StringDict.cpp   [plain text]

/*   Copyright (c) AT&T Corp.  All rights reserved.
   
This software may only be used by you under license from 
AT&T Corp. ("AT&T").  A copy of AT&T's Source Code Agreement 
is available at AT&T's Internet website having the URL 

http://www.research.att.com/sw/tools/graphviz/license/

If you received this software without first entering into a license 
with AT&T, you have an infringing copy of this software and cannot 
use it without violating AT&T's intellectual property rights. */

// adaptation of agraph's refstr

#include <stdlib.h>

#include "common/StringDict.h"

StringDict g_stringDict;
const DString::size_type DString::npos = DString::size_type(-1);

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)
};

#ifdef DEBUG
static int refstrprint(refstr_t* r)
{
	fprintf(stderr,"%s\n",r->s); return 0;
}

agrefstrdump(void)
{
	dtwalk(dict,refstrprint);
}
#endif

StringDict::StringDict() {
	init();
}
void StringDict::init() {
	if(!dict)
		dict = dtopen(&Refstrdisc,Dttree);
}
const char *StringDict::enter(const char* s) {
	if(!dict)
		init();
	refstr_t		*key,*r;

	if (s == NULL) return s;

	key = (refstr_t*)(s - offsetof(refstr_t,s[0]));
	r = (refstr_t*) dtsearch(dict,key);
	if (r) r->refcnt++;
	else {
		int size = sizeof(refstr_t)+strlen(s);
		r = (refstr_t*) malloc(size);
		r->refcnt = 1;
		strcpy(r->s,s);
		dtinsert(dict,r);
	}
	return r->s;
}

void StringDict::release(const char* s) {
	refstr_t		*key,*r;

	if ((dict == NULL) || (s == NULL)) return;
	key = (refstr_t*)(s - offsetof(refstr_t,s[0]));
	r = (refstr_t*) dtsearch(dict,key);

	if (r) {
		r->refcnt--;
		if (r->refcnt <= 0) {
			dtdelete(dict,r);
			free(r);
		}
	}
	else throw DictStringLost(s);
}
void StringDict::ref(const char *s) {
	if(!s)
		return;
	refstr_t *key = (refstr_t*)(s - offsetof(refstr_t,s[0]));
	key->refcnt++;
}