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
if (depth >= MAX_DEPTH) {
264
return(CORD_balance((CORD)result));
266
return((CORD) result);
273
CORD CORD_from_fn(CORD_fn fn, void * client_data, size_t len)
275
if (len <= 0) return(0);
276
if (len <= SHORT_LIMIT) {
277
register char * result;
279
char buf[SHORT_LIMIT+1];
282
for (i = 0; i < len; i++) {
283
c = (*fn)(i, client_data);
284
if (c == '\0') goto gen_case;
288
result = GC_MALLOC_ATOMIC(len+1);
289
if (result == 0) OUT_OF_MEMORY;
292
return((CORD) result);
296
register struct Function * result;
298
result = GC_NEW(struct Function);
299
if (result == 0) OUT_OF_MEMORY;
300
result->header = FN_HDR;
301
/* depth is already 0 */
304
result->client_data = client_data;
305
return((CORD) result);
309
size_t CORD_len(CORD x)
323
char CORD_index_access_fn(size_t i, void * client_data)
325
register struct substr_args *descr = (struct substr_args *)client_data;
327
return(((char *)(descr->sa_cord))[i + descr->sa_index]);
330
char CORD_apply_access_fn(size_t i, void * client_data)
332
register struct substr_args *descr = (struct substr_args *)client_data;
333
register struct Function * fn_cord = &(descr->sa_cord->function);
335
return((*(fn_cord->fn))(i + descr->sa_index, fn_cord->client_data));
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). */
342
CORD CORD_substr_closure(CORD x, size_t i, size_t n, CORD_fn f)
344
register struct substr_args * sa = GC_NEW(struct substr_args);
347
if (sa == 0) OUT_OF_MEMORY;
348
sa->sa_cord = (CordRep *)x;
350
result = CORD_from_fn(f, (void *)sa, n);
351
((CordRep *)result) -> function.header = SUBSTR_HDR;
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. */
360
/* A version of CORD_substr that assumes i >= 0, n > 0, and i + n < length(x).*/
361
CORD CORD_substr_checked(CORD x, size_t i, size_t n)
363
if (CORD_IS_STRING(x)) {
364
if (n > SUBSTR_LIMIT) {
365
return(CORD_substr_closure(x, i, n, CORD_index_access_fn));
367
register char * result = GC_MALLOC_ATOMIC(n+1);
369
if (result == 0) OUT_OF_MEMORY;
370
strncpy(result, x+i, n);
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;
380
left_len = LEFT_LEN(conc);
381
right_len = conc -> len - 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));
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;
395
left_part = conc -> left;
397
left_part = CORD_substr_checked(conc -> left, i, left_part_len);
399
if (i + n == right_len + left_len) {
400
right_part = conc -> right;
402
right_part = CORD_substr_checked(conc -> right, 0,
405
return(CORD_cat(left_part, right_part));
407
} else /* function */ {
408
if (n > SUBSTR_LIMIT) {
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);
415
return(CORD_substr_closure((CORD)descr->sa_cord,
419
return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
423
register struct Function * f = &(((CordRep *)x) -> function);
424
char buf[SUBSTR_LIMIT+1];
425
register char * p = buf;
428
register int lim = i + n;
430
for (j = i; j < lim; j++) {
431
c = (*(f -> fn))(j, f -> client_data);
433
return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
438
result = GC_MALLOC_ATOMIC(n+1);
439
if (result == 0) OUT_OF_MEMORY;
446
CORD CORD_substr(CORD x, size_t i, size_t n)
448
register size_t len = CORD_len(x);
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;
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. */
459
return(CORD_substr_checked(x, i, n));
462
/* See cord.h for definition. We assume i is in range. */
463
int CORD_iter5(CORD x, size_t i, CORD_iter_fn f1,
464
CORD_batched_iter_fn f2, void * client_data)
466
if (x == 0) return(0);
467
if (CORD_IS_STRING(x)) {
468
register const char *p = x+i;
470
if (*p == '\0') ABORT("2nd arg to CORD_iter5 too big");
471
if (f2 != CORD_NO_FN) {
472
return((*f2)(p, client_data));
475
if ((*f1)(*p, client_data)) return(1);
480
} else if (IS_CONCATENATION(x)) {
481
register struct Concatenation * conc
482
= &(((CordRep *)x) -> concatenation);
486
register size_t left_len = LEFT_LEN(conc);
489
return(CORD_iter5(conc -> right, i - left_len, f1, f2,
493
if (CORD_iter5(conc -> left, i, f1, f2, client_data)) {
496
return(CORD_iter5(conc -> right, 0, f1, f2, client_data));
497
} else /* function */ {
498
register struct Function * f = &(((CordRep *)x) -> function);
500
register size_t lim = f -> len;
502
for (j = i; j < lim; j++) {
503
if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
512
int CORD_iter(CORD x, CORD_iter_fn f1, void * client_data)
514
return(CORD_iter5(x, 0, f1, CORD_NO_FN, client_data));
517
int CORD_riter4(CORD x, size_t i, CORD_iter_fn f1, void * client_data)
519
if (x == 0) return(0);
520
if (CORD_IS_STRING(x)) {
521
register const char *p = x + i;
526
if (c == '\0') ABORT("2nd arg to CORD_riter4 too big");
527
if ((*f1)(c, client_data)) return(1);
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;
538
left_len = LEFT_LEN(conc);
540
if (CORD_riter4(conc -> right, i - left_len, f1, client_data)) {
543
return(CORD_riter4(left_part, left_len - 1, f1, client_data));
545
return(CORD_riter4(left_part, i, f1, client_data));
547
} else /* function */ {
548
register struct Function * f = &(((CordRep *)x) -> function);
552
if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
555
if (j == 0) return(0);
560
int CORD_riter(CORD x, CORD_iter_fn f1, void * client_data)
562
return(CORD_riter4(x, CORD_len(x) - 1, f1, client_data));
566
* The following functions are concerned with balancing cords.
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.
582
size_t len; /* Actual length of c */
585
static size_t min_len [ MAX_DEPTH ];
587
static int min_len_init = 0;
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 */
597
void CORD_init_min_len()
600
register size_t last, previous, current;
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;
611
CORD_max_len = last - 1;
616
void CORD_init_forest(ForestElement * forest, size_t max_len)
620
for (i = 0; i < MAX_DEPTH; i++) {
622
if (min_len[i] > max_len) return;
624
ABORT("Cord too long");
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. */
632
void CORD_add_forest(ForestElement * forest, CORD x, size_t len)
635
register CORD sum = CORD_EMPTY;
636
register size_t sum_len = 0;
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;
646
/* Sum has depth at most 1 greter than what would be required */
648
sum = CORD_cat(sum, x);
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 */
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. */
665
forest[i].len = sum_len;
668
CORD CORD_concat_forest(ForestElement * forest, size_t expected_len)
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;
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. */
687
void CORD_balance_insert(CORD x, size_t len, ForestElement * forest)
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);
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);
708
CORD CORD_balance(CORD x)
713
if (x == 0) return(0);
714
if (CORD_IS_STRING(x)) return(x);
715
if (!min_len_init) CORD_init_min_len();
717
CORD_init_forest(forest, len);
718
CORD_balance_insert(x, len, forest);
719
return(CORD_concat_forest(forest, len));
723
/* Position primitives */
725
/* Private routines to deal with the hard cases only: */
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. */
730
void CORD__extend_path(register CORD_pos p)
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);
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;
744
left_len = LEFT_LEN(conc);
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;
751
current_pe -> pe_cord = top = conc -> left;
752
current_pe -> pe_start_pos = top_pos;
757
/* Fill in leaf description for fast access. */
758
if (CORD_IS_STRING(top)) {
760
p[0].cur_start = top_pos;
761
p[0].cur_end = top_pos + top_len;
765
if (pos >= top_pos + top_len) p[0].path_len = CORD_POS_INVALID;
768
char CORD__pos_fetch(register CORD_pos p)
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);
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));
779
void CORD__next(register CORD_pos p)
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;
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)) {
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;
793
if (cur_pos < end_pos) {
794
/* Fill cache and return. */
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;
800
if (limit > end_pos) {
803
for (i = cur_pos; i < limit; i++) {
804
p[0].function_buf[i - cur_pos] =
805
(*fn)(i - start_pos, client_data);
807
p[0].cur_start = cur_pos;
808
p[0].cur_leaf = p[0].function_buf;
809
p[0].cur_end = limit;
814
/* Pop the stack until we find two concatenation nodes with the */
815
/* same start position: this implies we were in left part. */
817
while (p[0].path_len > 0
818
&& current_pe[0].pe_start_pos != current_pe[-1].pe_start_pos) {
822
if (p[0].path_len == 0) {
823
p[0].path_len = CORD_POS_INVALID;
828
CORD__extend_path(p);
831
void CORD__prev(register CORD_pos p)
833
register struct CORD_pe * pe = &(p[0].path[p[0].path_len]);
835
if (p[0].cur_pos == 0) {
836
p[0].path_len = CORD_POS_INVALID;
840
if (p[0].cur_pos >= pe -> pe_start_pos) return;
842
/* Beginning of leaf */
844
/* Pop the stack until we find two concatenation nodes with the */
845
/* different start position: this implies we were in right part. */
847
register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
849
while (p[0].path_len > 0
850
&& current_pe[0].pe_start_pos == current_pe[-1].pe_start_pos) {
856
CORD__extend_path(p);
859
#undef CORD_pos_fetch
862
#undef CORD_pos_to_index
863
#undef CORD_pos_to_cord
864
#undef CORD_pos_valid
866
char CORD_pos_fetch(register CORD_pos p)
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]);
871
return(CORD__pos_fetch(p));
875
void CORD_next(CORD_pos p)
877
if (p[0].cur_pos < p[0].cur_end - 1) {
884
void CORD_prev(CORD_pos p)
886
if (p[0].cur_end != 0 && p[0].cur_pos > p[0].cur_start) {
893
size_t CORD_pos_to_index(CORD_pos p)
895
return(p[0].cur_pos);
898
CORD CORD_pos_to_cord(CORD_pos p)
900
return(p[0].path[0].pe_cord);
903
int CORD_pos_valid(CORD_pos p)
905
return(p[0].path_len != CORD_POS_INVALID);
908
void CORD_set_pos(CORD_pos p, CORD x, size_t i)
910
if (x == CORD_EMPTY) {
911
p[0].path_len = CORD_POS_INVALID;
914
p[0].path[0].pe_cord = x;
915
p[0].path[0].pe_start_pos = 0;
918
CORD__extend_path(p);