTH(y);
248 depth = DEPTH(x) + 1;
249 if (depthy >= depth) depth = depthy + 1;
251 result_len = lenx + LEN(y);
253 register struct Concatenation * result;
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;
263 return((CORD) result);
269 CORD CORD_from_fn(CORD_fn fn, void * client_data, size_t len)
271 if (len <= 0) return(0);
272 if (len <= SHORT_LIMIT) {
273 register char * result;
275 char buf[SHORT_LIMIT+1];
278 for (i = 0; i < len; i++) {
279 c = (*fn)(i, client_data);
280 if (c == '\0') goto gen_case;
284 result = GC_MALLOC_ATOMIC(len+1);
285 if (result == 0) OUT_OF_MEMORY;
288 return((CORD) result);
292 register struct Function * result;
294 result = GC_NEW(struct Function);
295 if (result == 0) OUT_OF_MEMORY;
296 result->header = FN_HDR;
297 /* depth is already 0 */
300 result->client_data = client_data;
301 return((CORD) result);
305 size_t CORD_len(CORD x)
319 char CORD_index_access_fn(size_t i, void * client_data)
321 register struct substr_args *descr = (struct substr_args *)client_data;
323 return(((char *)(descr->sa_cord))[i + descr->sa_index]);
326 char CORD_apply_access_fn(size_t i, void * client_data)
328 register struct substr_args *descr = (struct substr_args *)client_data;
329 register struct Function * fn_cord = &(descr->sa_cord->function);
331 return((*(fn_cord->fn))(i + descr->sa_index, fn_cord->client_data));
334 /* A version of CORD_substr that simply returns a function node, thus */
335 /* postponing its work. The fourth argument is a function that may */
336 /* be used for efficient access to the ith character. */
337 /* Assumes i >= 0 and i + n < length(x). */
338 CORD CORD_substr_closure(CORD x, size_t i, size_t n, CORD_fn f)
340 register struct substr_args * sa = GC_NEW(struct substr_args);
343 if (sa == 0) OUT_OF_MEMORY;
344 sa->sa_cord = (CordRep *)x;
346 result = CORD_from_fn(f, (void *)sa, n);
347 ((CordRep *)result) -> function.header = SUBSTR_HDR;
351 # define SUBSTR_LIMIT (10 * SHORT_LIMIT)
352 /* Substrings of function nodes and flat strings shorter than */
353 /* this are flat strings. Othewise we use a functional */
354 /* representation, which is significantly slower to access. */
356 /* A version of CORD_substr that assumes i >= 0, n > 0, and i + n < length(x).*/
357 CORD CORD_substr_checked(CORD x, size_t i, size_t n)
359 if (CORD_IS_STRING(x)) {
360 if (n > SUBSTR_LIMIT) {
361 return(CORD_substr_closure(x, i, n, CORD_index_access_fn));
363 register char * result = GC_MALLOC_ATOMIC(n+1);
364 register char * p = result;
366 if (result == 0) OUT_OF_MEMORY;
367 strncpy(result, x+i, n);
371 } else if (IS_CONCATENATION(x)) {
372 register struct Concatenation * conc
373 = &(((CordRep *)x) -> concatenation);
374 register size_t left_len;
375 register size_t right_len;
377 left_len = LEFT_LEN(conc);
378 right_len = conc -> len - left_len;
380 if (n == right_len) return(conc -> right);
381 return(CORD_substr_checked(conc -> right, i - left_len, n));
382 } else if (i+n <= left_len) {
383 if (n == left_len) return(conc -> left);
384 return(CORD_substr_checked(conc -> left, i, n));
386 /* Need at least one character from each side. */
387 register CORD left_part;
388 register CORD right_part;
389 register size_t left_part_len = left_len - i;
392 left_part = conc -> left;
394 left_part = CORD_substr_checked(conc -> left, i, left_part_len);
396 if (i + n == right_len + left_len) {
397 right_part = conc -> right;
399 right_part = CORD_substr_checked(conc -> right, 0,
402 return(CORD_cat(left_part, right_part));
404 } else /* function */ {
405 if (n > SUBSTR_LIMIT) {
407 /* Avoid nesting substring nodes. */
408 register struct Function * f = &(((CordRep *)x) -> function);
409 register struct substr_args *descr =
410 (struct substr_args *)(f -> client_data);
412 return(CORD_substr_closure((CORD)descr->sa_cord,
416 return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
420 register struct Function * f = &(((CordRep *)x) -> function);
421 char buf[SUBSTR_LIMIT+1];
422 register char * p = buf;
425 register int lim = i + n;
427 for (j = i; j < lim; j++) {
428 c = (*(f -> fn))(j, f -> client_data);
430 return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
435 result = GC_MALLOC_ATOMIC(n+1);
436 if (result == 0) OUT_OF_MEMORY;
443 CORD CORD_substr(CORD x, size_t i, size_t n)
445 register size_t len = CORD_len(x);
447 if (i >= len || n <= 0) return(0);
448 /* n < 0 is impossible in a correct C implementation, but */
449 /* quite possible under SunOS 4.X. */
450 if (i + n > len) n = len - i;
452 if (i < 0) ABORT("CORD_substr: second arg. negative");
453 /* Possible only if both client and C implementation are buggy. */
454 /* But empirically this happens frequently. */
456 return(CORD_substr_checked(x, i, n));
459 /* See cord.h for definition. We assume i is in range. */
460 int CORD_iter5(CORD x, size_t i, CORD_iter_fn f1,
461 CORD_batched_iter_fn f2, void * client_data)
463 if (x == 0) return(0);
464 if (CORD_IS_STRING(x)) {
465 register const char *p = x+i;
467 if (*p == '\0') ABORT("2nd arg to CORD_iter5 too big");
468 if (f2 != CORD_NO_FN) {
469 return((*f2)(p, client_data));
472 if ((*f1)(*p, client_data)) return(1);
477 } else if (IS_CONCATENATION(x)) {
478 register struct Concatenation * conc
479 = &(((CordRep *)x) -> concatenation);
483 register size_t left_len = LEFT_LEN(conc);
486 return(CORD_iter5(conc -> right, i - left_len, f1, f2,
490 if (CORD_iter5(conc -> left, i, f1, f2, client_data)) {
493 return(CORD_iter5(conc -> right, 0, f1, f2, client_data));
494 } else /* function */ {
495 register struct Function * f = &(((CordRep *)x) -> function);
497 register size_t lim = f -> len;
499 for (j = i; j < lim; j++) {
500 if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
509 int CORD_iter(CORD x, CORD_iter_fn f1, void * client_data)
511 return(CORD_iter5(x, 0, f1, CORD_NO_FN, client_data));
514 int CORD_riter4(CORD x, size_t i, CORD_iter_fn f1, void * client_data)
516 if (x == 0) return(0);
517 if (CORD_IS_STRING(x)) {
518 register const char *p = x + i;
523 if (c == '\0') ABORT("2nd arg to CORD_riter4 too big");
524 if ((*f1)(c, client_data)) return(1);
529 } else if (IS_CONCATENATION(x)) {
530 register struct Concatenation * conc
531 = &(((CordRep *)x) -> concatenation);
532 register CORD left_part = conc -> left;
533 register size_t left_len;
535 left_len = LEFT_LEN(conc);
537 if (CORD_riter4(conc -> right, i - left_len, f1, client_data)) {
540 return(CORD_riter4(left_part, left_len - 1, f1, client_data));
542 return(CORD_riter4(left_part, i, f1, client_data));
544 } else /* function */ {
545 register struct Function * f = &(((CordRep *)x) -> function);
549 if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
552 if (j == 0) return(0);
557 int CORD_riter(CORD x, CORD_iter_fn f1, void * client_data)
559 return(CORD_riter4(x, CORD_len(x) - 1, f1, client_data));
563 * The following functions are concerned with balancing cords.
565 * Scan the cord from left to right, keeping the cord scanned so far
566 * as a forest of balanced trees of exponentialy decreasing length.
567 * When a new subtree needs to be added to the forest, we concatenate all
568 * shorter ones to the new tree in the appropriate order, and then insert
569 * the result into the forest.
570 * Crucial invariants:
571 * 1. The concatenation of the forest (in decreasing order) with the
572 * unscanned part of the rope is equal to the rope being balanced.
573 * 2. All trees in the forest are balanced.
574 * 3. forest[i] has depth at most i.
579 size_t len; /* Actual length of c */
582 static size_t min_len [ MAX_DEPTH ];
584 static int min_len_init = 0;
588 typedef ForestElement Forest [ MAX_DEPTH ];
589 /* forest[i].len >= fib(i+1) */
590 /* The string is the concatenation */
591 /* of the forest in order of DECREASING */
594 void CORD_init_min_len()
597 register size_t last, previous, current;
599 min_len[0] = previous = 1;
600 min_len[1] = last = 2;
601 for (i = 2; i < MAX_DEPTH; i++) {
602 current = last + previous;
603 if (current < last) /* overflow */ current = last;
604 min_len[i] = current;
608 CORD_max_len = last - 1;
613 void CORD_init_forest(ForestElement * forest, size_t max_len)
617 for (i = 0; i < MAX_DEPTH; i++) {
619 if (min_len[i] > max_len) return;
621 ABORT("Cord too long");
624 /* Add a leaf to the appropriate level in the forest, cleaning */
625 /* out lower levels as necessary. */
626 /* Also works if x is a balanced tree of concatenations; however */
627 /* in this case an extra concatenation node may be inserted above x; */
628 /* This node should not be counted in the statement of the invariants. */
629 void CORD_add_forest(ForestElement * forest, CORD x, size_t len)
632 register CORD sum = CORD_EMPTY;
633 register size_t sum_len = 0;
635 while (len > min_len[i + 1]) {
636 if (forest[i].c != 0) {
637 sum = CORD_cat(forest[i].c, sum);
638 sum_len += forest[i].len;
643 /* Sum has depth at most 1 greter than what would be required */
645 sum = CORD_cat(sum, x);
647 /* If x was a leaf, then sum is now balanced. To see this */
648 /* consider the two cases in which forest[i-1] either is or is */
650 while (sum_len >= min_len[i]) {
651 if (forest[i].c != 0) {
652 sum = CORD_cat(forest[i].c, sum);
653 sum_len += forest[i].len;
654 /* This is again balanced, since sum was balanced, and has */
655 /* allowable depth that differs from i by at most 1. */
662 forest[i].len = sum_len;
665 CORD CORD_concat_forest(ForestElement * forest, size_t expected_len)
671 while (sum_len != expected_len) {
672 if (forest[i].c != 0) {
673 sum = CORD_cat(forest[i].c, sum);
674 sum_len += forest[i].len;
681 /* Insert the frontier of x into forest. Balanced subtrees are */
682 /* treated as leaves. This potentially adds one to the depth */
683 /* of the final tree. */
684 void CORD_balance_insert(CORD x, size_t len, ForestElement * forest)
688 if (CORD_IS_STRING(x)) {
689 CORD_add_forest(forest, x, len);
690 } else if (IS_CONCATENATION(x)
691 && ((depth = DEPTH(x)) >= MAX_DEPTH
692 || len < min_len[depth])) {
693 register struct Concatenation * conc
694 = &(((CordRep *)x) -> concatenation);
695 size_t left_len = LEFT_LEN(conc);
697 CORD_balance_insert(conc -> left, left_len, forest);
698 CORD_balance_insert(conc -> right, len - left_len, forest);
699 } else /* function or balanced */ {
700 CORD_add_forest(forest, x, len);
705 CORD CORD_balance(CORD x)
710 if (x == 0) return(0);
711 if (CORD_IS_STRING(x)) return(x);
712 if (!min_len_init) CORD_init_min_len();
714 CORD_init_forest(forest, len);
715 CORD_balance_insert(x, len, forest);
716 return(CORD_concat_forest(forest, len));
720 /* Position primitives */
722 /* Private routines to deal with the hard cases only: */
724 /* P contains a prefix of the path to cur_pos. Extend it to a full */
725 /* path and set up leaf info. */
726 /* Return 0 if past the end of cord, 1 o.w. */
727 void CORD__extend_path(register CORD_pos p)
729 register struct CORD_pe * current_pe = &(p[0].path[p[0].path_len]);
730 register CORD top = current_pe -> pe_cord;
731 register size_t pos = p[0].cur_pos;
732 register size_t top_pos = current_pe -> pe_start_pos;
733 register size_t top_len = GEN_LEN(top);
735 /* Fill in the rest of the path. */
736 while(!CORD_IS_STRING(top) && IS_CONCATENATION(top)) {
737 register struct Concatenation * conc =
738 &(((CordRep *)top) -> concatenation);
739 register size_t left_len;
741 left_len = LEFT_LEN(conc);
743 if (pos >= top_pos + left_len) {
744 current_pe -> pe_cord = top = conc -> right;
745 current_pe -> pe_start_pos = top_pos = top_pos + left_len;
748 current_pe -> pe_cord = top = conc -> left;
749 current_pe -> pe_start_pos = top_pos;
754 /* Fill in leaf description for fast access. */
755 if (CORD_IS_STRING(top)) {
757 p[0].cur_start = top_pos;
758 p[0].cur_end = top_pos + top_len;
762 if (pos >= top_pos + top_len) p[0].path_len = CORD_POS_INVALID;
765 char CORD__pos_fetch(register CORD_pos p)
767 /* Leaf is a function node */
768 struct CORD_pe * pe = &((p)[0].path[(p)[0].path_len]);
769 CORD leaf = pe -> pe_cord;
770 register struct Function * f = &(((CordRep *)leaf) -> function);
772 if (!IS_FUNCTION(leaf)) ABORT("CORD_pos_fetch: bad leaf");
773 return ((*(f -> fn))(p[0].cur_pos - pe -> pe_start_pos, f -> client_data));
776 void CORD__next(register CORD_pos p)
778 register size_t cur_pos = p[0].cur_pos + 1;
779 register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
780 register CORD leaf = current_pe -> pe_cord;
782 /* Leaf is not a string or we're at end of leaf */
783 p[0].cur_pos = cur_pos;
784 if (!CORD_IS_STRING(leaf)) {
786 register struct Function * f = &(((CordRep *)leaf) -> function);
787 register size_t start_pos = current_pe -> pe_start_pos;
788 register size_t end_pos = start_pos + f -> len;
790 if (cur_pos < end_pos) {
791 /* Fill cache and return. */
793 register size_t limit = cur_pos + FUNCTION_BUF_SZ;
794 register CORD_fn fn = f -> fn;
795 register void * client_data = f -> client_data;
797 if (limit > end_pos) {
800 for (i = cur_pos; i < limit; i++) {
801 p[0].function_buf[i - cur_pos] =
802 (*fn)(i - start_pos, client_data);
804 p[0].cur_start = cur_pos;
805 p[0].cur_leaf = p[0].function_buf;
806 p[0].cur_end = limit;
811 /* Pop the stack until we find two concatenation nodes with the */
812 /* same start position: this implies we were in left part. */
814 while (p[0].path_len > 0
815 && current_pe[0].pe_start_pos != current_pe[-1].pe_start_pos) {
819 if (p[0].path_len == 0) {
820 p[0].path_len = CORD_POS_INVALID;
825 CORD__extend_path(p);
828 void CORD__prev(register CORD_pos p)
830 register struct CORD_pe * pe = &(p[0].path[p[0].path_len]);
832 if (p[0].cur_pos == 0) {
833 p[0].path_len = CORD_POS_INVALID;
837 if (p[0].cur_pos >= pe -> pe_start_pos) return;
839 /* Beginning of leaf */
841 /* Pop the stack until we find two concatenation nodes with the */
842 /* different start position: this implies we were in right part. */
844 register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
846 while (p[0].path_len > 0
847 && current_pe[0].pe_start_pos == current_pe[-1].pe_start_pos) {
853 CORD__extend_path(p);
856 #undef CORD_pos_fetch
859 #undef CORD_pos_to_index
860 #undef CORD_pos_to_cord
861 #undef CORD_pos_valid
863 char CORD_pos_fetch(register CORD_pos p)
865 if (p[0].cur_start <= p[0].cur_pos && p[0].cur_pos < p[0].cur_end) {
866 return(p[0].cur_leaf[p[0].cur_pos - p[0].cur_start]);
868 return(CORD__pos_fetch(p));
872 void CORD_next(CORD_pos p)
874 if (p[0].cur_pos < p[0].cur_end - 1) {
881 void CORD_prev(CORD_pos p)
883 if (p[0].cur_end != 0 && p[0].cur_pos > p[0].cur_start) {
890 size_t CORD_pos_to_index(CORD_pos p)
892 return(p[0].cur_pos);
895 CORD CORD_pos_to_cord(CORD_pos p)
897 return(p[0].path[0].pe_cord);
900 int CORD_pos_valid(CORD_pos p)
902 return(p[0].path_len != CORD_POS_INVALID);
905 void CORD_set_pos(CORD_pos p, CORD x, size_t i)
907 if (x == CORD_EMPTY) {
908 p[0].path_len = CORD_POS_INVALID;
911 p[0].path[0].pe_cord = x;
912 p[0].path[0].pe_start_pos = 0;
915 CORD__extend_path(p);