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authorIvan Maidanski <ivmai@mail.ru>2011-07-26 12:48:42 +0200
committerIvan Maidanski <ivmai@mail.ru>2011-07-26 12:48:42 +0200
commit7fd4efa1d0dbab63e6d9bddd1d72fa4aafc8ad52 (patch)
treef784c1f66c09df5e17aeb85cf5862b459d455ebd /cord/cordbscs.c
gc4.1 tarball importgc4_1
Diffstat (limited to 'cord/cordbscs.c')
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diff --git a/cord/cordbscs.c b/cord/cordbscs.c
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+/*
+ * Copyright (c) 1993-1994 by Xerox Corporation. All rights reserved.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ * Author: Hans-J. Boehm (boehm@parc.xerox.com)
+ */
+/* Boehm, May 19, 1994 2:18 pm PDT */
+# include "../gc.h"
+# include "cord.h"
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+
+/* An implementation of the cord primitives. These are the only */
+/* Functions that understand the representation. We perform only */
+/* minimal checks on arguments to these functions. Out of bounds */
+/* arguments to the iteration functions may result in client functions */
+/* invoked on garbage data. In most cases, client functions should be */
+/* programmed defensively enough that this does not result in memory */
+/* smashes. */
+
+typedef void (* oom_fn)(void);
+
+oom_fn CORD_oom_fn = (oom_fn) 0;
+
+# define OUT_OF_MEMORY { if (CORD_oom_fn != (oom_fn) 0) (*CORD_oom_fn)(); \
+ ABORT("Out of memory\n"); }
+# define ABORT(msg) { fprintf(stderr, "%s\n", msg); abort(); }
+
+typedef unsigned long word;
+
+typedef union {
+ struct Concatenation {
+ char null;
+ char header;
+ char depth; /* concatenation nesting depth. */
+ unsigned char left_len;
+ /* Length of left child if it is sufficiently */
+ /* short; 0 otherwise. */
+# define MAX_LEFT_LEN 255
+ word len;
+ CORD left; /* length(left) > 0 */
+ CORD right; /* length(right) > 0 */
+ } concatenation;
+ struct Function {
+ char null;
+ char header;
+ char depth; /* always 0 */
+ char left_len; /* always 0 */
+ word len;
+ CORD_fn fn;
+ void * client_data;
+ } function;
+ struct Generic {
+ char null;
+ char header;
+ char depth;
+ char left_len;
+ word len;
+ } generic;
+ char string[1];
+} CordRep;
+
+# define CONCAT_HDR 1
+
+# define FN_HDR 4
+# define SUBSTR_HDR 6
+ /* Substring nodes are a special case of function nodes. */
+ /* The client_data field is known to point to a substr_args */
+ /* structure, and the function is either CORD_apply_access_fn */
+ /* or CORD_index_access_fn. */
+
+/* The following may be applied only to function and concatenation nodes: */
+#define IS_CONCATENATION(s) (((CordRep *)s)->generic.header == CONCAT_HDR)
+
+#define IS_FUNCTION(s) ((((CordRep *)s)->generic.header & FN_HDR) != 0)
+
+#define IS_SUBSTR(s) (((CordRep *)s)->generic.header == SUBSTR_HDR)
+
+#define LEN(s) (((CordRep *)s) -> generic.len)
+#define DEPTH(s) (((CordRep *)s) -> generic.depth)
+#define GEN_LEN(s) (IS_STRING(s) ? strlen(s) : LEN(s))
+
+#define LEFT_LEN(c) ((c) -> left_len != 0? \
+ (c) -> left_len \
+ : (IS_STRING((c) -> left) ? \
+ (c) -> len - GEN_LEN((c) -> right) \
+ : LEN((c) -> left)))
+
+#define SHORT_LIMIT (sizeof(CordRep) - 1)
+ /* Cords shorter than this are C strings */
+
+
+/* Dump the internal representation of x to stdout, with initial */
+/* indentation level n. */
+void CORD_dump_inner(CORD x, unsigned n)
+{
+ register size_t i;
+
+ for (i = 0; i < (size_t)n; i++) {
+ fputs(" ", stdout);
+ }
+ if (x == 0) {
+ fputs("NIL\n", stdout);
+ } else if (IS_STRING(x)) {
+ for (i = 0; i <= SHORT_LIMIT; i++) {
+ if (x[i] == '\0') break;
+ putchar(x[i]);
+ }
+ if (x[i] != '\0') fputs("...", stdout);
+ putchar('\n');
+ } else if (IS_CONCATENATION(x)) {
+ register struct Concatenation * conc =
+ &(((CordRep *)x) -> concatenation);
+ printf("Concatenation: %p (len: %d, depth: %d)\n",
+ x, (int)(conc -> len), (int)(conc -> depth));
+ CORD_dump_inner(conc -> left, n+1);
+ CORD_dump_inner(conc -> right, n+1);
+ } else /* function */{
+ register struct Function * func =
+ &(((CordRep *)x) -> function);
+ if (IS_SUBSTR(x)) printf("(Substring) ");
+ printf("Function: %p (len: %d): ", x, (int)(func -> len));
+ for (i = 0; i < 20 && i < func -> len; i++) {
+ putchar((*(func -> fn))(i, func -> client_data));
+ }
+ if (i < func -> len) fputs("...", stdout);
+ putchar('\n');
+ }
+}
+
+/* Dump the internal representation of x to stdout */
+void CORD_dump(CORD x)
+{
+ CORD_dump_inner(x, 0);
+ fflush(stdout);
+}
+
+CORD CORD_cat_char_star(CORD x, const char * y, size_t leny)
+{
+ register size_t result_len;
+ register size_t lenx;
+ register int depth;
+
+ if (x == CORD_EMPTY) return(y);
+ if (leny == 0) return(x);
+ if (IS_STRING(x)) {
+ lenx = strlen(x);
+ result_len = lenx + leny;
+ if (result_len <= SHORT_LIMIT) {
+ register char * result = GC_MALLOC_ATOMIC(result_len+1);
+
+ if (result == 0) OUT_OF_MEMORY;
+ memcpy(result, x, lenx);
+ memcpy(result + lenx, y, leny);
+ result[result_len] = '\0';
+ return((CORD) result);
+ } else {
+ depth = 1;
+ }
+ } else {
+ register CORD right;
+ register CORD left;
+ register char * new_right;
+ register size_t right_len;
+
+ lenx = LEN(x);
+
+ if (leny <= SHORT_LIMIT/2
+ && IS_CONCATENATION(x)
+ && IS_STRING(right = ((CordRep *)x) -> concatenation.right)) {
+ /* Merge y into right part of x. */
+ if (!IS_STRING(left = ((CordRep *)x) -> concatenation.left)) {
+ right_len = lenx - LEN(left);
+ } else if (((CordRep *)x) -> concatenation.left_len != 0) {
+ right_len = lenx - ((CordRep *)x) -> concatenation.left_len;
+ } else {
+ right_len = strlen(right);
+ }
+ result_len = right_len + leny; /* length of new_right */
+ if (result_len <= SHORT_LIMIT) {
+ new_right = GC_MALLOC_ATOMIC(result_len + 1);
+ memcpy(new_right, right, right_len);
+ memcpy(new_right + right_len, y, leny);
+ new_right[result_len] = '\0';
+ y = new_right;
+ leny = result_len;
+ x = left;
+ lenx -= right_len;
+ /* Now fall through to concatenate the two pieces: */
+ }
+ if (IS_STRING(x)) {
+ depth = 1;
+ } else {
+ depth = DEPTH(x) + 1;
+ }
+ } else {
+ depth = DEPTH(x) + 1;
+ }
+ result_len = lenx + leny;
+ }
+ {
+ /* The general case; lenx, result_len is known: */
+ register struct Concatenation * result;
+
+ result = GC_NEW(struct Concatenation);
+ if (result == 0) OUT_OF_MEMORY;
+ result->header = CONCAT_HDR;
+ result->depth = depth;
+ if (lenx <= MAX_LEFT_LEN) result->left_len = lenx;
+ result->len = result_len;
+ result->left = x;
+ result->right = y;
+ if (depth > MAX_DEPTH) {
+ return(CORD_balance((CORD)result));
+ } else {
+ return((CORD) result);
+ }
+ }
+}
+
+
+CORD CORD_cat(CORD x, CORD y)
+{
+ register size_t result_len;
+ register int depth;
+ register size_t lenx;
+
+ if (x == CORD_EMPTY) return(y);
+ if (y == CORD_EMPTY) return(x);
+ if (IS_STRING(y)) {
+ return(CORD_cat_char_star(x, y, strlen(y)));
+ } else if (IS_STRING(x)) {
+ lenx = strlen(x);
+ depth = DEPTH(y) + 1;
+ } else {
+ register int depthy = DEPTH(y);
+
+ lenx = LEN(x);
+ depth = DEPTH(x) + 1;
+ if (depthy >= depth) depth = depthy + 1;
+ }
+ result_len = lenx + LEN(y);
+ {
+ register struct Concatenation * result;
+
+ result = GC_NEW(struct Concatenation);
+ if (result == 0) OUT_OF_MEMORY;
+ result->header = CONCAT_HDR;
+ result->depth = depth;
+ if (lenx <= MAX_LEFT_LEN) result->left_len = lenx;
+ result->len = result_len;
+ result->left = x;
+ result->right = y;
+ return((CORD) result);
+ }
+}
+
+
+
+CORD CORD_from_fn(CORD_fn fn, void * client_data, size_t len)
+{
+ if (len <= 0) return(0);
+ if (len <= SHORT_LIMIT) {
+ register char * result;
+ register size_t i;
+ char buf[SHORT_LIMIT+1];
+ register char c;
+
+ for (i = 0; i < len; i++) {
+ c = (*fn)(i, client_data);
+ if (c == '\0') goto gen_case;
+ buf[i] = c;
+ }
+ buf[i] = '\0';
+ result = GC_MALLOC_ATOMIC(len+1);
+ if (result == 0) OUT_OF_MEMORY;
+ strcpy(result, buf);
+ result[len] = '\0';
+ return((CORD) result);
+ }
+ gen_case:
+ {
+ register struct Function * result;
+
+ result = GC_NEW(struct Function);
+ if (result == 0) OUT_OF_MEMORY;
+ result->header = FN_HDR;
+ /* depth is already 0 */
+ result->len = len;
+ result->fn = fn;
+ result->client_data = client_data;
+ return((CORD) result);
+ }
+}
+
+size_t CORD_len(CORD x)
+{
+ if (x == 0) {
+ return(0);
+ } else {
+ return(GEN_LEN(x));
+ }
+}
+
+struct substr_args {
+ CordRep * sa_cord;
+ size_t sa_index;
+};
+
+char CORD_index_access_fn(size_t i, void * client_data)
+{
+ register struct substr_args *descr = (struct substr_args *)client_data;
+
+ return(((char *)(descr->sa_cord))[i + descr->sa_index]);
+}
+
+char CORD_apply_access_fn(size_t i, void * client_data)
+{
+ register struct substr_args *descr = (struct substr_args *)client_data;
+ register struct Function * fn_cord = &(descr->sa_cord->function);
+
+ return((*(fn_cord->fn))(i + descr->sa_index, fn_cord->client_data));
+}
+
+/* A version of CORD_substr that simply returns a function node, thus */
+/* postponing its work. The fourth argument is a function that may */
+/* be used for efficient access to the ith character. */
+/* Assumes i >= 0 and i + n < length(x). */
+CORD CORD_substr_closure(CORD x, size_t i, size_t n, CORD_fn f)
+{
+ register struct substr_args * sa = GC_NEW(struct substr_args);
+ CORD result;
+
+ if (sa == 0) OUT_OF_MEMORY;
+ sa->sa_cord = (CordRep *)x;
+ sa->sa_index = i;
+ result = CORD_from_fn(f, (void *)sa, n);
+ ((CordRep *)result) -> function.header = SUBSTR_HDR;
+ return (result);
+}
+
+# define SUBSTR_LIMIT (10 * SHORT_LIMIT)
+ /* Substrings of function nodes and flat strings shorter than */
+ /* this are flat strings. Othewise we use a functional */
+ /* representation, which is significantly slower to access. */
+
+/* A version of CORD_substr that assumes i >= 0, n > 0, and i + n < length(x).*/
+CORD CORD_substr_checked(CORD x, size_t i, size_t n)
+{
+ if (IS_STRING(x)) {
+ if (n > SUBSTR_LIMIT) {
+ return(CORD_substr_closure(x, i, n, CORD_index_access_fn));
+ } else {
+ register char * result = GC_MALLOC_ATOMIC(n+1);
+ register char * p = result;
+
+ if (result == 0) OUT_OF_MEMORY;
+ strncpy(result, x+i, n);
+ result[n] = '\0';
+ return(result);
+ }
+ } else if (IS_CONCATENATION(x)) {
+ register struct Concatenation * conc
+ = &(((CordRep *)x) -> concatenation);
+ register size_t left_len;
+ register size_t right_len;
+
+ left_len = LEFT_LEN(conc);
+ right_len = conc -> len - left_len;
+ if (i >= left_len) {
+ if (n == right_len) return(conc -> right);
+ return(CORD_substr_checked(conc -> right, i - left_len, n));
+ } else if (i+n <= left_len) {
+ if (n == left_len) return(conc -> left);
+ return(CORD_substr_checked(conc -> left, i, n));
+ } else {
+ /* Need at least one character from each side. */
+ register CORD left_part;
+ register CORD right_part;
+ register size_t left_part_len = left_len - i;
+
+ if (i == 0) {
+ left_part = conc -> left;
+ } else {
+ left_part = CORD_substr_checked(conc -> left, i, left_part_len);
+ }
+ if (i + n == right_len + left_len) {
+ right_part = conc -> right;
+ } else {
+ right_part = CORD_substr_checked(conc -> right, 0,
+ n - left_part_len);
+ }
+ return(CORD_cat(left_part, right_part));
+ }
+ } else /* function */ {
+ if (n > SUBSTR_LIMIT) {
+ if (IS_SUBSTR(x)) {
+ /* Avoid nesting substring nodes. */
+ register struct Function * f = &(((CordRep *)x) -> function);
+ register struct substr_args *descr =
+ (struct substr_args *)(f -> client_data);
+
+ return(CORD_substr_closure((CORD)descr->sa_cord,
+ i + descr->sa_index,
+ n, f -> fn));
+ } else {
+ return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
+ }
+ } else {
+ char * result;
+ register struct Function * f = &(((CordRep *)x) -> function);
+ char buf[SUBSTR_LIMIT+1];
+ register char * p = buf;
+ register char c;
+ register int j;
+ register int lim = i + n;
+
+ for (j = i; j < lim; j++) {
+ c = (*(f -> fn))(j, f -> client_data);
+ if (c == '\0') {
+ return(CORD_substr_closure(x, i, n, CORD_apply_access_fn));
+ }
+ *p++ = c;
+ }
+ *p = '\0';
+ result = GC_MALLOC_ATOMIC(n+1);
+ if (result == 0) OUT_OF_MEMORY;
+ strcpy(result, buf);
+ return(result);
+ }
+ }
+}
+
+CORD CORD_substr(CORD x, size_t i, size_t n)
+{
+ register size_t len = CORD_len(x);
+
+ if (i >= len || n <= 0) return(0);
+ /* n < 0 is impossible in a correct C implementation, but */
+ /* quite possible under SunOS 4.X. */
+ if (i + n > len) n = len - i;
+ if (i < 0) ABORT("CORD_substr: second arg. negative");
+ /* Possible only if both client and C implementation are buggy. */
+ /* But empirically this happens frequently. */
+ return(CORD_substr_checked(x, i, n));
+}
+
+/* See cord.h for definition. We assume i is in range. */
+int CORD_iter5(CORD x, size_t i, CORD_iter_fn f1,
+ CORD_batched_iter_fn f2, void * client_data)
+{
+ if (x == 0) return(0);
+ if (IS_STRING(x)) {
+ register const char *p = x+i;
+
+ if (*p == '\0') ABORT("2nd arg to CORD_iter5 too big");
+ if (f2 != CORD_NO_FN) {
+ return((*f2)(p, client_data));
+ } else {
+ while (*p) {
+ if ((*f1)(*p, client_data)) return(1);
+ p++;
+ }
+ return(0);
+ }
+ } else if (IS_CONCATENATION(x)) {
+ register struct Concatenation * conc
+ = &(((CordRep *)x) -> concatenation);
+
+
+ if (i > 0) {
+ register size_t left_len = LEFT_LEN(conc);
+
+ if (i >= left_len) {
+ return(CORD_iter5(conc -> right, i - left_len, f1, f2,
+ client_data));
+ }
+ }
+ if (CORD_iter5(conc -> left, i, f1, f2, client_data)) {
+ return(1);
+ }
+ return(CORD_iter5(conc -> right, 0, f1, f2, client_data));
+ } else /* function */ {
+ register struct Function * f = &(((CordRep *)x) -> function);
+ register size_t j;
+ register size_t lim = f -> len;
+
+ for (j = i; j < lim; j++) {
+ if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
+ return(1);
+ }
+ }
+ return(0);
+ }
+}
+
+#undef CORD_iter
+int CORD_iter(CORD x, CORD_iter_fn f1, void * client_data)
+{
+ return(CORD_iter5(x, 0, f1, CORD_NO_FN, client_data));
+}
+
+int CORD_riter4(CORD x, size_t i, CORD_iter_fn f1, void * client_data)
+{
+ if (x == 0) return(0);
+ if (IS_STRING(x)) {
+ register const char *p = x + i;
+ register char c;
+
+ while (p >= x) {
+ c = *p;
+ if (c == '\0') ABORT("2nd arg to CORD_riter4 too big");
+ if ((*f1)(c, client_data)) return(1);
+ p--;
+ }
+ return(0);
+ } else if (IS_CONCATENATION(x)) {
+ register struct Concatenation * conc
+ = &(((CordRep *)x) -> concatenation);
+ register CORD left_part = conc -> left;
+ register size_t left_len;
+
+ left_len = LEFT_LEN(conc);
+ if (i >= left_len) {
+ if (CORD_riter4(conc -> right, i - left_len, f1, client_data)) {
+ return(1);
+ }
+ return(CORD_riter4(left_part, left_len - 1, f1, client_data));
+ } else {
+ return(CORD_riter4(left_part, i, f1, client_data));
+ }
+ } else /* function */ {
+ register struct Function * f = &(((CordRep *)x) -> function);
+ register size_t j;
+
+ for (j = i; j >= 0; j--) {
+ if ((*f1)((*(f -> fn))(j, f -> client_data), client_data)) {
+ return(1);
+ }
+ }
+ return(0);
+ }
+}
+
+int CORD_riter(CORD x, CORD_iter_fn f1, void * client_data)
+{
+ return(CORD_riter4(x, CORD_len(x) - 1, f1, client_data));
+}
+
+/*
+ * The following functions are concerned with balancing cords.
+ * Strategy:
+ * Scan the cord from left to right, keeping the cord scanned so far
+ * as a forest of balanced trees of exponentialy decreasing length.
+ * When a new subtree needs to be added to the forest, we concatenate all
+ * shorter ones to the new tree in the appropriate order, and then insert
+ * the result into the forest.
+ * Crucial invariants:
+ * 1. The concatenation of the forest (in decreasing order) with the
+ * unscanned part of the rope is equal to the rope being balanced.
+ * 2. All trees in the forest are balanced.
+ * 3. forest[i] has depth at most i.
+ */
+
+typedef struct {
+ CORD c;
+ size_t len; /* Actual ength of c */
+} ForestElement;
+
+static size_t min_len [ MAX_DEPTH ];
+
+static int min_len_init = 0;
+
+int CORD_max_len;
+
+typedef ForestElement Forest [ MAX_DEPTH ];
+ /* forest[i].min_length = fib(i+1) */
+ /* The string is the concatenation */
+ /* of the forest in order of DECREASING */
+ /* indices. */
+
+void CORD_init_min_len()
+{
+ register int i;
+ register size_t last, previous, current;
+
+ min_len[0] = previous = 1;
+ min_len[1] = last = 2;
+ for (i = 2; i < MAX_DEPTH; i++) {
+ current = last + previous;
+ if (current < last) /* overflow */ current = last;
+ min_len[i] = current;
+ previous = last;
+ last = current;
+ }
+ CORD_max_len = last - 1;
+ min_len_init = 1;
+}
+
+
+void CORD_init_forest(ForestElement * forest, size_t max_len)
+{
+ register int i;
+
+ for (i = 0; i < MAX_DEPTH; i++) {
+ forest[i].c = 0;
+ if (min_len[i] > max_len) return;
+ }
+ ABORT("Cord too long");
+}
+
+/* Add a leaf to the appropriate level in the forest, cleaning */
+/* out lower levels as necessary. */
+/* Also works if x is a balanced tree of concatenations; however */
+/* in this case an extra concatenation node may be inserted above x; */
+/* This node should not be counted in the statement of the invariants. */
+void CORD_add_forest(ForestElement * forest, CORD x, size_t len)
+{
+ register int i = 0;
+ register CORD sum = CORD_EMPTY;
+ register size_t sum_len = 0;
+
+ while (len > min_len[i + 1]) {
+ if (forest[i].c != 0) {
+ sum = CORD_cat(forest[i].c, sum);
+ sum_len += forest[i].len;
+ forest[i].c = 0;
+ }
+ i++;
+ }
+ /* Sum has depth at most 1 greter than what would be required */
+ /* for balance. */
+ sum = CORD_cat(sum, x);
+ sum_len += len;
+ /* If x was a leaf, then sum is now balanced. To see this */
+ /* consider the two cases in whichforest[i-1] either is or is */
+ /* not empty. */
+ while (sum_len >= min_len[i]) {
+ if (forest[i].c != 0) {
+ sum = CORD_cat(forest[i].c, sum);
+ sum_len += forest[i].len;
+ /* This is again balanced, since sum was balanced, and has */
+ /* allowable depth that differs from i by at most 1. */
+ forest[i].c = 0;
+ }
+ i++;
+ }
+ i--;
+ forest[i].c = sum;
+ forest[i].len = sum_len;
+}
+
+CORD CORD_concat_forest(ForestElement * forest, size_t expected_len)
+{
+ register int i = 0;
+ CORD sum = 0;
+ size_t sum_len = 0;
+
+ while (sum_len != expected_len) {
+ if (forest[i].c != 0) {
+ sum = CORD_cat(forest[i].c, sum);
+ sum_len += forest[i].len;
+ }
+ i++;
+ }
+ return(sum);
+}
+
+/* Insert the frontier of x into forest. Balanced subtrees are */
+/* treated as leaves. This potentially adds one to the depth */
+/* of the final tree. */
+void CORD_balance_insert(CORD x, size_t len, ForestElement * forest)
+{
+ register int depth;
+
+ if (IS_STRING(x)) {
+ CORD_add_forest(forest, x, len);
+ } else if (IS_CONCATENATION(x)
+ && ((depth = DEPTH(x)) >= MAX_DEPTH
+ || len < min_len[depth])) {
+ register struct Concatenation * conc
+ = &(((CordRep *)x) -> concatenation);
+ size_t left_len = LEFT_LEN(conc);
+
+ CORD_balance_insert(conc -> left, left_len, forest);
+ CORD_balance_insert(conc -> right, len - left_len, forest);
+ } else /* function or balanced */ {
+ CORD_add_forest(forest, x, len);
+ }
+}
+
+
+CORD CORD_balance(CORD x)
+{
+ Forest forest;
+ register size_t len;
+
+ if (x == 0) return(0);
+ if (IS_STRING(x)) return(x);
+ if (!min_len_init) CORD_init_min_len();
+ len = LEN(x);
+ CORD_init_forest(forest, len);
+ CORD_balance_insert(x, len, forest);
+ return(CORD_concat_forest(forest, len));
+}
+
+
+/* Position primitives */
+
+/* Private routines to deal with the hard cases only: */
+
+/* P contains a prefix of the path to cur_pos. Extend it to a full */
+/* path and set up leaf info. */
+/* Return 0 if past the end of cord, 1 o.w. */
+void CORD__extend_path(register CORD_pos p)
+{
+ register struct CORD_pe * current_pe = &(p[0].path[p[0].path_len]);
+ register CORD top = current_pe -> pe_cord;
+ register size_t pos = p[0].cur_pos;
+ register size_t top_pos = current_pe -> pe_start_pos;
+ register size_t top_len = GEN_LEN(top);
+
+ /* Fill in the rest of the path. */
+ while(!IS_STRING(top) && IS_CONCATENATION(top)) {
+ register struct Concatenation * conc =
+ &(((CordRep *)top) -> concatenation);
+ register size_t left_len;
+
+ left_len = LEFT_LEN(conc);
+ current_pe++;
+ if (pos >= top_pos + left_len) {
+ current_pe -> pe_cord = top = conc -> right;
+ current_pe -> pe_start_pos = top_pos = top_pos + left_len;
+ top_len -= left_len;
+ } else {
+ current_pe -> pe_cord = top = conc -> left;
+ current_pe -> pe_start_pos = top_pos;
+ top_len = left_len;
+ }
+ p[0].path_len++;
+ }
+ /* Fill in leaf description for fast access. */
+ if (IS_STRING(top)) {
+ p[0].cur_leaf = top;
+ p[0].cur_start = top_pos;
+ p[0].cur_end = top_pos + top_len;
+ } else {
+ p[0].cur_end = 0;
+ }
+ if (pos >= top_pos + top_len) p[0].path_len = CORD_POS_INVALID;
+}
+
+char CORD__pos_fetch(register CORD_pos p)
+{
+ /* Leaf is a function node */
+ struct CORD_pe * pe = &((p)[0].path[(p)[0].path_len]);
+ CORD leaf = pe -> pe_cord;
+ register struct Function * f = &(((CordRep *)leaf) -> function);
+
+ if (!IS_FUNCTION(leaf)) ABORT("CORD_pos_fetch: bad leaf");
+ return ((*(f -> fn))(p[0].cur_pos - pe -> pe_start_pos, f -> client_data));
+}
+
+void CORD__next(register CORD_pos p)
+{
+ register size_t cur_pos = p[0].cur_pos + 1;
+ register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
+ register CORD leaf = current_pe -> pe_cord;
+
+ /* Leaf is not a string or we're at end of leaf */
+ p[0].cur_pos = cur_pos;
+ if (!IS_STRING(leaf)) {
+ /* Function leaf */
+ register struct Function * f = &(((CordRep *)leaf) -> function);
+ register size_t start_pos = current_pe -> pe_start_pos;
+ register size_t end_pos = start_pos + f -> len;
+
+ if (cur_pos < end_pos) {
+ /* Fill cache and return. */
+ register size_t i;
+ register size_t limit = cur_pos + FUNCTION_BUF_SZ;
+ register CORD_fn fn = f -> fn;
+ register void * client_data = f -> client_data;
+
+ if (limit > end_pos) {
+ limit = end_pos;
+ }
+ for (i = cur_pos; i < limit; i++) {
+ p[0].function_buf[i - cur_pos] =
+ (*fn)(i - start_pos, client_data);
+ }
+ p[0].cur_start = cur_pos;
+ p[0].cur_leaf = p[0].function_buf;
+ p[0].cur_end = limit;
+ return;
+ }
+ }
+ /* End of leaf */
+ /* Pop the stack until we find two concatenation nodes with the */
+ /* same start position: this implies we were in left part. */
+ {
+ while (p[0].path_len > 0
+ && current_pe[0].pe_start_pos != current_pe[-1].pe_start_pos) {
+ p[0].path_len--;
+ current_pe--;
+ }
+ if (p[0].path_len == 0) {
+ p[0].path_len = CORD_POS_INVALID;
+ return;
+ }
+ }
+ p[0].path_len--;
+ CORD__extend_path(p);
+}
+
+void CORD__prev(register CORD_pos p)
+{
+ register struct CORD_pe * pe = &(p[0].path[p[0].path_len]);
+
+ if (p[0].cur_pos == 0) {
+ p[0].path_len = CORD_POS_INVALID;
+ return;
+ }
+ p[0].cur_pos--;
+ if (p[0].cur_pos >= pe -> pe_start_pos) return;
+
+ /* Beginning of leaf */
+
+ /* Pop the stack until we find two concatenation nodes with the */
+ /* different start position: this implies we were in right part. */
+ {
+ register struct CORD_pe * current_pe = &((p)[0].path[(p)[0].path_len]);
+
+ while (p[0].path_len > 0
+ && current_pe[0].pe_start_pos == current_pe[-1].pe_start_pos) {
+ p[0].path_len--;
+ current_pe--;
+ }
+ }
+ p[0].path_len--;
+ CORD__extend_path(p);
+}
+
+#undef CORD_pos_fetch
+#undef CORD_next
+#undef CORD_prev
+#undef CORD_pos_to_index
+#undef CORD_pos_to_cord
+#undef CORD_pos_valid
+
+char CORD_pos_fetch(register CORD_pos p)
+{
+ if (p[0].cur_start <= p[0].cur_pos && p[0].cur_pos < p[0].cur_end) {
+ return(p[0].cur_leaf[p[0].cur_pos - p[0].cur_start]);
+ } else {
+ return(CORD__pos_fetch(p));
+ }
+}
+
+void CORD_next(CORD_pos p)
+{
+ if (p[0].cur_pos < p[0].cur_end - 1) {
+ p[0].cur_pos++;
+ } else {
+ CORD__next(p);
+ }
+}
+
+void CORD_prev(CORD_pos p)
+{
+ if (p[0].cur_end != 0 && p[0].cur_pos > p[0].cur_start) {
+ p[0].cur_pos--;
+ } else {
+ CORD__prev(p);
+ }
+}
+
+size_t CORD_pos_to_index(CORD_pos p)
+{
+ return(p[0].cur_pos);
+}
+
+CORD CORD_pos_to_cord(CORD_pos p)
+{
+ return(p[0].path[0].pe_cord);
+}
+
+int CORD_pos_valid(CORD_pos p)
+{
+ return(p[0].path_len != CORD_POS_INVALID);
+}
+
+void CORD_set_pos(CORD_pos p, CORD x, size_t i)
+{
+ if (x == CORD_EMPTY) {
+ p[0].path_len = CORD_POS_INVALID;
+ return;
+ }
+ p[0].path[0].pe_cord = x;
+ p[0].path[0].pe_start_pos = 0;
+ p[0].path_len = 0;
+ p[0].cur_pos = i;
+ CORD__extend_path(p);
+}