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/*
* Generate unique IDs.
*
* TO DO: Also generate "readable" IDs if the text uses non-ASCII
* characters.
*
* Copyright © 2000 World Wide Web Consortium
* See http://www.w3.org/Consortium/Legal/copyright-software
*
* Author: Bert Bos <bert@w3.org>
* Created: 4 August 2000
**/
#include "config.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_ERRNO_H
# include <errno.h>
#endif
#include <ctype.h>
#ifdef HAVE_SEARCH_H
# include <search.h>
#else
# include "search-freebsd.h"
#endif
#if STDC_HEADERS
# include <string.h>
#else
# ifndef HAVE_STRCHR
# define strchr index
# define strrchr rindex
# endif
# ifndef HAVE_STRSTR
# include "strstr.e"
# endif
#endif
#include <export.h>
#include "heap.e"
#include "types.e"
#include "tree.e"
#include "errexit.e"
#define MAXIDLEN 45 /* Max len of a generated ID */
typedef int(*compar_fn_t)(const void *, const void *);
static void *idtree = NULL; /* Sorted tree of IDs */
/* storeID -- remember the existence of an ID (allocates a copy of the ID) */
EXPORT void storeID(conststring id)
{
/* Case-insensitive: necessary for HTML, only a little wasteful for XML */
(void) tsearch(newstring(id), &idtree, (compar_fn_t)strcasecmp);
}
/* gen_id_r -- find some text suitable for an ID recursively */
static void gen_id_r(Tree t, string s, int *len, int maxlen)
{
int i;
Tree h;
assert(s); /* s at least maxlen long */
/* Loop over children looking for useful text */
for (h = t->children; h && *len < maxlen - 1; h = h->sister) {
switch (h->tp) {
case Text:
for (i = 0; *len < maxlen - 1 && h->text[i]; i++)
if (isalpha(h->text[i])) s[(*len)++] = tolower(h->text[i]);
else if (h->text[i] == '@') {s[(*len)++] = 'a'; s[(*len)++] = 't';}
else if (*len == 0) ; /* Wait for a letter first */
else if (h->text[i]=='-') s[(*len)++] = h->text[i];
else if (h->text[i]=='.') s[(*len)++] = h->text[i];
else if (h->text[i]=='_') s[(*len)++] = h->text[i];
else if (isdigit(h->text[i])) s[(*len)++] = h->text[i];
else if (isspace(h->text[i]) && s[*len-1] != '-') s[(*len)++]='-';
break;
case Element: /* Recursive */
gen_id_r(h, s, len, maxlen);
break;
default:
break;
}
}
#if 0
/* Look for a nice break, i.e., just before a '-' */
while (*len > 0 && s[(*len)-1] != '-') (*len)--;
if (*len > 0) (*len)--;
#endif
s[*len] = '\0';
}
/* gen_id -- try some heuristics to generate an ID for element t */
EXPORT string gen_id(Tree t)
{
string s;
int len = 0;
if (! (s = malloc(MAXIDLEN + 1))) errexit("Out of memory\n");
assert(MAXIDLEN > 4);
gen_id_r(t, s, &len, MAXIDLEN - 4);
if (len == 0) {
s[len++] = 'x'; /* At least one character */
s[len] = '\0';
}
if (tfind(s, &idtree, (compar_fn_t)strcasecmp)) {
/* No suitable text found or text is already used elsewhere */
int seqno = 0;
do { /* Try adding digits */
sprintf(s + len, "%d", seqno);
seqno++;
} while (seqno != 10000 && tfind(s, &idtree, (compar_fn_t)strcasecmp));
if (seqno == 10000) { /* 10000 tried, giving up... */
free(s);
return NULL;
}
}
(void) tsearch(s, &idtree, (compar_fn_t)strcasecmp); /* Store it */
return s;
}
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