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/* $Id: refstr.c,v 1.3 2009/06/03 01:10:53 ellson Exp $ $Revision: 1.3 $ */
/* vim:set shiftwidth=4 ts=8: */
/**********************************************************
* This software is part of the graphviz package *
* http://www.graphviz.org/ *
* *
* Copyright (c) 1994-2004 AT&T Corp. *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Corp. *
* *
* Information and Software Systems Research *
* AT&T Research, Florham Park NJ *
**********************************************************/
#include "libgraph.h"
#include <assert.h>
static unsigned int HTML_BIT;
static unsigned int CNT_BITS;
#ifdef DMALLOC
#include "dmalloc.h"
#endif
typedef struct refstr_t {
Dtlink_t link;
unsigned int refcnt;
char s[1];
} refstr_t;
static Dtdisc_t Refstrdisc = {
offsetof(refstr_t, s[0]),
0,
0,
((Dtmake_f) 0),
((Dtfree_f) 0),
((Dtcompar_f) 0), /* use strcmp */
((Dthash_f) 0),
((Dtmemory_f) 0),
((Dtevent_f) 0)
};
static Dict_t *StringDict;
#ifdef DEBUG
static int refstrprint(Dt_t * d, Void_t * obj, Void_t * env)
{
refstr_t *r = (refstr_t *) obj;
fprintf(stderr, "%s\n", r->s);
return 0;
}
void agrefstrdump(void)
{
dtwalk(StringDict, refstrprint, 0);
}
#endif
/* initialize_strings:
* Create dictionary and masks for HTML strings.
* HTML_BIT must be the most significant bit. We assume 8-bit bytes.
*/
static void initialize_strings(void)
{
StringDict = dtopen(&Refstrdisc, Dttree);
HTML_BIT = ((unsigned int) 1) << (sizeof(unsigned int) * 8 - 1);
CNT_BITS = ~HTML_BIT;
}
char *agstrdup(char *s)
{
refstr_t *key, *r;
if (StringDict == NULL)
initialize_strings();
if (s == NULL)
return s;
key = (refstr_t *) (s - offsetof(refstr_t, s[0]));
r = (refstr_t *) dtsearch(StringDict, key);
if (r)
r->refcnt++;
else {
r = (refstr_t *) malloc(sizeof(refstr_t) + strlen(s));
r->refcnt = 1;
strcpy(r->s, s);
dtinsert(StringDict, r);
}
return r->s;
}
/* agstrdup_html:
* For various purposes, including deparsing, we have to recognize
* strings coming from <...> rather than "...". To do this, we set
* the top bit of the refcnt field. Since the use of html strings
* is localized, we allow the application to make the distinction.
*/
char *agstrdup_html(char *s)
{
refstr_t *key, *r;
if (StringDict == NULL)
initialize_strings();
if (s == NULL)
return s;
key = (refstr_t *) (s - offsetof(refstr_t, s[0]));
r = (refstr_t *) dtsearch(StringDict, key);
if (r)
r->refcnt++;
else {
r = (refstr_t *) malloc(sizeof(refstr_t) + strlen(s));
r->refcnt = 1 | HTML_BIT;
strcpy(r->s, s);
dtinsert(StringDict, r);
}
return r->s;
}
void agstrfree(char *s)
{
refstr_t *key, *r;
if ((StringDict == NULL) || (s == NULL))
return;
key = (refstr_t *) (s - offsetof(refstr_t, s[0]));
r = (refstr_t *) dtsearch(StringDict, key);
if (r) {
r->refcnt--;
if ((r->refcnt && CNT_BITS) == 0) {
dtdelete(StringDict, r);
free(r);
}
} else
agerr(AGERR, "agstrfree lost %s\n", s);
}
/* aghtmlstr:
* Return true if s is an HTML string.
* We assume s points to the datafield s[0] of a refstr.
*/
int aghtmlstr(char *s)
{
refstr_t *key;
if ((StringDict == NULL) || (s == NULL))
return 0;
key = (refstr_t *) (s - offsetof(refstr_t, s[0]));
return (key->refcnt & HTML_BIT);
}
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